[From the U.S. Government Printing Office, www.gpo.gov]
I 1oll1 TEZSESEHI~J aSZLZSifllDA I\s' Coastal Zone Mivlageirlent C~ rleEi'rlnoran SE P 28 1977 Prepared for: Virgin Islands Planning Office Office of the Governor The Honorable Cyril King, Governor St. Thomas, U.S. Virgin Islands Prepared by: Island Resources Foundation Lagoon Marina, Red Hook Post Office Box 4187 St. Thomas, U.S. Virgin Isl CCASTAL ZO NE EA:FOR ATION CENTER ands Property of CSC Library The preparation of this report was financed in part through a Coastal Zone Management Program Develop- ment Grant as provided by Section 305 of the Coastal Zone Management Act of 1972, administered by the Of- fice of Coastal Zone Management, National Oceanic and Atmospheric Administration. U. S. DEPARTMENT OF COMMERCE NOAA COASTAL SERVICES CENTER 2234 SOUTH HOBSON AVENUE CHARLESTON SC 29405-2413 I-en "1 " Staff Dr. Edward L. Towle Mr. David I. Grigg 4 Mr. William E. Rainey I S Consuitants Dr. Maynard Nichols (Oceanographer) Mr. John McEachern (Resource Planner) Mr. James A. Dobbin (Landscape Planner) (Project Director) (Senior Biologist) (Ecologist) REVISED JUNE 1976 t 1_, A_ kncvAedgemerfls I Robart S. Mathes Virgin islands Department of Conservation and Cultural Affairs David Olsen Virgin islands Department of Conservation and Cultural Affairs Timothy B. Still Virgin Islands Department of Conservation and Cultural Affairs Robert Teytaud Virgin islands Department of Conservation and Cultural Affairs Robert P. vanEepoel Virgin Islands Department of Conservation and Cultural Affairs Werner Wernicke Virgin Islands Department of Conservation and Cultural Affairs John A. Yntema Virgin islands Department of Conservation and Cultural Affairs Ervin H. Zube University of Massachuset-ts Virgin Islands Planning Office Thomas R. Blake, Director of Planning Dar'-an Brin, Assistant Director of Planning and Project Director Edward E. Lindelof, Project Coordinator Steven L. Colman Marsha S. McLaughlin Louis Mills Walter L. Stewart Roy Adams IResource People Tefollowing people were helpful ih i~den'tlfying'-existing resource information: E. A. Bertrand Lagoon Marina St. Thomas, Virgin Islands John R. Clark The Conservation Foundation Washington, D.C. Arthu--, E. Dammann Virgin Islands Department of Conservation and Cultural Affairs I I I I I I I I I I Robert Dill West Indies Laboratory St. Croix, Vi-rgi-n Islands Johnny Harms Lagoon Marina St. Thomas, Virgin Islands Project Staff and Consultants James A. Dobbin Maynard Nichols Kathleen Finnerty William E. Rainey David I. Grigg Edward L. Towle Christopher Howell Judith A. Towle John McEachern John Trude I I I a ISLAND RESOURCES FO,UNDATION P.O. BOX 4187, ST. THOMAS, U.S. VIRGIN ISLANDS 00801 o (809) 775-3225 C~T~ April 8, 1976 Mr. Thomas R. Blake, Director of Planning V.I. Planning Office, Office of the Governor Government of the U.S. Virgin Islands Dear Mr. Blake: The Virgin Islands constitute a unique island system -a place of value, beauty, and inspira- tion, possessing a rich history, spectacular marine life, diverse coas-tlines ana a salubrious climate. They also have a promising future as a habitat for r~esident faunal, floral., and hu- man species, living in a balanced, natural harmony. There is, however, mounting evidence that the human component of our islands' population has, through oversight, uncontrolled expansion, and ill conceived actions, induced a broad Spec- trum of stresses that threaten the natural viability of the island system and could destroy what Alexander Pope referred to as "the genius of the place." This process is especially apparent in the coastal zone of the Virgin Islands where competing human interests and dynamic components of natural ecosystems interface and interact. The present effort to develop a management plan for this critical zone of man-environment inter-relationship offers the promise of minimizing environmental conflict, improvi-ng re- source allocation decisions, preserving our insular heritage and restoring the intricate balance with natural systems. our mission was to establish a point of departure in assess- ing the marine segment of the endangered coastal zone, reviewing what is known, preparing an inventory,and classification or component subsystems and defining thei-r inter-relation- ships. Lastly, we have sought to suggest preliminary guidelines for the planner who bears the ultimate responsibility for devising procedures and making recommendatons to our govern- ment on how to improve upon management of the coastal zone. This has been an exciting, awesorae and inspiring project. Thank-you for the opportunity to undertake this study. I take great pleasure in submitting this report. We trust you will find it useful in the tasks which lie ahead. sincerely yours, Edward L. Towle, Ph.D. President a ontents~ I I I ANALYSIS OF BIOPHYSICAL RELATIONSHIPS 119 119 INTRODUCTION I INVENTORY OF NATURAL RESOURCES Oceanog&aphy and CZimauoZogy Tides and CuAt&ents Wave,s and Swet-L Wa-te QuLaZity P/LevaiZing Winds StofLmzS and Huwicanes P&ecipitation and EvapoaLtion Geoph-ysicaZ FactoiL Bacthymect&yq Seismic Activity Ma.kine EcoZogy Fis h e&~i es O-the&t CoaztaZ WiZdZide CoastaZ and Submatine Hab-&t~atiS Beachez Rocky Shoaes SaZ't Ponds Mangt o v e Co.kaZ~ Ree~,6 Sandy Bottoms Oj,sho/Le Cays OtheiL Matine Resoutce E emen t Cta,5iLcation o6 Coastat Ecos y,6 te em, C&iticat AAea,5 A&'ea, oS HLigh P oducxtivity Ake.a, Undea Skt&els UnAque Afteas SYNTHESIS - COASTAL ZONE PLANNING GUIDELINES Regionat Context PZanning Concept: Ecosysteemz AppAoach GUIDELINES FOR RESOURCE YMANAGEMENT 126 126 127 128 129 129 130 I 13 16 35 38 44 46 46 50 52 52 62 64 131 I 131 Vitac Ateeaz 70 83 86 92 101. 107 109 113 Aft,eaz06 Envi&oneraen-tat Conce&n A,teaz o6 NokmaZ ConcuLn 132 133 AMeaz o6 Regionat, Nat&ionat 133 and In~tenationaZ Signiicance 134 GuidetLine 6otr Ecoy&cstem Manageme.nt 117 I I U RECOMMENDATIONS FOR 142 I ~FURTHER STUDY I ~SUMMARY 144 ANNOTATED BIBLIOGRAPHY 160 SUPPLEMENTAL BIBLIOGRAPHY 187 I ~INDEX 190 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Ctl oe I I igures FIGURES 1. Predicted and observed tidal ranges in St. Thomas harbor, March - April, 1972 2. Variations in the character of the tide displayed in time-height curves in Christiansted harbor, June 29 - July 19, 1971. 3. Annual prevailing currents in the Caribbean. 4. General current patterns on the island platforms. 5. Mean surface current, speed and direction for Christiansted harbor currents and for littoral currents, August 1971. 6. Maximum bottom currents recorded at ten points in Caneel Bay, St. John. 7. Surface currents near Great St. James Island in August. 8. Water movement in Jersey Bay and Mangrove Lagoon, St. Thomas. 9. Average sea and swell conditions for Virgin Islands coasts. 10. August surface temperatures. 11. January surface temperatures. 12. Winter-Spring (December-April) inshore water temperatures, St. Croix. 13. Summer-Fall (June-October) inshore water temperatures, St. Croix. 14. Winter-Spring (December-April) inshore water temperatures, St. John. 15. Summer-Fall (June-October) inshore water temperatures, St. John. 16. Winter-Spring (December-April) inshore water temperatures, St. Thomas. 17. Summer-Fall (June-October) inshore water temperatures, St. Thomas. 18. Contours of equal salinities (isohalines) in Jersey Bay and Mangrove Lagoon. 19. Diurnal variation of disolved oxygen, salinity, pH and temperature measured at one foot depth in south Jersey Bay. St. Thomas, 1970. 20. Wind direction and speed frequency, central Caribbean, January- June. 21. Wind direction and speed frequency, central Caribbean, July - December. 22. Tropical cyclone frequencies: latitude 15� - 200 N. 23. Hurricane paths that have affected the Virgin Islands since 1876. 24. One hundred year frequency and standard project tidal flood stage hydrographs. 25. Bathymetry of Virgin Islands basins and plateaus. 26. Profiles of bottom topography across the Virgin Islands shelf south of St. Thomas and St. John. 27. Distribution of Caribbean seismic and volcanic activity. 28. Coastal and submarine habitats, St. Croix. 29. Coastal and submarine habitats, St. Thomas and St. John. 30. Beach profile showing beach terminology and component parts in relation to high and low water. 31. High energy winter profile and moderate energy summer (beach) profile. 32. Summer and winter beach profile in relation to beach rock. 3 4 6 7 9 10 11 12 14 21 22 2 3 24 3 25 26 2 7 3 30 31 3 6 1 3 7 42 43 4 7 51 65-66 I 67-68 71 7 2 1 73 I I I I i PI, 33. Representation of sand transport in an enclosed bay. 75 34. Profile of a beach indicating physical zonation and characteristic organisms. 76 35. Typical rocky shoreline of eroded volcanic rock with boulder and rubble bottom. 84 36. Cross-section of a salt pond. 87 37. Salt River, St. Croix, showing drainage patterns and protective reefs. 92 38. Profile of a mangrove forest showing typical zonation and associated habitats. 93 39. Marine ecological zones of Jersey Bay and Mangrove Lagoon, St. Thomas. 95 40. Benthic communities of Salt River estuary. 96 41. Diagramatic profile of an offshore reef system. 104 42. Profile of a sand-dominated bottom. 108 43. Typical shallow water sea grass bed. III 44. Rocky shoreline and associated sea bottom. 120 45. Typical sand beach ecosystem showing relationship of component habitats. 121 46. Mangrove dominated ecosystem with lagoonal flats and protective reef. 123 47. Man-dominated bay ecosystem. 124 TABLES 1. Major element composition of sea water. 28 2. Occurrence of tropical storms and hurricanes within 240 nautical miles of 41 St. Croix. 3. Location of Virgin Islands salt ponds, excluding cays. 91 4. Partial list of birds from Jersey Bay mangrove lagoon including cays. 98 5. Inventory of offshore cays. 115- 116 I IntroductC- on I I I I The coastal zone is an area that, far from separating land from sea, brings the two together in a complex i nteraction of living and physical features. Tt is an, area of constantly active forces that makes it probably the most dynamic por- tion of the earth's surface. Some of the interp~lay of forces are constant, even subtle (currents, evaporation-, tides, biological processes); while others can be sudden, dest-ructive and catastrophic (hurricanes, earthquakes, drought, flooding). Between these extremes, one finds a continuum of natural pro- cesses which are ongoing and inter- active, often poorly understood and some, no doubt, ye't unknown. The complexity of processes in the coastal zone is amplified and modified by human activities but continues never- theless, sometimes shunted or temporar- ily obstructed as a result of man's ac- tivities along inexorable patterns dic- tated by natural evolutionary systems. Thus, while man has further complicated the kaleidoscope of coastal interactions, he finds it necessary (more so because of his intrusion) to identify and under- stand the pieces of the pattern and their mechanations. increasing human modificaticon and exploitation of coastal resources demand an identifIication and understanding of these resources, their attributes, inter-relationships, con- straints and limits. Only from such a starting point can workable plans be de- veloped for maximum multiple-use management of coastal resources. Some level of resource protection and conservation is imperative, at the very least for self-serving, short-term develop- ment related reasons. However, protection and preservation of portions of the en- vironment can also be compatible with other valuable functions including bio- logical prod-uctivity, recreation, environ- mental diversity, aesthetics and cultural preservation. Perhaps the greatest value of preservation is the mai-ntenance of op- tions for further uses. Development and mnodification of natural resources are fre- quently destructive in the sense that re- source attributes are permanently com- mitted to a particular use and no longer available for alternative -uses. Protec- tion not only maintains natural produc- tivity and aesthetic values, but pre- serves use options for future generati6ns. The following compilation is intended as a first effort survey of Virgin Islands coastal resources, an interpretive summation of our knowledge of their in- teractive processes, values and capaci- ties, and our needs for addi-tional in- formation. It is important to recognize the neces- sity for understanding the coastal zone - or any natural system for that mnatter - as a complex interaction of many pieces, processes and problems. It must be un- derstood also that any modification of a single part or process will cause some response in other parts of the system. Natural systems as a whiole maintain their integrity by a process of dynamic equi- I I I i I I I I n librium and must change in response to external stimuli. Somnetimes this re- sponse is negligible, sometimes catas- trophic. Often it is subtle and im- perceptible to human scrutiny - assuming an effort at observation is even made. It is counterproductive, therefore, to .1 approach problems of resource develop- ment and exploitation as separate, segmented actions dealing with indi- vidual resources or separate developmnent schemes. Ignoring the interdependen't aspects of natural systems and the ad- ditive and secondary effects of indi- vidual resource manipulations is un- likely to promote optimum sustained multiple-use management of these re- The information compiled herein is the I ~most comprehensive treatment to date on the marine component of the Virgin Islands coastal environment. It should be noted that a great amount of eso- teric detail has not been included, primarily because it is not suited to the scope of a general inventory, re- I ~view and management document. More imLportant is the fact that a yet greater amount of necessary informa- I. tion is simply not available. We have attempted at several points and in the m ~Recommendations to identify these voids * ~in our knowledge of the Virgin Islands - ~coastal ecosystems and to suggest how . some of these lacunae may be fil-led in. The final section of the report is an annotated bibliography to the marine com- ponent of the Virgin Islands Coastal Zone Management Plan, organized alphabetically by author and publication date. An attempt has been made to distinguish between documents which are of a general or overview nature, those whioh have particular relevance to local coastal zone management, and those which are technical or specialized. The key word index refers to appropriate sections of the text and is cross-refer- enced to provide leads to related in- formation. ~~rut f( ~~~~~~~~~ t ~~~I U I level. When the planetary pos-itions are such that a given point on the earth ex- periences only minimal tidal ranges (from lower high water to higher low water), the tides are called nen Since the relative positions of the sun, moon and earth change constantly, but cyclically, on a daily and annual basis, the magnitude and locations of tidal maxima and minima also change. Tides are also complicated by such factors as winds, the centri-fugal force of the earth and local geography and bathyme- try. As a resualt, the times of high or low water and their heights can vary greatly along a large, complex shoreline. In the Virgin Islands, tidal ranges are not great, and tidal currents, except in some inshore localities, are not significant. The small islands, lacking complex shoreline physiography, do not restri-ct changes in water level. The sea flows around the islands relatively unimpeded, resulting in tidal fluctua- tions of only a few inches to a foot. Further, the steep slopes of the islands rising out of the water means that the intertidal zone - the part of the shore- line regularly covered and uncovered by the tides - is very narrow. We there- fore do not have large areas of tidal flats uncovered at low tides as in other places in the world, especially along continental coastal zones. One of the consequences of this small tidal action is that water exchange in Tides and Currents TIDES Tides are regular cyclical rises and falls of sea level induced by astro- nomical forCes. The gravitational pull of the moon, and to a lesser degree the sun, in effect, create a giant global wave system which produces the earth's tides. Inshore, the tide height and time of occurrence is affected by coastal and bottom geography, biut the magnitude of tides generally depends on the relative positions of the earth, moon and sun. Maximum gravitational attraction of the earth's oceans - and thereforo maximum tides - occur when the three planets are in a straight line relationship. Thus, high tides are generated on the sides of the earth nearest to and fur- thest from the moon and maximumi tides (as well as minimum - lowest - tides at tangential points) when the sun and moon are aligned in the same plane with the earth, i.e., at new and full moons. Tides of maximum ranges are called spring tides, when the water level reaches from the higher high water level to the lower low water I I I I I I I I I I I ~~~~~~~~~~II U circulation of Caribbean water on the other, the north and south coasts of St. Thomas and St. John experience different tidal activities. on the north, tides are similar to the north coast of Puerto Rico, being semi-diurnal (two cycles of high and low water per 24 hours) . The time of tide stages in the Virgin Islands are earlier than in Puerto Rico, however. On the south coasts of St. Thomas and St. John, and for all of St. Croix, tides are primarily diurnal (only one high and low water per day)., The second cycle is reduced to very slight ebbs and floods, and on some days is not measurable at all. The mean range of local tides is 0.8- 1.0 feet (0.24 - 0.30 meters). The mean range of spring tide is about 1.3 feet (0.4 meters). Changes in tidal height with time can be displayed graphically by a marirm chart which plots the water level as measured by a tidal gauge. Such mari- grams have been constructed for Lameshur Bay, St. John (Dammann, et al, 1969) , St. Tho- mas harbor (Percious, et al, 1972) and Christiansted harbor (NiFchiols, et al, 1972) . The latter two clearly show the vanishing semi-diurnal (second cycle) component of south coast tides (Figures 1 and 2). bays due to tidal action is usually very small. For example, it is estimated that 24 to 40 tidal cycles alone would be necessary to exchange all the water in the main part of St. Thomas harbor (Percious, et al, 1972).~ Fortunately, waves, swells- a-nd oceanic currents us- ually do a good job of flushing most bays. However, these forces are con- siderably reduced by the time they reach the heads of deep embayments. As a result, circulation may be poor in the inner reaches of some of our larger embayments. The innermost por- tions of the mangrove lagoon on St. Thomas, of Salt River, St. Croix and of Coral Day, St. John are like this. To a lesser extent, similar coTlditions have been observed at the head of VeSSup Bay (Redhook) , St. Thomas and Cruz Bay Creek, St. John, and probably occurs in other similar locations. For the planner and decision maker, these conditions are important because it means that pollutants introduced to these calm areas will be very slowly dispersed. For the same reason, such quiet areas are sites of relatively rapid deposition. Sand transported naturally through these bays, as well as silt and debris from the land, tend to settle out in the quieter areas, filling the bottom and eventually ex- tending the shoreline. Because of different exposures to open ocean water on one side and modified 2 I I I I I I I I I I I I PRIDICI'm heights in Feet, referenced� to MEAN LOW W~TER UZL2AII OBSERVED heights in FEET above arbitrary reference level, frcm gauge in lHarbor Master's Dock NOT referenced to DATLM I. o--. AE . 0 A S / ~ I %-ftt 1,? I3.0 0 2 . 5m .2.5 0- I -. I) 2. 0 5 23 24 25 26 27 28 29 30 31 1 2. 3 w5 1. IS. - 2. 5 Po a, I 2.0 14 1. 5 t4 1 lz) C14 5 6 7 8 9 10 11 12 13 14 15 1 16 I I I Time- days Figure 1. Predicted and observed tidal ranges in St. Thomas harbor, March - ApriI, 1972. From Percious, vanEepoel, and Grigg, 1972. 3 U I , E I C) I 2 JUNE JULY TIDE MIXED ~ I E 0 1_ m JULY Figure 2. Variations in the character of the tide displayed in time-height curves, from predicted tables and from observed tides in Christiansted harbor, June 29- July 19, 1971. From Nichols, et al, 1972. 4 I I and Grenada and eventually joins the north equatorial. water in the Yucatan Basin. However, this southern current, with a velocity about twice that of the north- ern Caribbean current does not impinge directly on the West Indian archipelago. The major bottom features (ridges and troughs) of the Caribbean, described .in the section on Bathymetry, act to restrict movement of deep water through the Caribbean. Movement of the upper layer water is complicated when it flows over the shallow island platforms. For most purposes, these are defined as the submarine shelf from the shoreline to 100 fathoms (183 meters) depth. Here, coral reefs, other bottom irregulari- ties, winds, shoreline configurations and tides act to divert and diverge the prevailing ocean currents. on the virgi-n islands platform, while the prevailing mass flow of water is still dominated by the west-northwest drift, passage of water between islands and in bays varies depending on location and exposure to the open sea. General- ized flow on the islands' shelves has been plotted by Dammann, et al (1969) and is shown as Figure 4. Because of seasonal changes in wind direction, water is driven across the shelf from the east in the winter and from the southeast in the summer. in individual bays, unless they have eastern exposures, water movement is controlled primarily by wind and swell. I CURRENTS Currents are defined as horizontal move- ment of water as a result of any of sev- eral driving forces. In actual practice it is often difficult to determine what the causative forces are, and for most purposes it does not matter. Thus, tidal currents are water flow resulting as changes in sea level drive water through channels or embayments. Den- si-ty currents are generated by differ- ences in dissolved solids (salinity) and/or temperature. Culrrents are also generated by the rotation of the earth and the resulting wind stress at the surface. Density and pressure account for the general large-scale currents of the ocean, including the North Equatorial Current which pushes water through the Caribbean Basin (Figure 3) to the west- northwest to eventually join the Gulf Stream. ocean water from the Tropical North Atlantic (Northi Equatorial or Canary Current) enters the Caribbean Basin be- tween the islands of the Lesser Antilles. in most localities, the submarine ridge on which the islands lie is less than 1,000 meters deep, therefore admitting primarily upper water from the Atlantic. This water flows west-northwest past the Lesser and Greater Antilles, entering the Gulf of Mexico and Florida Straits through the Yucatan Channel. Atlantic water from south of the equator also enters the Caribbean 'between Trinidad I I I I I I I I I I I I 5 a Figure 3. Annual prevailing currents in the Caribbean. From U.S. Naval Oceanographic .Office, Sailing Directions, 1963. 6 I- ;rrrryr=5_ ~~~~~~~~~~ref .... aneadat I~~~~~~~~~~~ jo s gun refm a no. / han~s lb 100 fa thom rroc.. A '/arracuda ~O .-�bn5' kingfish '' barracouta banks banks jost guana camanoo pi a' . van dykZ - buck v. na vigi tobago~ tortola n a ~ hans :lcbuck been k/ drol~S~,p; ird. ?barracuda thoas ~ pter~ nor/ an JANUARY buck~ - I * frenchcap �" ; Firgen islands F 7-. , rbuc bank, Figure 42. General current p?atterns on the island plaU~orms. From Dammann, et al, 1969.I 7I a if the bay's exposure and shape permits access of offshore current driven water, then often bays on the north exhibit a clockwise movement of bay water, while in those on the south, the circulation I ~is counter clockwise. Many factors interact to determine the direction of water flow in a bay however. Some of I ~these are relative strength of tides, winds, wave, swell, and external currents in addi-tion to the bay's bathy- I metry, shoreline shape and size. It is therefore not surprising that patterns of water movement in bays, especially the larger more complex ones, change as the relative strength of-the various determinants change. For the planner, this is important because it po?ints to I ~the need for site specific studies of currents when these are important for * ~decision making. Furthermore, such studies should be conducted during a long enough period and under various conditions to deter- mine not only prevailing conditions, but variations thatL may occur. Figures 5 through 8 show some available current information for specific bays and point to the variety of circulation patterns which can he encountered locally. B I Pe I ic ENTRANCE -' ~~~~~~~~~~~~~~~~~~~~~~Bank XX ~~\.. L ong Reef -. v,~~~~� Sorensen k ,~ Al t~~~~~' 6, ~ ~ ~ ~Ground ,o .011~~~~~~~~~~~~~~~~~ HARBOR CURR EN TS ..... .-- ' . .....inferred Direction A. Mean Velocity, rn/sec, measured I 06.06- .06-.10 .10- .13 > .1 7, 7BXy LITTORAL CURRENT -----Measured km.S~U ..... Inferred .. Figure B. Mean surface current, speed and direction for harbor currents and for littoral currents August 19'/1. Length and width of arrow indicates speed in meters per second. Harbor- currents based on anchor station measuremnents; littoral currents on dye patch measure- ments. *indicates two alternating predominate directions. From Nichols, et al, 1972. 9I N c)I 0 12 .246 KT. 4332 KT, .270 KT. lv-~ o4 P2t' 706 .362 K.T. CANEEL BAY, ST. JOHN 01 12' .332 KT .228( KT. _ 4 02 iI' 246 KT. o3 8' Figure 6. Maximum Bottom Currents Recorded at Ten Points in Caneel Bay, St. John. Recording Depths (feet) shown at each station. From Dammann, et al, 1969. 10 I I I I I I I I I I I I I I ST. THOMAS GREAT ST. JAMES FiSH CG .j,;9 .. n cl . ' ; (. -� Figure 7. Surface currents near Great St. James Island in August. Determined by dye diffusion. Data from Brody in Dammann, et al, 1969. 11 1 a K I I I 16 Zi . ~ ~~.' 2 '6 .1~~~~" i .. �: LI 3 6 ~2 261 aP P '2 :1g. 78 2 9 9A -1~3 .14 : -. 5AID EIAU1L -: B It ' II 7 4 2 f : :13� V -e9 3 -... '" ! v 0 eZ 20 25 36 52 52 65 53 70 67 70 71 67 I Figure 8. Water movement in Jersey Bay and Thomas. From McNulty, Robertson the Mangrove Lagoon, St. and Horton, 1968. I I Waves and Swell By contrast, during winter when the dol- drumn belt is located farther south along the equator and the Bermuda High is weak, a long length and long period northern Swell develops. Although the swell off- shore is only one to five feet high and occurs only four percent of the'time, it is significant because it gains heights of ten to twelve feet nearshore. By re- fracting around the west coasts of the islands, this swell affects leeward coasts for short periods. Variations in the depth of water and orientation of the coast nearshore greatly mnodify the height and length of approaching swells. As a result of refraction, wave energy is concentrated on seaward projecting points and, at the same time, it is diffused within the bays. Thus, waves tend to straiglhten the north coast of St. Croix by erosion. of headlands and deposition of sand in the bays. Straightening along the north coast of St. Thomas and St. John is op- posed by the variations in resistance to erosion of different rock types. For example, the projecting points on the north side of Magens Bay, St. Thomas, at Mary's Point, St. John and of Thatch and Grass Cays owe their origin to the Tutu rock formation which is more resistant than the Brass limestone. Commonly, on the north coasts, waves approach the shore frcm two principal directions. Short period waves and chop approach from the east and north- Waves are the main source of energy that move beach sediment and that af- fect shipping and shoreline structures during storms. Waves differ widely according to their heights, length, period and speed. Their energy de- pends mainly on height and period. The deepwater wave regime of offshore waters is driven by the northeast trade winds most of the year. On the average, wave heights of one to three feet ap- proach from the east.42 percent of the time throughout the year. For short periods, 0.6 percent of the time, these easterly waves reach 12 feet. Intermediate wave heights and corres- ponding frequencies of occurrence (Figure 9) are summarized in Deane, et al (1973) . In addition to the nor- mal easterly swell that affects the windward coasts of the islands, there are two seasonal modes of wave app-roach that affect leeward coasts: a south- easterly chop and swell and a northern swell. The southeasterly swiell with waves one to twelve feet high becomes significant in late summer and fall when the trade winds blow from the east or when tropi- cal storms anid hurricanes pass the is- lands at a distance to t'he south. The east-southeasterly wind and wave regime is associated with the doldrum belt located over the interior of Venezuela and with an intensive high pressure area over Bermuda. I I I I I I I I I I I I I 13 a I l 3 " 72 71 70 69 69 1 67 I" 6 0 94 9* 91 61 .S P I AVEF WINTER RAGE SEA AND SWELL CONDITIONS FOR COASTAL WATERS (PERCENT) 19I IV' - . la. * II' - 16' -15' -11. -13' -12' -11' - 10' .9. SEA II, I <3' 3'-5'1 5H-' H-IS' 112' TOTAL NIX 4 SUMMER -NE I 3 8 43 E I 52 61 * 34 F 71* 13 N56 SE 7 21 * 10 L. IS s I S~~~~~~* W A STALl RI IA I I * 55 64 14 TOTALI at 1 6 1 g-g9 if'i THIS FIGURE IS DESIGNED TO GIVE THF. PERCENT FRESUETICY OF SEA AND SWELL BY DIRECTION AND HEIGIIT FOR VARIOUS C-OASTAI. ALIN.1IFENTS. THE DATA ARE APPLICABLE TO NEARSAORE WATERS WITHIN TEN MILES OF THE COAST; CONDITIONS FOR THE NEARSHORE WATERS OF RAPRADOS ARE VERY SIMILAR TO THOSE SHOWN ON THE EAST AND WEST EXPOSURES OF THE LEEWARD A110 WINDWARD ISLANDS. TIlE ALINEMENTS HAVE BEE'I SELECTED ON THE EASIS OF SIMILARITY OF EXPOSIJRE, METE. OROLOGICAL. CONDITIONS, AND OBSERVED SEA AND SWELL DATA. WAVE CONDITIONS AT SPECIFIC COASTAL LOCATIONS MAY VARY FROM THE PRE. SENTED DATA BECAUSE OF NONCONFORMITY TO THE GENERAL CHARACTERISTICS OF THE ALINE- MENT. THE GENERAL NATURE OF THIS STUDY DOES NOT PERMIT AN ANALYSIS OF SEA AND SWELL CON. <5�I'-' H-IS'll2' SGH132. 'i'. 'I .12' IXIRIL N 3 1 I *I+i i 4 N I NE 24 14 1 * 43 NE 14 121411 I i3I 0 20 S2 5i1l* 30 E 27 22 j 11*1I46 So i . L2 SE N II 1 SI I S I i L �KL......s..........L 1 SW" I*SW * A W *4 I 1 * W * I* NW A * 2 1 NW * 2 L* TRIAL S 28112 21 * HA TOTALS SD ID 2 AL RN CALM 2 CONFUSID N rO 063. 5473 CALM I CONFUSED 0 ~D. -05. 6122 15'_ CONFUSED * NG. OfS.l.46 CALMSI CEDRrUIED 0 SWELL 14 1- z,I DID ' NE E E SE 7 2 R I 5 4 4 * 12 13' - SWELL 1 - i * i - _ DITIOlS FOR EACH SPECIFIC COASTAL LOCALIIT. SW * !** I * - MEANS LESS THAN 0.E _!wV L..... _ I I I ' IV ' 61 ' 1 iTiR 2'-1' T-ITA LI> 1 TOTAL NW I I NW I I NW I I ~~~~NE 18 is I 34 NE tiI to I 22 TOTAL B 1 2 - 10 TOISALI B 4 4 1 E 52 CALM 904 co POSE D R0. 09.3614 CALM 88 CONFUSED *4387 S E S3E SE~~~ S W I IE c S I Ir 'I! NW /I i' I I( CALM? 2~ CORFASER * R GRO 45214 CALM 27 CONFUVSED * TSR. 053.4342 j lit I lo 9' iv h3' 77' 71' 7I' 8 9' E' E 9 E' 6.5' 64' 63' 6' 62' 6' 69' Figure 9. Average sea and swell conditions for Virgin Islands coasts. From U.S. Naval Oceanographic Office, 1963. 14 I I that can drive ships sideways against the dock. Such move-ments have not been observed in Virgin islands harbors, but they need to be taken into account when evaluating proposed changes in harbor geometry. east, and, at the same time, long per- iod swells approach from the north. However, in the wi-nter, from November through March, the northern swells are larger than in summer, and they are refracted and redirected more around points and islands. Because of their high angle of approach and large size, such waves create strong longshore currents. Around islands like Dutch- cap C ay, St. Thomas and Buck island, St. Croix, the two wave types produce very complicated patterns of crossing sea and swell which can be observed on aerial photographs. Along coasts fronted by partly sub- merged reefs.. waves play a sicgnificant role in circulating back reef water. As demonstrated in Christiansted har- bor (Nichols, vanEepoel, Grigg, et al, 1972) , the mass transport of wa-ves breaking over Long Reef drives a harbor-wide circulation (Figure 5) that flushes most of the harbor water through the entrance in about fourteen hours. Consequently, the response of waves to reefs and nearshore bathy- metry is significant in reducing pollution and i-mproving water quality. I I I I I I I I In imany harbors and bays, periodic durgi-ng of the water surface, called ifseiching" or "surginig", has been re- corded. Although the seiches are us- ually less than 15 centimeters high, they create oscillations within a harbor that induce horizontal movements I I 15 0 Water Quality The discussion below has been limited to .major parameters most commonly used to describe water quality. While the o- ceans contain at least traces of almos-t every chemical element known, obvious- ly the discussion of all of them is impossible and inappropriate to this document. Furthermore, little or nothing is known about the levels of most of the elements in local waters. oceanographic parameters treated are those commonly used to characterize bodies of water. For most purposes, they reflect the general quality of water and indirectly suggest something about the presence or absence of other broad quality determinants and give inferences about the biota. Physical and chemical properties are important as they affect the behavior and physiology of the sea's inhabitants from the lowliest to the most complex. Only a relatively small amount of in- formation exists on the biological implications of water quality for tro- pical organisms. Much of it is general and qualitative. Quantitative data on the effects of specific parameters on specific tropical organisms is par- ticularly scarce. Even such definitive information is not universally and readily transferable to situations out- side the closely defined limits of the experimental setting within which it was determined. Part of the enormous complexity of bio- logical relationship is that there are interacting effect relationships among the many component parameters of the en- vironment. For example, the response of a given organism, including its toler- ance, to temperature may vary with salinity. Furthermore, this variable response relationship may be different for different life stages (i.e., egg, larva, juvenile, adult). Levels of turbidity and sedimentation which per- mi-L the survival of established coral colonies may not allow settlement of larvae and development of new colonies. Acclimatization also affects an or- gjanism's response. For example, an organism accustomed to a relatively high temperature, salinity, turbidity, etc. may often exhibit a higher upper limit of tolerance to said parameter than the same species which' is accli- matized to a lower prevailing level of the same parameter. Acclimatization responses are also related to other factors in the organism's environment. Given such innumerable complex relation- ships governing the establishment and survival of marine life, it is no w7on- der that we are, in the main, ignorant of most details of marine ecology. This fact explains why-biologists are unable to specify, in fine, cause-effect re- lationships of observed phenomena and *why they are hesitant to make unequivoc- able predictions about specific effects of particular environmental modifica- tions. Our present knowiledge of bio- logical responses to a few.-variables is simply too inadequate to extend, 16 I without reservations, even to the same organism at another time in another setting. Even naturally occurring envi-ronmental comqponents can assume pollution roles when increased beyond normal levels. Thus, thermal pollution can result from heated industrial discharges which raise water temperature beyond the tol- erance limit of organisms. Hypersaline effluents or those abnormally high in other natural sea water constituents can likewise be lethal. Sewage, even treated sewage effluents, can add a variety of chemi-cals which are directly or indirectly an,tagonistic to marine life. Organic matter removes, oxygen from the water directly or in the course of its degradation by micro- organisms. Nutrients (nitrogen, phosphorous, silicon), when elevated above their normaally low concentra- tion can increase the growth of nuisance species of algae, molds, diatoms, etc. Explosive growth of such forms can smother normal or- ganisms, produce toxins, remove oxygen from the water and may even- tually, if conditions persist, change -the en-tire ecosystem. There is always a normal background amount of suspended matter in the sea and fine particulate matter is con- stantly settling to the bottom at a slow rate, even in the cleanest water. In some inshore areas, turbidity and siltation may be naturally high, but in both extremies the local biota is com- posed of speci-es adapted to or tolerant of the prevailing conditions. Chronic increases in turbidity and the rate of siltation will stress and finally ex- tirpate the more sensitive organisms, and their place will be taken by more tolerant ones. However, even the most tolerant organism has a finite ability to endure a given stress. organisms in- habiting turbid, muddy areas will per- haps survive longer under greater in- creases of suspended and settleable matter than those inhabiting relatively clear water, but can ultimately be des- troyed by chronic, extremely severe conr- diti-ons. The effects of pollution are less damag- ing, in the direct sense, to motile forms than to fixed (sessile) forms. While several environmental modifications (di- versity, predator-prey relationships, fishery yield, etc.) may result from the loss of mnobile organisms, they can leave an unsuitable area for better surround- ings. Fixed forms - plants, corals, sponges, oysters, etc. - must perish if they cannot tolerate the induced stresses. In the larger sense, this loss of sessile organisms has muich greater implications than the displacement of mobile ones. Fixed organisms are not simply living componexits of an environment; -they, in large measure, are both physically and biologically the determinant structure of the ecosystem. The corals on a reef - apart fromn their roles as living mnem- bers of that diverse community - are the I I I I I I U I I I I 1 7 a actual physical material of the reef. They provide food, shelter and anchorage for all of the thousands of other species * ~living there. The same is true of sea grass and algae pastures and mangrove I ~forests. If these basic determinant elements of the ecosystem perish, then the rest of the associated biota - even * ~if not directly affected by particular stress'factors - will be adversely affected. The parameters most frequently used to describe basic water quality are temp- erature, salinity, dissolved oxygen, I ~transparency and sometimes color. For more critical definition of a water- body, especially where pollution is present, bacteria, oxygen demand, pH and nutrients ("fertilizers" important for algae growth) are often measured. For assessment of water quality rela- tive to other specific problems, there is an almost unlimited list of other chemical and physical measurements I ~which may be made. Selection of specific ones depends on the informa- tion that is needed and on the nature of factors which may be influencing water quality (i.e., the type and source of pollution). The following discussion treats the more common quality determinants and our know- ledge of their natural levels and man- induced variations in local waters. TEMPERATURE I ~Most frequently reported in degrees Celcius (or centigrade) in technical lit- erature, water temperature is a function of radiation at the surface. Insolation (exposure to the sun) warms the water; radiation of heat from the surface re- sults in cooling by a loss of "excess" heat (roughly the difference between the water temperature and the night- time air temperature) . Water is more heat stable than the land. Thus, while the land surface heats up rapidly under the sun and cools rapidly at night, the sea is able to absorb considerable heat without a resulting large increase in temperature and to hold that heat with- out rapid loss. The result is that ocean temperatures are-much more stable than air or land temperatures and do not show the same wide daily fluctuations. The larger the volume of the water, the more temperature stable it is. There- fore, shallow headwaters, tidal flats and ponds tend to reach very high tem- peratures during the day (sometimes 3Q00C and higher) . At night. they may cool to air temperature or lower if a stiff breeze promotes evapo ration. In contrast, offshore water measured at perhaps one foot below the surface may fluctuate as little as 2-3o C diurnally. Mixing of the water by waves, swell and current improves temperature stability by reducing localized areas of anomolous temperature and by distributing heat energy mtore evenly throughout the water mass. 18 I I a result of the southerly encroachment of colder Atlantic water in the winter, while the shallower, warmer Caribbean water to the south is less affected by this sea- sonal cooling. Inshore temperatures are more variable and generally warmer than off- shore. This is perhaps to be expected from the shallower depth and greater vari- ety of water characteristics inshore. Part of the wider temperature range, however, may also be due to the larger number of inshore measurements made. The Virgin Islands Division of Natural Resources Management (formerly Division of En- vironmental Health) has been making in- shore water quality measurements monthly since November, 1972. Their temperature data from bays on St. Thomas show minima of 24.6 - 26.70 C in January-February and maxima of 27.1 - 29.00 C between June-Octo- ber. Average winter-spring and summer- fall temperatures for the three islands are given in Figures 12-17. During the three years from November, 1972 to Septem- ber, 1975, a cooling trend is apparent with winter minimum falling from about 26.70 Cto 24.60 Cand summer maximum fall- ing from 29.00 Cto 28.40 C. These data are from clean open-coast bays; areas such as Benner Bay and St. Thomas harbor have been excluded. Data from St. John show the same cooling trend over the past three years. SALINITY The saltiness of sea water results from the various minerals dissolved in it. The most abundant is sodium chloride. The relative proportions of the consti- Biologically, temperature is important because every organism has a limited range of temperature within which it can survive. There is usually an even narrower range within which the organism will flourish, exhibit optimum growth and reproduce. Frequently these nar- row temperature optima are not the same; organisms may grow faster and reproduce better at different tempera- tures. Very often optimum temperatures are different for juveniles and adults. Temperature is also biologically impor- tant for several other reasons. Gen- erally, warmer water can hold larger quantities of dissolved salts, but less dissolved gases, including oxygen, than colder water. Organisms, as a rule, tend to be more active as temper- ature increases within their range of tolerance, although near their upper limits many exhibit behavioral or physiological maneuvers to curtail energy loss and heat exhaustion. The lowered oxygen capacity of very warm water can result in anoxia or death for oxganisms if they cannot leave the area or reduce their activity and oxygen demand. Offshore surface water around the edge of the northeast Virgin Islands platform is in the range 27.5- 27o90 C in August (Dammann, et al, 1969; Figure 10) . In January, offshore surface water on the north was measured at 24.0- 25o50 C, but on the south was reduced only to 25.5 - 27.00 C (Figure 11). This is undoubtedly I I I I I I I I I I I I 1 9 I a i / (2) 6 i f i (2. Tc i N loo t~~t~~n~om dro~~G~~IG~/ 28.6, ::'' barracouta banks g 27. guana camanoe ba'nks ic t c guan V)as d y k orairi tobagoP gd9, I.860C **`�.." van;~J: vir~laoi~i �3h~L~c~ bans i:lolli 27.6C(6) bssf 0 27.6 h s rocJl' 27 6barracuda e gc� salt(Irs ) rd. rork.-'12� thoq 7'. . ,2 - bank p(zt(2r cooper--. savana 28.5 buck ~ 28.50 (5 nor~man./p -70 6/ 27.5 85 uck Ov 66~C 1 f ronchcap �00 275C (2) virgin islands la ng ~' ~buck bank. st. croix -, ~~drop Figure 19. August Surface Temperatures. Temperatures are the average of the number of separate-day samples given in parenthesis. From Dammann, et al, 1969. 20 / so - - -, V' ,.~~~~~' I I I I I I I I I I I I I I / / ,/ (26.oC0 C' / N ,J '..,barracuda . , bank 'oo100 ??�.Om- _ _2'� banks savana I s. - _ . '. , f _,- , v irgin islands / Figure 11. January Surface Temperatures. Temperatures are the average of the number of separate-day samples given in parenthesis. From Dammann, et al, 1969. 21 ha4-lh Cek=i V 5.- 2-cw_.3' N"fh& ; 50aA~~~~Jh Co0sJ Av-cgces, 2~5. - 2G5-C Nosnih41 N I Figure 12. Average Winter-Spring (December-April) inshore water temperatures. Data from the Division of Natural Resources Management, Virgin Islands Department of fl| ~Conservation and Cultural Affairs. 22 11 I I I I L I I I I I I I I I H6,1h Z-O-iG A9S - -z%I C t16pS'h VBI 0 '12 1 2 a Zodop"J"11 ZZ7--P - - 945-&5 C P Figure 13. Average Summer-Fall (June-October) inshore water temperatures. Data from the Division of Natural Resources Management, Virgin Islands Department of Con- servation and Cultural Affairs. 23 n Nor/b'West Coasi aVercr9eS 206 - Z6_57'c Ponigbly SaSt~h 3 Coat ercs0eS i6-- 27Arc Afonth 1I0" ~ ~ t 0 5,c~o esoo _o.,;l ' .o. Figure 14.' Winter-Spring (December-April) inshore water temnperatures around St. John. From data of the Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. 24 Figure 15 Summer-Fall (June-October) inshore water temperatures around St, John.th From dat-a of the Virgin islands Department of Conservation anid Cultural Affairs, 1973- 74 25 C5 U Aoerfth Cosl As a-=,Gi Are Z5&8 ' - ZZ71C Hcnt IMy So5.aIh ConS- Avrre Z5 $ - CaZG tonh& a 1/'O' Yl I 92 ~H 5 ,1jd Figure 16. Winter-Spring (December-April) inshore water temperatures around St. Thomas. Data from Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. 26 I --------- I I I I I I I I I i I Nc,bh Ctast e rcg es 7T,O -Z3.7C 6orh-. L 5ctti Costf AXrcies 27-& - O '40%'C-C P1o-aXtdh N C> V2 a a (1 m1i.S I U I Figure 17. Summer-Fall (June--October) inshore water temperatures around St. Thomas. From data of the Virgin Islands Department of Conservation and Cultural Affairs, 1973-74. 27 I *tuents is almost constant regardless of 3salinity. Significant departures from * constant composition ratios occurs as a result of pollution. Table I indicates the relative abundance of the 11 major I constituents in sea water. In determin- ing salinity, the chloride content is determined andsalinity derived from it by an empirical relationship. Salinity can also be derived from measurement of conductivity and temperature. I Table 1. Major element composition of sea water. tion and renewal by offshore water. In- shore salinity can also vary considerably over the year for the same reasons. In protected inshore localities where cir- culation is poor, evaporation during hot, dry periods can increase salinity to 40 o/oo or more. on the other hand, heavy rains can reduce it to 20 0/00 or less. in fact, for short periods in protected bays, an almost pure fresh water layer or "lens" may lie on top of the sea water. in most localities, how- ever, wind, waves and currents constant- ly exchange the water for offshore water of relatively "constant" salinity and so dampens salinity fluctuations. UJnder these conditions, water in most local bays is almost or exactly the same sa- linity at all depths, shows only small annual vari-ations and, following torren- tial rain, can recover to pre-flood salinity within a few days after runoff stops. Oceanographers frequently measure salin- ity to define bodies of water and iden- tify circulation patterns. The areal distribution of salinity in a bay, for example, can be contoured to produce isohalines - lines of equal salinity. These distributions can reveal sources of wiater, mixing zones and paths of water flow. Isohalines constructed for Jersey Bay mangrove lagoon on St. Thomas (McNulty, Robertson and Horton, 1968) show the in- creasingly higher salinities of the inner areas where poorer circulation and evap- gm./kg. of water of salinity 35 o/oo 19.353 10.76 2.712 1.294 0.413 0.387 0.142 0.067 0.008 0. 004 0.001 Constituents Chloride uSulphate Magnesium . I Calcium Pot ass iurn Bicarbonate IBromide IStrontium B oron a Fluoride Salinity is reported in parts per thou- msand or grams per litter of salts, more 3often represented as o/oo. offshore sea water around the islands has a rather constant salinity of 35. .5 to 36.2 o/oo I in winter-spring and 34.0 to 35.2 0/00 in summer-fall (WU!st, 1964) . inshore salinity varies from place to pla-ce a- * round the islands dependingj on the relative rates of evaporation, fresh water add'&- 2 8 9 I to carry life processes through the night. Diurnal oxygen production cycles lhave been measured locally at Cruz Bay and Chocolate Hole, St. John (Brady, Grigg, Raup and vanEepoel, 1970) , at Vessup Bav (Grigg, vanEepoel, and Brody, 1970) , and in Benner Bay - Mangrove La- goon, St. Thomas (Grigg, vanEepoel and Brody, 1971) . Figure 19 reproduces characteristic oxygen curves from, a highly productive site in Jersey Bay, St. Thomas on two differentu days. oxygen production begins at about 6 A.M. and the concentration in the water in- creases rapidly to a peak at 3 P.M., after which it begins to fall and reaches a moinimum, below the saturation level, at about 3 A.M. The open-circled points on the graph represent the oxygen saturat'ion capacity of the water based on its temp- erature and salinity whi-ch also vary di- urnally, the latter in response to changes in circulation and the volume of offshore water entering the area. During peak production hours, an obser- ver in the water in such areas can see bubbles of oxygen rising from th6 sea grasses to the water surface. Under such conditions, the water is super- saturated with oxygen and is passing the excess to the atmosphere. oxygen is re-moved from the water by or- ganisms, including aerobic bacteria feeding on wastes. it is also removed by chemical reaction with waste products and pollutants. increased amounts of oration promote salt concentration (Figure 18). DISSOLVED OXYGEN oxygen, dissolved in the water, is necessary for life support. At the sea surface, oxygen may be absorbed fromn the air, a process which is aided by surface agitation of waves. The largest part ofE sea water oxygen, however, is produced by marine plants on the sea bed and floating planktoni-c algae (phytoplankton) . This production is the source of most oxygen in the lower layers of inshore water. The oxygen holding capacity of sea water is inversely proportional to temp- erature and salini-ty. Cold, fresh water can hold mnore oxvgen than warm, salty water. Excess oxygen produced beyond the abi-lity of the sea to dis- solve it diffuses into the atmosphere. In fact, marine producti-on accounts for a major proportion of atmospheric oxy- gen, a fLactor which contributes to same of the serious concern about the effects of increasing glo-bal pollution of the oceans. PI-ants produce oxygen as a by-product of photosynthesis, a process whiclh re- quires light. Therefore, oxygen is not produced at niglht, but animal re- quirements for respiration continue. In addition,plants respire (use oxv- gen) in the dark. Therefore, it is necessary, duri-ng sunlight hours, for a net surplus of oxygen to be generated I I I I I I I I I I I I I 2 9 ml LI- (1 '3~~~1 .N~~~T ( :AY 31~~~3 6 14 E ~~~~~I 7 4 . _Yi.oo . . 9 3 5 . .5**...._ '. [6_ 23 II 25 ..... . 36 _ PA_I_1(. PT. _ ._4 1? 36 20 j , N"IN is *14 14 37 31e 59 7w 5 52 - -,~~~ -.- - 49 5 3 .1 .1. . .65 B 7 -.-. b2 71 A? GZ - 70 k_l Figu~re 18. Contours of equal salinities (isohalines) in Jersey Bay and Mangrove Lagoon, St..,Thomas. From McNulty, Robertson and Horton, 1968. I N t la f k k ~ 'C U, Ui I I I I I I I I o-_- -5.0 ~~~~~~~~~~~~~~~~~~I., p~~~~~~~~~~~~~~~~~~~~~~~~~~~~L t X~~~~~~~~~~N 1J- . a-- - - - 29q -- � a I I I I N IN /' / N- I ~./~~~~~~~a /7/ I-, 21 -- . -,.- -. - bW _ II I I -CpqcOc I-cC e/CO o30C Diurnal variation of disolved oxygen, salinity, pH and temperature measured at one foot depth in south Jersey Day, St. Thomas. Solid lines March 21-22, 1970; broken lines April 20-21, 1970. Open circles represent dissolved oxygen saturation. Re- drawn from Grigm, vanEepoel, and Brody, 1971. 31 Figure 19. I more common are Secchi disk depths, turbidity units, and concentration (weight/volume) of suspended solids. The first two give estimates of light penetration, while the third is diffi- cult to relate to actual clarity except in the extremes because it depends con- siderably on the size and nature of the suspended particles. Many small par- ticles will cloud the water more than the same weight of larger, but fewer particles. Suspended solids concen- trations cannot be related or con- verted to Secchi depth or turbidity, but under some conditions Secchi depth and turbidity may be quantitatively related. Secchi disc depth is the depth to which a white or black and white disk can be distinguished when lowered into the water. Turbidity is a measure of light scat- tering by suspended particles in a water sample. It is reported in Jack- son or FormAzin turbidity units, de- pending on the method of calibrating the measuring instrument. The units are interchangeable. Suspended solids concentrations are determined by filtering a water sample through a fine membrane, g.enerally with nominal pore sizes of 0.45 micron, drying and weighing to determine the suspended solids concentration in mg/I. Transparency in most local waters is organic poll1utants remove more oxygen by chemical reaction anid by the life processes of bacteria and other micro- organisms which feed on it. Surface waters around the islands are usually oxygenated at or near satura- * ~tion during the day. In very productive areas, such as over dense turtle grass beds, supersaturation may occur during mid-day. Because of generally pre- vailing temperature and salinity, sat- uration values are about 6. 0 - 6. 6 milli- grams per litre (mg/1). Because of this, annual variations in dissolved oxygen (d.o.) tend to follow annual variations in temperature; salinity vari-es much less than temperature. At night, especially near the bottom, d. o. may be reduced to 5. 0mg/l or less, depending on local conditions of the sediments, water and biota. Point sources or concentrations of pollutants also depress oxygen concentration,,by utilization and can further depress local production by destruction of planit life. However, in areas of good water circulation, these effects I ~may be masked by oxygen transport from other areas. In shallow, polluted Inshore parts of the St. Thomas harbor, 3 ~surface d. o. as low as 4. 3mg/I have on occasion been measured in the past (Percious, vanEepoel, and Grigg, 1972) TRANSPARENCY ClIarity and transparency of the.water is a function of suspended matter. it I ~m'ay be estimated in several ways. The 3 2 I I rapidly. Shorter, higher energy spectra (violet, blue) penetrate farther and therefore dominate the light that finally reaches the bottom and is re- flected. Therefore, deeper water appears to be blue or dark blue, while shallow water is greener. Very shallow water will appear clear or colorless if the bottom is sandy, or green if it is covered with seagrasses and green algae. Water color can also be affected by phytoplankton which may be red, green, brown or yellow-green. Turbidity makes the water brown while dissolved mater- ials can produce a variety of colors. Water color may sometimes be of interest in describing local sites or charac- terizing a particular pollutant, but in most cases color alone is not particu- larlv meaningful. OTHER QUALITY PARAMETERS Frequently it is valuable to estimate the density of some type of bacteria in the sea. Since this is most often done to monitor pollution by sewage in coastal waters, one of the common in- dicator species is usually monitored. Eschereschia coli, the most character- istic bacteria in feces of warm- blooded animals, including man, is most often tested for. New methods of analy- sis are simple and rapid and give re- sults in 16-24 hours. Bacterial den- sity in the water is useful for pin- pointing sources of pollution, evaluat- ing public health acceptability and the excellent. A secchi disk can easily be seen to depths of 30 feet, frequently more, in normal water. This means that in most bays the bottom is visible from the surface, i.e., Secchi depth is 100 percent of the water depth. Three years of data from the Division of Natural Resources Management reveals that turbidity in undisturbed bays generally is 6.3 -0.7 Formazin Turbid- ity Units (F.T.U.). The St. Thomas harbor, an example of a turbid bay, had Secchi Disk depths only 50-60 percent of the water depth. Since sewage has been removed from the harbor, Secchi depths have increased to 80-90 percent of the water depth. Turbidity in the harbor formerly was as high as 4.5 F.T.U., but since 1973 has fallen to 1.0- 2.5 F.ToU. Turbidity of the water is important primarily because it reduces the amount of light reaching plants on the bottom. It is also associated with increased siltation of the bottom because many particles eventually settle out of the water in calm areas. Both effects place stresses on living systems. WATER COLOR The apparent color of clear sea water is a result of absorption and reflec- ticn of light and of the color of sand or organisms on the bottom. As light penetrates the water, the longer wave lengths (red, yellow) are absorbed I I I I I I I I I I I I 3 3 I 0 efficiency of sewage treatment facili- ties. Chemical ions such as nitrate, phos- phate, silicate and their related com- pounds are often studied as means of assessing the productivity or eutro- phication ("enrichment") of the water. These compounds are highly concen- trated in sewage, even treated sewage effluents, and also occur in flood- water from the land. High. concentra- tions of these compounds promote in- creased growth of plants, partcularly phytoplankton and filamentous types. Rapid growth of these plants, which require or can tolerate high nut- rient concentrations, can smother normal clean water forms or prbduce toxins which are harmful to other organisms. Organic matter in the water is fre- quently estimnated-indirectly by measuring biochemical oxygen demand (B.O.D..) or chemical oxygen demand (C.O.D.). The first is a bioassay which measures the consumption of oxygen by micro-organisms feeding in a water sample under standard condi- tions, usually for five days. Chemical oxygen demand measures the oxygen uptake of a sample using strong oxi- dizing agents. Since many substances not easiiy attacked by bacteria (as in B.O.D. test) are thus oxidized, the C.O.D. value of a given sample is higher than the B.O.D. it is also a more rapid test than B.O.D. 3 4 December - February. During the winter the trade winds reach a maximum and blow with great regularity from the east-northeast. Wind speeds range eleven to twenty-one knots about sixty percent of the time. Speeds greater than twenty knots occur about twenty- five percent of the time in January. This i-s a period when the Bermuda HighI is intensified with only nominal com- pensating pressure changes in the Ecua- torial Trough.I The trade winds during this period are interrupted by "Northerners" or "Christ- mas Winds" whi-ch blow more than twenty knots from a northerly direction in gusts from o-ne to three davs. Such outbreaks average about thirty each year. TheyI are created by streng-thening of high pressure cells over the North American continent, which, in turn, allows weakI cold fronts to move southeastward over the entire Caribbean region. These storms are accompanied by intermittentI rains, by clouds and low visibility for mariners. March - May. During the spring, the tradeI winds are reduced in speed and blow main- ly from the east. Wginds exceed twenty knots only thirteen percent of the timeI in April. The change in speed and direc- tion mainly result from a decrease in pressure of the Equatorial Trough.I 351 Prevailing Winds The Virgin Islands lie in the belt of "Easterlies" or "Trade Winds" which tra- verse the southern part of the "Bermuda High" pressure area. The trade winds approach the islands with great con- stancy of direction, primarily froma the east-northeast and east. The trade winds vary in magnitude and di-rection as the position of the sun changes seasonally in relation to the earth's surface. Major seasonal changes relate to the normal variations in position and intensity of the "'Bermuda High" and "Equatorial Trough." In contrast to the Bermuda High, the Equatorial Trough is a zone of low pressure south of the islands -between the sub-tropical high pressure belts in the southern and northern hemispheres (which includes the Bermuda Hligh). Since the wind blows around the low pressure zone as a coun- terclockwise inf'low in the northern hemisphere, the Equatorial Trough directly affects the easterly winds of the islands. The average percentage frequencv of wind speeds for different directions is illustrated in the monthly wind roses of Figures 20 and 21 (U.S. Navy Hydro- graphic office, 1963). The annual wind regime can be broadly divided into four seasonal modes: (1) December to Feb- ruary; (2) March to May; (3) June to August; (4) September to November (Brown and Root, 1974). Characteristics of each seasonal mode are discussed below. a Figure 20. Wind Direction and Speed Frequency, Central Caribbean, January -7 June. From U.S. Naval oceanographic Office, 1963. 36 I I I I I I I I I I I I I 74' 73' 72' ll' 70' 69' ~' 57' ~* 65� ' ~� 63' 62' GI� ,~' 59'. I Figure 21. Wind Direction and Speed Frequency, Central Caribbean, July- December. From U.S. Naval Oceanographic Office, 1963. I 37 S-torms and Hurricanes June - August. Trade winds reach a second- ary maximum during this period and blow predominantly from the east to east- southeast. Speeds exceed twenty knots twenty-three percent of the time during I ~July. The trend for increasing winds results from the strengthening of the Bermuda High and a concurrent lowering I ~of pressure in the Equatorial Trough. Trade wvinds during this period are in- terrupted by occasional hurricanes. September- November. During the fall, winds mainly blow from the east or southeast and speeds reach an annual -minimum. Only seven percent of the winds exceed twenty knots in October. The low speeds result from a decrease in pressure in the Bermuda High with only a slight compensating pressure decrease in the Equatorial Trough. I ~During this period, especially dur-ing late August through mid-Octuober, the. normal trade wind regime is often broken down by easterly waves, tropical, I. storms and hurri-canes. The major disturbances affecting normal trade wind circulation are caused by the passage of squalls, easterly waves, tropical cyclones and hurricanes. SQUALLS AND THUNDERSTORMS The islands are affected by numerous squalls which are often accompanied by thunder and lightening. in the vicinity of land, where the squalls are most frequent, cold air rushes down the mountain sides and moves out over harbors and bays with substantial force. These disturbances are most common in the summer months during per- iods of s-ultry weather and light var- iable winds. Because the squalls last only a few hours, they do not cause a pronounced change in the trade wind speed or direction over large areas. Thunderstorms are localized wind storms associated with cumulus cloud types that may occur in all months but are most common between June and January. TROPICAL CYCLONES AND HURRICANES These storms are of great significance to the wind regime although they occur infrequently. When tropical cyclones sustain wind speeds that exceed 74 miles per hour, they are termed hurricanes. Tropical cyclones form or pass through the eastern Caribbean mainly from August through October. Peak activity is dur- ing Septemtber (Figure 22) . The pro- bability of tropical sto.rms and hurri- canes occuring in the islands at dif- 3 8 H Categories 1 and 11 ( Storms) Categories 111 and 1V C Hurricanes) I I I I Il "4 0 '4 0i 0 0 K ,j)I t QY 8 6 4 0 June July Aug Sept Oct Nov Dec to May Figure 22. Tropical Cyclone Frequencies: Latitude 15� -20� N. From Deane, Thom, and Edmunds, 1973. 39 storma waves can be heavy. Moreover, passing hurricanes may create a minus tide of as much as 1.0 feet below maean low water that can temporarily cause grounding of vessels in shoal water and exposure of tidal flats. ferent seasons is given in Table 2 (Brown and Root, 1974) . Annually there is an expected probability of one cy- clone in sixteen years (Bowden, 1974). Since 1900, 24 hurricanes have passed within fifty mailes of the Virgin Is- lands (U.S. Army, 1975) . Of these, the hurricanes,of 1916, 1924, 1928, and 1932 caused the most damage. Hur- ricane' paths that have affected the islands since 1876 are shown in Figure 23. STORM WAVES AND TIDAL FLOODING Tidal flooding, created-by major hur- ricanes having a frequency on the average of once in 33 years, r.aise water levels in St. Thomas from fi-ve to twelve feet above normal. A six foot tide height would flood lower parts of Charlotte Amalie for 800 feet landward from the shoreline. A graph prepared by the U.S. Army Crops of Engineers (1975) , showing the height of a hypothetical hurricane flood having a frequency of occur- rence of once in 100 years, is repro- duced as Figure 24. Also presented is the height of the "standard project flood" which is defined as the largest tidal flood that can be reasonably ex- pected to occur as a result of the most critical combination of conditions that are considered characteristic of the re- gion,~ excluding extremely rare events. Besides flooding, damage to waterfront facilities and erosion of shores by 40 I I I Table 2. Occurrence of tropical storms and hurricanes within 240 nautical miles of St. Croix. I Tropical Storms Average Interval Occurrence Average Between Probability Number Storms, On Any Day Per Year Years In Period Hurricanes Average Interval Occ Between Pro Storms, On Years In urrence bability Any Day Period I Average Number Per Year Period of Hurricane Season I July 6- Aug 5 (31 Days) (Inactive Early Season) Aug 6- Sep 30 (56 Days) (Active Mid-Season) Oct 1- Nov 30 (61 Days) (Inactive Late Season) Entire Season (148 Days) 0.16 6.4 0.70 1.4 0. 2 0 5. 1 1. 0 5 0 .95 0. 5 0% 1.24% 0.32% 0. 70% 0.05 0.85 0.13 1.03 20.4 1.2 7. 8 0.97 0.15% 1.52% 0.20% 0069% I I I I Maximum Number of Hurricanes and Tropical Storms in Any Year: 9, 1933 Minimum Number of Hurricanes and Tropical Storms in Any Year: 0 (occurred in several years) Source: Brown and Root, 1974. I I I I I 41 I - m m I- - - - m - - - - Im N N ~ 1908 Figure 23. Hurricane paths that have affected the Virgin Islands since 1876. From U.S. Army, 1975. I I I I I I I I I I I I TE~LANDFL l Q L2 LA NFA L LLLEziI 'fPOST,LNFL~ --T.4.-. AA ~~~~~~IR E 4 --- DMA -=-AND- SIA JAR PO.H.T t 9' u .-I 0, pJr-we lmflc-f 4 o'iF'c r;ze i 8 6 4 1 LU 0 co Lu z 0 LU LU 2 0 ~ T- 6 T-2 T-0 TIME(HOURS) T+2 T4 4 14 I I Figure 24.. one hundred year frequency and standard project tidal flood stage hydrographs. From, U.S. Arnmy, 1975. 43 I n Precipitation and Evaporation Rainfall in the islands is limited and variable, The amount of rain varies monthly, annually, by island and with areas on a given island. Average rain- fall data, compiled froim several years records at various stations, can be misleading in that it probably poorly represents the available precipitation at a particular area even over a year's time. The U.S. Virgin Islands receive an average of 41 inches of rain per year (Bowden, et al, 1970). The wettest months are September to December. The dry season is February to July. St. Thomas, including Water Island and Hassel island, receives 'about 42 inches. St. John receives about 47 inches. The larger cays probably average between 30-35 inches. A small area of Crown Mountain, St. Thomas averages slightly more than 50 inches. The eastern and southern low- lands of the islands generally are the driest and the central higher eleva- tions wetter. Most of St. Croix re- ceives 35-45 (average about 40) inches of rainfall a year. The northeast hills receive slightly more and Annaly, the wettest area, receives on the average 52 inches a year (Bowden, et al, 1968). in addition to sparse rainfall, dryness of the islands is heightened by rapid evaporation of surface and soil water by intense solar radiation and constant breezes, most marked on exposed coastal ridges. Soil retention of the sparse rainfall is hampered by the steep slopes which promote rapid runoff instead of infiltration and by the shallowness of most topsoils and their paucity of moisture-holding organic matter. In addition, plants remove moisture from the soil, pumping part of it back to the atmosphere by transpiration. .Rainfall and evaporation are importan't in the coastal mrarine environment as they affect salinity, turbidity and other pollutants carried to the sea with stormwater. Most of the light, brief showers which fall are not sufficient to run off the land. This is primarily because the soil is al- most always dry and rapidly absorbs these brief showers. During rainy per- iods when freqluent showers may bring soilI moist-are to saturation, further rainfall runs off the steep slopes to the sea. In flat areas, excess soil water may be able to percolate into the ground before running off.. Vegeta- tion, in addition to slope, is also important in determining t-he speed and extent of runoff. Plants help 1~y in- terrupting the sheet flow of surface water, reducing its velocity and al- lowing more time for it to infiltrate the soil. Plants can also absorb and transpire water back into the atmo- . sphere. in addition, their roots help to hold the soil in place. Areas which have been stripped, cut or burned do not offler these advantages, and much less rain is required to promote run- 4 4 I I I noticeably in the past several years, and areas of coral and marine plants have been reduced. These trends in the en- vironment result from essentially per- manent changes in water quality, in part, as a result of frequent rain in- duced runoff. However, most of these areas are also subject to stress from other Zources (i.e., dredging, marinas, boat traffic, sewage). Rare inundation bv fresh water, even without large amount-s of other pollu- tants, can da-mage or kill most marine o,rganisms. Natural forces usually re- turn normal salinity levels in a matter of days in most locali-ties, and the biota can recover. Hiowever, increas- ing frequency and se-verity of these episodes will eventually modify the impacted ecosystem. off, which carries soil with it. Local bays receiving drainage from highly de- veloped watersheds (St. Thomas harbor, Christiansted harbor, Benner Bay and Water Bay, St. Thomas) are now subject to discoloration and siltation follow- ing good rainfall of an hour or more, while most other drainacfes do not shed water as readily. Historically, flooding of the coastal zone was infrequent and probably had negligible consequences for mvarine or- ganisms. The lack of rivers was for- tunate in the sense that coral growth was not hampered by low salinity, tur- bidity and other terrestrial contami- nants whi-ch restrict reef growth around larger islands and continental coasts. Without constanit or frequent pollution by fresh water, silIt and other pollutants, clean-water communi- ties were able to develop almost every- where arouind the islands and could recover from the brief impact of per- iodic torrential rains. Today, fresh water (and a wide variety of trans- ported pollutants) reaches the coastal sea quicker, more frequently, and in greater amounts than in the past. The frequency and severity of these occur- rences has begun to be reflec-ted in the condition of the affected environments. In Christiansted and St. Thomas harbors, as well as Benner Bay and Water Bay, and to a 'Lesser degree Cruz Bay, St. John and Stumpy Day, St. Thomas, tur- bidity and bottom silt have increased I I I I I i I I I I I I 45 U Ueophysicao Factors the slopes, e.g., off the north coast of St. Croix. Topographic evidence suggests t-he slopes are of fault origin. They are relatively straight, steep and parallel known major faults on land. Despite the relatively smooth form of the depth curves in Figure 25, the slope contains many local irregularities on its surface. Relief of the slopes is known mainly from a study (vanEepoel, et al, 1971) to determine the feasibility of laying submarine cables between the islands. Reportedly, the slopes are a region of great relidf with thick sedi- mentary deposits filling the valleys be- tween peaks. The steep slopes and pro- bable existence of a westerlv bottom current have contributed to deposition in the valleys. These deposits are be- lieved to consist of turbidities, i.e., deep sea deposits laid down by acti-on of turbidity currents. The records also show evidence of slumping. A detailed description of downslope movement in .~ubmarine channels off Cane Bay, St. Croix is given by Multer and Gerhard, 1974. Bathymetry of the, insular shelf is best known from. a reconnaissance study of the shelf south of St. Thomas and St. John (Garrison, et al, 1971). This shelf has an average wi.dth of 22 miles (14 kilo- meters) , and it slopes about 16 meters per kilometer from the shoreline to 30 meters depth. West of Charlotte Amalie, the profile is smooth and regular (Fig-_ ure 26) . By contrast, profiles to the east are broken by a few 'hills and I ~Bathymetry The northern Virgi-n Islands lie on the Puerto Rican Plateau, a submuerged plateau defined by the 100 fathom (183 meter) depth curve. This plateau is like a small continental mass siurround- ed by steep slopes and deep water (Dam- mann, 1969). The Puerto Rican Trench, with depths to 27,500 feet (9,166 meters) I ~lies to the north, the Virgin islands Basin with depths reaching 13,500 feet (4,500 meters) lies to the south, and I ~the St. John and Anegada Passages with d.'epths of about 6,000 feet (2,000 meters) lies to the east (Figure 25). The plateau mnainly consists of an in- sular shelf with depths less than 300 feet. I ~St. Croix lies on a submerged ridge which is separated from the Puerto Rican Plateau by the Virgin islands I BEasin. The ridge is broken by the Jungfern Passage to the west and by the St. Croix passage to the east. The sill depths in these passages report- I ~edly control the movement of deep wa- ter between the Atlantic Ocean and the * ~Caribbean Sea. The slopes that border the plateau and ridge and lead down into the adjoining I ~basins or passages are commonly long and relatively straight. Several are more than ten miles long. Locally, * ~there are occasional offsets on the slopes more or less at right angles to 46 I -< ( --~~~~~~~~~---. /i ::---:I 7, ... ~ ~ / / NO 'K! N,/ ~~~~- - ' ~- I' /- 'I- 0mq i -- 1~~~~~~~~~~~- q -. - ol ,T \ 'i -~~~-Z .� -, t , /; / <Y' "/ b:~~,~: I��I:;,/ /( ''4~~~~~~. ~- '�.'._~ ��0 /��- I ~~ \'2' 7' >-:~� .1~~~~~~~~~~~,� 0i; '. :�oZ- /7/ �-- ---%-=- - ' 0,; C~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~/ I -----~~~~~~~~~~~~~-~~~~~1- "-'----- .-- 1,~~ ~ N 17 ~~~- \q.x h'.,- - 1 -- / 'N .i L~~~~~~~~~~~~~~~~~~ Figr 25 ah~ityo ignIlnsbsn 'dpaeu etsi G\i . i~~~~~~~~~~~~~~~~~ \O ~ mtr rmvn~eol ta01/ 0 4 50- 1 E 60 - E 0 . 10- st. james bay > 0 20 SheF edge frenchman's cap 30- 40-1 50- .n.m. Figure 26. Profiles'of bottom topography across the Virgin Islands shelf south of St. Thomas and St. John. From Garrison, et al, 1971. For location, see Figure 25. 48 I I Inner parts of the shelf that surround St. Thomas and St. John exhibit a flat floor or terrace at about the 60 foot depthi. On the south coast of St. Thomas, the terrace extends about 0.8 mile offshore, whereas on the north coast and elsewhere, it is narrow, less than 0.3 mile. The relatively flat surface most likely wqas formed by wave erosion during Pleistocene lower sea levels. Inner parts of the shelf are extensi-vely broken by reef masses or dotted with heads of li-ving cocra.l. Many of these inshore reefs merge with living frinig- ing reefs on island headlands. Con- sec~uently, most of the inshore bathy-. metric curves of minus 30 feet or less tend to follow the shoreline. Along the south coast of St.Croix, the i-nner shelf is very shoal, less than 36 feet, and varies from 0.5 mile wide in the east to two miles wide in the west. Ree-fs form elongate barriers in the eastern part and large patch reefs oriented in lines paralling the coast in the central and western paX.t. Else- where, the i,nner shelf consists of coral sand initerspersed with grass beds. ridges that rise about 36 feet (12 meters) above the floor. Most of these features are oriented northeast -southwest and represent fault scarps and partly buried reef masses. Some of the faults are associated with faults mapped on the islands. Another prominent feature of the shelf profile is the serrated ridges and valleys that run along the edge of the shelf with a relief as great as 90 feet (30 meters). These features represent drowned reef masses believed to be active during Pleistocene low sea le- vels. Their relie f 4is greatest on the eastern portion o.f the shelf particu- lar'ly along segments thatu are oriented northeast-southwest. This orientation probably allowed optimumn exrposure to nutrient-bearing currents which were from the southeast essentially as they are today (Garrison, et al, 1971). Sediments of the slheif surface mainly consist of calcareous sands inshore and carbonate nodules plus coral rubble off- shore, below 34 meters. The nodules are less commion at shallow depths because wave action tends to break them down into sand. in a few locations, the underlying igneous basement rocks 'pro- trude above the shelf surface in the form of small islands or shoals. Ac- cording to Garrison, et al (1971), blanketing sediments are relatively thin, and thus the subsurface structure "shows through" as lines of low escarp- ments or reef-capped shoals. I I I I I I I I I I I I I 4 9 a Seismic Activity Since the Caribbean island arc marks a transition zone between continental and oceanic crustal masses, it is a nearly continuous belt of shallow focus earth- quakes, Although seismic activity I ~was more frequent in the vicinity of Hispaniola during 1950-1964, most shallow focus earthquakes in the re- I ~gion are distributed at random through- olit the belt. Figure 27 shows the loca- tion of earthquake epicenters in the re- gion together with related volcanic and storm surge activity as recorded by the U.S. Naval oceanographic office (1963). Earthquakes are generally more frequent in the vicinity of volcanically active islands such as Guadeloupe and Martinique. In the I ~Virgin Islands region, Sykes and Ewing (1965) located the hypo-centers of earthquakes occurring between 1950 and 1964 with a magnitude greater than 3. 5 Richter. At this magnitude, which is low to moderate, one earthquake occurs once every three years. Most of these I ~probably occur along the Anegada fault which trends northeast from a position south of Puerto Rico, continues north- I ~east through St. John Passage and Ane- gada Passage and terminates in the Puerto Rican Tranch. Large sea waves of extraordinary length, often called tsunamais, have been reported for the area. In deep I ~ocean water they reach 100 miles in length from crest to crest, buat their height from trough to crest is only a I ~few feet. When a tsunami enters shoal w.aters around coasts, the speed de- creases but the wave height increases, especially in broad bays. Tsunamis are associated with submarine seismic dis- turbances, either an earthquake along a fault or an explosion of a volcano. Although most local tsunamis originate in the Caribbean earthquake belt, a few arrive from the mid or eastern Atlantic Ocean. The Lisbon, Portugal earth- quake of 1755 created a damaging seismic sea wave throughout the West Indies. Observations are spotty, but small waves seem to occur about every ten or fifteen years (vanEepoel, et al, 1971) A preliminary study of tsunami fre- quencies by Deane, et al (1973) for the period 1965-1969 _in~dicates a tsunami wAve having a maximum two meter wave height will occur once in 75 years. 50 74' 73, 72 . 71 B 7p &B ka ~ 61 6? 6 6,1 - O 60, ...SE2ISMIC AND VOLCANIC ....... ~ ~ ~ ~ ~ ~ACTIVITY lB~ ~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. ~ ~ ~ ~ K. . __ . 15 ............. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-I....... ................ ..............~~~~ I 1i- jE AREAS IN WHICH BUILDINGS HAVE BEEN DESTROYED :... .. ...... flItU-~~E BY EARTHQUAKES ~....... _______~~~~~~~~....... ...........................VE.B.......... .............~.n ILAD OLANE i17*. AREOALS IN WEPORTE SUBMARINGH AE BENDESTROYED ..:::::::.. . MDVLANOEAS AN D WDISAPPEARDINGS ISLAVBENDAMAGE .. COASTAL SECTOR~~ARES INO WHICH EATHQUNAKES H AEEEE*ET.... ARASND SNHICH SEAUAKES MAVE BEE REXPECTEDO . / ISLAND~~~~~~~~~~~~~~~~~~~~~~~~~~~ VOCAOE Al LOCALS OF REPORTED SUBMAINVLAOE MUD~~* V OCNE N IAPERN SAO ..........~~~~~~~~~~~~~~~~~~ ...::2:: _ _ _ ~ ~ ~ ~ ~ ~ ~ ~ 4& & SA SE C OR _ R_ WI CHTUAI ............ 13t 72..... . .. . 1 0 6 B 6 G' 5 4 3-6 0 4 Figure 27 D~~~~~~~~~~~~As~i iNo STORMbea SUREiSi HAndVElai Aciit. FrmE Nal REORE Oceanographic... .............. 51~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-2 0 Fisheries The striking similarity of various stud- ies of fishing in the Virgin islands going back over forty years emphasizes how fisheries have been relatively static in a period of generally rapid change. The outboard motor, galvanized mesh fish pots, and nylon nets have largely re- placed sails, woven wicker pots, and cotton or hemp nets. DiVing has ac- quired greater importance as a fishery method. Catches have climbed gradually in association with improved technology. Fishery resources - particularly, high value semi-sedentary organisms such as conch, whelk, mangrove oyster, etc. - have been reduced to very low densities in accessible areas near population centers. Bar Jack or Carang (Caranx ruber) As the economy and population have bur- geoned, the demand for fish and the price per pound have climbed, but the number of fishermen has not changed signifi- cantly, except for slight temporary in- creases during periods of slack in major economic activities (tourism, construction). Personnel from the Virgin islands Bureau of Fish and Wild- life report such an increase in local fishermen currently. The retarded growth (or decline in some locales) of fishing is part of the general decline of fisheries and agriculture in the West Indies, but specific constraints on fisheries will be treated herein. FISHES The limited pelagic fish resources (bill- fish, tuna, wahoo, etc.) of the northern Virgin islands support a sport fishery along the edge of the shelf, but repeated exploratory fishing has made it clear that stocks are not sufficient to support an industrial fishery. The primary commercial resources are demersal fish (and inverte- brates) aLssociated with coral reefs and other,.usually irregular, "live bottom." A secondary finfish resource is inshore schooling fish, generally jacks, which are traditionally taken with haul seines. 5 2 I .1 for increased yields, primarily by fish- ing stocks which are now only lightly exploited. Fish tend to be concentrated around small irregularities at the bottom which provide refuge. many of the i-r- regularities in the open shelf and its elevated margin are coral reefs pro- duced at lower sea levels duri-ng the Pleistocene and now only veneered with living coral or other organisms. Even though primary productivity of these deeper reefs (below 20 fathoms) is lower than shallower reefs, the areas are ex- tensive and currently little exploi-ted. Thus, substantial stocks of fish are present. On deeper reefs, the herbi- vores (surgeon fish, damsel fish, parrot fish, etc.) which may dominate shallow water trap catches are less common, and' catches are more often snappers and groupers which bring a higher price. I I I I I I Black Grouper (Kyteroperea bonaci) OTHER VERTEBRATES Two other groups make up a small part of the biomass of marine vertebrates on the Virgin Islands shelf - sea turtles and marine mammals. Marine mammals (here whales, dolphins, and porpoises) are not currently regarded as an exploitable re- source by Virgin Islanders, buit the es- Beyond the shelf edge reefs, the bottora drops to 100 fathoms or more before be- coming gently sloping again. On the south side of the Virgin Islands plateau, the "drop off" is often a sheer wall from 40 to 100 fathoms, but there are areas, particularly along the northern edge, where the slope is relativelv gradual down to 80 fathoms or miore.' The resources of the shelf edge zon-e are considerable (primarily several species of red snapper and grouper), but the rough seas and the greater working depths demand a substantial in- crease in capital investment in gear and boats for effective fishing. F~infish stocks alone among the living marine resources offer long-term potential i I I I I 5 3 IL GI tablishment of a system for reporting I sightings or strandings would be of scientific interest. Among these large marine mammals, hump backed whales, pilot whales and bottle-nose dolphins migrate through our waters in the spring. Sea turtles have been a traditional fishery in the Virgin islands, and, although relatively few people still Ifish fot them regularly, any turtle encountered incidentally is caught. islanders still seasonally monitor beaches where turtles are known to nest in order to collect eggs and per- I haps capture the nesting.female. Un- like lobster or other animals with pelagic larvae, once a sea turtle I nesting colony is extirpated, it is probably, in human time frame, gone forever. I.Sea turtle species in probable order of abundance in local waters are: hawks- I bill, green turtle, loggerhead. Des- pite its relative abundance in the Virgin Islands, the hawksbill turtle is ser- iously endangered world wide, by a combination of hunting for food and shell. A tJNDP-sponsored (United Nations Development Programme) crafts training project in Tortola, British Virgin Is- lands has contributed to the general resurgence of sales of hawksbill shell artifacts. In the U.S. Virgin Islands, 1the hawksbill and leatherbacks are completely protected (and the green Hand loggerhead may be shortly) under the federal Endangered Species Act. Consequently, it is illegal for a tour- ist to purchase hawksbill products in the British Virgin Islands 'or elsewhere and import them into the United States. Seizure of endangered species products in U.S. Customs is becoming increasingly likely. The stocks of hawksbill shell being sold in St. Thomas shops were con- fiscated years ago. Kingfish (Scomiberomorus cavalla) SPINY LOBSTERS In the Virgin Islands, the spiny lobster fishery is second only to finfish in economic importance. *The current fish- ery is a relatively young, one which has developed in response to tourist demand and with improved transport'ation pro- 54 I fishermen diving for lobsters was 44.7 pounds/boat/day (Olsen, 1975). Lobster landings in the U.S. Virgin Is- lands in 1967 were 85,900 pounds from U.S. Virgin Islands fishermen and 18,640 pounds worth $15,844 (at,$0.75/pound) from British Virgin Islands fishermen (Swingle, et al, 1969). Most local lobster were and are sold whole. If 1967 imports from non-Virgin Islands sources of lobster tail are multiplied to approximate live weight, local lob- ster made up approximately one-fourth of the total consumed. Thus, a sub- stantial demand exists, but marketing problems, as usual, are serious. In the U.S. Virgin Islands and elsewhere, con- tractual buying by commercial consumers I of lobsters (restaurants, hotels) assures a steady source of supply in the face of fluctuating availability of local pro- duct, but this means that the local fish- erman, particularly the one who dives for lobster on occasional days-off, has no assured market and may actually lose his catch to spoilage before he can sell it. A substantial (but unknown) pro- portion of the demand in St. Thomas is now supplied by small-scale entrepre- neurs flying lobsters in from nearby islands. I I viding access to more distant markets. Conversations with older Virgin Islands fishermen suggest that spiny lobsters were not formerly relished as food by most of the residents of the English- speaking Caribbean, but, like conch, they were abundant and easily caught and made excellent bait for traps or handline fish. Currently, lobsters are fished by traps and by divers using wire snares. Rela- tively small amounts of lobster per haul are caught in traditional fish traps, but specialized lobster traps catch virtually no fish, and there is no clear-evidence that they are superior for catching lobsters in this region. For most fishermen, it is a better stra- tegy to set fish traps. A few Virgin Islands fishermen, who have made a sub- stantial investment in large boats and power hauling equipment, have also tried using substantial numbers of lobster pots. Many have eventually rejected them. The average annual catch per boat of lobster by St. Thomas-St. John fishermen using fish traps and fishing 5.8 days/month is reported at 200 pounds (Olsen, 1975) - a yield of 0.17 pound/lobster/trap/haul. Free diving for lobsters requires relatively little capital investment (in addition to a boat) and can provide substantial cash rewards for even weekend efforts. Diving for lobster is the primary employment for only a few Virgin Is- ianders. For a relatively small sample of boat days (21) distributed over nine months, the mean catch by St. Thomas a QUEEN CONCH Aboriginal conch shell mounds on Anegada * ~and elsewhere in the Caribbean attest to a long history of exploitation, but des- pite its continuing economic importance, I relatively little is known about the sta- tus of conch populations in the Virgin Is2ands. Most of our limited knowledge of the biology of the queen conch (,Strombus gigas) is contained in a paper by Randall (1964) based on work on St. 5 ~John. Adult conchs generally occuir in areas of low wave energy in beds of sea grass (admixed or sometimes dominated by algae) , on open sand, and on rocky * pavements veneered with sediment and an algal- mat. Adult queen conchs are not frequently encountered below 80 I ~feet, roughly the lower depth limit of sea grasses. * Juvenile conchs generally occur in shallow, relatively quiet water (less than 40 feet deep) on coral rubble, sand or sediment with sparse growths of sea I grasses. Juveniles smaller than about three inches are rarely, if ever, found and are presumed to be buried in bottom I sediments most of the time. -Conchs feed on plant materiall (primarily soft algae) and organic detritus. Female conchs deposit large masses of eggs in open sandy areas. These hatch releasing larvae with a pelagic life of about three weeks. Like Virgin islands lobsters, unless larval adaptations to * local water circulation patterns de- ' posit them back more or less where they hatched, conch populations in one area are probably dependent for recruitment on larvae produced in some distant un- known area and more directly on the vagaries of water mass movements. For reasons and in patterns as yet unknown, conchs are migratory and 'seem to move in groups. High catches may be made one year in areas which yielded increas- ingly fewer conch for the preceding sev- eral years. Therefore, any efforts at monitoring the fishery must be suffic- iently prolonged to differentiate low yields from natural causes and those from over exploitation. Queen conch are collected in the Virgin Islands almost exclusively by diving, generally without compressed air. Where conch populations have been more or less exhausted in free diving range (to 50 feet) , a few people have found it profitable to dive for them with com- pressed air. These deeper areas are less productive, and probably conch growth rates are lower. In the past, they constituted a refuge which by migra- tion probably provided some gradual in- put into the more heavily exploited in- shore waters. Thoroughgoing extraction by SCUBA diving bodes ill for anyone still engaged in low technology, sub- sistence fishing in the same or ad- jacent- areas. in 1974 the four major food wholesalers in'St. Thomas were importing 35,000 pounds per year from dealers in Florida or Puerto Rico at roughly $0.65 per pound 5 6 r delivered. At that time, little or no local conch appeared to be moving through commercial channels (Stott ms., 1974). Most of the imported conch in 1974 and the local conch in 1967 was used by commercial outlets (restau- rants, hotels). There is clearly a strong market for conch, but consis- tent availability is important for large scale commercial outlets. The quantitative data are not avail- able, but there are numerous instances in the Caribbean of economically serious local depletion of conch populations (e.g., the Grenadines) . There are suggestions of similar trends in the Virgin islands, with exploitation converging on Anegada, the only island with fairly extensive habitat and remaining stocks of conch. Intensification of the existing conch fishery should not be contemplated un- til a serious evaluation of stocks is undertaken. This may require an investment of man days seemingly disproportionate to the commercial value of the fishery, but it should be remembered that conch have some traditional subsistence role. The in- direct costs (in imported food pur- chased, for instance) of eliminating (or at least making inaccessible) the resource for some years are rarely properly tallied up against the small gains in cash income. WHELKS The whelk, wilk or West Indian topshell (Cittarium pica) is a large marine snail formerly common on exposed rocky shores in the Virgin Islands and elsewhere in the West Indies. it is a traditional food in the Virgin Islands and is the only gastropod, other than the queen conch, of any general economic import- ance. The narrow habitat zone occupied by whelk extends from the upper limit of rocks constantly wetted by wave splash to perhaps five feet (generally less) below the surface. The upper limit of whelk distribution probably is con- trolled by dessication and availability of algae for food, and the lower limit by predation. Generally, smaller animals occur in the upper tidal zone, and the largest animals (four to five inches basal diameter) occur below the low tide mark in crevices in areas of heavy surge. Whelks are harvested by walking along rocky shores and picking them from the rock surface or by snorkelling near steep rock shores. The ease and lack of equipment required for gathering whelks partly accounts for their vir-- tual disappearance near populated areas. Whelk larvae are probably at least briefly planktonic, but marking ex- periments suggest that after juveniles settle out of the plankton, they move only short distances. I I I 57 a More mobile animals (fish, lobsters, and even conch) may disperse from unexploited areas into those which have been heavi- ly fished and consequently maintain an exploitable population. But in areas depleted of whelk, it will take a num- ber of years for newly recruited juven- iles to grow to exploitable size. The only paper on whelk biology useful to management is by Randall (1964)t which includes studies on distribution, diet, size structure,.growth and re- production in a population on the south shore of St. John, U.S. Virgin Islands. Using boats and/or snorkelling gear to collect in previously unexploited areas (rocky cliffs inaccessible from land or the shores of isolated cays), it is possible to collect commercially signi- ficant quantities of whelk. Swingle, et al (1969) reported that 22,305 pounds of whelk ($8,900 at $0.40 per pound) were sold to commercial out- lets in the U.S. Virgin islands in 1968. No whelk were imported from outside the Virgin Islands. Presently, at least one retailer is importing from other islands. Probably collection for home use is of equal or greater mag- nitude. In terms of catch per unit effort, each of six U.S. Virgin Islands fishermen reported collecting a mean of 500 pounds/day of whelks for a total of ' 15 days (Olsen, 1975). Again, without some stock assessment and monitoring of catch, whelk collecting should be discouraged as a means of diversifying the fishery. The pelagic phase of the life cycle, secretiveness and a prefer- ence for rough water on rocky coasts means that some whelks will always be.present, if unexploitable, but some decision needs to be made whether whelk are to be viewed as a subsistence or "recreational" re- source or one to be exploited commer- cially. In the event of the development of a regulatory mechanism, any number of arrangements are possible, but the sim- plest for optimizing yield will pro- bably be a minimum size. If the sub- sistence aspect is important, a catch limit is also useful. Blue Runner (Caranx fusus) 58 I Many potential commercial consumers of local fish in St. Thomas avoid it not only because of high price for unpro- cessed fish, but because of concern about poisoning their guests. Presumably part of this is reputation and other concerns about liability. The Island Resources Foundation of St. Thomas maintains an epidemiological re- gister of intoxication incidents, and a laboratory at Bitter End, North Sound, Virgin Gorda in the British Virgin Is- lands is surveying the distribution of toxic fish and collecting them in order to extract and characterize the toxin. Work is also going on in other parts of the world, but despite considerable ef- fort (Brody, 1972, a summary of cigua- tera in the Virgin Islands including lists of toxic species), there is no simple way to determine if a fish is toxic.I I Great Barracuda or Barra (Sphyraena barracuda) I I CIGUATERA FISH POISONING Fish poisoning is a relatively common event in the Virgin Islands and, in addition to the public health problem, constitutes a major impediment to fishery development, particularly in expanding marketing to the tourism sector. In St. Thomas, any mass poi- soning resulting from sales of toxic fish to residents temporarily depresses the market for local fish. The general strategy of fishermen is to avoid certain localities, or par- ticular species in particular local- ities, which are traditionally known to harbor poisonous fish. Incidental poisonings of non-residents unfamiliar with ciguatera are relative- ly common (bare-boat charterers, down- islanders, etc.). Fishermen are also poisoned by taking a chance eating a fish they are unwilling to sell. However, toxic localities are subject to little fishing pressure, and a some- what unscrupulous fisherman can readily make a good catch and substan- tial income if he is willing to risk poisoning his customers. As populations rise in the Virgin Islands and com- munity cohesiveness declines, this problem is likely to increase. Any middleman (e.g. p a cooperative market- ing operation) can fall victim to this unless some system of fisherman account- ability is established. 0 PRODUCTION AND HARVESTABLE YIELDS The preceding pastiche of biology, ecology, exploitation history and qualitative recommendations are in- tended to give a predominantly bio- logical overview of the primary fishery resources of the Virgin Is- lands shelf which are accessible to current fishing gear and methods. The basic objecti-ve of fishery man- ageme,nt could be described as ob- taining the greatest yield of useable product at the least effort over some extended period of time. it is also desirable that the yield be, if not uniform, at least predictable through time so that large amounts of effort are not wasted at the wrong time looking for resources that are not there. As pointed out in the individual re- source discussions, the life histories and primarily the lower reproduc- tive potential of marine mammals and turtles make their management very different from that of most fish and marine invertebrates. This l-atter group, including virtually all of the species exploited in the Virgin Is- lands, produce large numbers of plank- tonic larvae which drift for weeks or months before transforming into some- thing resembling the adult form. In the case of reef associated organ- ismis, they then may establish them- selves in some possibly permanent abode an the bottom. The survival of the dispersing planktonic larvae is re- lated to nutrient availability, temperature, and related physical parameters in the waters in which they drift. Thus, the number of new recruits annually to a fish or lobster population is not dependent on local egg production. There are some unexplained activities of tropical fish whi.ch make one somewhat uneasy about the complete- ness of the picture presented by these assertions, but they are, in the main, true. Though over-exploitation of a fish stock is possible, planktonic larvae and wide distribution make biological exti-nction of a species by traditional fishin g me- thods extremely unlikely. However, the substantially lower reproductive potential of marine mammals (for many one young/ 2 years) and sea turtles (a few hundred eggs/3-4 years) make it quite possible that continued or expanded harvesting will lead to biological extinction within a region. Geographic extent of habitat, mobility and/or site fixity of a species also affect the vulnerability for local stock depletion by exploitation. Contrast the restricted habitat and low mobility of whelks with coral reef fish which are relatively rapidly recruited from ad- jacent areas to occupy desirable habitats from which other fish have-been caught. The growth of most animals asymptom- atically approaches an upper limit; thus, growth per unit time decreases. Any fish population is also subject to some mortali- 60 I I I ty, probably through predation and fish- ing pressure. The mortality is re- flected in the size structure of a pop- ulation (many small fi-shes versus few large ones). Using basiQally this in- formation and some assumptions which are reasonably wvell founded, it is pos- sible to calr-ulate a minimum size lirait which will provide a maximum yield. Market preferences and avail- able gear may require mrodifying the figure somewhat, but it may also turn out that some fisheries are, in a senise, self-regulating, in that fish are caught only at or above the recom- mended minimum. The issue that then remains is whether the regulatory agency proposes to control the number of fishermen between whom the available catch is distributed or will permit economi-cs to take its course. In a multi-species fishery, like a coral reef trap fishery, interactions may develop, i.e., if heavy selective fishing removes large predatory species like snapper and grouper, their prey species, including smaller her- bivorous species and lobster, may in- crease in numbers. I I I I I Hogfish (Lachnolaimus-maximus) PECULTAR LOCAL RESTRICTIONS Basic restrictions on the developmrent of large-scale fisheries are imposed by the size of the Virgin Islands Plat'eau and its geological irregularities. While improvements in technology can no doubt increase the yield of varidus commercial species, the relatively smaall plateau areas available for fishi-ng precludes sustained production of vast quantities of most species. I I I I I I Also, while most of our fishery is associated with reefs, the irregular, hard bottom of most of the Virgin is- lands shelf and the concentration of fish in areas of rugged physiographic I I 6 1 a fl relief makes trawling impractical and * ~interferes with the use of bottom set- lines, multiple traps on a single ground- line, and stationary nets of various sorts. * ~The low productivity of the fishery (both in total catch and catch per unit effort) is also a reflection of the naturally low primary productivity (little growth of phytoplankton, the base of oceanic food chains) of Virgin Islands waters. Most primary produc- tion inshore is benthic - coral reefs, U ~algae and grass beds - and most fish are caught in these areas. Much of the open shelf of the Virgin islands I ~is relatively flat but too deep (thus the light is too dim) for sea grasses or vigorous coral reef growth. I ~Thus, while there is room for improve- ment-in fisheries, local conditions which limit production and harvesting I do *not allow development of a fishing industry akin to that of continental - ~shelf areas. queen Triggerf'ish or ola wife (Balistes vetula) Other Coastal Wildlife in addition to strictly marine species, other typical Virgin islands wildlife are found in coastal areas. Many of our birds depend heavily on mangrove areas and offshore cays as feeding and nesting grounds. The mangroves are apparently the major nesting areas of the vanishing white capped pigeon. Most of the doves which fLeed and are hunted,on St. Thomas nest on the off- shore'cays. The common,brown pelican- a permanent resident - is in danger of extinction but nests on some of the cays. Other permanent resident sea birds are brown boobies and frigate 6 2 I birds. Laughing gulls, terns, blue- faced boobies and tropic birds come here to nest on the cays. Coastal man- groves provide protective habitats for several other birds and reptiles (liz- ards and snakes) which are infrequently seen elsewhere. Some offshore cays ap- pear to be the last outposts of rare I lizards, skinks, and snakes. . Coastal salt ponds are feeding areas for ,!; .... several kinds of wading birds, espec-. ially when they are closed from the sea and the birds do not have to compete - '::'' with invading fishes for food organ- - isms living in the pond. . I Chelonia mydas Green turtle 63 ! a Coastal and Submarine Habitats These natural systems, separately and in combination, perform countless valuable functions for man at no cost, drawing energy from the sun. They buffer storm winds and waves, stabilize and protect the shoreline with its expensive man- made infrastructure and facilities, purify water and offer an immense variety of diverse vistas and interest- ing wildlife and vegetation. The habi- tats and their associated processes support the safety, health and welfare of every Virgin islands resident and must be preserved. Different segments of each island contribute in varying de- grees to each particular fLunction, and these elements are treated separately. The following sections describe the major coastal and shallow water marine habitats of the Virgin islands (to 10 fathoms depth). These include beaches, rocky shores, salt ponds, mangroves, coral reefs, sandy sea beds, grass beds, and the offshore cays. Gays, more than other small oceanic islands including the three larger Virgins, are "scoastal't in entirety. Because of their very small size, the entire area of a cay is continually subjected to the in- fluences of oceanic winds and salty air. Also because of their small size, a much higher percentage of their area is bathed by the sea in comparison with larger land masses. Almost all have salt ponds which often occupy a large percentage of their acreage. These factors are strongly determinant of the physiography, -hydrology, soil, vegetation and fauna of the cays. There- fore, it is important to include them in the discussion of the coastal zone of the Virgin Islands. The discussion of each coastal unit procedes from description of charac- teristic physical and biological processes. Attributes, use options and use limitations are based on these natural characteristics. Figures 28 an-d 29 present the distribution of each habitat type and highlight other pertinent information. 6 4 Fig 28 Coastal and Submarine Habitats, St. Croix J 4f-,,, ?' , I. ~._-. .. . ..._ - . ....- �~~~~......... . .~ .. .,. .. _ ,, , , , , .. . , _ - - -- -- - -1,N .... II I" I -------- 11 ( D '-V.- 0 C 0 a) 4 > S C Lesz K >P 0 -VI4 e"nd 0 0 00( Steep rccA_j aflorte Lcn.ti ni/cf rock _ _kI-_oreC Salt oanc_ts It! cun 9ro *3 Man matte (se-a*icwik ,.pk's) &each Areas '1 hig!-, proo/uc-tn-Jly Un,q ac- areas Areas tenSer otress 0 .I U I Frig 29 Coastal and Submarine H-abitagts, St.Thomas and St. John I I I I < tt,Azre i-frCA5---,r kobtaj~ I I u 'N'- I,-. V Shlj ~i-~3 IhrI45 T 0 FR c' 0 . A K� 54ielf kecJo flOln O l k~s 'ciy. irin I I I I I -7- 2 / I 'K i_'<\ L. I Fm I ''_'_,1 I' _L . I I- 7 {'- -, \ \ \\i _&K \y_' %.-_ �- A '_ _ \ p7; k_ V / '_ 2 V I 'C' -. p \+_ \\ "NV _ I I I I I U BEA CHES Beaches are parts of the shore that are covered with sand, gravel or de- bris and which are covered and uncov- ered by the tide. Beach sediments are highly mobile, and thus beaches are con- stantly changing their form and dimen- Beaches are mainly the end product of the interplay of water movements and sediment supplied by cliff erosion or from coral reefs. Beach organisms, how- ever, also contribute to the supply, erosion and consolidation of beach sedi- ments. Beach semiments of the Virgin I Iislands consist of a variety of mater- ialIs. They contain within them evidence of their origin, either terrigenous or I ~marine. SOURCES OF BEACH SEDIMENT The terrigenous material consists of mi-nerals either eroded from cli-ffs or eroded from soils that are transported to the shore by streams. The terrn- I ~genous comaponents typically consist of quartz and feldspar which are light- colored components, or of rock parti- I ~cles which are dark-colored components. Coarse gravel and boulder material is usually of terrigenous origin, but cob- bles often consist of coral debris. The marine components consist of frag- ments torn from coral reefs or frag- I ments of shell and algal bits thrown up from the nearshore bottomi. They are com- * posed of calcium carboniate which imparts a light color to, the sand, compmon'ly white. Coral particles are the maain com- ponent of island beach sand, but the rate of production of coral sediment supplied to a beach is generally low. Calcareous algal particles as Halimeda and Coral- linacaea also contribute to beach sand. Algal sediments are produced faster, but they are exceedingly brittle, readily broken at each joint, and reduced to a fine sand or silt which is easily trans- .ported away from a beach. Beach stabili- ty, therefore, depends on a supply of sediment ei-ther from the land or from the sea which is the main source. Con- sequently, most beach sands are a mix- ture of different types of material that varies in size and composition according to its source and rate of supply as well as according to the wave and current pro- cesses acting on it. BEACH PROCESSES IN PROFILE Most beaches are fashioned into a sloping. foreshore and a flattened backshore or berm (Figure 30) . The foreshore lies between the low water level and the berm crest, whereas the berm lies between the berm crest and the coastline beyond the reach of ordinary waves. The be:rm height gives an estimate of the height of storm waves that can he expected. The beach is backed by a cliff or low dune ridge where- as seaward it faces a shallow nearshoke bottom fronted by a coral reef. The inter- play of waves and currents with different types of beach materials produces dis- tinct profiles. The high energy of wash and backwash acting on windward facing coasts or sides of projecting headlands 70 Ia I I <:- coast ~ -backstlore ....-- noehr- -ea rshore=- dune /berm\ /beach face I breaker ---high waete -- ---~~--low water grz Bs beds Figure 30. Beach profile showing beach terminology and component parts in relation to high and low water. I I I 1 I tions in wave height, wave length and direction. Thus, high energy waves of "northerners" acting on a beach will e- rode the foreshore producing a steep slope and narrow berm (Figure 31). E- rosion is also indicated by undermining of trees, exposure of beachrock and a steep beach face (Figure 32). When average waves of less intensity act on the same beach, they tend to deposit sand and build the berm seaward pro- ducing a gentle slope. These profile I produces steep beach foreshores and nar- row berms. Sediments, too, respond to the high energy by accumulating as coarse sand, gravel or coral debris, Beach- rock is often exposed in lower parts of the profile. Beach profiles not only change from place to place, but also with time at one place as wave energy changes from season to sea- son. The foreshore is continually ad- justing its shape in response to varia-- I I 71 a dune /winter I: - -~~~~ 5 summer - beach . - - - . _m.hw. Figure 31. (dotted). High energy winter profile and moderate energy summer profile Modified from Environment Consultants, 1969. 1. The width of the berm is wider in summer than in winter. Accretion is indicated by several berms. 2. A sharp beach face or scarP indicates beach is undergoing erosion under prevailing waves. 3. The shoreline moves with each wave. Erosion varies with wave height and period. Steepness of the fore- shore varies with wave height and permeability and coarseness of the sand. changes reflect the onshore-offshore I shuttli-ng or exchange of sand between the beach slope and the inshore. In the process, some of the sediment is lost to deeper water; some is pushed landward a,cross the berm to form dunes or overwash deposits. For another part, the sediment is carried laterally along the beach. Changes in the beach profile are in- I ~dicated by the following features. Numbers refer to features in Figure - ~31. 7 2 a I I I I I I Winter storm erosion Grosion leve l subsurface boach rock -beach rock I I Figure 32. Summer and winter profile in relation to beach rock. Modified from Environment Consultants, 1969. I 4. Longshore troughs and bars develop in winter as beach sand moves off- shore. 5. Base of dunes is steep when beach undergoes erosion during high storm tides. Trees and banks may be under- cut and beach rock exposed in fore- shore (Figure 32). By contrast, the moderate energy of swash and backwash acting on leeward coasts or heads of bays produces gentle beach foreshores and wide berms. Sedi- ments are typically fine-grained car- bonate sand. BEACH PROCESSES IN PLAN When waves approach the beach from an angle, the water runs up and over the sand at an angle, but then recedes at right angles to the shore. Consequent- ly, sand which is carried by the receding wave is transported downdrift of its origin. Called littoral drift, this transport is a major factor in deter- mining beach width and slope. In the breaker zone, the residual angle of wave I I I I 7 3 I U The lateral movements of sand result in a change in the width and type of sedi- ment residing on a beach. In general, sedimaent becomes finer with distance away from a headland, i.e., downstream from its source of supply, and also away from the transporting energy source. Consequently, the beach ~ediments like those at Botany Bay (Clark, et al, 1964-65) Are graded along their length from -relatively coarse gravel to coral rub- ble and finally to sand at the other end. Similarly, beach deposits are relatively narrow and t'hick on the coarse-grained end and wide and thin on the fine-grained end, i.e., away from the source. The deeply indented or pocket bays of St. Thomas and St. John display little change in plan. Most changes are on- shore and offshore, and miany of these beach faces show little seasonal change. Sand transport is largely within the bay itself, and the rates of s-and input, transport and loss are more or less in equilibrium. There is little exchange of sediment from bay to bay around the enclosing headland. Typically, littoral drift and longshore currents along sides of the bays drive the sand inward where it accumulates near the current convergence at the bay head. This is the case for Magens Bay beach (Figure 33) where the con- vergence is marked by widening of the berm and seaward extension of the shore- approach creates a current along the shore called a littoral or a longshore cur- rent. The comabined littoral transport is significant in beach stability on re- I latively straight north and south coasts since these coasts are aligned approxi- mately parallel to the direction of wave approach. As a result of waves approach- I ing the west coast of St. Croix at an an- gle, particularly during "northerners," sand is continually transported south- ward by the littoral drift. Thus, the northwestern beaches are narrow and e- roding while the southwestern beaches which receive the sand are broad and I accreting. Along the south coast a littoral drift directed westward also contributes sand. The combined trans- port from the north and the east provides an excess amount of sand to the region and thus tend to extend Sandy Point seaward. Similar lateral movements of sand occur on a single beach as the direction of I predo-minate wave approach changes. For example, at Chenay Day, which *faces northwest on the north coast of St. I Croix, swells from the north and north- east drive sand eastward along the beach,whereas local trade wind waves I drive sand to the west (Environment Consultants, 1969). During winter "northerners," when swells gain height and become more frequent, this change results in a reversal in the net direc- tion of sand transport: east in winter * and west the rest of the year. 7 4 I line in central reaches of the beach (Robinson, T., et al, 1970). Part of the sand may be carried toward the sea by rip currents directed offshore from the bay head. Another portion of the sand may be driven back ashore by waves acting on the central bay floor. Some bays show a 'long-term history of accretion at the bay head, particularly where streams contribute sediment to the nearshore zone. By contrast, bays having deep floors, as Cane Bay on the north coast of St. Croix, permanently lose sand from the beach by transport down submarine channels that terminate 3 close to shore (Multer and Gerhard, 1974). 1% \N >%' \ % I, N "I" ~ I / I / beach Xi d t "d :: ;:-., deposition transport .. tronvsperenc o/ nshore transport headland. / / Nave/approach ( reftracted) I I I I I I I I BIOLOGICAL PROCESSES Although physical processes acting on a beach are the most obvious, organisms are also active in the formation of Virgin Islands beaches. Calcareous algae, coral and invertebrates not only supply most of the sediment to local beaches, but they buffer much wave energy and, in turn, promote accumula- tion on the beach. Once the sand is de- posited, salt-tolerant plants may en- croach on the backshore and stabilize the sand. In some places organic de- bris and grass which inhabits nearshore bottoms is torn loose and deposited on upper parts of the beach. This nearshore grass bed contributes stability to beach sand, acting as a footing to control seaward loss of sand. Island beaches are not rich in animals, but neither are they sterile. A number reef i # J )~l / / / \ J/ ..~~~~~~~~~. ,f~~~~ '" / / / Figure 33. Representation of sand transport in an enclosed bay . 75 I of small crabs, clams, worms, and sand dollars live in the sand between the I backshore and nearshore zones. Occa- sional schools of fish fry come close to shore. The offshore grass beds, i which may lie in water as shallow as three feet, are rich in plants and animals. Figure 34 relates biological features to the physical zonation of a beach. BEACH ROCK Many sand beaches of the Virgin Islands are broken by a ledge of rock that typ- ically runs parallel to the beach and protrudes seaward to the low water line. However, the ledges may be found com- pletely submerged offshore or partly above the high water line or buried with- in the beach under a thick layer of sand. The rock layer itself is often two to. I Beaches OFFSHORE Seagrass zone - large variety of organisms NEARSHORE Bare sand zone - sand dollars, burrow- ing crabs BACKSHORE Sand berm zone ghost crabs, beach hoppers FORESHORE Surf zone - mole crabs, clams COASTAL DUNE Vegetation zone - coconuts, sea grape, dune grass,. ' . . sea pur- ' slane . Figure 34. Profile of a 'beach indicating physical zonation and characteristic organisms. 76 I I five feet thick and mainly consists of calcareous sand and shell debris that is held together by carbonate cement. Fiaure 32 shows the relationship of beach rock to erosion profiles on a beach at Chenay Bay, St. Croix. The mode of beach rock formation is not fully known, but it is generally believed to be formed in place, below the beach surface, by the natural cementing action of ground water as dissolved calcium carbonate precipitates. in a detailed study of beach rock at Boiler Bay, St. Croix, Moore and lianer (1974) indicated that biological activity, contributes to cementation p)rocesses. Intermittant ex-' posure in the intertidal zone also may enhance conditions for cementation. Since recent artifacts and debris are occa- sionally found in the rock, cementation evidently takes place quickly, within a few years. Most beach rock occurs on exposed windw;kard coasts. GENERALIZATIONS ON STABILITY AND EROSION Most Virgin Islands beaches are under- goi-ng erosion at varying rates. Erosion rates are generally greatest on exposed windward coasts especially where the rate of sand supply from coral reefs, streams or cliff recession is low. Beaches on windward coasts are generally narrow and less stable than on leeward coasts inasmuch as they are affected by seasonal changes in wave direction and wave height created by '"northerners" and passing hurricanes. Beaches along deeply indented bays on St. John and St. Thomas are more stable seasona'lly than those on open, exposed bays. Deposition- al beaches, wliich are r-elatively wide and often backed by dunes, occur on coasts having coral reefs that protect the beach and supply sand. A few are associated with intermittent stream deltas, a source of supply at some localities. The most rapid accretion occurs around Sandy Point along the southwest end of St. Croix where the beaches receive a dual supply of sand by littoral drifts fromt west and south coasts. USES BY MANZ Beaches benefit man directly in five ways: (1) they serve as a buffer zone between land and sea within an ocean island system; (2) they are a source of sand used in concrete aggregate; (3) they are sites for recreati-on; (4) they serve as termninals for small boat transportation and sites for small boat repair; and (5) some serve as a place to dump wastes or to store sand. Many were also used for nesting by sea turtles in the past, but turtle nesting on Virgin islands beaches is an extremely rare event now. As a buffer zone, beaches protect pro- perty from wave attack. This use be- comnes important where shorefront real estate has a high value and where dunes lie close to the beach. Instead cf eroding coastal property., the beach has the ability to re-shape itself to the changing physical forces and thus to I I I I I I I I I I I I 7 7 a * ~assimilate wave energy. If sand is temp- orari ly lost offshore, it mav be re- t'urned later under normal wave condi- tions. Similarly, if the be-ach is backed by dunes, sand is often replenished I ~by long-term transfer from the dunes to the beach. Dunes are not only a re- servoir of sand but act as a dike that I prevents massive flooaing of the land by storm tides. Beach sand has been a traditional source of fine construction aggregate in the Virgin Islands inasmuch as there is no river sand. With rapid growth in con- I ~struction during the 1960's, mining of'sana by both government and private groups led to nearly complete stripping of some beaches. At Boiler Bay and East End Bay, St. Croix, sand was stripped down to the underlying beach rock. As shorefront property values in- creased and as detrimental effects to recreation and conservation became rea- lized, the Virgin islands government prohibited mining of beach sand in * ~When large quantities of sand are re- moved from the beach, the natural transport dynamics are affected in several ways: (1) the wave refraction pattern is changed so that sand from both sides of the excavation is moved into the void; (2) sand transported by I ~littoral drift is trapped in the exca- vation. Therefore, less sand is available for nourishing the beach down I ~coast. ,on exposed coasts, removal of large quantities of beach sand results in rapid erosion over the entire beach. The beach slope steepens and the sand becomes coarser. However, on leeward coasts, only a slight local recession of the highwater line is experienced over long periods. A severe swell or hurricane wave attack may cause sudden recession over a wide stretch of beach. -The rate of beach recovery from sand mining is reportedly slow, especially where the nearshore bed is excavated and the rate of sand sUipply to the beach is low as is partly the case for coral sand in Brewers Bay, St. Thomas (Herrick, 1966; Tabb, 1967; Grigg, et al, 1972). Because production of coral beadh sand is slow, erosion caused by sand mining is semi-permanent. Offshore sources of sand on the in- sular shelf provide the best alterna- tive for the longterm needs of an ocean island. A-s zones for recreational use, the beaches of the Virgin Islands have ex- ceptional value. They are best used for short-term contact sports, fishing, beach comabing, picnicking, camping, horse riding, sunbathing, viewing, and as sites of departure for swimnming, surfing, skin diving, small boat launch- ing and SCUBA diving. Recreational uses are described elsewhere in this report. Although most trans-shipment and boat repair is now accomplished at modern 7 8 I I docks and berths, a few beaches in Charlotte Amalie, Christiansted (Nichols, Grigg, vanEepoel, et al, 1972) , and out- lying areas serve as siLtes for launch- ing and off-loading small fishing craft. For early islanders, this was the most useful aspect of the beach. Beaches were widely used by lighters and fish- ing craft as a trans-shipping area in preference to rocky coasts or distant harbors. Around the urban harbors, beaches have served as sites for waste disposal in an effort to fill and to extend low land. For example, a former bathing beach along Frederiksberg Point, Charlot-te Amalie was eliminated prior to 1925 by solid wastes and landfill. A similar case existed along the shore at Truman airport and near Anguilla, St. Croix. Although most disposal is now contained on land, the former fill sites are subject to erosion. Release of former wastes by hurricane presents a potential for pollution of nearshore water. STRUCTURAL MODIFICATIONS Engineering structures intended for the beneficial purpose of shore protec- tion often cause deleterious effects when they interfere with natural pro- cesses. Effects similar to those caused by sand mining take place when indiscriminate alteration of the beach profile is made by developers. Shore protection structures are of three types: (1) jetties and groins intended to interfere with currents and drift that transport sand; (2) sea walls and bulk- heads intended to inhibit direct attack by waves, and (3) beach nourishment by emplacing sand. By interfering with litt oral drift and longshore transport, groins (structures at right angles to the beach) are de- signed to build up beaches. However, they often cause a shortage of sand on the downstream side of the structure and erosion sets in. A groin only fifty feet long at the Mill Harbor condominium on St. Croix created a wide and high beach but caused severe erosion at neigh- boring Turquoise Beach. Failure of groins attests to the lack of knowledge con- cerning the behavior of wave and current processes that they are intended to re- sist. Groins work best when (1) lit- toral drift is significant in volume; (2) the material is at least of sand size (between 0. 062 and 0. 5 millimeter); and (3) when the downstream shore is considered expendable. By absorbing or reflecting wave energy, sea walls may protect the shore, but they do not prevent the loss of sand on the beach in front of them. In fact, they often accelerate the loss of sand by deflecting wave forces downward onto the beach deposits. At LaGrande Princess, St. Croix, construction of a sea wall in front of the Cruzan Princess condominium not only cau-sed the beach to recede 23 feet within one year, but also caused severe erosion on adjoining pro- I I I I I I I I I I I 7 9 0 I ---. - I perty to the east that received much deflected energy from the wall (Environ- ment Consultants, 1969). In short, the structures are often as deleterious as they are beneficial. ARTIFICIAL BEACHES When sand is placed on a beach in an attempt to rebuild it artificially, the natural processes continue essentially unhampered. Beach nourishment not only checks erosion but also supplies sand to adjacent belaches. It is economi- cal when large, quantities of sand are available and when it does not require long-term management commitment, as do sea walls an.d groins. Moderately successful beach land fill and nourish- ment projects >-ve been completed at Protestant - % ear Fort Louise Augusta, Christiansted (Nichols, et al, 1972) and at:Brewers Bay, St.,Thomas (Grigg, et al, 1972). With the sharp rise in.beach property values during the late 1960's, there have been at- tempts to,pump offshore sand onto the beaches at several resorts, notably at Grapetree Bay Hotel, St. Croix. USE IMPACTS As previously noted, mining of beach sand promotes rapid erosion over an entire beach. Often little sand is left to supply dunes or to buffer the shore against hurricane waves. Dredg- ing of sand has caused moderate damage to reefs in Christiansted harbor (Nichols, et al, 1972), in Brewers Bay (Grigg, et al, 1972), but effects else- where are not well known. Although the best use for beaches seems to be for recreation, even these activi- ties tend to destroy aesthetic and recrea- tional values through littering and pollu- tion. Since backshores are washed only during storm tides, trash and litter often accumulate in this zone. A critical factor for upper backshore dune stability is vegetative cover. Dune buggies, motorcycles and over- grazing by animals can be damaging since exposure of the sand to wind and waves can trigger erosion. Without sanitary facilities on a beach, recreational activitiep can have a degrading impact on future use. Together with the addi- tion of solid wastes, they present a potential for pollution of shallow ground water supplies and nearshore waters. Unregulated construction and improperly designed structures present a potential threat to life and property when they fail during storms. Besides accelerat- ing erosion, such structures may result in a recreational hazard as well. Scour holes often develop at the toe of verti- cal walls and broken masses of concrete and steel rod often protrude from dis- placed sections. At Cinnamon Bay, St. John, a rock revetment constructed to protect an old Danish warehouse created wave reflections (rather than energy dissipation) that increased scour at the base of the wall and produced sediment plumes extending offshore onto the reefs (Hoffman, et al, 1974). The wall itself was undermined and collapsed. 80 ---------m I I I I I I I I I I I the beach by absorbing energy, they pre- sent problems for heavily used beach areas. Thick plant growth makes swimming uncom- fortable, while heavy deposition of de- tached grass on the beach produces noxious odors and makes walking and sunbathing uncomfortable. But when grass beds are eliminated nearshore, sands are subject to erosion. Plants comprising the beach litter.mainly are Thalassia (turtle grass) and Syringodium (manatee grass) Beaches are subject to a variety of dif- ferent impacts from time to time, and these may have cumulative effects over the years. For example, dredging or blasting of coral reefs off a beach often leads to a die- off of the reef. In turn, this reduces the rate of reef-borne sand supply and increases wave attack and erosion on the beach. In areas of high ship and motor boat traffic, boat wakes cause erosion and turbidity of nearshore water. Large- scale reclamation of lowlands disturbs the natural equilibrium of the beaches over wide stretches of coast or through- out a coastal compartment. Along some coasts a small change in coastline geome- try or the vitality of mangroves and near- shore grass beds can have a large effect as demonstrated at Estat9 Whim, St. Croix (Environment Consultants, 1971). Human interference with natural processes is one of the major causes of beach erosion in the Virgin Islands. Artificially nourished beaches display the following impact features: (1) a steep beach foreshore or scarp caused by disequilibrium of the beach profile with nominal wave forces; (2) beach material is often coarse-grained and contains coral debris; (3) lowering of the nearshore profile accompanied by erosion of the deposited sand, and (4) ' a lag deposit of coarse, gravel or coral debris often accumulatkes in the breaker zone, while fines are released from the nearshore bed or foreshore, cause a turbidity. These effects often extend to nearby marine commun- ities as turbidity reduces light pene- tration and as the substrate becomes unstable for benthic organisms. Re- establishment of 'pioneer' species in dredge holes and beach fill areas is typically slow (Cronin, et al, 1969; Grigg and vanEepoel, 1971). Additionally, beaches are increasingly subject to the impact of containerized or accidental discharges of wastes in the open ocean. Floatables found on island beaches inc'lude plastics, tar balls, and oil coatings. These typi- cally accumulate on, the upper berm and are deleterious to both the biota and aesthetic aspects of the beach environ ment. Besides long-term accretion of ocean wastes, island beaches are con- tinually threatened by major oil spills from transfer facilities, refining storage and tanker wrecks. Although nearshore grass beds stabilize EFFECTS OF DREDGING Channels and ditches dug across beaches to drain and flush back beach lagoons 81 I II or salt ponds have a history of self- healinq closure shortly after'they are opened. This is well documented at Altona Lagoon and to some extent at Southgate Pond (Environment Consultants, 1971). At Maqens Bay, St. Thomas, torrential rains occasionally overfill the mangrove pond behind the beach causing it to break through the middle of the beach. The resulting canal is reclosed naturally within a few days. Dredginq nearshore beds too close to shore causes sandy beaches and dunes to either erode severely or to slump .away into the dredged hole. The beach at Sugar Bay on the south shore of Water Bay, St. Thomas was lost in this way (Grigg and vanEepoel, 1970). Dredginq and extensions of the shore- line seaward through landfill in Gordon Bay, St. Thomas harbor allowed wave energy to extend farther land- ward than normal and caused erosion of the n6arshore bottom by two or three feet in forty years. The effects of dredging may be ex- tended to distant beaches via near- shore transport.s Serious erosion in Estate Whima, Long Point Bay, St. Croix relates to dredging of the Ness Oil channel five miles to the east (En- vironment Consultants, 1971). In this' case, turbidity generated by dredqe spoil caused a reduction in the near- shore grass cover off the beach. Such grass beds normally absorb wave energy, but waithout them wave energy is entirely expended on the beach. This case illus- trates how beaches may be linked to a sequence of impacts in a chain of causes and effects. ATTRIBUTES, USE OPTIONS *Highlv desirable recreational areas, Besides swimming, provide easy access to snorkelling, SCUBA diving, sailing, water skiing, etc. *Generally protected from heavy seas providing safety for recreational uses. *Plastic nature of sandy shore changes in response to seasonal sea conditions, absorbing wave energy and protecting back shore. USE LIMITATIONS *Sa'nd dynamics make beach unstable for structures. *Structures across beach usually inter- fere with natural sand movement, often having undesirable effects. *Not suitable for sand mining.w-hich usually causes destructive redistri- bution of remaining sand. *Not suitable for discharge of wast-es. Suscepti-lble to aesthetic and micro- biological (public health) degrada- tion. INVENTORY OF BEACHES Locations of beaches on the three islands are shown in Figures 28 and 29. St. 82 I ROCKY SHOR-ES I I Rockyshorelines are here defineld as steep slopes or cliffs formed by weathering and wave action on rock outcrops or promon- tories. These are distinguished from rocky beaches which have a gentle seaward slope but are covered with rock and/or coral rubble. Rocky shorelines vary from vertically exposed rock faces (parts of the wind- ward slides of most islands and cays) to angular sloping blocks of bedrock (north- west St. Thomas) to boulder strewn shore- lines (occurring scattered on all coasts). Occasionally there are eroded outcrops of sandstone or fossil reef areas, particu- lryon southern St. Croix. The shore- line at the tidal level and some distance below is strewn with boulders derived from the land or -eroded projections of the bedrock. Thomas and St. John, because of their more irregular shorelines, have more beaches than St. Croix. in addition, much of the gently sloping shoreline of St. Croix, physically des- cribed as beach, is poorly suited for swimming because of beach rock, near- shore reefs and, in some areas, highly turbid water or exposure to strong sea and currents. On the other hand, be- cause of its straighter shoreline, St. Croix possesses longer stretches of beach than the o.ther islands. The continuous sandy beach from Concordia to'Frederiksted is unparalleled any" where else in the Virgins. I I i I I i ECOLOGY Rocky shores are rigorous envqironments, but far-from sterile. The area above the water supports a few specialized salt tolerant plants and related fauna, but below the water there may be well de- veloped coral growth attached to the bed- rock and boulder rubblel~(Figure 35). Hardy members of the adjacent terres- trial vegetation may cling to the upper- most rocky area where there are pockets of soil or fissures in the rock. Common types are Agave (century plants) , barrel cactus, pipe organ cactus and g-rasses. On some remote rocky cliffs sea birds roost and nest. Lower down where sea I I I I 8 3 U Rocky Shores SPLASH HARD CORAL WEATHERED OUTCROP ZONE ZONE SOFT CORAL ZONE Worn by wind, Snails, Acropora corals Sea fans, Gorgonia on hard bottom. waves and rain chitons, dominate coral Sand cover thin. Water clear. usually to bed- seaweeds. growth on bould- rock. Boulders er and rubble and bed- substrate. rock. :::.::::::::::.:.::::::::::::::: ..So -.-.,,,,,,,,,.,,.;:,,i ....' * , ........ 3.. rubble bottom :::::::::::::::..............:: : ~g .............~ ~ ~ ~ ~ ~~~~~s~8 a:II:::::::::::::::::::::::: :::::~i.:rQ u :::j::::::::::::::::.:::::::::::.............. rubble bottom. 84 a .1 spray occasionally hits the rock a fewA hardy marine animals can be found: peri- winkles and an occasional crab. Closer to the water, the numbers and kinds of organisms increase. In the splash zone oysters, small fish, sea urchins and a wide variety of molluscs can be found, including the edible whelk (Cittarium The underwater rocky substrate is per- fect for coral attachment and the shal- low, clear, turbulent water ideal for their growth. In these areas, coral usually follows the hard bottom con- tour around the land. AdJacent areas - where the shoreline slope is gradual and wave attack is gentler - usually have sandy or intermittently rocky beaches. At the deeper subsea base of the rocky shore, the reef is often composed of sea fans, sea whips, etc. (gorgonians or "soft" corals). Here land-derived boulders and rock mray also be found, but, frequently, the shoreline bedrock is exposed or lies under a very thin layer of sand. Both "hard" and "soft" corals require a hard, stable substrate for attachment. Further offshore, the sand layer becomes thicker, and beds of sea grasses and algae may develop if the water is not too deep. There is almost always a band of bare sand, one or more meters wide, separating the rock and reef area from the sea grass beds. This sandy strip is maintained by browsing fishes and sea urchins which live on the reef and forage on the edge of the grass areas. Because of the steep slope into the water and their usual occurrence on headlands and points, rocky shores are areas of high wave energy and turbulience. T-his activity keeps the water well mixed and aerated and discourages siltation. Because of the immediate shore topography, there is usually no local source of concentrated drainage discharge. ATTRIBUTES, USE OPTIONS *Frequently good spocts for hard. line fishing. *Good spots for snorkelling and SCUBA - often have whelks and lobsters. *Because of turbulence and water move- ment, are relatively well suited to receive treated effluents but outfall must be some distance offshore. *Provide scenic vistas from sea and shore. *Locally may be important rookeries for sea birds. USE LIMITATIONS *Usually rugged and inaccessible, making construction difficult.- *Because of exposure, sites face heavy sea and wind damage in storms. *Rock and coral bottom and turbulence I I I I I I I I I I I I I 8 5 U SALT PONDS precludes safe boat docking and an cho rage. *Lack of topsoil precludes use of septic tank and drain fields. INVENTORY OF ROCKY SHORES Rocky shores are extensive on all is- lands, especially on the north (wind- ward) coasts. St. Thomas and St. John are rockier and steeper than St. Croix, even on their southern coasts. The south of St. Croix is mostly flat with beach shores, although these may he low level rocky or gravel beaches. The distribution of steep rocky coasts on the islands is included in Figures 28 and 29. DESCRIPTION (Figure 36) Most salt ponds are isolated former bays or parts of a bay. Over time, they have become closed by reef or mangrove growth across the bay. The closure may be ac- celerated by sand and rubble tossed up on the shallow closing bank by storms. They may receive outside bay water slowly by percolation through the berm if it is porous enough. Evaporation in a closed pond is very rapid so that the sal-inity increases and the pond, if not replenished from the bay or by r.ain water, will dry up completely leaving crystallized salt on the surface. Occasionally, a pond berm will be breached by storm water from the land or sea, When this occurs, the pond can be reinvaded by marine animals, usually crabs and fishes. These will die off as the pond recloses and salinity increases again. ECOLOGY The biota of a salt pond is very specia- lized and limited compared to that of the adjacent bay, but its ecology is complex and dynamic. Common animals a.re fiddler crabs and larger land crabs (Cardisoma guanhumi) . Several kind of insects which prefer saline environments live or breed there, including a fly (Salina gracilis) and several kinds of midges. Mosquitoes may breed there during brief periods when heavy rains lower the salinity suf- ficiently. Several kinds of microscopic algae float in the water sometimes giving it a green, pink, orange, brown, or red color. other micro-algae grow as-mats on the shallow margins. A number of wading 86 a I ~~~~~~~~~~~~~~~~~~~~~~~~~~~ I Salt Ponds I I Inland man- groves and xe- rophitic scrub,. land crabs Dune or berm of sea sand. Rock, gravel, coral rubble. Beach morning glory, sesuvium, scrub growth, hermit crabs. Red and black man- groves, beach vegeta- tion. Turbid water, usually hypersaline, phyto- plankton, brine shrimp. Mud and silt bottom, algal mats, occasionally mullet. Bay bean, portula- ca, sea purslane, fiddler crabs, wading birds. I I =-- ,~ ~ I 1- -- -?- _5 __ .71 l I I Figure 36. Cross-section of a salt pond. Slopes to beach at right; landward at left. I 87 I U birds (stilts, sandpipers) feed along the edges of the ponds on crabs, in- sect larvae and other small animals. Ponds frequently contain large numbers of brine shrimp (Artemia) which is in great demand throughout the world as food for aquarium fish, aquaculture and research organisms. Thick blooms of Artemia can give the pond water a brownish-pink tinge. If the pond is or has been recently open, it will con- tain fishes (sennet, small barracuda, mullet, tarpon, snook) and marine crabs.. These are fed upon by king- fishers, herons and ospreys. King- birds ("chincheri") martins and swal-- lows frequently feed on flying insects over the water. The local animals and plants associatea with salt ponds are not well known, and the complex ecology of the ponds can only be inferred in simple outline. They have never been studied properly. We do know, that salinity changes over a very wide range. It may concentrate to more than three times that of sea water (over 100 parts per thousand) or be depressed by heavy flooding to al- most fresh water (depending on the volume of flood water, the size of the pond and the permeability of the pond- bay barrier) . Periodic changes of even one-third of this magnitude would cause significant changes in the types and numbers of organisms inhabiting the pond. Slow changes, as by evapora- tion concentrating the salt, would pro- mote a gradual die-off of some forms and a gradual invasion and development of others. There would be a constant, slow modification of the natural community in response to this change. Sudden changes in salinity, as by flood water, causes catostrophic changes in the biota. masses of halophilic (salt- loving) forms are killed while other types, suited to the new, less saline environment, quickly invade the ppnd and become established. Following heavy flooding, many ponds contain great a- mounts of dead halophilic algae, in- sects, etc. These often account for the occasionally bad odor of a pond. Other environmental characteristics of salt ponds are high concentrations of hydrogen sulfide, especially in the sedi- ments (from the decay of dead organiic mat- ter) , high temperature (from isolation with lack of shade) , low dissolved oxy- gen (from high temperature, salinity and .B.O.D.), and high turbidity (from large concentrations of land and pond-derived solids). Although no specific data is available, it is safe to assume that ponds also con- tain higher concentrations of most pollu- tants than, for example, their adjacent associated bays. This is likely because of the natural ecosystem function of salt ponds as buffer zones and sumps. As they are located between the bay and its up- land watershed, they receive and trap most of the runoff from the land, thus protecting the bay. BB I I I Sediment coringsin several local ponds have revealed tlhick layers of terri- genous (land-derived) mud and silt interbedded with layers of organic muck, algal mats and occasional sand lenses. The latter may have been de- posited when a hurricane or other violent storm broke open the pond or threw waves o-ver the berm bringing sea sand into the pond. Somewhere at .the bottom (depending on the age and depth of the pond) lies the original bay bottom and, below that, bedrock. Because most of the upper layers of pond -sediment are highly organic and being anaerobically decomposed, dis- turbing these sediments usually re- leases obnoxious sulfide orders. When these materia'ls are di-spersed, they use up the available oxygen rapidly. This can kill animals in the water. ATTRIBUTES, USE OPTIONS * Act as natural catchment and set- tling basins to protect marine re- sources. * Provide feeding places for wading birds, insectsand fi-sh eating birds. * Low in dissolved oxygen, frequently less than 4 parts per thousand. * Biota limited to few organi~sms which are tolerant of hi-gh and changeable salinity. USE LIMITATIONS Use constraints include, but may not be limited to, the following: *Sedi-ments unstable for foundations; pilings almost always required. *Sediments - fine, toxic, and with high B.O.D. and C.O.D. - can be dangerous to adjacent marine biota if released, *modifi-cation may adversely alter drainage and runoff patterns. *If filled, weight of overburden may, depending on nature of pond sediments, extrude pond sediments at certain points. Overburden may be plastic. *Nature of sediments may limnit use of deep-rooted vegetation on ovjerfill. *Modification will alter or destroy habitat for associated birds. Tolerancesof the system appear to be wide, but this appearance is largely because we know very little about the functioning of the system. All systems and their com- ponents have tolerance limits. Obviously, massive inputs of toxic materials will des- tro)y the ability of the system to function. Filling a pond will completely destroy its function as a catchment basin and aquatic habitat. Opening it to the sea will sig- nificantly change its ecological function and perhaps that of the adjacent bay. I I I I I I I I I I I 8 9 I U INVENTORY OF SALT PONDS The locations of salt ponds on the three main islands are given in Table 3 and shown in Figures 28 and 29. They have been identified from personal knowledge, aerial photographs and various charts. Some very small ponds may not have been accounted for, and some areas with only minimal topographic depressions which hold ver-y shallow lenses of water for shor't periods after heavy rains have not been included. St. Thomas and St. John have many more ponds than St. Croix and, like the many pocket beaches, this is largely a consequence of the difference in shoreline irregularity. Most salt ponds form at the head of embayments, a setting which also favors beach formation. In fact, in most cases, beaches and salt ponds occur together - a characteristic association in the Virgin Islands coastal zone. 9 0 I Table 3. Location of Virgin Islands salt ponds, excluding cays. I I I I I I I I St. John lawksnest Bay (west) Foot of More Hill Newfound Bay Calabash Boom Turner (Enighed Pond) Chocolate Hole Hart Bay Europa Bay Great Lameshur Bay. Grcotpan Bay Kiddel Bay Salt Pond- Drunk Bay Harbor Point, Coral Bay Fortsberg Turner Point Elk Bay Haulover Bay Pond Bay Privateer Bay St. Thomas St. John Bay Smith Bay Foster Point Mandahl Point Foot of Flag Hill Frenchman Bay Little Coculus Bay Coculus Point Bolongo Bay Cabrita Hill Water Point Great Bay St. Thomas (continued) Muller Bay Vessup Bay Krabbepan Point Compass Point Mandahl Bay Smith Bay St. John Bay Red Bay Vessup Bay Great Bay (north) Great Bay (south) Water Point Scott Beach Benner Bay Mangrove Lagoon Long Point Bovoni Bay Bolongo Little Coculus Bay Frenchman Bay Cove between Frenchman and Morningstar Perserverance Fortuna St. Croix Great Pond Bay Robin Bay West End Coakley Bay Chenay Bay smaal I small small small large 2 small 1 large small medium small large small medium small small small small small medium small 1 large 2 small 1 (cove) 2 small 1 very large 1 small 1 medium 3 small 1 small 1 medium 2 small 1 medium 3 small 2 medium 2 medium 1 large 1 small 1 medium large 2 small small large large small medium small small small large 2 large small small small 2 small small small small small very large large very large large large I I I I I II 91 MANGROVES DESCRIPTION Mangrove habitats are limited in the Virgin Islands, probably because of the lack of rivers or streams. The largest areas which did exist have been destroyed by filling for land develop- ment. Mangrove plants, in narrow strips along the coast, are fairly common, but well developed mangrove forests and their associated marine nursery areas survive only at Salt River, St. Croix (Figure 37) and Jersey Bay, St. Thomas (Figures 8 and 18). The greatest mangrove lagoon systems in the islands- Krause Lagoon on St. Croix and Mosquito (Lindbergh) Bay oni St. Thomas- have been filled for land de- velopment. Some of the remaining man- grove plants at Krause Lagoon are slow- ly succumbing to air and water pollu- tion and continued construction. Mangroves are flowering trees which can live in salt or brackish water. Sev- eral different trees are referred to by the common name "mangrove," but the most common are Red Mangrove (Rhizophora mangle) , White Mangrove (Languncularia racemosa) and Black Mangrove (Avicenia nitida). Rhizophora, known as "the plant that makes land," is the most typically recognized spe- cies. It grows at the water's edge, and new seedlings become established to seaward. Besides providing support and hiding places for a wide variety of marine animals, the prop root sys- tem of the plants traps sediments that Figure 37. Salt River, St. Croix, showing drainage patterns and protective reefs. From U.S.G.S. 1954 Topographic Chart. 92 I Mang roves Red mangroves growing at edge of quiet shallow lagoon. Black mnangroves on higher we-t soil, white mangroves on drier inland soil. Red mangrovze prop roots trap sediment, support and shelter organisms, extend shore. Litter contributes organic matter to water and sediments. Lagoonal grass and algae provide oxygen, food, shelter for other organisms. Nurseries for juvenile reef and pelagic fi-sh. I I I I I I I I Figure 38. Profile of a mangrove forest showing typical zonation and associated habitats. I I I I I mangrove is at the water's edge, black mangroves occupy a zone behind and white mangroves are more inland, but still in sand soil. MAangroves, therefore, by their dense coverage and complex root structures at the shoreline, interrup-t runoff from the land and help to trap f1resh water, sediment and debris at the shoreline, thus protecting offshore marine areas from these pollutants. accumulate from the plants or are washed down froma the land. By this pro- cess, the shoreline is slowly extend- ed. Once the sediment becomes rather firmly established, the red rtangroxves die off naturally and are succeeded by other plants, initially black and then white mangroves. This sequence of suc- cession creates a pattern of zonation (Figure 38) in which the pioneer red I 9 3 n ECOLOGY Each year red mangroves drop large quan- tities of leaves and seedlings, all of which do not survive to become new plants. The natural decomposition of these materials sustains a complex food web beginning with micro-organisms and scavengers and culminating in such higher trophic members as snappers, barracuda, lobsters and birds. The nutrients and other food energy sup- plied by plant litter decomposition account for the large numbers and wide variety of plants and animals which are-found in climax mangrove communi- ties. Biotopic maps-have been con- structed for Jersey Bay Lagoon (Figure 38) by McNulty', et al (1968) and for Salt River (Figure 39) by Gerhard and Bowman (1975) Mangroves require certain conditions for establishment and sustenance and, in turn, modify the environment in a characteristic way which further favors their proliferation. Red mangroves grow from a floating cylindrical seedling which may float miles from the parent tree. As these mature, the root end becomes heavier so that it bangs downward with the future leaf end sticking up. Eventually,, the pod sinks. When it does, it maust encounter a muddy or sandy bottom with sufficient nutrients (fertilizer). The water must be shallow enough to allow the seedling to reach air and sunlight. The water must be calm e- nough to allow the seedlings to take root and grow. .These requirements ex- plain why mangroves do not usually estab- lish on windward coasts except where some shoreline features *offer necessary protection and substrate. Salt River, St. Croix, is a good example where pro- tective reefs and the long channel-like embay-ment offer suital�le conditions (Fig- ure 37). By their development, mangrove areas fur- ther promote sedimentation and quiet waters. In turn, expansion of mangrove growth is facilitated. Wildlife diversity in man- grove ecosystems is second only to the coral reefs locally. Considering that .both Jersey Bay and Salt River mangrove areas are immediatelv adjacent to beauti.- ful, rich reefs, these combined environ- ments are incomparable resource pools. But the mangrove forests are by far the most noteworthy because only two such areas remain while we have hundreds of fine reefs. Perhaps because reefs have attracted more attention, we are now in the process of constructing additional artificial reefs. An attempt has not been made yet to construct a mangrove lagoon. The large numbers of fishes, birds, crustaceans and other animals that live in a mangrove area are dependent basical- ly on the nutrients and vegetable matter produced from the leaves of mangroves and sea grasses. This material, is eaten by vegetarian and omnivorous animals. Their excrement and the organic soup from rotting of other leaf litter provide food for 9 4 I14 .I I I I I I I I I I I I Yair d - A u ,. _ 0 1- 500 500 1000 0 K r v v v 0 7k rI yv Q~~~~ V4~~~ y Yy y' Y I' v ' 1' 'v I I/ r YYYY~~ ~~ ~ yr Y V us~~~~~ -, 8j. 1. IN\IZID 4 -W~~~~ v Y VdV cZ~~~~~~~~~~~n _ NI)?i 1~ ALCYOf4ARIAZ-CORA4LLINE 10 Fathoms~-~~ -~ ~ ~ (~) OPLOR/A-ONrASTd?A (Not Shown) 00 A I Figure 39. Marine ecological zones of Jersey Day and Mangrove Lagoon, St. Thomas. From McNuiLty, Robertson and. Horton, 1968. 95 I U *1- - RCANULK) . � jt-.. plankton (single-celled plants, larval 7cli *\ o ........... -� . are eaten by larger animals, including :i:..':{RE SAND D those harvested by man. 5 ~xS ~ ,AN--~ Natural development of mangrove forests ~C ::>~3A.S:C :'- .tends toward the formation of closed ASS.~~ ~ponds. As the plants continue to grow ~,q.,_ ~ G:._~ASr_S : ;'-.---= : across a shallow bar or spit, they may eventually merge with other mangroves or a headland on the other side of a - ~body of water. For a time the water behind the mangroves may have limited communication with the outside through the prop roots or via narrowing channels. \. M~'Such channels may be maintained indefi- N E.'4PEDAD,:,- ,DL Cmnitely if a sufficiently strong current N -~ M-,. ,; ,;,;g- :;; Gruns through periodically. This sweeps sedimentation out of the channels so -~'-', ~-=--:--,---- or: athat they are often surprisingly deep in relation to the general shallows within the lagoon. Current flow and depth also work to prevent new seedlings from rooting and thereby closing the channel. .S�~I ....Under other conditions, however, mangrove growth eventually seals off a body of water. :or a while, high tides may be able to wash water through the mangroves ��ff> s . ; 2 ......... into the pond, but eventually the pond cefflzavt~~IUn~ t is cut off from open water and a salt pond is formed. Salt ponds may also be 'P*>XVt~p=HvL~ila 9formed through a similar sequence by gAts, :I-.- *.'* the growth of a coral reef. They are fAA-. -.fAur, kd' discussed in more detail in.the section _A~ Tfi~~~ <')$ Fon salt ponds. Tidal ponds, flats and salt ponds, therefore, are frequently .20KM. associated with mangrove forests, but they may also develop where there is Figure 40. Benthic communities of Salt River estuary. Source: Gerhard 96 and Bowman, 1975. a I I little or no mangrove growth. Mangrove forests frequently develop at the mouths of streams and rivers. On larger tropical islands and mainlands where these occur, really spectacular mangrove estuaries can be found. Al- though historical records indicate that there used to be several perennial streams in the Virgin Islands, none exist now. Therefore, local mangrove areas are not estuaries in the usual sense except periodically when the guts which terminate in mangrove bays discharge storm water. At these times, extensive lenses of fresh water can be found in the lagoons. Salinity as low as 10.8 parts per thousand (ppt.) has been measured in the Jersey Bay Lagoon after heavy rains. The usual range is 35-37 ppt. Actually, under usual local conditions of low rainfall and intense radiation, the shallow, quiet inner regions of the lagoon experiance considerable evaporation, and salinity in some places may increase above 38 ppt. to higher 'Levels in the backwaters at the head of the lagoon. This condition lhas sometimes been described as a "hypersaline estuary." At any rate, the lack of a regular brackish water zone has several consequences for local mangrove areas. One is that many organisms requirinag low salinities for all or part of their 1life cycle and found in "true" estuaries are absent or rare here. Some of these are species of crabs, shrimap, fish and bivalve mollusks. Besides many com- mercially valuable, edible species, the relatively narrow salinity range precludes the establishmnent of. a host of other organisms which are physio- logically dependent on low or variable salinity. This is a manifestation of a basic biological rule: habitat diversity - at any level - fosters biotic diversity. A furtlher consequence of the local sali-n- ity regime is that since local lagoon inhabitants are adapted to normal or high salinity, when the salinity is suddenly reduced by flooding rain, many of the organisms perish. At such times, large amounts of plant and animal debris from dead and damaged organisms are released into the lagoon water. This organic material has been observed in Jersey Bay to reach a peak about a week following flooding, after mtost of the washed in mud had settled. At such ti-mes, also, phytoplankton bloomis usuaally occur, probably triggered by the unus- ually h_igh levels of nutrients co-ming from the land and the decaying plant and animal matter. Wlithin weeks normal salinity can be re- established by a viariety of forces, and the organisms begin to resume their natuiral mode of existence. Bioturba- tion (the mixing of sediment by animals living in and on it) incorporates alluv- ial mud into the natural sediments. Or- I I I I I I I I I I I I 9 7 a ganic debris is assimilated and water clarity improves again. MANGROVES AS WILDLIFE HABITATS Large mangrove areas provide home and food for thousands of plants and animals. Numerous kinds of birds roost, feed and nest in and around the mangroves. A- mong the more important of these are doves and pigeons, pelicans and the osprey or fish hawk. The cattle egret also roosts and nes,ts in mangroves although it makes a daily trip inland to feed on insects near cattle. Some of our rarer species of reptiles are also found in mangroves, very possibly because they are less accessible to predation by humans, mongoose and domestic animaals. iguanas find good protection there. The small local snake Alsophis occurs in the aersey Bay area as well as ground lizards (Amaeiva) other than marine life, the main wild- li'fe value of the mangroves is as a habitat for birds. Jersey Day Lagoon is a major habitat for about twenty species of heronse egrets, dudes, gallinules, mountain doves, white- crowned pigeons and Bahama pintail ducks. Table 4 lists birds observed in the lagoon area. Several are rarely, if ever, seen elsewhere on the islands, and so the maangrove la- goon is critical for their sur.vival locally. This list does not pretend to be complete. Observations of birds and other wildlife in the lagoon, as Table 4. Partial list of birds from Jersey Bay mangrove lagoon including cays. SPECIES Great Blue Heron Common Egret Louisiana Heron Snowy Egret Clapper Rail White Crowned Pigeon Mountain (Zenaida) Dove Osprey Bahama Pintail Duck Blue (scaly-naped) Pigeon Mangrove Cuckoo Ki.ng Bird Kingfisher B an anaqui t Antillean Crested Hummingbird Brown Pelican Cattle Egret White Tailed Tropic Bird Red Billed Tropic Bird American Oystercatcher Roseate Tern Least Tern SOURCE I I I 1, 2 1 1, 2 1, 2 2 1 2 2 2 2 2 2 1 , 2 2:. I I -i I I Sources: (1) MCNUlty, Robertson, Horton, 1968; (2)-personal observation. 98 I I I 1 I I I I I sand, terrigenous silt. 4. Wide variety of habitats and niches, e.g., shoreline forest, prop root zone, bare sand, muddy areas, algal beds, sea grass meadows, coral areas. 5. Usually receive some degree of periodic fresh water inflow. 6. Subject to greater spatial and temporal salinity variation than other coastal zones (excepting salt ponds). 7. Shallow depths, quiet waters and secluded setting restricts larger predators (sharks, etc.). 8. Usually backed upland by flat flood plain or tidal marsh of black and white mangroves,obuttonwood, marsh plants, etc., which affords protection from excessive siltation. 9. Because of the wide variety of environmental conditions andeco- logical niches in a rather small area, mangrove forests are charac- terized by an unusually wide variety of wildlife, particularly marine life and birds. in most other locales in the islands, has been brief and at scattered times. Fish trapping in Jersey Bay, St. Thomas and Manning Bay, St. Croix (Olsen, Dammann, et al, 1972) , produced 79 and 61 species, respectively, in addi- tion to spiny lobsters. These are only types that enter traps- many species do not. For the species trapped, it was estimated these mangrove areas supported populations of more than 50,000 at Jersey Bay and more than 68,000 at Manning Bay. The majority of the fishes were ones also found on coral reefs. Many of the species trapped in the mangroves were juven- iles or both adult and juvenile, in- dicating that the fishes use the areas as nursery grounds. ENVIRONMENTAL CHARACTERISTICS OF MANGROVE ECOSYSTEMS The following list attempts to identify some of the unique and characteristic physical and biological aspects of mangrove ecosystems that account for their high intrinsic value and pro- ductivity. 1. Energy production (food supply) is high from mangroves, grasses, and plankton. I I I I 2. Protection from strong waves and swell creates quiet water. 3. Relatively rapid-sediment depo- sition via plant litter, biogenic I I 99 B MANGROVE AREAS IN THlE VIRGIN ISLANDS *Jersey Bay, St. Thomas The most extensive system remaining in the Virgin islands. Includes several cays, salt ponds, lowland marshes and reef areas in about 850 acres. *Salt River, St. Croix - Second only to Jersey Bay in size and complexity. *Manning Bay, St. Croix - South of the airport and racetrack. Small area stressed by effects of nearby open shoreline garbage dump (now closed) and heavy industrial area. Very rich fish population. *Great Pond, St. Croix - Primarily black mangrove. *Westend Salt Pont, St. Croix - Mostly black mnangrove. *Altona Lagoon, St. Croix. *Krause Lagoon, St. Croix - No longer exists. Lagoon filled. Somae plants of all three species remain mostly in nearshore bands, but suffering from. effects of industrialization. * Miscellaneous small patches on the perimetek of most remaining undis- turbed salt ponds. These areas are located on Fiqures 28 and 29. * Lameshur, Leinster, and Coral Bays, St. John have small s-tands of mangroves. I CORAL REEFS I I A tropical coral reef is a complex assoc- iation of hundreds of kinds of plants and animals, Corals are the dominant organ- ism in terms of area coverage and, more importantly, they comprise the basic phy- sical structure of the reef. Corals are colonial animals. The pores in a piece of coral each contain a small animal - a polyp. One of their life processes is extracting soluble calcium carbonate from the water and precipitating it in solid form to comprise the rock skeleton which surrounds the polyps. Coral colonies grow by asexual budding - polyps spli-t into two. This increases the size of the colony laterally and upward. New growth piles up on top of old skeletal material, so that below the living part of the reef there may be hundreds of feet of fossilized coral rock from previous reef growth. Corals can also reproduce sexually. Periodically, the polyps expell clouds of eggs and sperm into the sea. Ferti- lization results in a mnicroscopic larva which is distributed by ocean c-urrents. After a period of development in the plankton, the larva settles to the bot- tom. If they encounter suitably clean, hard, stable substrate, they attach and begin a new colony by budding. Many of the planktonic 'Larvae are eaten by other animals, including coral colonies which feed by filb~ring a host of small 'Plants, animals, eggs and larva from the water. Corals as a group require warm water and their global distribution is generally confined between the tropics of Cancer and Capricorn. They also require clean, clear water so that withi-n suitable tempera- tures their occurrence is also locally interrupted in areas sub)ected to out- pourings of large ri-vers and pollutants. Close relatives of the stony, reef build- ing corals are the gorgonians or soft corals. These include such forms as sea fans, sea whips, and sea pens wihich are commo-n on reefs. As a group, they tend to do better in deeper or murkier water than the hard corals, although there are numerous in- dividual exceptions. Coral reefs are common characteristic features of the islands' coastal zone and are of fundamental environmental and economi-c value. Besides their intrinsic beauty which is apparent only to the relatively few who observe them directly, they are important as producers of sand for natural and man- made beach cover and for construction. As such, they represent one of the territory's few naturally replaceable resources avail- able for extraction. Reefs also provide pro- tection for harbors, shorelines and shore structures by abatement of waves and dis- sipation of their energy which otherwise would be expended on the shore with great force. Thirdly, reefs provide perhaps the largest portion of seafood presently har- vested in the islands. most species of fish consumed locally either li-ve on the reefs or depend on them in some measure for their food. Lobsters, too, are taken I I I I I I I I I I 101I U - as well as shells and sand - is composed) is produced at the average rate of 0.32 pounds per square foot per-year. Roughly half of this was in reef framework and half was sediment. Many fishes, crus- taceans, echinoderms, sponges, mollusks and algae chew off pieces of coral or bore into it. Waves and other physical forces break off pieces. Physiological and physical factors slowi down the rate of coral growth as the colony reaches the water surface. The surface ex- periences greater flu.ctuations in tempera- ture, salinity and pollution levels. Corals near the surface are subject to wave destruction and at low tides may be exposed to drying and heating. These factors operate to slow down and finally stop reef growth as it reaches the water surface. Oneestimate indicated that rasping reef fishes alone (parrot fishes in particu- lar) , by feeding on the coral, rede- posited about 108 grams of calcium car- bonate per square meter per year. This is one route for sand produc~tion. Others are via wave breaking and grinding of coral and other plant and animal skele- tons. Other organisms contributing to sand production are certain algae, mollusks, crustaceans, echinoderms and foraminifera. In short, an animal or plant with a hard shell or exoskeleton will contribute to the sand supply when it dies or is killed and its hard parts disintegrate. In some localities, species of green algae whic-h deposit calcium carbonate in their tissues (e.g. , primarily from reef areas. The new sciences of mariculture and marine pharmacology promise to bring even more awareness of the productive capacity of reefs and probably greater pressures for their exploitation and the need for sound * management. REEF ECOLOGY Reefs are among the most diversenatural. I communities and in terms of produotivity are comparable to prime farm land. Pro- ductivity - the rate at which inorganic carbon (from the water in the case of I marine plants and from the atmosphere in the case of lan.d plants) is converted to plant tissue - is rapidly ut-ilized by other reef organisms for community main- tenance and growth. This primary pro- duces oxygen for the support of respira- tory organisms both on land and in the sea. Most studies of reef productivity have been conducted in the Pacific, but the results are generally applicable to estimates of production on other tropi- cal reefs. These studies indicate reef height increases at 8 - 13 millimeters I. per year. This actual net increase in reef height does not represent the total *gross growth and production of the reef flcorals because their structures are con- stantly being reduced by living and physical forces. One Hawaiian study estimnated that calcium carbonate (the mineral material of which coral skeletons 10 2 ! I Halimeda) can account for large volumes of sand, sometimes piled in deep de- posits where the plants are numerous and wave action does not rapidly dis- perse the resulting sediment. It is often possible by microscopic examina- tion to determine the origin of sand particles and sometimes to estimate roughly the percentage contribution from various organisms. The biogenic origin of sand makes it a renewable natural resource which, pro- vided proper management is employed, can be harvested indefinitely within rates which will allow for its replenishment. The problem in most cases - as it is with the utilization of any renewable resource - is that not enough is known about local rates of replenishment, sources of production or factors con- trolling it. Given other suitable conditions, reefs develop upon hard, stable substrates: rocks or other reef structures. Small reef areas occur at the base of most rocky promontories. Patch reefs of various sizes occur scattered in many areas. Long offshore barrier reefs, roughly parallel to the shoreline, have developed on the edges of ancient is- land platforms now submerged (Figure 41). ATTRIBUTES, SENSITIVITY AND CONSTRAINTS Attributes of reef areas include the following: Valuable production of marine life including most species harvested for food. Scenic value for underwater recreation. Educational value. * Shore protection by sea, abatement (energy absorption). * Sand production. * Produces other potentially valuable products, i.e., anti-biotics, other drugs, sea urchins, precious coral. Tolerances are known mostly in a general sense relating to reef building corals as a group. Corals are generally acknow- ledged to have a narrow range of toler- ances to many environmental variables. These limits vary, however, with species and with the setting. The following are some general descriptions of forms with differing sensitivities; blanket state- ments are difficult and at best broadly applicable. * Temperature tolerance 160 - 36� C, optimum development between 230 - 250 C. Salinity below 25 parts per thousand (ppt.) or greater than 40 ppt. usually harmful. Optimum for most appears to be 34 - 38 ppt. * Siltation - tolerances of various local species vary widely and has not been quantified for most. Reefs are generally considered to be relatively susceptible to continued heavy silta- I I I I I I I I 103 a Coral Reefs - LAGOONAL INSHORE Sand and grass areas leading to shore beach or mangroves. Abun- I Idant bottom fauna among plants. LAGOONAL PATCH REEF Quieter water. Finger corals common forming large masses to four feet high. Numerous small fishes and invertebrates. Sea grasses often on surround- ing sand. BARRIER REEF CREST Dominated by elkhorn and staghorn corals. Deeper face with organ pipe and other hard,corals, sea fans, sea whips, Abundant fish and invertebrates. 16 9F1 4> Figure 41. Diagramatic profile of an offshore reef system. Seaward barrier Iv reef drops to deep water. 104 I i I *Turbidity - corals contai-n symbiotic algae which are critical to the life of the coral. These algae, if not the coral polyps themselves, require light. T.hey apparently produce oxygen which is used by the coral polyps. Because light is absorbed rapidly as it penetrates the water, reef building corals are seldom found below 150 feet in clear water. Real-ly *good reef growth occurs in 90 feet or less. In turbi.d water the amount of light reaching the bottom is further reduced. Prolonged light reduction may alter the species composition of a reef or kill it completely. Specific light requirements for corals are not known. It is reasonable to assume, however., that local reefs, accustomed to very clear water, are very sensitive to light reduction. This assumption seems proven by qualitative observa- tions on reefs subjected to prolonged turbidity. *-Eutrophication - enrichment of water in the vicinity of reefs may he bene- ficial up to a point. Corals are filter feeding animals and take'fine digestible organic matter and small organisms from the water. Enriched water may increase the supply of these items but will also increase the growth of algae and other forms which can overgrow, smother and comnpete with the corals for food and oxygen. in addition, enriching nutrients in ex- cessive concentrations can be toxic or be accompanied by substances toxic even tion. The definition of "heavy" is not available in the literature. Corals have a limaited ability to cleanse t11hemselves, but may expend too much energy in eliminating non-nutritive particles or may be literally smother- ed. organic sediiment, particularly, can deplete the oxygen supply to lethal levels. Siltation is closely related to turbidity, being caused by solid parti-cles, and their effects may be difficult to separate. A great deal of siltation occurs during most dredg- ing operations as fine-- particles set- tle slowly and siltation, therefore, can continue for some time after dredg- ing and may occur at far removed sites. its effects can be catastronhic for sessi-le organisms. If the rate of fall- out is too great, many sedentary organisms, particulax ly corals, are literally smothered if they cannot cleanse themselves rapidly enough. Beyond this, the coating of the sub- strate by silt size particles is dis- advantageous to the settling of most invertebrate larvae and so recoloni4- zation is obstructed. Such surfaces are favored by some species of algae which give the advantage of stabiliz- ing the bottom, hut also effecti-vely exclude the establishment of reef- builders. In fact, such alterati-on of the environment has been known to banish corals forever from an area where they were formerly well-developed. I I I I I I I I I I I I I105 I a discharges lowering salinlitY below 30 .Ppt. can be expected to affect reef composition. Sediment and other pol- lutants in the discharge can be harm- ful to reefs. Sewage discharges add a wide variety of ingredients to th'e water which have a number of effects. The more obvious contributions of sewage are lower salinity, high oxygen demand, high nutrients, turbidity, sediment and toxic compounds. REEF INVEiNTORY ShQreline reef areas and major offshore reef banks are shown in Figures 28 and 29. An original detailed bottom map of the nearshore area to ten fathoms has been prepared as a segment of this stu- dy but is not included with this report. It is available at the Virgin islands Planning Office. Reefs of various types and sizes are widespread and common around the is- lands. Mbst of the best examples of extensive reef development are on St. Croix where the submarine shelf is es- pecially wide and relatively shallow. The more notable are Long Reef at Chri- stianisted, Buck Island Reef, Tague Bay Reef, Long Bank on the east end, Great Pond Bay Reef and Long Reef on the south central coast. The latter has been extensi-vely dama ged by industrial development. On St. Thomas large, well developed reefs occur at Long Point, fronting the mangrove lagoon, at Flat in low concentration. Artificial enri- chment of naturally low-nutrient envir- onments is a dangerous business and not to be recommended generally. simple com- mon sense dictates against eutrophying an ecosystem which has developed axnd flourished under native conditions. Use constraints and limitations for reefs derive primarily from their relatively stringent environmental requirements. The following are some representative activities inconsistent with the main- tenance of healthy reef ecosystems. *Effluent Discharges - any discharge ex- cept almost pure sea water may be ex- pected to have some detrimental effect on a reef. Fortunately, the location of most reefs in active, flowing water, us- ually assures rapid dilution and di~s- persal of pollutants. Only a relativ- ely small area immediately surrounding the discharge may be affected, but this . depends on the nature and rate of the discharge and the effectiveness of dis- persal. Hot discharges, although they may be clean, are nevertheless destruc- tive. Most tropical organisms exist near their upper temperature limits. Corals, made up of countless minute in- dividual delicate polyps, have an ex- tremaely high surface to mass exposure. Heated effluents mounting water temper- atures above 300C will adversely affect many corals. Prolonged temperatures above 400C will kill most corals. Pro- longed exposure to hypersaline dis- charge elevating salinities above 4Oppt. is detrimental to reefs. Fresh water 106 SANDY BOTTOMS Cays off the southwest coast and at Tri- DESCRIPTION angle reef just east of the harbor en- Sandy bottoms are defined as areas with, trance. On St. John large reefs occur at most, sparse sea grass or algal coy- at Ramshead on the southeast and Johnson er. reef on the northwestern coast. Large areas of sandy sea bottom are scattered throughout the platform. Sometimes they occur in shallow bays without apparent reason, as most shal- low bays are vegetated. The most ex- tensive areas of essentially bare sand occur below 60 feet depth. Even here, the lack of extensive plant growth is not easily explained, but may be due to low light intensity and/or the nature " ? of the sediment. Another possible ex- planation may be that the sand is shift- ing at a rate which prevents plant es- tablishment. .....These areas are not, of course, barren. They usually support scattered algae and the flowering plant Hlalophila. Oc- casional sponges, anemones, tunicates and small solitary corals are usually present (Figure 42) especially where there is some solid object - usually a ~Q"~ .:::<: '/ iiiiiiiiipiece of debris - for attachment. Bot- tom fishes are few, but lizard fish and tile fish are not uncommon. Conch, es- pecially the small fighting conch, and hermit crabs may sometimes be numerous. The preponderance of animals in this habitat are infauna, burrowing or tube dwelling forms in the sand. Among the most numerous are several kinds of worms which may occur in densely packed beds. A large variety of mollusks, 107 U I Sand Bottoms Dominated by sand, usually with worm and shrimp burrows and hummocks. Thin, slattered coverage of algae, grasses, sponges, occasional solitary corals and fish (mostly pelagic with few bottom-associated types). I *C"ch"~-h-"^"~`~`rr")`^~LCIC-O=Ch~L*~~- 1~-121'~ &41 & V80 4; 14 q`g~'O 4o *"-9' > 41-0 V Figure 42. Profile of a sand-dominated bottom, usually grades into a reef or grass area. 108 108 v GRASS BEDS I I I I I I I I DESCRIPTION Grass beds are frequently referred to as marine pastures because they are areas of thick growth of sea grasses and algae resembling pastures on land and serving essentially the same func- tions. Most inshore bay bottoms are covered with such pas'tures as are some extensive areas outside of bays. The distribution of a marine pasture is controlled by a number of factors in- cluding sediment quality and stability, depth, water clarity, currents, graz- ing by herbivorous animals and, in some instances, factors which are not apparent. The pastures usually do not extend below 60-70 feet depth. Their growth is interrupted in channels or other areas with swift currents or in surge areas when the sediment is con- stantly tossed, for example, close to a beach. Their edges are grazed away near reefs or other solid objects by fishes and sea urchins which live there and for- age on the edge of the pasture. Thus, there is almost always a band of bare sand between a reef or rubble pile and the surrounding pasture. The dominant plant in local marine pas- tures is turtle grass (Thalassia test- udinum). The second most abundant is manatee grass (Syringodium filiforme) a grass with thin cylindrical blades (about one millimeter diameter) . A third, less frequently encountered grass is Diplanthera wrightii, various- ly called shoal grass or eel grass, crabs and shrimp live in the sand. Most of these animals are rarely seen unless the sediment is dug up. Many are noc- turnal feeders and when they emerge at night, fish, lobsters, rays, sharks and other predators from adjacent areas move in to feed on them. ATTRIBUTES, USE OPTIONS Sandy areas are not well understood, and the extent of their significance to re- gional ecosystems is unknown. It may be that they represent areas of active sand transport via which sediment is slowly moved inshore and offshore. They are pot- entially good sites to consider for sand mining providing the depth is not finan- cially or technically prohibitive and that adjacent, more sensitive resources will not be unduly affected. As a group the associated organisms are relatively tolerant of turbidity and silt- ation. This, coupled with the usual deep- er open water location of sandy areas, makes them more suitable than most other habitats for effluent discharges. LIMITATIONS, USE CONSTRAINTS Limitations on uses of sandy bottoms de- rive principally from their relative in- accessibility. Possible limitations de- riving from their environmental import- ance are, at best, speculative because of the degree of their importance is un- known. INVENTORY OF SAND AREAS Sandy areas are mapped on separate charts available from the Virgin Islands Planning Office. I I I I I I _09 U pastures, but more important, a larger variety of others come here to feed on the plants and myriad creatures that live here. This is the habitat of the queen conch (Strombus gigas) and feed- ing grounds of the sea turtles. A di- verse group of animals live in the sand between the plants, and the bottom is often heaped into mounds marking the burrow entrances of large worms and shrimp. Grass beds help to stabilize the sand, and where they front a beach it has been postulated that they act as a "footing" to retard seaward loss of sand from the beach. There is a very close knit relationship between the plants and animals in this habitat, both spatially and physiolog- ically. The pasture is a low profile environment. The plants usually do not exceed eight inches in height, and all but a few of the associated animals live within this zone or in the sedi- ment. Thus, except for visiting for- agers and predators, the majority of community energy cycling goes on in close quarters. Wastes from the anim- als are utilized by the plants which produce oxygen and forage. Mild enrichments of the water as by small continuous sewage discharges can caupe affected areas of grass to grow extremely rapidly and produce long leaves. Prolonged enrichment usually encourages atypical species of algae, indicative of pollution (Ulva, Enter- although elsewhere these common names ap- ply to other species. On some shallow banks with fine sand, Diplanthera may form large beds as on the inshore south coast of St. Croix. The three plants are usually referred to as sea grasses. They are unlike the majority of marine plants, which are algae, in that they are true flowering plants. Annually they produce flowers and seeds. However, the prolific growth is mostly due to spreading via run- ners with emergent shoots. A fourth flo- wering plant, often found intermixed in small amounts in the grass beds is Halo- phila baillonis, but it is more common in deeper water where it sometimes dominates the flora. Scattered among the sea grasses in the pasture is a large variety of algae in various shapes and colors (Figure 43). However, the largest and most numerous are staked greens. Commonly encountered genera are Penicillus (shaving brush), Udotea (fan algae) , several species of Caulerpa and Halimeda which has hard cal- careous blades and becomes sand when it dies. ECOLOGY Marine pastures produce a significant amount - perhaps most - of the oxygen generated in local inshore waters. On a bright day dissolved oxygen over a healthy grass bed will exceed the satur- ation value (i.e., the water becomes sup- ersaturated), and small bubbles rise from the leaves to the surface. Several species of small fish live in the 110 Grass Beds Primarily turtle grass with various green algae. High oxygen and biological productivity. Great diversity of inhabitants, many edible species: turtles, conch, fishes. Stabilizes and assimilates wastes, and absorbs wave energy thereby protecting adjacent beaches. _4-6 I (_11 _1_10 lp -n S:_O 414 .4 w 6.< - I I Figure 43. Typical shallow water sea grass bed. 111 3 bidity is degtructive. Quantitative tolerances have not been determined. DISTRIBUTION OF GRASS BEDS Shallow water sea qrass bed's are widely distributed in the islands. Major dis- tribution patterns are shown on large scale charts available' separately from the Virgin Islands Planning Office. omorpha, Cladophora). For unexplained reasons, patches of grass removed by various means (dredging, boat anchors) may not be replaced for years. In most bays which have been dredged, the marine pasture has not become re-establi- shed in the dredged areas for many years. in the case of Lindbergh Bay, St. Thomas, 40 years have elapsed, and a barren hole remains off the western portion of the .beach. Even small swatches cut by an anchor, a dredge or a boat's propeller may remain bare for a year or longer. ATTRIBUTES, USE OPTZONS *Grass areas have mild capabilities for assimilating wastes, but gQod flush- ing of the overlying water is advan- tageous. *Usually are associated with clear wa- ter, but can tolerate some increased turbidity; limit has not been guant-. i fi ed - Associated animals can remove silt from periodic flooding, incorporate it in sediment and "cleanse" the bot- tom. LIMITATIONS, USE CONSTRAINTS *Once destro.yed, marine pastures us- ually require a long time to recov- er. Deep holes may never recover. *Since the community is dom.inated by plants a critical m-inimum amount of light is needed. Chronic, heavy tur- 11 2 a OFFSHORE CAYS I I I ment of Conservation and Cultural Af- fairs is presently preparing an atlas of the cays in an attempt to draw at- tention to their value and uniqueness. This document should be a useful man- agement tool. Among the birds which hest on our cays is the brown pelican, a species which is in danger of extinction. Resident colonies breed on Whistling, Congo and Dutch Cap cays off St. Thomas and St. John and on Buck Island, St. Croix. A large colony of terns nests on Flanagan Island. The beautiful tropic birds nest on some cays, and mountain doves .use most cays, but favor Turtledove, Saba, Buck, Capella and Flat Cays. Oth- er important nesting sites are Little Hanis Lollick, Cockroach, Sula, Sail Rock, French Cap, Kalkun and Dog Is- land. The salt ponds on most cays seasonally harbor some ducks, including the loc- ally rare Bahama pintail. One attribute of the numerous cays arouind St. Thomas and St. John is their abatement of large ocean waves and swell and protection of the coastal areas of the main islands. ATTRIBUTES, USE OPTIONS *Unique wildlife habitats, mostly mon- goose-free. *Usually have unspoi led reefs. *Provide coastal protection for main DESCRIPTION The small offshore islands vary in size from bare protruding rocks to over 170 acres. Most are 5 - 50 acres. A few are inhabited by one or two families - and many are difficult to get onto even by boat. Simple rock protrusions like Booby Rock, Sail Rock and Cricket Rock serve mainly as roosting and nesting sites for sea *birds. The larger islets have beaches, rocky shores, cliffs, and some vegetation, mainly xeric scrub. Most have at least one salt pond and are surrounded by some degree of reef development. Most off the more than 60 emergent rocks and cays are around St. Thomas. ECOLOGY Because of their remoteness, the cays are popular nesting sites for many local birds~ including migratory sea birds and are the last remaining local rookeries for sever- al species. Although they usually harbor rats, with a few exceptions there are no mongooses. A major exception is Buck Is- land, St. Croix. The lack of these voc- acious predators permits ground nesting by many birds and the su_rvival of some lizards anid snakes which have been exti-r- pated on the mai-n islands. However, con-- siderable poaching of sea bird and dove nests as well as illegal hunti-ng has been practiced by man, despite the prohibition of hunting on publicly owned cays at any time, a law which is difficult to enforce. The value of the cays as bird sanctuaries has been stressed in the past (McNulty, Robertson and H-orton, 1968) and Dr. Arthur E. Dammann of the Virgin Islands Depart- I I I I i I I I I I 1 13 I 2 islands. * Most are suitable and recommended as wildlife sanctuaries, others as re- creational parks or multiple use re- sources in keeping with their fragile nature. LIMITATIONS, USE CONSTRAINTS * Small size, easily subject to envir- onmental damage. * Lack fresh water resources. * Exposure to drying wind and salt spray. * Many poorly accessible. 114 I I Table 5. Inventory of offshore cays. Elevation Acres (Feet) Beach Shore Rocky Shore I Booby Rock Bovoni Cay Brass, Inner Brass, Outer Buck I., St. Croix Buck I., St. Thomas Capella I. Carval Rock Cas Cay Cinnamon Cay Cockroach I. Cocoloba Cay Congo Cay Cricket Rock Current Rock Dog Island Dutchcap Cay Fish Cay Flannagan I. Flat Cay, Big Flat Cay, Little Frenchcap Cay Grass Cay Green Cay, St. Croix Green Cay, St. Thomas Gr. Hanslollik I. Lt. Hanslollik I. Hassel I! Henley Cay Kalkun Cay Leduk I. Lovango Cay Mingo Cay Patricia Cay 0.5 50 128 108 179 41 22 0.5 16 1 19 1 25 3 0.4 12 32 3.5 21.5 3 0.4 10.5 49 13 0.7 489 100.5 139.5 11.5 3.5 13.5 118 48 33.5 35 75 256 412 330 125 121 67 99 32 151 36 170 46 13 78 278 21 127 32 11 183 230 63 24 704 204 267 70 73 85 255 186 75 all north, n.w. all north all all all east all all north north all all all all all north, east, south scattered scattered all no., so., east, west north, northwest south, east no., so., east, west no., so., east, west south, east, north northeast, west all - north north, east north, west, east I (all mangroves) east, so., west, n.e. south northwest I I I I II I I I south south west scattered scattered south southeast, east west northeast, southeast southeast west south - south west, south south s outh (mangroves elsewhere) I I I ].15 U Elevation (Feet) Beach Shore Rocky Shore Acres Pelican Cay Perkins Cay Protestant Cay Ramgoat Cay Range Cay Rotto Cay Saba I. Sail Rock Gr. St. James I. Lt. St. James I. Salt Cay Savanna I. Shark I. Steven Cay Sula Cay Thatch Cay Trunk Cay Turtledove Cay Two Brothers Water I. Water Lemon Cay West Cay Whistling Cay 4.5 0.5 4 2.7 4.6 2 30.3 1.6 156.8 68�7 55.8 173.3 1.25 2 1.8 236.8 1 3.8 0.4 491.4 0.7 40.3 18.6 15 25 33 30 25 33 202 125 175 142 242 269 32 32 100 482 48 50 10 294 35 121 202 all all east all all south, west, east all all scattered north, east, west all all southeast, southwest all north east, northeast, west north, east, west all scattered south, west, north scattered north west (all mangroves) north north scattered south northwest, rubble south north, northwest south scattered southeast scattered south 116 I I Other Marine Resource Elements Although the waters of the island shelves are noticeably low in dissolved nutrients (nitrates, phosphates, silicates) and of uniformly warm temperatures down to about 125 feet, the deep water of the submerged shelf faces and trenches is cold and high in dissolved nutrients. This deep water is below the photic zone, the depth limit at which sufficient light is available for grass, algae and plankton growth which would use up nutrients. The lack of cur- rent upwelling prevents this water from reaching the photic zone and enriching the upper levels of coastal water. Thus, this denser (colder, richer) water is stratified and essentially confined ver- tically. Temperatures in the deep basins are 5-10� C and nutrient concentrations are up to 200 times as high as surface water. These temperature and nutrient differentials are a potentially valuable resource of enor- mous scale (Gerhard and Rohls, 1970). Off the southeast coast of St. John and the north coast of St. Croix deep water occurs fairly close to shore. If drawn to the surface, this cold water is pot- entially valuable for mariculture, in- dustrial cooling, fresh water production by condensation, and power generation. Columbia University's mariculture re- search project at Rust-op-Twist on St. Croix's north shore has proven the tech- nical, if not the financial, feasibility of the mariculture aspect. For other ap- plications, considerable technological development is needed, but the possib- ilities are certainly worth exploring. Discharging the high nutrient water in- to the coastal waters is an aspect that deserves to be monitored closely for adverse effects. Of the innumerable species of marine life around the islands, only a handful are presently used by man. A consider- able number of others are suitable for food and other uses but have tradition- ally been ignored. Snails of the genus Astrea occur in similar habitats to Cit- tarium (the welk) , sometimes in large numbers. While they do not grow as large, they reach sizes comparable to that of harvested welk and are just as tasty. The small fighting conch (Strom.- bus pugilus) frequently occurs in large aggregations at accessible depths, is similar to queen conch in taste and is larger than all but the largest welk, which are extremely rare. A crab of the family Portunidae, similar to the North American blue crab, but slightly smaller, has been taken incidentally in local fish pots for years but never con- sidered as a food item, The Virgin Is- lands Division of Fish and Wildlife is now trapping seiectively large numbers of these crabs from flat bottoms great- er than 100 feet deep. Their work in- dicates that this crab is numerous on most of the deep, flat shelf areas a- round St. Thomas. Recently in California a commercial I I I I I I I I I I I 117 a Black coral grows very slowly, and har- vesting needs to be regulated to avoid extirpation. Research on growth rates of Antipatharia is currently being car- ried out in Curacao at the Caribbean Marine Biological Institute. fishery has been developed for spiny sea urchins similar to our Diadema antillarum (sea egg). The roe is extracted and used as a sort of "caviar". In some other West Indian islands the roe of the larger short-spined sea urchin Tripneustes, which also occurs locally, is relished as a del- icacy. Shark meat and by-products are in great demand all over the world. They are fish- ed in other parts of the Caribbean and the world, and a small venture had been oper- ating locally for a time. There is a mar- ket for virtually every part of a shark. The meat is used as human and pet food. The skin is used like leather for a var- iety of products, and vitamin rich oil is extracted from the liver.' Other parts including fins and eyes are marketable for various uses. There probably are suf- ficent numbers of sharks in local offshore waters to support some commercial effort. Various kinds of precious coral occur loc- ally, mostly at depths beyond 100 feet. These are bush or tree-like forms with hard horny skeletons which can be polish- ed to a rich texture and color, The most popularis black coral (Antipatharia) which occurs locally. Other precious cor- als are pink, rose or white, but their oc- currence locally is unknown although pos- sible. Precious corals are made into jew- elery which brings a good price. Trad- itionally it is harvested by SCUBA divers, but recently in Hawaii commercial collect- ors have begun using a submersible vehicle with mechanical arms. 118 Fn an Is yfs. . a L' 1at"o'SM' SALT POND - BAY ASSOCIATIONS (Fig. 45) Dominant features: protected bay with sea grass bottom and beach shoreline sometimes with near-shore patch reefs, hypersaline and separated from sea by sand or pebble beach and berm combin- ations, often surrounded by mangrove. Characteristics: very low energy water motion in bay, pond acts as catchment and filter for flood water from land, usually supports wading birds and other wildlife in associated mangrove. Suitability: low energy bay usually good for watersports, boat anchorage. Pondp may be filled for development or opened for marinas. Restrictions: structures on filled ponds need pilings, opening of ponds can release fine sediments and toxins to upset bay organisms and water qual- ity. Filling or opening pond incurs water quality stresses on the adjacent bay. SAND BEACH - GRASS BEDS ASSOCIATIONS (Figure 45) Dominant features: sandy beach, with gently sloping bottom leading to sea grass and algal pasture on bottom of protected bay. Characteristics: beach sediments, grain size and profile change const- antly in response to wave and currents. Sea grass acts as stabilizing factor in offshore movement of sand. Plants I I I CGassfica',21'n of Coastal Ecosystems The composition of coastal ecosystems varies considerably, but certain com- binations of habitats occur frequently in the island areas. The Virgin Islands are no exception, and the following typ- ical systems have been chosen for illus- tration. ROCKY SHORELINE ASSOCIATIONS (Figure 44) Dominant features: shoreline of hard resistant, highly fractured rock extend- ing under and resulting in active coral growth on the rocky base along shore and extending onto hard substratum at great- er depth. Characteristics: salt-tolerant plants on shore; turbulent, usually clean, clear well oxygenated water with tough hard and soft coral community and other living forms highly resistant to wave action. Bedrock usually lies beneath thin sand cover up to several meters offshore. Suitability: snorkelling, fishing, good dispersal for treated effluents, scenic value above and below the surface of the water, Restrictions: wave action precludes mooring, anchorage; light struttures on shoreline rocks subject to wave, storm and corrosion damage. I I I I I I I I I I 119 n Rocky Shoreline Associations I CACTUS - AGAVE SCRUB Shoreline vegetation tolerant of salt and drying. Soil thin. CORAL COMMUNITY SEA GRASS AND ALGAE Sand layer thin near- shore deepening off- shore,,grading to grass or algae bed. Bedrock and boulder substrate. Corals near surface. Sea fans, sea whips deeper. Figure 44. Rocky shoreline and associatedsea bottom. 120 a Sand Beach - GresG Beds - Salt Pond - Reef Associations SALT POND BEACH SDEA GRASS BED REEr Traps runoff, Dune Berm Foreshore Stabilizes sand. Pro-tects shore sediment, pollu- Provid~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5 oxygen. from waves~~~~~~~PrvdZs xyen roiiwae tants. Controls Recreational sites. vegeta- Assimilates waste$_ and swell. drainage. tion stabilizes shore. Berm Feeds and shelters Sand and bio- and foreshore constantly diverse biota. logical pro- changing i-n "dynaniic equilib-dutohi. r iuri. it Filters water leaving the land. U~~~~~~~~~~~~~~~~~. ...... ......... .. ......... ....~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ...........~~ ........I ......... . ...... ........~~~~~~~~ ..................... ........ ....... .............. ...... ....... .... ........ ..a.. be.ch ......te Ohwn reat T . of cmoetabat. . .... 1 2 1 oxygenate water, assimilate community wastes, provide food and shelter for wide variety of animals. Suitability; good swimming and recrea- tion areas, usually suitable for small boat anchorages and moorings. Attrac- tive areas for shoreline development. Frequently provide harvestable quanti- ties of reef fish and conch. Restrictions: solid structures on the submerged beach act as barriers, inter- rupt sand transport, change beach shape and quality. Structures on pilings less so. Excessive development in the water- shed can result in deterioration of water quality, affecting recreational potential. Excessive and/or poorly designed dredg- ing for sand can severely damage beach, coral communities and marine vista. MANGROVE - LAGOON - REEF ASSOCIATIONS (Figure 46) Dominant features: mangrove fringed shore or dense multi-species mangrove forest, mangrove mini-islands, landward salt ponds or tidal flats, quiet small lagoons between mangroves and protective adjacent offshore reefs, usually shallow with narrow entrance channels. Characteristics: extremely high system productivity and utilization of energy, rich in edible and other organisms, food chain based on mangrove leaf litter, quiet water with low flow promotes sedimenta- tion. Area is important feeding and breeding ground for many birds, juvenile fishes and shellfish. Suitability: recreation, education, faunal preserves, fishing, marinas. Restrictions: low water flow makes areas unsuitable for waste discharges. Filling land to shoreline will kill eco- system base - the mangrove plants. Sus- ceptible to turbidity and rapid sedimen- tation. While potentially good sites for marinas and sand dredging, they are generally intolerant of the impacts gen- erated by these activities. Natural at- tributes of mangrove areas subject them to secondary environmental stresses they cannot tolerate. MAN-MADE SNORELINE AND STRUCTURES (Figure 47) Dominant features: developed shoreline with altered topography and drainage, high percentage of impermeable surface, unnatural shoreline (bulkhead, landfill, docks, etc.), usually low-energy quies- cent protected bay. Characteristics: high use levels, in- creased addition of pollutants and tox- ins to the bay, abnormally high turbid- ity and pollutants, impoverished floral and faunal communities, increased sed- imentation, subject to rapid runoff, frequent hydrocarbon slicks, often dev- elop colored phytoplankton blooms. Suitability: as previously modified natural systems, these areas could have priority consideration for sand dredg- 122 I I Mangrove - Lagon - Reef Assocations MANGROVE I I I I I I SEA GRASS FLAT I I I 7 I I SALT POND MANGROVE CAY BACK REEF FLATS FRINGING REEF Traps run- off. Black and white mangroves landward. Red mran- groves seaward. Blackc and white mangroves landward. Traps sediment expanding shore- line. Quiet wa- Trapped sediments and mangrove roots. Larger cays with mangrove zonation and terrestrial vegetation. Wild- life sanctuary. Sea grass, algae, scattered corals, clean sand, reef rubble. Typically Acropora near surface. Or- gan corals, sea fans, etc. seaward. Finger coral landward. A- bundant sea life. Wave protection. Sand produc- tion. sand sed- iment, grass growth, abundant sea life, I I I Figure 46. Mangrove dominated ecosystem with lagoonal ilats and protective reef. Food chain centered on sea grasses and mangrove litter. c 123 Man-made Shoreline & Structures DEVELOPED SHORELINE Heavy use, altered drainage, high proportion of impervious surface, vegetation cleared, high runoff, pollution sources. STRESSED BAY Heavy use, increased turbidity, silty bottom, reduced bottom diversity and productivity, possible phytoplankton blooms, boats disturb bottoia, con- tribute hydrocarbons, heavy metals, sewage, structures may redulce circulation. Often require mtaintenance dredging. Figure 47. Man-dominatedl Bay Ecosyst.em. 12 4 Ii I ing for channel maintenance or construc- tion sand (if properly executed) to pro- tect adjacent resources. Within limita- tions of the ecosystem these bays should be considered first as sites for further I development. Restrictions: because of limited circula- tion and existing pollution loading, should not be considered for direct waste I discharge of any type. Future develop- ment needs to be gauged carefully to i avoid exceeding ecosystem capability and acceptable pollution loading levels. I Dog Snapper or Dog Tooth (Lutjanus jocu) I I I I 125 U Critical Areas 2. Coral' Bay and environs - heavily Areas of High Productivity fished area, some mangroves. Area ofighProductivity Few quantitative measurements of produc- tivity have been made in the Virgin Is- lands. The following areas are listed because the site-specific environment there is known generally, from research on similar sites, to be highly productive, or because it yields especially large amounts of seafood, although production may not be in situ. Thus, the list is conservative. Most reef banks are fished by traps and handlines. All grass beds sometimes contain harvestable q~uantities of conch. ST. THOMAS 1. Jersey Bay Mangrove Lagoon - breed- ing area, wildlife refuge. 2. Southern Shelf Edge (100 fathom drop- off) - high fish concentrations, heavily fished. 3. North Central and West Shelf - produc- tive fishing areas. ST. CROIX 1. Sandy Point - traditional fishing area apparent good sand source. 2. Manning Bay Mangrove Area - wildlife habitat, fish and bird breeding. 3. West Coast Shelf - heavily fished., 4. East End Reefs (Lang Bank) - biolo- gically productive area. ST. JOHN 1. South Shelf Edge - popular fishing area. 126 I Areas Under Stress ST. THOMAS 1. St. Thomas Harbor and Crown Bay - urban runoff, sewage, dredging, maril- nas and ship traffic. 2. Lindbergh Bay - urban runoff, sewage, thermal-saline effluent, dredging. 3. Fortuna Bay - periodic stress by run- off from Estate Bordeaux and surround- ing residential area. Apparently tol- erating stress, recovers quickly from each episode but cumulative effects of continued increasing stress may produce long-term noticeable degrad- ation. 4. Stumpy and Santa Maria Bays - ambient turbidity appears to be increasing, caused by runoff from developing north shore mountain slope areas. 5. Water Bay - attrition of iearshore grasses and algal beds probably due to dredging, filling of salt pond and in- creasing siltation from residential development. 6. Vessup Bay - stress sources: marinas, boat traffic, sewage, runoff. 7. Jersey Bay Mangrove Lagoon - stress sources: marinas, boat traffic, sew- age, runoff, filling of ponds, cut- ting mangroves, canalizing drainage. ST. CROIX 1. Christiansted Harbcr - stress sources: dredging and filling, urbanization, runoff, sewage, thermal--saline eff- luents, marinas, boat traffic. 2. Altona Lagoon - stress sources: chan- nel restriction, urban runoff. 3. Canegarden Bay to Port Harvey -- stress sources: dredging, filling, runoff, oil spills, air pollucion, thermaal- saline discharges, ship traffic. 4. Manning Bay - stress sources: gar- bage, dumping, periodic petroleum spills. ST. JOHN 1. Cruz Bay - stress sources: dredg- ing, pond-filling, marina, boat tra- ffic, sewage. 2. Great Cruz Bay - stress sources: dredging, pond filling. 3. Enighed Pond - stress sources: gar- bage, solid wastes. I I I I I I I I I 127 Unique Areas ing mangroves, partially dedicated to public use. ST. JOHN 1. Lagoon Point, Coral Bay - excellent well developed fringing reef, broad coral flat, inner shallow lagoon with turtle grass ~tands, asso�iat- ed red mangrove and salt pond. War- rants inclusion in territorial park system. 2. Newfound Bay - excellent example of reef-choked bay combining classic fringing reef complex and coastal land-formation dynamics. 3. Carval Rock and Congo Cay - import- ant nesting sites:for sea birds, scenic. Miscellaneous Attention is directed to :the published inventory of "Potential National Nat- ural Landmarks" of the U.S. Virgin Is- lands, prepared by the West Indies Lab- oratory for the National Park Service (May, 1975); a priority rating system is us,ed. ST. THOMAS 1. Jersey Bay Mangrove Lagoon - largest original surviving mangrove stand in the Virgin Islands. 2. Coki Point Peninsula - unique pre- tertiary marine fossils. 3. Magens Bay Valley and Beach area - significant concentration of doc- umented pre-Columbian archaeological sites. Superb public beach, archaic botanical garden, publicly acknowl- edged as an aesthetically unique ele- ment of the Virgin Islands coastal zone. 4. Botany B$ay Estate - deciduous forest, high diversity, adjacent patch and fringing reef, scenic - high recrea- tion potential for territorial park. 5. Most offshore cays, especially Savana, Little Saba, Turtledove, Cockroach, Cricket Rock, Flat Cay, Whistling, Congo and Dutch Cap Cays - all are important nesting sites for doves and sea birds, the last three especially for pelicans which are an endangered species. ST. CROIX i. Lang Bank - unusually large area of reefs extending westward on both north and south sides of island. 2. Salt River - largest remaining man- grove estuary on St. Croix. 3. Westend Salt Pond - unique combination of large pond, sand dunes, and xeric forest. 4. Great Pond - the largest remaining marsh area on St. Croix with fring- 128 I IZ IeI -fes the islands, only two remain. The maj- ority have been committed to the sin- gle purpose of land development and vir- tually obliterated. The remaining two sites represent the Virgin Islands' only surviving opportunities to provide alternate allocations of these extrem- ely important, highly threatened and presently unique resources. A second example is the last remaining areas of native rainforest vegetation, primarily on St. Croix with a small area on St. Thomas.- Although not coas- tal, they provide glaring examples of how individual resources may be deci- mated for a single purpQse without thQught to alternate uses. Regional Cotext Formulation of a Virgin Islands Coastal Zone Management Plan should reflect over- all requirements for services, facilities environmental diversity, and the preser- vation of natural and cultural assets. We recommend that, in consonance with loc- al requirements, an evaluation be made o. the regional need for various resource al- locations. There is probably no defens- ible basis on which to argue for the ab- solute protection of all of the approxim- ately 100 remaining salt ponds, but it is also indefensible to argue that they should all be filled for construction or opened as marinas, given the interdepen- dent relationships of the U.S. Virgin Is- lands to adjacent island areas to leeward and windward I I I I I Local planning should be geared to provid- iiig rational resource allocation consis- tent with maintaining regional environ- mental diversity. The development of mar- inas, as one example, should not be lim- ited only by current economic demand or the availability of suitable sites, but ultimately by the regional need for al- locating available sites for alternate uses, given the pattern of small boat vis- itation in the eastern Caribbean. The need for this type of evaluation for many coastal resources is mounting and, in at least two site-specific cases, is long overdue. Of the several extensive man- grove forest areas originally found in 129 I I I I I I U Plannng Concept: Ecosystem Approach The foregoing descriptions of coastal and marine habitats have touched frequently on interactions between these component units. Future assessment of the Virgin Islands coastal zone and development of management strategies needs to keep the interactive perspective of natural sys- tems in focus in understanding coastal processes for planning purposes. Manage- ment plans must be built on a comprehen- sive approach reflecting an appreciation N of the interactions and interdependencies of the various physical and biological components within the larger scale. This ecosystem approach must consider the in- tegrity of larger systems as related to singular manipulations of component parts. Inherent in this approach is the consid- eration of the secondary impacts of all resource manipulations, for whatever pur- pose. S An "ecosystem" comprises a complete in- tegrated unit of physical and biological components within which no part functions independently of the others. As such, coastal ecosystems can logically exclude neither the contributing inland watershed nor the adjacent marine area. Management of any ecosystem should have the fundamental purpose of maintaining the system at "best achievable ecosystem function" (Clark, 1974). 130 I Gadidl___e fr 11sp e managmn II Concepts of resource management have been developed along the lines of Clark's (1974) Coastal Ecosystems: Ecological Considerations for Management of the Coastal Zone, which is highly recom- mended for the planner and decision- maker. The principles therein have been applied to specific local re- sources and their management require- ments so far as we now understand them. In this regard, it is necessary to broad- ly classify and identify coastal areas according to their needs for planning concern. Clark describes three cate- gories of concern: (1) Vital Areas are ecosystem elements of such high value and critical importance that they must be set aside as preserves, protected intact from outside stresses. They must be encompassed within (2) an Area of Environmental Concern which serves as a buffer zone. Areas of Environmental Concern are conservation areas which require special conservation and man- agement protection because of broad environmental sensitivity. (3) Areas of Normal Concern are areas where only normal, but planned and enforced, methods of utilization and exploitation are necessary. Vital Areas CAYS Most offshore cays must be considered vital. Specifics on individual import- ance and management requirements should come out of work now b'einig done by the Virgin Islands Department of Conserva- tion and Cultural Affairs. These areas are extremely important to vanishing lo- cal as well as internationally migrat- ing bird species. Because of their small size, the cays are very suscep- tible to man-made stresses, inadvert- ant or otherwise. I I I I I I I I I I I I 131 0 Areas of nvirofnental Concern MANGROVES Jersey Bay mangrove forest, St. Thomas, and Salt River and Great Pond on St. Croix represent ecosystems of proven importance to local commercial fish and lobsters as well as many birds. Much of their actual and potential value is still not apprec- iated or understood. They are extremely critical also because they are the only remaining areas of their kind in the Vir- gin Islands. it may be necessary to set aside small, special sections as vital areas, and this is strongly indicated in the case of Cas Cay and Patricia Cay in the Jersey Bay lagoon. RAIN FOREST Remaining rain forest areas on St. Thom- as and St. Croix are vital for the same reasons. Although not coastal, the pro- tection of the large watershed areas which they cover is important in the man- agement of the coastal receiving waters. Again, they represent the last remnants of original "coastal" vegetation and are a refuge for numerous plants and animals not found elsewhere in the extant coast- al zone. SURFACE WATER Caledonia Gut and Cregue Dam on St. Croix are the most impressive fresh water habi- tats left in the islands and deserve spec- ial efforts for protection and manage- ment. All remaining fresh water streams and perennial ponds in the islands need special status and enforcement of exist- ing laws for their protection. Turpen- tine Run Gut on St. Thomas formerly har- bored a variety of fishies, crustaceans and water birds. It has been decimated by constant sewage and laundry waste discharges, and most of its biota has vanished. Again, these guts have sig- nificance for coastal water quality in. addition to their own intrinsic value. These surviving areas are now unique in the Virgin Islands and require strin- gent, well planned protection and man- agement. It is probably not necessary to set them aside as inviolate pre- serves. They can be maintained as sanc- tuaries for important wildlife while providing properly controlled, mult- iple usage for recreation, education, research, water storage and agricul- ture. 132 I I Areas of Regionag National, and Intrnational s$n f kance The areas already cited as vital to the Virgin Islands and requiring special concern are significant in a larger sense, outside of their site-specific natural value. On one hand, they re- present unique remnants of the islands' natural heritage and, as such, should be maintained for future generations. In a larger frame, we suggest that man- grove areas, for example, may be signi- ficant to the production of regional populations of lobsters and several species of commercially important fish- es. In an even larger sense, mangroves, cays, and rain forests are known to be critical habitats for many species of migratory birds, some in danger of ex- tinction. In addition, they harbor many of our locally rarer reptiles and birds. Areas of M orairna All other habitats and ecosystems in the islands are sufficiently extensive so that requirements for their protection are not yet critical. Some specific sites are approaching the point of needing spec- ial restricted management to insure their continued use, consistent with maintain- ing basic environmental quality. What is critical, however, is the need for regional and local assessment of resource allocation requirements and a local man- agement plan to insure proper allocation and environmental maintenance constraints. It should never be construed that areas not specified as vital or requiring en- vironmental concern do not warrant man- agement controls. Uncontrolled resource exploitation will lead to crisis situa- tions in all ecosystems eventually, and proper management of the entire coastal area is in order. I I I I I I I I I I I 133 U Guidelines for Ecosystem Management The following general principles of coastal ecosystem management are cited from Clark (1974). ECOLOGIC PRINCIPLES Eleven principles derived from ecology that underlie major management functions are given below: 1. Ecosystem integrity-no one part of an ecosystem operates inde- pendently of any other. 2. Linkage - water provides the essential linkage of land and sea elements of the coastal ecosystem. 3. Inflow- the natural volume, pattern and seasonal rate of fresh water inflow provides for optimum ecosystem function. 4. Basin circulation - the natural pattern of water circulation within basins provides for optimum ecosystem function. 5. Energy- the flow and amount of available energy governs life processes within the coastal ecosystem. 6. Storage- a high capability for energy storage provides for optimum ecosystem function. 7. Nitrogen -productivity in coastal waters is normally governed by the amount of available nitrogen. 8. Light- the natural light regime provides for optimum ecosystem function. 9. Temperatures - the natural temper- ature regime provides for optimum ecosystem function. 10. Oxygen - high concentrations of dissolved oxygen provide for optimum ecosystem function. 11. Salinity - the natural salinity regime provides for optimum ecosystem function. MANAGEMENT PRINCIPLES AND RULES 1. Ecosystem integrity: each coastal ecosystem must be managed with respect to the relatedness of its parts and the unity of its whole. 2. Drainage: A fundamental goal of shoreland management is to retain the system of land drainage as near to the natur- al pattern as possible. 3. Drainageway buffers: the need to provide vegetative buffer areas along drainageways in- creases with the degree of development. 134 I I 4. Wetlands and tiaelands: the need to preserve wetlands and vegetated tidelands increases with the degree of development. 5. Storage: storage components of ecosystems are of extreme value and should always be fully pro- tected. 6. Energy: to maintain an ecosystem at optimum function, it is neces- sary to protect and optimize the sources and the flows of energy that power the system. MANAGEMENT RULES 1. Drainageways: alteration of any drainageway by realignment, bulkheading, filling, impounding, or any other process that short- cuts the natural rate or pattern of flow or blocks or impedes its passage is unacceptable. 2. Basin circulation: any signif- icant change from the natural rate of water flows of a coas- tal water basin is presumed to be ecologically detrimental and is unacceptable. 3. Nutrient supply: reduction (or increase) of the natural supply of nutrients to the coastal ecosystem by alteration of fresh water inflow is unac- ceptable. 4. Nitrogen: discharge of nitrogenous compounds into confined coastal waters is presumed to have ad- verse effects through eutro- phication and is unacceptable. 5. Turbidity: turbidityof higher than natural levels is to be presumed detrimental to the coastal ecosystem and is un- acceptable. 6. Temperature: significant altera- tion of the natural temperature regime of the coastal ecosystem is presumed adverse and is un- acceptable. 7. Oxygen: any significant reduction from the natural concentration of oxygen is presumed to be adverse and is unacceptable. 8. Salinity: any significant change from the natural salinity regime is presumed ecologically detri- mental and is unacceptable. 9. Runoff contamination: any signi- ficant discharge of suspended solids, nutrients, or toxic chemicals is to be presumed adverse and is unacceptable. CONTROLS Because both land and water use controls are necessary for best achievable eco- system function, it is necessary to regulate both the location and the design I I I I I I I I I 135 U 3. Structures (pipes, docks, groins, walls) should never be constructed across (or at right angles to) a beach unless carefull extensive study of alongshore sand trans- port regimes indicate they will be innocuous or advantageous. 4. Sand should not be removed from beaches. 5. Shoreward earth change and drainage modifications muqst be controlled to protect beach areas from pollu- tion by storm water. MANAGEMENT GUIDELINES FOR ROCKXY SHORES 1. Structures on rocky shores should be securely anchored to stable footings. 2. Soil and other land materials should not be pushed over the shore into the sea. 3. If effluent discharges are con- templated, site studies are needed to determine where currents will carry pollutants, perhaps to more sensitivre adjacent communities. If so, alternate out11fall locations should be selected. 4. oh cliffs, a construction set-back requirement may -be advisable in some locations for safety and to avoid effects of er'osion on near- shore resources. of projects in shoreland and coastal I water provinces. Also, many types of humani activities must be con- trolled to some degree. in addition, the construction of many types of pro.- jects and their operations will have to conform to certain performance * standards. IIn addition to general principles ap- plicable to specific types of environ- ments, management guidelines should be flexible enough to allow for site- *1 specific evaluations of 'control and management needs.. The followinig guidelines are provided as a prelimi- I narv basis for developing management plans for the ecological units des- * cribed in this report. MANAGEMENT GUIDELINES FOR BEACHES 1. Dredging in bays with beaches should not be allowed except under care- fully designed plans to prevent loss of important sea grass beds, the creation of deep depressions, I ~~water quality degredation and deleterious changes in sand trans- port mechanisms. 2. Beach restoration with dredged sand should never be accomplished by simply pumping the sand onto the shore. It should be pumped i-nto settling ponds and later spread on the beach mechanically, I ~~not hydraulicallv. 136 U I IU basin, the connecting channel depth should be continuous with the depth of the pond basin. 4. Openings to the sea should not be made until all internal work in the pond is completed. 5. Based on the sediment profile of the pond bottom, nature of the adjacent bay environment and action of flushing currents, dredged pond and access channel depths should be designed to a- void releasing extremely fine, toxic pond sediments to dispersal in the sea. 6. The relationship of the pond to the surrounding watershed should be determined. This consideration maydetermine whether or not pond modification is advisable and what alternate or restorative drainage provisions are required. 7. Because of the smallness and close spatial relationship of most Virgin Islands, the importance of a salt pond as a wildlife habitat should be determined in advance as it relates to the availability of similar habitats in the islands. 8. If the pond is to'be opened to the sea, it is advisable to know some- thing of the surrounding marine environment, including water move- ment and biota. MANAGEMENT GUIDELINES FOR SALT PONDS Management and use allocations of salt ponds should be approached generally on an individual basis. Decisions need to be based on a fairly thorough under- standing of the functions and relative importance of the salt pond in relation to its total ecosystem setting, that is, its importance to surrounding resources and other use requirements. It is pro- bably not necessary that every salt pond in the islands be preserved as is. Salt ponds vary in their relative im- portance to the surrounding watersheds and as wildlife habitats. The poten- tial impact of pond modification, there- fore, is a site specific function. How- ever, the following considerations gen- erally should be applied: 1o In any case where a pond is to be opened to the sea, or an existing opening enlarged or otherwise mcLodified, an adequate description of pond bathymetry and sediments based on soundings and borings should be available. 2. Sediments dredged from a pond should not be deposited directly in the sea or on the bay shore- line. Such disposal should only be considered if the sediments are clean sand or coar3er material, a condition which usually does not occur under such circumstances. 3. Where a pond is deepened and o- pened to the sea, as for a marina I I I I 1 137 [ 5 . Boat traffic within the area -must be strictly controlled. Some portions may be opened to small outboard powered boats, while other, areas (shallows, quiet waters, miuddy bottoms) should be closed to all motor boats. 6. No anchorage for boats should be permitted anywhere in the mangrove system. No live-on boats should he allowed. 7. Cutting of shor'eline mangroves or of a trail through the mangroves for boat maooring or any purpose other than the planned area manage- ment and use program should be pro- -hibited. 8. Points for small boat docks, launching ramps or other access structures should be carefully selected and structures carefully planned, constr-ucted, licensed and managed. 9. No waste discharges or polluting substances of any kind should be permitted into the area. Sewage systems shoulId provide for treat- ment and recycling of the effluent unless suitable soil is available for septic tanks and leach fields which would not allow seepage of effluents to shore waters. 10. By zoning, licensing 'or other ap- propriate controls, buffer zones MANAGEMENT GUIDELINES FOR MANGROVE AREAS, * ~1. The remaining large mangrove areas (especially Salt River, St. Croix and Jersey Bay, St. Thomas) should be placed in the I ~~territorial park system. Their development should be stringently restricted only for recreational, I ~~aesthetic and academic use. only minimal, carefully planned con- struction, compatible vwith their protected status, should be per- 2. Drtedgin and filling as a rule shoaldbeprohibited except on a small, carefully controlled scale and only if thorough study has I ~~indicated its absolute necessity for some purpose consistent with * ~~protective management. 3. Collection of mariLne or terres- trial living or physical materials should be prohibited except under a carefully controlled permit sys- tem for educational or scientific pur-poses. Guidelines for such a I ~~permit system may be adapted from the similar National Park Ser- vice permit system. Comrmercial. I ~~exploitation should generally not be allowed. * ~4. Sport fishing may be permitted, but it may he necessary to specify allowable areas, fishing gear and perhaps species, sea- I ~~sons and size limits. 138a 9 I should be maintained adjacent to the mangrove area to minimize runoff, erosion, air or water pollution which may adversely affect the mangrove area. Buf- fer zones adjacent to water areas should be at least ]150 feet wide to provide runoff in- terruption, soil infiltration and plant absorption of ground water. The width of the buffer zone should be wider where vegetation is sparse or the slope is steep or the soil is not porous. In some cases reforestation may enhance the buffer zone. 11. Hunting of birds or the taking of eggs should be prohibited. 12. Restraint must be employed in constructing access roads. In keeping with recreational, edu- cational and preservational ob- jectives, access roads should be of minimum number and size, consistent with management goals. In no case should causeways be built across channels or ponds. 13. Development restraints should be promulgated for the watershed which drains into the mangroves to control the volume and fre- quency of runoff. Canalization and other drainaae modifications which would adversely affect the marine mangrove area should be prohibited. New drainage sys- tems should utilize natural drainage ways wherever possible and should be designed so as not to increase stream discharge to the mangroves. Subsoil infiltra- tion should be strictly controlled. Revegetation of cleared upland areas should begin as soon.as possible. 14. Impervious surfaces (asphalt, concrete, etc.) should be kept at a minimum and provisions made to impound runoff from such surfaces and store it for use or percolate it into the soil. SUGGESTIONS FOR MANAGED MULTIPLE USES OF MANGROVE AREAS Within the context of the recommended protective status, the natural attri- butes of the two large mangrove areas should be developed to translate these attributes into useable social resources. Possible use of the areas include the following: 1. Recreation. * Nature trails, underwater trails, bird watching, hiking. * Fishing on a controlled basis by conservative methods. * Swimming. 2. Education. Thepotential for edu- cating students atall levels in areas of West Indian natural his- tory is limitless. The mangrove lagoon on St. Thomas has already been used on a limited basis by the Environmental Studies Program I I I I II I I I I I I I I 139 0 reefs should be designed to minimize i-mpact on the reef. Monitoring is essential. 5. All shore and water related de- velopment should be evaluated for their relationship and pos- sible effects upon adjacent reefs. MANAGEMENT GUIDELINES FOR SANDY BOTTOMS 1. Use options should be considered in light of the relatively tolerant. quality of the habitat. 2. Where sand mining is proposed, adequate prior borings and sedi- ment analyses should be conducted to describe the nature of the sedi- ments and determine spoil handling requirements. 3. Where dredging is proposed, final depth contours should be as natural as possible, eliminating deep iso- lated holes. 4. Uses of sandy areas should be con- sistent with maintenance of adja- cent reefs, beaches, grass beds, etc. MANAGEMENT GUIDELINES FOR GRASS BEDS 1.Dredging should be avoided in these areas wherever possible. If necessary, it is absolutely essential that the design slopes be natural and open the dredged area to free coinmunication with the rest of the bottom. Isolated of the Virgi-n Islands Department 3 ~~of Education. 3. Research. The mangrove areas provide the opportunity for re- I ~~search into (1) coastal geologi- cal processes, land formation and sediment production and (2) I ~~life histories and ecology of many forms of terrestrial and marine li-fe, many of them im- pratand valuable food species. 4 .Commercial activity. For areas already irrevocably committed to marina/small boat/dockage/service functions, a non-expansi-ve man- agement plan should be developed, I ~~imposing flexible constraints on current practices and non-flexible constraints on all proposed utili- I ~~zation. MANAGEMENT GUIDELINES FOR REEFS 1. Except where absolutely necessary, I ~~reefs should not be subjected di- rectly to filling, cutting, blasting or waste discharge of any type. 2. Heated effluents should never be discharged i-n reef areas. 3. Except under careful control and I 1~~icehsing, corals and other reef organisms should not he collected commercially. Recreational collect- fl ~ing should be discouraged. 4. Dredging operations adjacent to 14 0 MANAGEMENT GUIDELINES FOR CAYS 1. In conjunction with planning recommendations from the Virgin Islands Department of Conservation and Cultural Affairs, certain cays should be set aside as inviolate wildlife sanctuaries. 2. Other publicly owned cays should be developed for multiple use as recreation and nature areas, but any alternate or coincident use of a cay should be compatible with maintaining its value as a wildlife area. 3. Consideration should be given to establishing ranger or warden stations on strategically lo- cated cays, from which it would be easy to patrol and monitor the other islets. 4. Each cay should be evaluated individually to determine its use potentials. deep holes are definitely to be avoided. To this end, it may be better to make shallower cuts over bigger areas to obtain a given volume of sand. While areas stripped of grass and algae take surprisingly long to recover, deep pits create and perpetuate a number of other problems which can permanently alter the ecology of an entire bay. 2. Dredging, where permitted: should begin at the mouth of a bay and proceed inward with an upward slope. It is prefer- able to restrict dredging'to bay mouths rather than the in- ner shallower bottom. Dredging close to the beach should be absolutely prohibited. At least several hundred feet of shoreward grass beds in front of a beach should be left untouched. 3. Boat anchorages in enclosed bays with grass beds can be destruc- tive if vessel density over time becomes too high. Unless a bay has been committed specifically for anchorage, it may become necessary to specify permitted anchorage areas and boat density. Fixed moorings, privately or publicly maintained and leased, are to be preferred. I I ! U 141 Recommndat'oiw o Frhr td * The general inshore current regimes I of the islands need to be investigated and determined. Prevailing, as well as periodic, departures from the norm need to be quantified, especially in any areas programed for a change in use patterns. A prime example is the in- Idustrial southwestern half of St. Croix where, despite at least two large scale environimental studies, current patterns are unknown except primarily from quali- I tative subjective descriptions from local residents. * Long Reef in Christiansted harbor should he restudied at intervals to follow up on two previous studies which I Also a unique opportunity exists to study reef recovery after termination of sewage discharge, which is expected shortly. * Techniques need to be developed for tracing sources of oil pollution. Procedures should be developed and implemented for enforcing Virgin Islands laws relating to oil and hazardous materials spills. * offshore cays should be studied I continuously for the purpose of de- veloping management plans consistent with their frailty, ecologic and rec- I reational value. They represent an irreplaceable local resource espec- ially in view of the present population Idensity loading on the larger islands. * Sand resources inventories sh-ould be conducted in offshore areas around all islands to locate deposits which can be mined economically with minimal environmental im-pact. * T-he effects to tu rbidity on local marine organisms and communities should be quantified 'as a means of assess- ing the possible impact of runoff, dredging,. waste di-scharges, etc. Local water quality criteria for turbidity should reflect the fin.dings of such a study. * Periodic monitoring of heavy metals should be conducted in marine sediments subjected to municipal and industrial discharges. * Runoff from the land should be investigated during the rainy season to identify areas subjected to tur- bidity and siltation. Analysis of the watershed, rainfall and other information should be used to esti- mate discharges. Q uantitative studies should be mounted to describe the marinie envir- onment in strategic areas, i.e., all harbors, the south shore of St. Croix~, the mangrove lagoons, and Fortuna and Perseverance Bays on the southwestern end of St. Thomas. These should be followed annually by quantitative surveys to assess change. 14 2 a i general. Responsibility for enforcing all aspects of environmental controls should be consolidated in a single agency. * The government should secure title to critical offshore cays, declare cer- tain ones as closed wildlife preserves and develop multiple use'conservation plans for others. * The taking and sale of seabird eggs should be prohibited. * Laws relating to the clearing and development of guts should be strengthened and enforced. The "earth change" law should be rigorously enforced. These measures are needed to protect the unique and vanishing flora and fauna of the guts and to reduce destructive runoff to the area. * Detailed studies should be con- ducted on major balt ponds co quantify their functions and natural values and to provide rational basis for manage- ment and use allocations. * Establishment of "marine preserves" should be given immediate priority, especially in the last remaining man- grove areas: Salt River and Great Pond, St. Croix and Jersey Bay, St. Thomas. * Existing and planned municipal and industrial facilities on the south shore of St. Croix dictate a need for a com- prehensive environmental assessment of the entire area. Such an assessment should stress the cumulative and secondary impacts of the total south shore development. * The feasibility of restorative action in bays damaged by past destructive dredging should be investigated. In certain cases, it is apparent that con- siderable environmental damage re- sulted, not simply because the bay was dredged, but because the operation was poorly designed and executed. I I I I I I I I I * A permanent committee, similar to Florida's Coastal Coordinating Council, should be established to coordinate the Coastal Zone Management Plan. * Because of the small size and steep terrain of the islands, it is imprac- tical to separate Coastal Zone Manage- ment from environmental management in I I I I 143 U urnniary physical resource information, classi- fies coastal ecosystems and processes, identifies critical areas of high pro- ductivity, under stress or of a unique quality, and indicates some of the ex- isting and potential impacts along the coastal zone. The Synthesis and Guidelines sections provide management recommendations for vital areas, areas of environmental con- cern, areas of normal concern, and for ecosystem quality co'ntrol. Where pos- sible, site specific constraints, de- gradation thresholds or limiting factors are also cited. The study concludes with a list of recommendations for fur- ther investigation and an annotated bib- liography. INVENTORY OCEANOGRAPHY AND CLIMATOLOGY - (1) TIDES In the Virgin Islands, tidal ranges are not great, and tidal currents, except in some inshore localities, are not signi- ficant. There is one high *and one low tide per day on the north coasts of St. John and St. Thomas, on the south coasts of St. John and St. Thomas, and on all St. Croix coasts .there is a second, re- duced cycle of high and low tides. For- tunately, waves, swell and ocean currents usually do a good job of 'flushing most bays. These forces, however, are con- siderably reduced by the timLe they reach ,the heads of deep embayments. As a re- sult, circulation may be very poor in the inner reaches of some of our larger INTRODUCTION With greater understanding of the complex interactions of natural coas- tal systems, we can develop improved plans for maximum multi-use manage- ment of the Virgin islands' limited coastal resources. Appropriate re- source protection and wise use are iiaper ative to mainitain natural pro- duictivity and aesthetic values and to preserve options for future gen- erations. The preceding compilation is intended as a first effort survey of the Virgin Islands' coastal, resources describing our present knowledge of thei.r inter- active processes, values and capaci- ties and our needs for additi-onal i-n- formation. The report deals with the major biological and physical compon- ents of the marine resource base and their intrinsic limits to man-induced perturbations. The Inventory section describes im- portant oceanographic, climatological, geomorphological, and marine ecology features of the islands' coastal zone. Beaches, rocky shores, salt ponds, mangroves, reefs, sandy bottoms, ana grass beds are defined and described, as well as smaall cays and mLajor biota. As far as possible, natural attributes, tolerances and cons-traints are identi- fied. The Analysis section reviews bio- 1 44 I I embayments. These conditions are impor- t-ant for the planner because pollutants introduced to these ca'lm areas will be very slowly dispersed. These quiet areas also are sites for relatively rapid deposition. Sand transported naturally through thiese bays, as well as silt and debris from the land, tends to settle out, filling the bottom and evenitua'lly extending the shoreline. .(2) CURRENTS Many factors interact to determine the direction of water flow in a bay. These include relative strengths of tides, winds, waves, swell, water den- sity 'and pressure as well as the bay's bathymetry, shoreline shape and size. Thus, patterns of water movemnents are changeable. This fact is important for the planner because it demonistrates the need for site specific studies of currents to determine prevailing condi- tions and variatioxns. Generally, cur- rents around the islands are driven by the North Equatorial or Canary Current which moves through the Caribbean from east to west axnd eventually joins the Gulf Stream off the south coast of North America. Local currents in in- dividual bays vary considerably due to exposure, winds, tides, shoreline, and bottom geometry. (3) WAVES AND SWELL Waves are the main source of energy that moves beach sedimient and that'affects shipping and shoreline structures during storms. The deepwater wave regime is driven by the northeast trade winds most of the year. Besides the normal east- erly swell that affects windward coasts on the islands, there are two seasonal modes of wave approach that affect leeward coasts: a southeasterly chop and swell and a northe,rn swell. Along coasts fronted by partly submerged reefs, waves play a significant role- in. ci-rculating back reef water, thus dis- persing pollution and diluting its effects. (4) STORM WAVES AND TIDAL FLOODING Ti-dal flooding, created by major hurri- canes having an average frequency of once in 33 years, raise water levels in St. Thomas from five to twelve feet a- bove normal. A six foot height floods lower parts of Charlotte Amalie for 800 feet landward from the shoreline. Be- sides flooding, damage to waterfront facilities and erosion of shores by storm waves can be heavy. Moreover, passing hurricanes may create a minus tide of as much as 1.0 feet below mean low water that can -temporarily affect grounding of vessels in shoal water and exposure of tidal flats, Large sea waves of extraordinary length called tsunamtis are associated with sub- mariiie seismic disturbances. These waves seem to occur about once every 10 or 15 years in the Caribbean area. (5) WATER QUALITY Water quality may be defined by any numaber of parameters depending on what I I I I I I I I I I I I I 14 5 U information is required. Common quality indicators are temperature, salinity, dissolved oxygen, transparency and bac- teria. Additional measurements often required are biochemical oxygen demand (B.O.D.), chemical oxygen demand (C.O.D.) , nitrogen, phosphorous, sili- con. Estimates of water color have limited value. The effects of these constituents on water quality are significant to the well-being of individual organisms, whole communities and entire ecosystems. All of these water components may assume pollution roles if changed from normal levels. Shoreline waters of the Virgin Islands have temperatures of 25. 5 - 28. Oc C be- tween December - April and 27.0 -29. 0O C between June - October. Salinity (the amount of salt in the water) generally averages 35.5- 36.2 parts per thousand and 34.0 - 35.2 parts per thousand dur- ing the same periods. Almost all our waters contain dissolved oxygen near saturation. Turbidity in local waters is generally low, and in most bays the sea bottom is visible. In areas where runoff from the land, sewage and boat traffic cause murkiness, the botto-m is often not visible at ten feet depth. Local waters are low in nutrients which accounts f'or the low levels of planktonic productivity. However, localized productivity by reefs and sea grasses is very high. (6) PREVAILING WINDS AND HURRICANES The Trade Winds approach the islands with great constancy in direction pri- marily from the east-northeast and east. Hurricanes or tropical cyclonic stormis constitute a seasonal threat of Do- tentially catastrophic proportions. Frequency, probability, seasonality and dimensional aspects are reviewed in the basic text. Adequate pre- ventative natural disaster planning is an essential element of any coastal zone management plat, and greater emphasis is needed on this requirement. (7) PRECIPITATION AND EVAPORATION Rainfall is low, evaporation is hi-gh, producing very dry conditions over most of the islands excepting some high mountain forests. Dryness and water loss are heightened by steep slopes which promote runoff, shallow rocky soil which holds little mois- ture, and strong sun and constant breezes which promote evaporation. Rainfall varies over the year, by is- land and by areas within a gi'ven is- land. On the average, St. Croix re- ceives 40 inches per year, St. John 47 inches and St. Thomas 42 inches. Heaviest rainfall occurs at Dorothea on-St. Thomas and Analy on St. Croix, The wettest months are September - December; the driest, February - July. Rainfall is important to the coastal zone as it promotes runoff into t'he 146 I I I to -the east and west, respectively, of St. Croix. (2) SEISMIC ACTIVITY Since the Caribbean island arc marks a tr-ansition zone between continental and oceanic cru.stal masses, it is a nearly continuous belt of shallow focus earth- quakes, none of which seriously affect the Virgin islands. MARINE ECOLOGY - (1) FISHERIES The stri-king simtilarity of various stud- ies of fishing in the Virgin Islands going back over forty years emphasizes how fisheries have been relatively static in a period of generally rapid charge. As the economy and population have burgeoned, the demand for fish and the price per pound have climabed, but the number of fishermen has not changed significantly. The limited pelagic fish resources (billfish, tuna, wahoo, etc.) of the northern Virgin islands support a sport fishery along the edges of the shelf, but repeated exploratory fishing has made it clear that stocks are not suf- ficiLent to support an i-ndustrial fish- ery. The primary commercial. resources are demersal fish (and invertebrates) associated with coral reefs and tending to be concentrated around small irregu- larities at the bottom which provide refuge. A secondary finfish resource is inshore schooling fish, generally jacks, which are traditionally taken sea. Developmnent in the watershed in- creases runoff. Bays suffering the ef- fects of runoff (turbidity, silta- tion, eutrophication, etc.) are St. Thomnas and Christiansted harbors and Water Bay and Stumpy bays on St. Thomas. Evaporation affects the coastal zone by increasing salinity in salt ponds and shallow restricted parts of embay- ments. Biotic composition shifts in adaptation to high salinities, but when heavy rains catostrophicallv depress salinity to very low levels, many halophilic (salt tolerant) organisms die. GEOPHSICA FACTORS - (1)~ BATHY.~-ETRY St. Thomas and it. John lie onth Puerto Rican Plateau, a submerged an- cient island mass. This submarine shelf extends from the shoreline to the 100 fathorm depth, where coral reefs, other bottom irregularities, winds, shoreline configuration and tides act to divert and diverge prevailing ocean currents. St. Croix lies on a shallow p'latform, separated from the Puerto Ricani Plateau by the Virgin Islands basin with depths to 4,500 meters. North of the Virgi-ns, the Puerto Rican Trench with depths to 9,170 meters is the deepes-t known area of the Atlantic. Other deep Caribbean basins around the Virains are the Anegada and St. john passages and the St. Croix and Jungfern passages I I I I I I I I I 1 47 I Uf with haul seines. valuable for recreation for which they are in great demand. Beach sediments are highly mobile and thus beaches are constantly changing their form and di- mensions. Stability depends on a sup- ply of sediment either from the land or from the sea which is the main source. Consequently, most beach sands are a mixture of different types of material that vary in size and composition, according to the source and rate of sup-- ply, as well as according to the wave and current processes acting on it. Back- shore dunes act as a reservoir of sand and prevent massive flooding by storm tides. When sand is placed on a beach in an attempt to rebuild it artificially, natural processes continue unhampered, erosion is checked and sand is supplied to adjacent beaches. Grain size of ar- tificially placed sand should approximate natural beach sand found on the site. BEACH ROCK Many sand beaches of the Virgin Islands are broken by a ledge of rock that typical- ly runs parallel to the beach or may be partially or completely submerged offshore. Beach rock is formed in place, below the beach surface, by the natural cementing action of ground water as dissolved calcium carbonate precipitates. Biological acti- vity contributes to the cementation pro-, cesses which take place quickly, probably within a few decades, perhaps even faster. IMPACT OF MAN ON BEACHES Human interference with natural pro- cesses is one of the major causes of Finfish stocks alone among the living marine resources offer long-term po- tential for increased yields, primarily by fishing stocks which are now only lightly exploited. Other species currently exploited include the sea turtle (often illegally), the conch, whelk, billfish (by sport fishermen), and the spiny lobster (currently re- duced by over exploitation). The low productivity of the fishery (both in total catch and catch per unit effort) is also a reflection of the naturally low primary productivity (little growth of phytoplankton, the base of oceanic food chains) of Virgin Islands waters. Most primary production inshore is benthic - the coral reefs, algae and grass beds and most fish are caught in these areas. Much of the open shelf of the Virgin Islands is relatively flat but too deep (thus the light is too dim) for sea grasses or vi- gorous coral reef growth. Thus, while there is room for improve- ment in fisheries, localconditions which limit production and harvesting do not allow development of a fishing industry akin to that of continental shelf areas. (2) BEACHES As a buffer zone, beaches protect pro- perty from wave attack. They are also 148 I I I beach erosion in the Virgin islands. (1) mining large quantities of sand can cause rapid erosion by changing the wave refraction patterns. (2) Dredging nearshore sand deposits in- duces erosion and/or slumping. Tur- bidity generated by dredge spoil fines reduces nearshore grass cover which normally absorbs wave energy. (3) Sites once used for waste dispoEdl on beaches to fill and to extend low land are now subject to erosion. Release of former was-tes also presents a potential for pollution. (4) Engineering struc- tures intended for shore protection, such as jetties and sea walls, often cause deleterious effects when they interfere with natural coastal pro- cesses such a-- littoral drift. (5) Unregulated construction and impro- perly designed structures present a potential threat to life and property when they fail during storms. (6) Recreati-on can contribute to litCter- ing and pollution. A critical factor for upper backshore dune stability is vegetative cover. Motorcycles, auto- mobile traffic, trampling, etc. can trigger erosion. (3) ROCKY SHORES Whether steep and cliff-1like or slop- ing and irregular with rock rubble at the watcr's edge, rocky shore areas are probably the most stable, leas-t threatened component of the Virgin Islands coastline. They require little immedi-ate concern, per se. (4) MANGROVES Mangroves are flowering trees which can live in salt or brackish water. Several different trees are referred to by the common name "mangrove," but the most common are re~l mangrove, white mangrove and black muangrove. Rhiz- ophora, known as "the plant that makes land," is the most typically recog- nized species. It grows at the water's edge, and new seedlings become estab- lished to seaward. The prop root sys- tem of the plants, besides providing support and hiding places for a wide variety of marine animals, traps sedi- ments that accumulate from the plants or are washed down from the land. in so doing, the shoreline is slowly ex- tended. Once the sediment becomes rather firmly established, the red mLangroves die off naturally and are suc-ceeded by other plants, initially black and then w-hite mangroves. With their dense coverage and complex roots at the shoreline, they interrupt run- off from the land a-nd help to trap fresh water, sediment and debris at the shoreline, thus protecting offshore marine areas fromn these pollutants. Each year r-ed mangroves drop large quantities of leaves and seedlings, all of which do not survive to become new plants. The natural decomposition of these materials sustains a complex food web beginning with micro-organisms and scavengers and culminating in such higher trophic members as snappers., I I I . I I I I I I i I I I 14 9 U barracuda, lobsters, and birds. The nutrients and other food energy sup- .plied by plant litter decomposition accounts for the large numbers and wide variety of plants and animals which are found in climiax mangrove communities. (5) SALT PONDS Natural development of mangrove forests tends toward the formation of closed ponds. Plants growing across a shallow bar or spit may merge with other man- groves. Channels may be maintained if a sufficiently strong current runs through periodicallv, or a body of water may be sealed,offE. When the pond is cut off from open water, a mangrove or coral growth, for example, a salt pond is formed. An inventory of salt ponds in the Virgin islands is included in the basic text. (6) CORAL REEFS A reef is an area of extremely diverse marine life. Structurally, it is composed of the stoney skeletons of hard corals which also are the dominant life forms. This living structure provides shelter and food for innumerable other organisms. Coral reefs are common characteristic features of the islands' coastal zone and are of fundamnental environmental and economic value. Besides their in- trinsic beauty, they are important as producers of sand for natural and man- made beach cover and for construction. As such, they represent one of the territory's very few naturally replace- able resources. Reefs also provide protection for harbors, shorelines and shore structures by abatement of waves and dissipation of their energy which otherwise would be expended on the shore with greater force. Also, reefs provide perhaps the largest portion of seafood presently harvested in the is- lands. Most species of fish consumed locally either live on the reefs or depend upon them in some measure for their food. Lobsters, too are taken primarily from reef areas. .The high productivity of coral reefs, through photosynthesis, produces oxy- gen for the support of respiratory organisms both on land and in the sea. The miost damaging effect upon coral reefs of dredging in most cases is the clouding of the water by very fine suspended particles. This turbidity cuts down the amnount of light which reaches the corals and other reef organisms, threatening theiLr survival. Another result of dredging is siltation of soli-d particles. Corals can be smothered because of their inability to cleanse themselves of heavy loads of sediment over time. (7) SANDY BOTTOMS AND, GRASS BEDS Large areas of sandy sea bottom are scattered throughout the platform. Sometimes they occur in shallow bays withouit apparent reason as most shal- low bays are vegetated. The miost ex- 15 0 larger variety of others comne here to feed on the plants and myriad crea- tures that live i-n the pastures. This is the habitat of the queen conch (Strombus gigas) and feeding grounds of the sea turtles. There is a very cl-ose knit relationship between the plants and animals in this habitat, both spatially~ and physiolog- ically. The pasture is a low profile environment. The plants usually do not exceed eight inches in height, and all but a few of the associated animals live within this zone or in the sediment. Thus, except for visiting foragers and predators, the majority of community energy cycling goes on in close quarters. Wastes from the animals are utilized by the plants which produce oxygen and forage. once destroyed, marine pastures usually require a long time to recover. Deep holes may never recover. Since the community is dominated by plants, a critical minimum amnount of light is nieeded. Chronic, heavy turbid-ity i-s destruct11ive. Quantitative toler- ances have no-t been determined. (8) OFFSHORE CAYS The small offshore islands vary in size from bare protruding rocks to over 170 acres. Most are 5 - 50 acres. A few are inhabited by one or two famili-es - and many are difficult to get onto even by boat. Simple rock I tensive areas of essentially bare sand occur below 60 feet depth. Even here, the lack of extensive plant growth i-s not easily explained but raay be due to low light intensity anad/or the nature of the sediment. Another possible ex- planation may be that the sand is shifting at a rate which prevents plant establishment. These areas are not, of couirse, barren. They usually support scattered algae and the flowering plant Halophila. Sandy areas are not well understood, and the extent of their significance to re- gi-onal ecosystems is unknown. Grass beds are frequently referred to as marine pastures because they are areas of thick growth of sea grasses and algae resembling pastu-res on land and serving essentia'lly the same functions. Most inshore bay bottoms are covered with such pastures as are some extensive areas outside of bays. Marine pastures produce a significant amount - perhaps most - of the oxygen generated in local inshore waters. On a bright day dissolved oxygen over a healthy grass bed will exceed the sat- uration valiue (i.e. , the water becomes supersaturated), and small bubbles rise from the leaves to the surface. Grass beds help to stabilize the sand. Several species of s-mall fish live in the pastures, but.more important, a I I I I I I I I I I 15 1 protrusions like Booby Rock, Sail Rock and Cricket Rock serve mainly as roosting and nesting sites for sea birds. The larger islets have beaches, rocky shores, cliffs, and some vege- tation, mainly xeric scrub. Most have at least one salt pond and are sur- rounded by some degree of reef-devel.- opment. Most of the more than 60 emergent rocks and cays are around St. Thomas. ANALYSIS AND SYNTHESIS OF BIOPHYSICAL ASSOCIATIONS The composition of coastal ecosystems varie.s considerably, butL certain combinations of habitats occur fre- quently in the island areas. The Virgin Islands are no exception, and the fol- lowing typical systemns have been chosen for illustration. (24 ROCKY SHORELINE ASSOCIATIONS Dominant features: shoreline of hard resistant, highly fractured rock extend- ihg under the surface, resulting in active coral growth on the rocky base along shore. Characteristics: salt-tolerant plants on shore; turbulent, usually clean, clear well oxygenated water with toughi hard and soft coral community and other living forms highly resistant to wave action. Bedrock usually lies beneath thin sand cover up to several. meters offshore. Suitability: snorkelling, fishing, good dispersal for treated effluents, scenic value above and below the surface of the water. Restrictions: wave action precludes mooring, anchorage; light structures on shoreline rocks sub'ject to wave, storm and corrosion damage. (2) SALT POND - BAY ASSOCIATIONS Dominant features: protected bay with sea grass bottom and beach shoreline sometimes with near-shore patch reefs, hypersaline and separated from sea by sand or pebble beach and berm combina- *tions, often surrounded by mangrove. Characteristics: very low energy water motion in bay, pond acts as catchmnent and filter for flood water from land, usually supports wading birds and other wildlife in associated mangrove. Suitability: low energy bay usually good for watersports, boat anchorage. Ponds may be filled for development or opened for marinas. Restrictions: structuares an filled ponds need pilings, opening of ponds can release f'ine sediments and toxins to upset bay organisms and water qual- ity. Filling or opening.pond incurs wat'er quality stresses on the adjacent bay. (3) SAND BEACH - GRASS BEDS ASSOCIATIONS Domtinant features: sandy beaclh, with gently sloping bottom leading to sea 1 52 U, I I low with narrow entrance channels. Characteristics: extremely high system productivity and utilization of energy, rich in edible and other organisms, food chain based on mangrove leaf litter, quiet water with low flow promotes sedi- mentation. Area is important feeding and breeding ground for many birds. juvenile fishes and shellfish. Suitability: recreation, education, faunal preserves, fishing, marinas. Restrictions: low water flow makes areas unsuitable for waste discharges. Filling land to shoreline will kill ecosystem base - the mangrove plants. Susceptible to turbidity and rapid sedimentation. While potentially good sites for marinas and sand dredging, they are generally intolerant of the impacts generated by these activities. Natural attributes of mangrove areas subject them to secondary environmental- stresses they cannot tolerate. (5) MAN-MADE SHORELINE AND STRUCTURES Dominant features: developed'shoreline with altered topography and drainage, high percentage of impermeable surface, unnatural shoreline (bulkhead, landfill, docks, moorings, etc.), usually low- energy quiescent protected bay. Characteristics: high use levels, in- creased addition of pollutants and tox- ins to the bay, abnormally high turbid- ity and pollutants, impoverished floral grass and alcral pasture on bottom of protected bay. Sometimes combined with salt pond habitat. Characteristics: beach sediments, grain size and profile change constantly in response to wave and currents. Sea grass acts as stabilizing factor in offshore movement of sand. Plants oxy- genate water, assimilate community wastes, provide food and shelter for wide vari- ety o` animals. Suitability: good swimming and recrea- tion areas, usually suitable for small boat anchorages and moorings. Attrac- tive areas for shoreline development. Frequently provide harvestable quanti- ties of reef fish and conch. Restrictions: solid structures on the submerged beach act as barriers, inter- rupt sand transport, change beach shape and quality. Structures on pilings less so. Excessive development in the water- shed can result in deterioration of water quality, affecting recreational poten- tial. Excessive and/or poorly designed dredging for sand can severely damage beach, coral communities and marine vista. (4) MANGROVE - LAGOON - REEF ASSOCIATIONS Dominant features: mangrove fringed shore or dense multi-species mangrove forest, mapgrove mini-islands, landward salt ponds or tidal flats, quiet small lagoons between mangroves and protective adjacent offshore reefs, usually shal- I I I I I I I I I I I I I 153 U and faunal communities, increased sedi-. mentation,. subject -to rapid runoff, frequent hydrocarbon slicks, often de- velop colored phytoplankton blooms. Suitability: as previously modified natuiral systems, these areas could have priority consideration for sand dredg- ing for channel maintenance or construc- tion sand (if properly executed) to pro- tect adjacent resources. Within limita- tions of the ecosystem, these bays should be considered first as sites for further development, rather than opening up new areas. Restrictions: because of limiited cir- culation and existing pollution loading, should not be considered for direct waste discharge of any type. Future develop- ment needs to be gauged carefully to avoid exceeding ecosystem capability and acceptable pollution loading levels. CRITICAL AREAS - (1) AREAS OF HTGH PRO- DUCTIVITY Few quantitative mieasurements of pro- ductivity have been made in the Virgin Islands. The following areas are listed because the site-specific environment there is know generally, from research on similar sites, to be highly produc- tive, or because it yields especially large amounts of seafood, although pro- duction may not be in situ. Thus, the list is conservative. Most reef, banks are fished by traps and lhandlines. All grass beds sometimes contain harvest- able quantities of conch. St. Thomas - Jersey Bay Mangrove Lagoon Southern Shelf Edge North Central and West Shelf? St. Croix - Sandy Point Manning Bay Mangrove Area West Coast ,Shelf East End Reefs (Lang Bank) St. John - South Shelf Edge Coral Bay and Environs (2) AREAS UNDER STRESS St. Thomas - St. Thomas Harbor, Crown Bay Lindbergh Bay Fortuna Bay Stumpy and Santa Maria Bays Water Day Vessup Bay Jersey Bay M4angrove Lagoon St. Croix -Christiansted Hiarbor Altona Lagoon Canegarden Bay to Point Harvey Manning Bay St. John -Cruz Bay Great Cruz Bay Enighed Pond (3) UNIQUE AREAS St. TFhomas - Jersey Bay Mangrove Lagoon Coki Point Peninsula Magens Bay Valley and Beach Botany Bay Estate Most Offshore Cays 154 I I I grove areas, for example, may be signifi- cant to the production of regional popu- lations of lobsters and several species of commercially important fishes. In an even larger sense, mangroves, cays, and rain forests are known to be critical habitats for many species of migratory birds, some in danger of extinction. In addition, they harbor many of our locally rarer reptiles and birds. SUMMARY GUIDELINES FOR MANAGEMENT OF COASTAL FEATURES In addition to general principles ap- plicable to specific types of environ- ments, management guidelines should be flexible enough to allow for site- specific evaluations of control and management needs. The following sum- mary provides a preliminary basis for developing management plans for the ecological units described elsewhere in this report. See the full section (page 131 et seq) for detailed recom- mendations. (1) PLANNING GUIDELINES FOR BEACHES 1. Dredging in bays with beaches should not be allowed except under care- ful supervision and rigid controls. 2. Beach restoration with dredged sand should never be accomplished by simply pumping the sand onto the shore. 3. Structures on beaches should not be permitted except after careful study of potential impact. St. Croix - Lang Bank Salt River Westend Salt Pond Great Pond St. John - Lagoon Point, Coral Bay Newfound Bay Carval Rock and Congo Cay REGIONAL CONTEXT Local planning should be geared to pro- viding rational resource allocation con- sistent with maintaining regional environmental diversity. The develop- ment of marinas, as one example, should not be limited only by current economic demand or the availability of suitable sites, but ultimately by the regional need for allocating available sites for specialized uses, given the pattern of small boat visitation in the eastern Caribbean. The need fr this type of evaluation for many coastal resources is mounting and is long overdue. Of the several extensive mangrove forest areas originally found in the islands, only two remain. The majority have been committed to the single purpose of land development and virtually ob- literated. The remaining two sites represent the Virgin Islands' only surviving opportunities to provide alternate allocations of these extrem- ely important, highly threatened and presently unique resources. They re- present valued remnants of the islands' natural heritage and, as such, should be maintained for future generations. In a larger frame, we suggest that man- I I I I I I I I I I I I 155 U 4. Sand should not be removed from beaches. 5. Shoreward earth change and drainage modifications near beaches must be carefully regulated. (2) PLANNING GUIDELINES FOR ROCKY SHORES 1. Structures on rocky shores should be securely anchored to stable footings. 2. Soil and other land materials or waste products should not be pushed over the shore into the sea. 3. if effluent discharges are con- templated, site studies are needed to determine where currents will carry pollutants and reduce impact. 4. On cliffs, a construction set-back requirement may be advisable in some locations for safety and to avoid effects of erosion on near- shore resources. (3) PLANNING GUIDELINES FOR SALT PONDS Management and use allocations of salt ponds should be approached generally on an individual basis. It is probably not necessary that every salt pond in the islands be preserved as salt ponds vary in their relative importance to the surrounding watersheds and as wild- life habitats. 1. In any case where a pond is to be opened to the sea, or an existing opening enlarged or otherwise modified, an adequate description of pond bathymetry and sediments should be prepared and analyzed, 2. Sediments dredged from a pond should not be depo~sited airectly in the sea or on the bayv shore- line. 3. Mangrove stands should be main- tained as a high priority comnpo- nent. 4. Openings to the sea should not be made until all intern-al work in, the pond is completed. 5. The relationship of the pond to the surrounding watershed and its importance as a wildlife habitat should be determi-ned in advance as it relates to the availability of similar babitats in the islands. (4) PLANNING GUIDELINES FOR MANGROVES 1. The remaining large mangrove areas (especially Salt River, St. Croix and Jersey Bay, St. Thomas) should be placed in the territorial park system. Th-eir development should be stringently restricted only for recreational, aesthetic and academic -use. 2. Dredging and filling as.a rule should be prohibited except on a small, carefully controlled scale and only after thorough study. 1 56 I I 11. Hunting of birds or the taking of eggs should be prohibited. 12. Restraint must be employed in constructing access roads to maintain optimum natural tidal flushinq and water circulation. 13. Development restraints should be promulgated for the watershed which drains into the mangroves to control the volume and frequen- cy of runoff. 14. Possible permissible uses include: Recreation as nature trails, underwater trails, for bird watching, hiking, and fishing on a controlled basis by con- servative methods. * Education and research devel- oping potential for use by stu- dents at all levels in areas of natural history. Commercial activity for areas already irrevocably committed to marina/small boat/dockage/ service functions. (5) PLANNING GUIDELINES FOR REEFS 1. Except where absolutely necessary, reefs should not be subjected di- rectly to filling, cutting, blast- ing or waste discharge of any type. 2. Heated effluents should never be discharged in reef areas. 3. Collection of marine or terrestrial living organisms or physical mater- ials should be prohibited or at least discouraged and regulated. 4. Limited sport fishing may be per- mitted, but it may be necessary to specify allowable areas, fishing gear and perhaps species, seasons and size limits. 5. Boat traffic within the area must be strictly controlled. 6. No anchorage for live aboard boats should be permitted. 7. Cutting of mangroves for any pur- pose other than the planned area management and use program should be prohibited. Annual mapping is recommended. 8. Access points for small boat docks, launching ramps or other access structures should be carefully selected and structures and opera-- tions closely monitored. 9. No waste discharges or polluting substances of any kind should be permitted into the area. 10. By zoning, licensing or other appropriate controls, buffer zones should be maintained adjacent to the mangrove area to minimize human impact. I I I I I I I I I I I I I 157 U If necessary, it may be better to make shallower cuts over big- ger areas to obtain a given volume of sand. 2. Dredging, where per'mitted,'should begin at the mouth of a bay anid proceed inward with an upward slope. Dreaging close to the beach should be absolutely pro~- hibitea. At least several hun- drea feet of shoreward grass beds in front of a beach should be left untouched. 3. Boat anchorages,in enclosed bays with grass beds can be destructive if vessel density over time be- comes too high. Fixed moorings, privately or publicly maintained and leased, are preferred. CS) PLANNING GUIDELINES FOR C-AYS 1. in conjunction with planning re- commendations fromn the Virgin is- lands Department of Conservation and Cultural Affairs, certain cays should be set aside as inviolate wildlife sanctuaries. 2. Other publicly owned cays should be developed for multiple use as -recreation and nat ure areas, but any alternate or coincident use of a cay should -be compatible with maintaining its value as a wildlife area and its scenic, 3. Except under careful control and licensing, corals and other reef organisms should not be collected commercially. Recreational col- lecting should be discouiraged and eventually regulated as in the case of Florida. 4. Dredging operations adjacent to reefs should be designed to minimize impact on the reef. Monitoring is essential. 5. All shore and water related de- ve'lopment should be evaluated for their relationship and pos- sible effects upon adj acent reefs. (6) PLANNING GUIDELINES FOR SANDY BOTTOMS 1. Use options should be considered in light of the relatively tol- erant quality of the habitat. 2. Where sand mining is proposed, adequate prior borings and sedi- mernt analyses should be conducted to describe the nature of the sedi- ments and determine spoil handling requirements. Final depth con- tours should be as natural as possible, eliminating deep iso- lated holes. (7) PLANNING GUIDELINiES FOR GRASS BEDS 1. Dredging should he avoided in these areas wherever possible. 1 58 I aesthetic value as part of the marine landscape. 3 .Consideration should be gi-ven to establishing ranger or warden stations on strategically lo- cated cays, from which it would be easy to patrol and monitor the other islets. OVERVIEW The Virgin Islands conlstitute a unique island system - a place of value, beauty, and inspiration-, possessing a rich history, spectacular marine life, diverse coastlines and a salub- riou-s climate. They also have a promising future as a habitat for resident faunal, floral, and human species? living in a balanced, na- tural harmony. ment plan for this critical zone of man- environment inter-rela-tionship offers the promise of minimizing environmental conflict, improving resource allocation decisions, preserving our insular heri- tage and restoxing the intricate balance with natural systems.' The suggested guide- lines outlined in the preceding pages are only a beginning. They will need contin- uous upgrading, updating and refinement, as independent and gjovernment sponsored research and more sitle-specific inventory data become available and as the competing interests and users of our coastal zone resources improve and expand upon their articulation of specific needs and. objec- tives. Developing an ecologically sound, informed and balanced perspective on re- source allocation is one of the principal objectives of planning. Coastal zone planning is no exception. There is, however, mounting evidence that the human component. of our is- lands' population has, through over- sight, uncontrolled expansion, and ill conceived actions, induced a broad spectrum of stresses that threat- en the natural viability of the is- land system anid could de-stroy what Alexander Pope referred to as "the genius of the place." This process is especially apparent in the coastal zone of the Virain islands where com- peting human interests and dynamic com- ponents of natural ecosystems interface and interact. The present effort to develop a manage- II I I I I 1 59 a el(c td Bibliograph These selected references, all of which are noW~ available in the Virgin Islands, have been reviewed and are recommended as basic documentary sources for fu- ture Virgin Islands coastal zone planning. Each annotation concludes with an evaluation code based on the following system keyed to documents of intrinsic utility to the planner. vation Conference, St. John, U.S. Virgin islands, October 1-4, 1965. Prepared by Caribbean Research In- stitute, College of the Virgin Islands, St. Thomas. Participants of widely varying interests and disciplines assessed island re_sources and planning. A resolution was passed establishing -the Caribbean Conservation Association. Includes papers on government planning, resources management, economic factors, parks and reserves, and historic sites. Marginal coverage of coastal and marine elements but useful for regional vari- ations on role of island planner, pro- blem identification. * **** Essential Planning Reference *** Usef-ul Planning Reference **Marginal (Technical, Scientific) I* Background Reference Only Armstrong, J.., November 1974. Coastal Zone Management: The Process of Pro- gram Development. Coastal Zone Man- agement Institute, Sandwich, Massa- chusetts. Developed as an unofficial technical guide for officials, dis-. cusses boundaries, uses, areas of concern, authority and organization, public participation anad estuarine sanctuaries.* Bandler, B.G., editor, November 1974. our Troubled Environment - Can We Save It: Proceedings of Conference on the Vir- gin Islands Environment, St. Thomas, U.S. Virgin islands, May 10-11, 1974. -Sponsored by the Caribbean Research Inst'i-tute, College of the Virgin Is- lands, St. Thomas. Varied conference discussions ranging from air and water to manpower training and econom- ics to environm6ntal researclh and land Adams, J.B., et al, 1975. Potential National Natural Landmarks, U.S. Virgin Islands. Prepared for the National Park Service by West Indies Laboratory, Fairleigh Dickinson U- niversity, St. Croix. Provides a classification system, priority ratings and a descriptive statement of seven sites on St. Croix, three on St. John, and four sites on St. Thomas. Excellent coverage for St. Croix but marginal for St. Thomas and St. John. Useful; needs follow up action. ** Anonymous, 1965. Conservation in the Eastern Caribbean: Proceedings of the First Easte-rn Caribbean Conser- 16 0 I I I I I I I I I I I Fairleigh Dickinson University, St. Croix (Special Project No. 2; Contri- bution No. 3). Large size and low species diversity suggest high energy conditions in Cottongarden Point yacht club basin lagoon type environment. 20 detailed plates. * Bowden, M.J., Allen, J., et al, 1968. Water Balance of a Dry Island: The Hydrocli- matology of St. Croix, Virgin Islands and Potential for Agriculture and Ur- ban Growth. Clark University, Worcester, Massachusetts (Geography Publications at Dartmouth College, No. 6) . Report of research to provide some data on rain- fall, evapotranspiration and water de- ficit aimed particularly to aid St. Croix farmers. ~* Bowden, M.J., Fischman, N., et al, 1970. Climate, Water Balance, and Climatic Change in the Northwest Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas. Re- search data collection for St. Thomas, St. John and British Virgin Islands, following same pattern as earlier St. Croix research. Collects data and discusses rainfall, rainfall varia- bility, evapotranspiration, water balance. Also discusses possible climatic change, seasonal and cyclic loss. **, Bowden, M.J., et al, 1974. Hurricanes in Paradise: Perception and Reality of the Hurricane Hazard in the Virgin Islands. Island Resources Foundation, St. Thomas. Historical review of incidence of, use. Emphasizes lack of local goals for research and development, lack of gov- ernment leadership and need for im-- proved planning and resource manage- ment strategies. * Beller, W.S., editor, October 1970. The U.S. Virgin Islands and the Sea. Re- port to the Governor. Released by Office of the Lieutenant Governor, Government of the U.S. Virgin Islands, St. Thomas. Citizens' report makes clear that the Virgin Islands' only major environmental resource, its marine assets, must be carefully used and actively protected. Recom- mendations aimed at formnulating policy are made for environmental quality, !iving/nonliving resources, industry, recreation, Caribbean re- lations, education and government. Black, Crow and Eidsness, Inc., October 1973. Water Reclamation at St. Croix, U.S. Virgin Islands. Second Interim Progress Report, June 1972 to Septem- ber 1973. Environmental Protection Agency Contract No. 1101GAK. Gaines- ville, Florida. Background data and information on geology, hydrology, soils and water quality in St. Croix groundwater recharge study area. Description of advanced wastewater treatment plant. * Bock, W.D., July 1969. Report on the Ecology of the Benthonic Foramini- fera in St. Croix, U.S. Virgin Is- lands. West Indies Laboratory, I I 161 a probability analYsis of, and damage assessment on storms and flooding, followed by detailed investigations of local perceptions, reactions and adjustmen-ts. Suggestions given for increased preparedness. *** Bowman, J., 1974. Sediment Source Study of the Salt River Estuary, St. Croix. Open File Student Reports, West In- dies Laboratory, Fairleigh Dickin- son University, St. Croix. Useful baseline data. Marginal value for management.* Brin, Darlan, 1973. Shoreli-ne Environ- mental Problems and Recommended Poli- cies for the U.S. Virgin islands. Unpublished Paper for Course at University of California-Berkeley. Issues of the Virgin Islands coastal environment discussed with relevancy to tourist industry, conservation and management coordination of planning and shoreline policy. makes detailed recommendations for development of a coastal zonae management program for the Virgin Islands. *** Brody, R.W., 1972. "Fish Poisoning in the Eastern Caribbean," Proceedings of the Twenty-fourth Annual Session, Gulf and Caribbean Fisheries Institute. U- naiversity of Miami, Rosenstiel School of Marine and Atmospheric Sciences. Best short sumimary of local fish poi- soning incidence. ** Brody, R.W., 1973. A Study of Ciguatera Fish Poisoning in the Virgin islands Area. Caribbean Research Institute, College of the Virgin islands, St. Thomas. Detailed report on NOAA, U.S. Office of Sea Grant Programs funded project on ciquatera in the Virgin islands. Excellent illustra- tions of potentially toxic fish, data on epidemiology, toxicity factors, locational considerations and intox- ication levels. ** Brody, R.W., et al, October 1969. Estuarine Environment at Cruz Bay, St. John, Phase I Report: A Study of Pollutants on the Waters and Sediments of the Bay. Report submitted to Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute, Coll-ege of' the Virgin Islands, St. Thomas (Water Pollution Report No. 2) . Base line information. ** Brody, R.W., et al, 1970. A Study of the Water, Sediments and Biota of Chocolate Hole, St. John, With Comiparison to Cruz Bay, St. John. Report submitted to Virgin islands Department of Health, Division of Environmental Health by Carib- bean Research Institute, Cblleqe of the Virgin Islands, SOt. Thomas (Water Pollution Report No. 3). Base line inf'ormation. * Brody, R.W., Towle, E.L., and Brownell, W., .1970. Marine Pollution in the Eastern Caribbean. Review paper prepared for FAO Technical Conference on Marine Pollution and Its Effects on Living Re- sources and Fishing, Rome, Italy. His- torical value only for placing Virgin islands within a regional context 16 2 I I vis a vis pressure on local environ- ments.* Brown and Root, Inc., 1974. Environmental Impact Assessment Report for Construc- tion of a Single Poin-t Mooring Terminal and Submarine Pipeline System, South Coast, St. Croix, U.S. Virgin Islands. Prepared for Hess Oil Virgi-n Islands Corporation. Extensi-ve technical data on marine and shoreline ecology of the south coast, oceanography anid climatology and their relationships to probable oil spills. Deficient in ocean cur-rent information. ** Brownell, W. and Rainey, W.E. '.July 1570. Exploratory Fishing for a Source of Non-Ciguatoxi-c Sport and Food Fish. Caribbean Research Institute, College of the Vi-rgin Islands, St. Thomas (Virgin islands Ecological Research Station Contribution No. 2) . An excel- lent, although specialized, report on the possibility of expanding local exploitation of deep water fisheries resources. ** Brownell, W. and Rainey, W. E. , August 1971. Research and Development of Deep Water Commercial and Sports Fisheries Around the Virgin Islands Plateau. Caribbean Research Irnstitute, College of the Virgin Islands, St. Thomas (Virgin Is- lands Ecological R.esearch Station Con- tribution No. 3). Excellent report on exploitation aspects of an underuti- lized local fisheries resource. Contains pr'actical recommendations on gear and method modifications. * 163 Candelas, G., July 1971. Ecological Study of St. Thomas Harbor and Adjoining Channels (East and West Gregorie Channels) . Prepared for the West Indian Company, St. Thomas. Cursory study, concluding that proposed re- clamation project,may have practically no effect on harbor ecosystems, if certain suggestions for careful dredging operations and sewage dis- charge are followed. Should be used with caution. * Clark, J. , 1974. Coastal Ecosystems: Eco- logical Consid-erations for Management of the Coastal Zone. The Conservation Foundation, W~ashington, D.C., in cooperation with the National Oceanic and Atmospheric Administration, Office of Coastal Environmient, U.S. Department of Commerce. Discusses coastal zone eco- systems and resources in terms of their ecologic makeup, impact sensitivity and limitations for specific uses. Presents concepts and processes governing coastal ecosystems and offers management prin- ciples and guidelines. Represents the best summary document available. Re- quired reading and availability as a reference. ** Clark, J. , 1974. Rookery Bay: Ecological Constraints on Coastal Development. The Conservation Foundation, Washington, D.C. While not a document dealing with the Virgin Islanas per se, this study is very pertinent, as it focusses on a mangrove area not unlike the St. Thomas mangrove lagoon and the Salt River area I I I I i I I I I a of St. Croix. Excellent guidelines and methodology. ** Clark, J., et al, 1964-65. The Botany Bay Survey Report, Botany Bay, St. Thomas, Virgin Islands: An Inventory of the Littoral Habitats and Living Resources of Greater Botany Bay. Sandy Hook Ma- riae Laboratory, American Littoral Society, Highlands, New Jersey. Eval- uates potential of site as nature sud sanctuary. Investigational sur- veys are reported, including habitat, underwater ecology and fishes ob- I ~~served. Only study of this site cov- ering floral and faunal features in systematic detail. Very useful.'~ Clark, J. and Brownell, W., October 1973. Electric Power Plants In the Coastal Zone: Environmental Issues. American Littoral Society Special Publication No. 7. Covers power plant design, vul- nerability of biota, internal and ex- ternAl impacts, federal regulations, and recommends siting guidelines. Clark, J. and Sarokwash, P.J., 1975. Rookery Bay Land Use Studies. En- vironmental Planning Strategies for the Development of a Mangrove Shore- I ~~line, Study No. 9: Principles of Ecosystem- Management. The Conserva- tion Foundation, Washington, D.C. I ~~Most recent update of mangrove man- ageraent guidelines. Very adaptable to Virgin Islands circumstances. For optimum value, see also the entire series available 'from the Conservation Foundation. ** Collette, B.B,. anid Earle, S.A., editors, October 1972. Results of the Tektite Program: Ecology of Coral Reef Fishes. Natural History Museum, Los Angeles. Paper detailing scientific results of Tektite Project relating to various ecological aspects 'of coral reef fishes. Base line value. Few management fac- tors covered. * Cosner, O.J., 1972. Wqater In St. john, U.S. Virgin Islands, with a chapter on "Al- ternatives of Water Supply" by Dean B. Bogart. U.S. Department of the Inter- ior, Geological Survey, in cooperation with National Park Service and the Government of the Virgin Islands (Carib- bean District open fi-le report) . De- tailed investigation of ground water sources of water supply for St. John resulted in developments of small sup- ply for Virgin Islands National Park. Rain water collection expected to coh- tinue as main domestic source. ** Coulbourn, W.C., et al, October 1973. ERTS-1 Virgin Islands Experiment 589. Determine Boundaries of ERTS and Air- craf-t Data Within Which Useful Water Quality Information Can Be Obtained. Prepared for Goddard Space Flight Cen- ter by Grumman Ecosystems Corporation. virtually useless, sophisticated high technology, research carried out in context external to the Virgin Islands. * Dammann, A.E., et al, 1969. Study of the Fisheries Po;tential of the Virgin Is- lands. Caribbean Research Insti-tute, 164 to soils and geologic processes. ** College of the Virgin Islands, St. Thomas (Virgin Islands Ecolcgical Research Station Contribution No. 1). Funded by the former U.S. Bureau of Commercial Fisheries, this is an extremely valuable historical docu- ment embracing a spectrum of data never previously or subsequently as- sembled in one source. Regretfully out of print and not readily available. Needs updating at earliest possible op- portunity. Includes catch, market, and importation data on food fish, in ad- dition to a broad view of the fishing industry of the Virgin Islands. Basic and essential. * Dasmann, R.F., Milton, J.P. and Freeman, P.H., 1973. Ecological Principles For Economic Development. The Conservation Foundation, Washington, D.C. General reference with excellent sections on tourism and humid tropics and a review of the interdependency of conservation, development and planning. See espec- ially Chapter 2 on carrying capacity, diversity versus simplicity, community resilience, and survival thresholds. Basic planning reference. *** Davis, J.H., Jr., September 1940. "The Ecology and Geologic Role of Mangroves in Florida," Papers from Tortugas Lab- oratory, vol. XXXII, pp. 307-409, Carnegie Institution of Washington. Extensive, detailed study of ecological relationships, environmental associa- tions and processes species of man- groves, particularly with reference Deane, C., Thom, M. and Edmunds, H., 1973. Eastern Caribbean Coastal Investiga- tions, 1970-73, 5 Mols. British Develop- ment Division in the Caribbean, Trinidad. Detailed review of West Indian natural coastal processes, dredging, sand ex- traction potential, covering also associated environmental problems and management components. A valuable basic study of an endemic Caribbean island problem - sand resources man- agement. * Ditton, R.B., 1972. The Social and Economic Significance of Recreation Activity in the Marine Environment. Wisconsin Sea Grant Technical Report No. 11, Green Bay, Wisconsin. A model, although brief, review of recreational aspects of a coastal zone. No local equivalent study is available. *** Donnelly, T., and Whetten, J., 1968. Field Guide to the Geology of the Virgin Is- lands. State University of New York, Binghamton, New York. Prepared for the Fifth Caribbean Geological Con- ference. Guide to geology of St. Thomas by Donnelly; field guide to geology of St. Croix by Whetten. Donnelly describes singularity of St. Thomas-St. John geology. Forma- tions are detailed, followed by a long listing of localities of geologic in- terest. A similar format is presented by Whetten for St. Croix. * I I I I I I I I 165 U Ellis, R.N., Cheney, D.B., et al, 1969. The Development of a Procedure anid Knowledge Requirements for Marine Resource Planning: The Cl-assification of Marine Resources. Travelers Re- search Corporation, Hartford, Connec- ticut. Outlines a systematic, anal- ytical methodology for marine re- source assessment and planning. Partially adaptable 'to the Virgin Islands. Deals with goal establish- ment, problem/conflict classification and information synthesis procedures for the planner. ** Engineering Science, Inc-., October 1968. Water Resources Study for the.Virgir� Islands of the United States /Water Reclamation Study7. Prepared 'For Government of the U.S. Virgin islands. Reviews water supply problems and in- vestigates feasible reclamation pro- grams for individual islands. Des- cribes direct reuse for irrigati-on, industLrial and sanitary uses and in- direct reuse via ground water re- charge. * Environment Consultants, Inc., 1969. Re- port on Beach Enhancement, Marina Development and Land Use, Tamarin.d Reef Hotel Property, St. Croix, Vir- gin islands. ChristiLansted, St. Croix. Site specific documentation and recommendations. Graphics, base line measurements and observations are useful. * Environment Consultants, Inc., 1970. Beach Erosion Survey, Forrest Waldo Property, La Grande Princess, St.. Croix, Virgin Islands. Christiansted, St. Croix Finds erosion at Waldo property due to sea wall constructed nearby.* Environment Consultants, Inc., 1970. En- vironmental Survey of Lemontree Bay Property, St. Croix, Virgin islands. Christiansted, St. Croix. Identifies sources of water, air pollution, and suggests solutions where possible. Also makes recomrftendations regarding surface drainage, ground water, soils, vegetation, beach and shore develop- ment.* Environment Consultants, Inc., 1971. En- vironmental Study of the Estate Whim Property, Long Point Bay, St. Croix, Virgin islands. Christiansted, St. Croix. Examines causes for shore ero- sion, beach instability, poor quality sand, reduced water quality and tur- bidity. Site specific; base line value only. * Erdman, D.S., 1.968. "Spawning Cycle, Sex Ratio and Weigh-ts of Blue MarliLn Off Puerto Rico and the Virgin Islands," Transactions of the American Fisheries Society 97 (2), pp. 131-137. Esoteric value only. Covers breeding cycle May-September, peaks July-August. Females average 2.5 times heavier than males. Discusses development of' ovar- ies and testes and size-frequency distri- bution of sexes. * 166 I I I I I I I I I I I I I I I Ewel, J.J. and Whitmore, J.L., December 1973. The Ecological Life Zones of Puerto Rico and the U.S. Virgin Is- lands. Institute of Tropical Forestry and U.S. Forest Service, Rio Piedras (Forest Service Research Paper UTF- 18). Maps Puerto Rico and Virgin Islands ecosystems with gross de- tails of soils, vegetation, climates, land use patterns, using Holdridge sys- tem of life zones (broad bioclimatic units). Appendices give data on bio- temperature and water balances. Mar- ginal value. Fosberg,. R.R., editor, 1963. Man's Place In the Island Ecosystem: A Symposium. Bishop Museum, Hawaii. Superb collec- tion of both technical and general studies by top specialists from di- verse disciolines. A very valuable re- ference. Basic planning tool. ~ Frankenhoff, C.A., et al, May 1974. En- vironmental Planning and Development in the Caribbean. Results of an en- vironmental planning workshop spon- sored by the Graduate School of Planning of the University of Puerto Rico. Contains sections written by Cruz Matos, John McEachern, Edward Towle, C. Frankenhoff and L. Guilini. Useful regional overview. Final chap- ter on oil pollution very relevant to Virgin Islands situation. * Freeman, P.H., 1974. Coastal Zone Pollution by Oil and Other Contamninants: Guide- lines for Policy, Assessment and Mon- itoring In Tropical Regions. Smithson- ian Institution, Washington, D.C. The best overview on the management aspects of oil pollution in tropical island areas. Basic planning reference. Garrison, L.E., Holmes, C.W. and Trumball, J. V.A., 1971. Geology of the Insular Shelf South of St. Thomas and St. John, U.S. Virgin Islands. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Special Publication No. 3). Preliminary re- port of reconnaissance study conduct- ed jointly by U.S. Geological_Survey and the Caribbean Research Institute. Purposes were (1) to provide recon- naissance map of distribution of sedi- ment types on shelf surface and (2) to map gross geological structure of the shelf. Results seen as useful for avoiding irreversible destruction of beaches, for providing geologic history: of area, for potential mining of ma- rine sand deposits offshore. Maps de- tail shelf-edge information. ** Gerhard, L. and Bowman, J., 1975. Sedimentation in the Salt River Es- tuary, St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dick- inson University, St. Croix, Special Publication No. 8. Site specific use- ful document. * Gerhard, R.D. and Roels, O.A., 1970. "Deep Ocean Water As A Resource For Com- bined Mariculture, Power and Fresh Water Production," Marine Technology 167 a Greiner Engineering Sciences, Inc., August 1974. Harry S. Truman Airport Master Plan, St. Thomas, Virgin Islands: Summary of Environmental Impact Assess- ment. Prepared for Virgin Islands Port Authority. Abbreviated version of en- vironmental impact statement (see also prior reference). Historical value only. * Griffin, G.M., 1974. Effects of Dredging On the Natural Turbidity Regime of the Northern Florida Keys. Harbor Branch Foundation, Publication No. 33. Lengthy technical document with a wealth of quantitative data on the effects of major dredging job. Base line data collected before dredging began and simultaneous data collected from unaffected area. ** Grigg, D.I., Crean, R.F., vanEepoel, R.P., 1972. Marine Environment of Brewers Bay, St. Thomas, Virgin Islands With a Summary of Recent Changes. Prepared for Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute; College of the Virgin'islands, St. Thomas (Water Pollution Report No. 15) . Covers turbidity and sediment changes asso- ciated with dredging in the bay. Des- cribes increase and decrease of tur- bidity during and after dredging as well as sediment character in the dredged hole. Useful summary data on Brewers Bay. See also subsequent stu- Society Journal, 4(5), pp. 69-78. Re- lates to Columbia University, Lamont Geological Laboratory, Rust-op-Twist upwelling project on St. Croix. Back- ground, historical value only. * Gill, A.M. and Tomlinson, P.B., 1971. "Studies on the Growth of Red Mangrove (Rhizophora mangle L.)," Biotropica, 3(2), pp. 109-124. Technical value only. * Greiner (J.E.) Company, Inc., January 1974. Summary: Feasibility Study, Improve- ments for Harry S. Truman Airport, St. Thomas, Virgin Islands. Prepared for the Virgin Islands Port Authority. Summary of feasibility study for im- provements at Truman airport covering analysis of airport conditions and deficiencies, including poor land use of airport, short and long term program, costs and scheduling. * Greiner Engineering Scienc-es, Inc., August ].974. Harry S. Truman Airport Master Plan, St. Thomas, Virgin Islands: En- vironmental Impact Assessment Report. Prepared for the Virgin Islands Port Authority. Environmental impact state- ment of project to expand Truman air- port, details expected impact on Lindbergh Bay marine ecosystems, on other areas by dredging, impacts on water quality, soils, air, noise, sur- face transportation, both temporary and long-term. See also revised 1975 version. * 168 I I St. Thomas. Caribbean Research Insti- tute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 10) . One of many sectoral site specific studies, containing useful base line data. Marginal use to planners. * Grossman, I.G., 1962. "Chemical Quality of Ground Water in St. Thomas, Virgin Is- lands," Geological Survey Professional Paper No. 450-B. U.S. Geological Survey, Washington, D.C. Describes chem- ical quality of ground water from 31 wells in shallow deposits (9-50 feet). Average dissolved solids was 1,650 ppm. Only 3 of 33 samples were less than 1,000 ppm. Wells in Charlotte Amalie had high chloride and nitrate concen- trates. The most promising source of acceptable quality ground water was Turpentine Run. * Grumman Ecosystems Corporation, 1971. Virgin Islands Test Site Program: Technical Pro- posal, Volume I, amended. Bethpage, Long Island, New York. A funded proposal to determine methods of in- vestigation to obtain coastal water quality information, ocean currents and pollution, and St. Thomas harbor status. Test site data to be used for other water research studies (see re- ference under Coulbourn for report). Marginal value. * Hackley-Masters Science Seminar, March 1974. An Ecological Survey of Buck and Capella Islands, U.S. Virgin Islands. Tarry- town and Dobbs Ferry, New York (Series No. 6). Hastily researched. Second- I dies on the environmental impact of St. Thomas airport expansion. ** Grigg, D.I., Rainey W.E., Towle, E.L., 1975. Some Effects of Dredging on Water Quality and Coral Reef Ecology. Island Resources Foundation, St. Thomas, Occasional Paper No. 22. Summarizes types of damage to reef areas caused by various types and methods of dredging. Outlines pro- cedures for reducing impact. * Grigg, D.I. , and vanEepoel, R.P., January 1971. Report on the Status of Water Quality in Cruz Bay and Chocolate Hole, St. John. Prepared for the Vir- gin Islands Department of Health, Di- vision of Environmental Health by Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 9) . Fol- low up on prior study; see Brody re- ference on Cruz Bay. Useful base line data. ** Grigg, D.I. and vanEepoel, R.P., June 1972. Water Quality and Benthic Biology With- in the Thermal Plume From Harvey Alu- mina, Virgin Islands Plant. Caribbean Research Institute, College of the Vir- gin Islands, St. Thomas. Description of suspended solids, transparency, dissolved oxygen and sea bottom com- munities in area of thermal plume. * Grigg, D.I., vanEepoel, R.P., Brody, R.W., 1971. Water Quality and Environmental Status of Benner Bay - Mangrove Lagoon, I I I I I I I I I I 169 a series of studies of a major tropical mangrove area. See also references under Clark. A very useful set of documents, with guidelines and planining strategies directly relevant to the Virgin Islands. * H-ernandez-Avila, M.L. and Roberts, H., August 1974. Form-Process Relation- ships on island Coasts. Technical Re- port 'No. 166, Coastal Studies Institute, Louisiana State University. Vari-ations in geometric properties and spatial arrangement of major coastal morpholog- ic landforms (beaches, cliffs, rocky shores, and swamps) of the iglands of Barbados, Dominica, Grenada, St. Lucia and St. Vincent were compared to coastal process sectors established by variations in mean wave power levels. * Herrick, T.R., 1966. Economic Study of the Submerged Lands of the Virgin Is- lands. Caribbean Research institute, College of the Virgin Islands, St. Thomas. Deals principally with sand resources and sand dredging. Histori- cal value only. * Herrmnann, R. and Schessel, D. (Hackley- Masters Science Seminar), March 1.971. An Ecological Survey of Steven Cay, U.S. Virgin Islands. Tarrytown and Dobbs Ferry, New York. Qualitative, low-key description of the natural history of the cay based on two week stay by group of high school seniors and staff. Contains many generalities and some apparent errors. Limited source ary school students made 10-day sur- vey, detailing geology, topography, vegetation, insects, rats, birds, reptiles, shoreline flora and fauna. Should be used with caution.-k Hackley-Masters Science Seminar, March 1975. An Ecological Survey of Saba and Tur- tledove Islands, U.S. Virgin islands. Tarrytown and Dobbs Ferry, New York (Series No. 7) . Covers same subjects as previous reference pertaining to Duck and Capella islands. * Hart, W.J., 1966. A Systems Approach To Park Planning. International Union for Conservati-on of Nature and Natural Resources (IUCN) , Morges, Switzerland. Basic methodology useful. * Heald, E.J. and Odum, W.E., May 1970. "The Contribution of Mangrove Swamps to Florida Fisheries," Proceedings of the Twenty-Second Annual Gulf and Caribbean Fisheries Institute. U- niversit~, ofL Miami, Rosenstiel School of Marine and Atmospheric Sciences. A classic and often cited, energetics oriented summary. ** Heald, E .J. and Tabb, D.C., 1973. Rookery Bay Land Use Studies. Environmental Planning Strategies for the Develop- ment of a Mangrove Shoreline, Study No. 6: Applicability of the Intercep- tor Waterway Concept to the Rookery Day Area. The Conservation Foundation, Washington, D.C. Part of a larger 1 70 I I I Insular Environments, Inc., April 1972. Marine and Environmental Factors in Red Hook Bay, St. Thomas. Prepared for P.F. Lopez Associates, St. Thomas. Site specific consulting report. ** Insular Environments, ln6., September 1972. An Investigation of the Site Proposed for an Ocean Outfall at Cruz Bay, St. John, U.S. Virgin Islands. Prepared for the Government of the Virgin Islands, Department of Health, Division of Environmental Health. Site specific consulting report. .4 Insular Environments, Inc., March 1973. Water Quality and Benthic Environment in the Area of the New Municipal Sewer Outfall at Red Point, St. Thomas, U.S. Virgin Islands. Prepared for the Govern- ment of the Virgin Islands, Department of Health, Division of Environmental Health. Site specific consulting re- port. ** Insular Environments, Inc., April 1973. The Potential Environmental Impact of the Construction of a Submarine Pipe- line and Deepwater Tanker Mooring and Unloading Terminal in the Caribbean Sea Off Limetree Bay, St. Croix, U.S. Virgin Islands. Prepared for Hess Oil Virgin Islands Corporation. Site specific consulting report. ** Insular Environments, Inc., May 1973. Preliminary Environmental Evaluation of Proposed Development at Fish Bay, St. John. Prepared for Cocoloba De- of information, but little else is available. Use with caution. I Herrnkind, W. and Olsen, D., April 1970- June 1971. Ecological Study for the Development of Lobster Management Techniques. Caribbean Research In- stitute, College of the Virgin Is- lands, St. Thomas (Sea Grant GH-86). Contains useful data but falls short of recommending workable management guidelines. Valuable only as his- torical document and research source. * Hite, J,C. and Stepp, J.M., editors, 1971. Coastal Zone Resource Management. Mass- achusetts Institute of Technology Press. Basic early text on coastal zone pro- blems and program design. Some con- tinuing value. * Hoffman, S., Robinson, A., Dolan, R., Feb- ruary1974. Virgin Islands Beach Pro- cesses Investigation: St. John, Vir- gin Islands. U.S. Department of In- terior, National Park Service, Wash- ington, D.C. (U.S. National Park Ser- vice Occasional Paper No. 1). Report examines relaticnships between surf zone processes and beach changes in reef-beach systems, emphasizing sedi- ment exchange, with much documenta- tion. Conclusion infers need to treat beaches as ephemeral. ,44 Hogben, N. and Lumb, F.E., 1967. Ocean Wave Statistics. National Physical Labora- tory, Ministry of Technology, Great Britain. Basic reference document. * 171 I I I I I I I I S Insular Environments, Inc. and Sigma En- vironmnental Sciences, Inc., September 1975. St. Thomas Sewage Treatment Plant Submarine Discharge Site Eval- uation. Prepared for Virgin islands Government, Department of Conserva- tion and Cultural Affairs, Division of Natural Resources Management. Describes benthic communities and water quality in area of sewage ef- fluent diffuser in 65-70 feet of water after nearly two years of discharge. * Insular Environments, Inc. and Sigma En- vironmaental Sciences, Inc., 1976. Environmental Assessment Report, Proposed Land Reclamation and Harbor Improvements, St. Thomias, Virgin is- lands. Consulting report for the West Indian Company, Ltd. (proprietary). Useful data. * Jacobsen, A.R., 1951. A Study of the Pollution of the Harbor Waters of the Virgin Islands. Government of the U.S. Virgin Islands, Department of Health. Early survey resulting from Department of Health concern about pollution from sewage, indus- trial waste and night soil disposi- tion. Historical value only.* Jadan, Doris, July 1971. A Guide to t'he Natural History of St. John. Virgi-n Islands Conservation Society and Promotion Graphics. Discusses natural resources on St. John, the Virgin Islands Department of Education's Environmental Studies Program (ESP) velopment Association, St. John. Site specific consulting report. * Insular Environmuents, Inc. , June 1973. Draft Envi-ronmental- Impact Statemient, Marine Sand Dredging, Christiansted Harbor, St. Croix, U.S. Virgin Is- lands. Prepared for Virgin Islands Port Authority. Site specific con- sulting report. ** Insular Environments, Inc., June 1973. Marine Environment of Canegarden Bay, St. Croix, U.S. Virgin Islands. Pre- pared for R. Weston, Inc., W. Chester, Pennsylvania. Site specific. * Insular Environments, Inc., J'uly 1973. Draft Environmental Impact Statement, Marine Sand Dredging, Red Hook-Vessup Bays, St. Thomas, U.S. Virgin Islands. Prepared for Virgin Islands Port Au- thority. Site specific consulting report. ** Insular Environments, Inc., July 1973. Draft Environmental Impact Statement, Harbor and Marine Terminal Expansion Port of St. Thomas, Virgi-n Islands. Prepared for Virgin Islands Port Authority. Site specific consulting report. ** Insular Environments, Inc. September 1973. Description of the Proposed Virgin Is- lands Refinery Corporati-on Site, St. Croix, U.S. Virgin Islands: Terrestrial Biota and Pelagic- Marine Macro-Fauna. Prepared for R. Weston, Inc., WJ. Chester, Pennsylvania. Site specific consulting report. * 1 72 I I Kumpf, H.E. and Randal, H.A., 1961. Chart- ing the Maxine Environments of St. John, U.S. Virgin Islands. Contribu- tion No. 348 from the Marine Labora- tory, University of Miami. In Bulletin of Marine Science of the Gulf and Caribbean, 11, no. 4, pp. 543-551. Landmark mapping effort to present coastal seabed features of St. John. Includes chart. *** LaRoe, E.T., 1974. Rookery Bay Land Use Studies. Environmental Planning Stra- tegies for the Development of a Man- grove Shoreline, Study No. 8: Environ- mental Considerations for Water Manage- ment. The Conservation Foundation, Washington, D.C. An important and use- ful segment of a larger, multi-faceted investigation of a major mangrove sys- tem, with relevance to Virgin Islands' shoreline management. ** Little, E.L., Jr. and Wadsworth, F.H., 1964. Common Trees of Puerto Rico and the Virgin Islands. U.S. Department of Agriculture, Forest Service, Washing- ton, D.C. Agricultural Handbook No. 249. Describes and illustrates 250 species of trees giving origin, dis- tribution, scientific and common names, and uses. Sound, valuable, and well illustrated. * Lopez, P.F., 1973. Outdoor Recreation in the Virgin Islands, Executive Summary: A Guide to Assist in the Implementa- tion of the Comprehensive Island-wide Outdoor Recreation Plan, 1973-1988. and details of study areas including Salt Pond Bay, Annaberg, Reef Bay. With bird list, vegetation list and many illustrations. Not scientific.* Johannes, R.E., 1970, 1972. "Coral Reefs and Pollution," Paper presented at FAO Technical Conference on Marine Pollution, Rome, Italy, December 1970. Published in Wood, E.J.F., Pollution of the Marine Environment, Amsterdam, 1972. ExDertly summarizes effects of various kinds of pollution on coral reefs. Good review.*** Kasperson, R.E,, 1971. Decentralized Water Rease Systems in a Water Scarce En- vironment: The Tourist Industry in St. Thomas, Virgin Islands. Caribbean Research Institute, College of the Virgin islands, St. Thomas (Water Pollution Report No, 13). Brief survey of impact of tourism on water supply and sewage disposal in St. Thomas. Estimates costs of water and sewage treatment at major hotels. * Kesterman, F. and Towle, E.L., 1]973. "Caribbean Weighs Impact of Stepped Up Oil Industry Activity," Journal of Maritime Law and Commerce, Vol. 4, No. 3; also, Island Resources Foundation, St. Thomas, Occasional Paper No. 8. Summarizes potential impact of expanded petroleum related activity (production, transhipment, storage, refining, and marketing) upon the Caribbean. Primarily of historical value. * I I I I I I I I I I I I I 173 n McNulty, J.K., Robertson, W.B., and Horton, B.F,, 1968. Departmental Study Team Report and Recommendations on Proposed New Jet Airport, St. Thomas, U.S. Vir- gin Islands. U.S. Department of the Interior, Washington, D.C. Accepting as fact the proposed development of the St. Thomas mangrove lagoon for a new airport site, this study first discusses the value of the present coastal resources -terrestrial eco- system, water hird and wildlife habi- tats, offshore islands and cays, sal-t ponds alteration, fish -and corals, currents and tides. The conclusions are drawn as to likely damage-result- ing from airport construction. Not a completely candid report. What is re- ported is accurate; what is not re- ported is important. Mann, R., et al, 1975. Aesthetic Resources of the Coastal Zone. Cambridge, Massa- chusetts. A planners handbook, pre- pared for the Office of Coastal Zone Management, NOAA, U.S. Department of Commerce. Provides a conceptual frame- work, an evaluation methodology, a listing of permissible uses, and suggestions for public participa~tion mechanisms. * Maquire, C.E., 1972. Solid Waste Planning Program for the U.S. Virgin islands. Providence, Rhode Is'-and. Consulting Report presented to the Government of the U.S. Virgin islands. Has useful site analysis of specific locations and incorporates a master plan for Prepared for the Government of the U.S. I ~~Virgin Islands, Department of Conserva- tion and Cultural Affairs. Contains use- ful graphic presentation of annual rain- fall and monthly temperature records, plus a preliminary analysis of use L * ~patterns and preferences for marine 3 ~~recreation sites. * McEachern, J. and Towle, E.L., 1974. Eco- logical Guidelines for island Develop- ment. International Union for Conser- vation and Nature and Natural Re- sources, morges, Switzerland. Use- * ~ ~ful general planning recommendations. Desi.gned as companion volume to Dasmann, Milton and Freeman study. - McEachern, J. and Towle, E.L., 1972. "Re- source Management Programs for Oceanic Islands,"Transactions of the Thirty- Se-venth Northi American Wildlife and Natural Resources Conference. Island I ~~Resources Foundation, St. Thomas, occasional Paper No.-I. A re- view article which is pertinent to the Virgin islands and a useful set of references. * McKinzie, W., et al, June 1965. Soils and Their Interpretations For Various Uses, St. Croix, American Virgin Is- 3 ~~lands. U.S. Department of Agriculture, * ~~Soil Conservation Service, Spartanburg, South Carolina. Distribution., descrip- tion and classification of St. Croix I ~~soils, their suitability and limita- tioiis for various purposes. ** 1 74 I I I I I f I I I I I I I I I I port at Long Beach Point, St. Thomas, Virgin Islands. University of Miami, RosenstielSchool of Marine and Atmos- pheric Sciences, Consulting Report to the Virgin Islands Port Authority. Useful for site specific data; other- wise of largely hisitorical value. * Michel, J.F. and Tabb, D.C., 1968. A Study of the Biological and Coastal Engineer- ing Aspects of the Proposed Jet Air- strip at Jersey Bay, St. Thomas, U.S. Virgin Islands. Part II: Coastal En- gineering Considerations. University of Miami, institute of Marine Sciences. Contains valuable base line data; other- wise useful only as an historical docu- ment on earlier development planning methodology with narrowly defined terms of reference. See also Tabb and Michel, 1968 for Part I. * Millas, J.C. , 1968. Hurricanes of the Caribbean and Adjacent Regions, 1492- 1800. Academy of the Arts and Sciences of the Americas, Miami, Florida. An historical summary based on an inten- sive search of sources. Useful for the researcher but of little use to the planner. ** Miller, J.W., VanDerwalker, J.G., and Waller, R.A., editors, August 1971. Tektite 2: Scientists-In-The-Sea. U.S. Department of the Interior, Wash- ington, D.C. Aquanauts conducted ma- rine research from ocean floor habi- tat at Lameshur Bay, St. John. Dis- cusses habitat engineering and training; solid waste management. Historical and contemporary value, but lacks sensitivity to special requirements and features of the coastal zone. * Mattson, P.H., editor, 1969. Transactions of the Fifth Caribbean Geological Con- ference, St. Thomas, July 1968. Oueens College, Flushing, New York. Papers on geophysics, marine geology, regional geology, geomorphology, hydrology, igneous petrology, paleontology, and stratigraphy, including several directly relevant to the Virgin Is- lands. Menasco-McGuinn Associates, August 1973. Virgin Islands Highway Functional Classification and Needs Study, Sum- mary Report. Prepared for the Govern- ment of the Virgin Islands, Department of Public Works in cooperation with the U.S. Department of Transportation, Federal Highway Administration, Hel- ena, Montana. Includes more than 30 maps developed by the contract firm from aerial photographs and field investigations and officially ac- cepted by the Public Works Depart- ment. In addition to inventories and traffic counts, standards are established for'design, pavement, present and anticipated use, routes, capital improvements, continuing data collection, and transportation planning. * Michel, J.F., 1970. A Study of the Hydro- dynamic Effects of the Proposed Air- 1.75 a lands. Dukane Press, Hollywood, Florida. Ten watercolor plates by the author, marginal sketches. Brief popularized descriptions of common avian residents and migrants. Several taxonomic inac- curacies and sketchy information. Use with caution. Neurauter, T., 1974. Past Depositional En- vironments of Lower Salt River. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Stu- dent Reports. Site specific useful data. * Nichols, M., et al, 1972. Environment, Water and Sediments of Christiansted Harbor, St. Croix. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 16). Ex- cellent detailed investigation of har- bor environment, including description, aerial photo studies, hydrography (tides and currents), water quality, reef ecology, fisheries, bottom vege- tation and sediment, sedimentation, utilization of harbor. ** Oakes, A.J. and Butcher, J.O., April 1962. Poisonous and Injurious Plants of the U.S. Virgin Islands. U.S. Department of Agricultural Research Service, Wash- ington, D.C. (Miscellaneous Publication No. 882). Covers selected vegetation with details for species outlining toxicity and symptoms'in humans. * gives detailed results of specific marine biological research missions and ocean survey. Largely a technical report of limited use. * Miller, W.R. and Whitney, S.C., 1975. "Data Management in Coastal Zone Planning," William and Mary Law Review, vol. 16, no. 4. School of Law, William and Mary College, Wil- liamsburg, Virginia. Useful exposi- tion of national/local information management problems with recommen- dations. * Mollica, T., 1973. Comparison of Grass Bed Sediments from Salt River and Tague Bay. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Re- ports. One of numerous site specific studies with intrinsic historical value as a source of local base line data. * Multer, H.G. and Gerhard, L.C., editors, 1974. Guidebook to the Geology of Some Marine and Terrestrial Environ- ments,St. Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Special Publication No. 5. An excel- lent, basic, academic document for serious investigators. An invaluable reference for any planner as it con- tains base line information, graphics and process descriptions obtainable from no other source. *** Murray, D., 1969. Birds of the Virgin Is- 176 I I I Ogden, J.C., editor, 1972. An Ecological Study of Taque Bay Reef, St. Croix, U.S. Virgin Islands. West Indies Lab- oratory, Fairleigh Dickinson Univer- sity, St. Croix. Special Publication in Marine Biology, No. 1. Student project to assemble data to serve as base line for detecting future change in this coral reef. Includes indivi- dual studies of benthic algae, grazers, fishes and other fauna. Well edited and useful. See also later publication by Multer and Gerhard. * Ogden, J.C, Yntema, J.A., and Clavijo, I., July. 1975. An Annotated List of the Fishes of St. Croix, U.S. Virgin Is- lands. West Indies Laboratory, Fair- leigh Dickinson University, St. Croix. Special Publication No. 3. Intended for use in conjunction with standard guides. Also includes description of St. Croix environments, ciguatera, and game and spearfishing records. Olsen, D., et a], 1972. The Ecology of Fishes in Two Mangrove Lagoons in the U.S. Virgin Islands. Marine Resources Development Foundation, San German, Puerto Rico and Virgin Islands De- partment of Conservation and Cul- tural Affairs. Reports trapping study of fishes in Manning Bay, St. Croix and Jersey Bay, St. Thomas. See also the following reference. ** Fisheries. Virgin Islands Department of Conservation and Cultural Affairs, Bureau of Fish and Wildlife. Annual Report for Project No. 2-239-R-l. Excellent specialized work by a trained statistical biologist. Sound methodology. Best used in conjunction with variously cited reports by Olsen, Dammann, Brownell, Rainey. ** Owen, W. and Konrad, M., April 1972. Thermal Survey: Harvey Alumina Dis- charge, St. Croix, Virgin Islands. Prepared for Caribbean Research Insti- tute, College of the Virgin Islands, St. Thomas by Vast, Inc., Frederiksted, St. Croix. Study of thermal plume of bauxite refining plant formerly owned by Harvey Alumina Corporation (now Martin Marietta), southwest of former Krause Lagoon area, St. Croix. Only study of its kind in Virgin Islands waters. Useful for base line data and methodology. * Percious, D.J., vanEepcel, R.P. and Grigg, D.I., 1972. Reconnaissance Survey of St. Thomas Harbor and Crown Bay, St. Thomas, Virgin Islands. Caribbean Re- search Institute, College of the Vir- gin Islands, St. Thomas (Water Pollu- tion Report No. 18). Useful survey with synoptic, site specific data. Principally historical value. A* Phillips, R.C., October 1960. Observations On the Ecology and Distribution of the Florida Sea Grasses. Florida State Board of Conservation, Marine Laboratory, I I I I I I I I I I I Olsen, D., 1975. Analysis of Catch Data for the Virgin I�slands Commercial 177 I a Science, Institute of Marine Science, University of Miami, 14, pp. 246-295. One of a very limited number of stu- dies of this species found in the Virgin Islands. ** Randall, J.E. , 1968. a'Conservation In the Sea: A Survey of Marine Parks,", Oryx, vol. 10, no. 4. Includes information on St. John and St. Croix (Virgin Islands National Park areas). * Ray, G.C., 1975. A Preliminary Classifi- cation of Coastal-and Marine Environ- ments. International Union for Conser- vation of Nature and Natural Resources (IUCN), Morges, Switzerland, Occasion- al Paper No. 14. Brief, useful review of problem of ecosystem definition, contrast between terrestrial and ma- rine areas, with a system for classi- fication by zoogeographic regions, by coastal biotic provinces, and by habitats. ** ,Ray, G.C., 1976. Critical Marine Habitats, Definition, Description, eriteria and Guidelines for Identification and Management (draft version).- Inter- national Union for Conservation of Nature and Natural Resources (IUCN), Morges, Switzerland. Expanded version of 1975 paper. See especially "Sum- mary Guidelines for Protection" and "Ecological Approach to Planning." Ray is currently heading an IUCN task force on a global inventory of criti- cal marine habitats, hence the empha- sis on a workable classification sys- tem. * St. Petersburg. Distribution, en- vironmental reauirements, limits and biology of 5 species of marine spermatophytes. Pertinent to Virgin Islands environments. * Pressick, M.L. and Towle, E.L., 1974. Marine Parks: Research and Educa- tion Programs as Feedback for Manage- ment. Paper presented at the Second International Conference on Underwater Parks and Reserves, Asilomar, Califor- nia, April 23-26, 1974. Also, Island Resources Foundation, St. Thomas, Occasional Paper No. 6. Outlines val- ue of advance planning for non-resi- dent research activity for manage- ment of special marine park areas. Relevant to the Virgin Islands Na- tional and Territorial park systems. * �ainey, W.E. and Pritchard, P.C.H., 1972. "Distribution and Management of Carib- bean Sea Turtles." Transactions of the Technical Session on Marine and Coastal Resources at the Thirty- seventh North American Wildife and Natural Resources Conference, spon- sored by the Wildlife Management In- stitute, Mexico City, Mexico, March 12-15, 1972. Also, Island Re- sources Foundation, St. Thomas, Occa- sional Papers No. 3. Summarizes the regional resource management pro- blems of the species, Chelonia my- das, * Randall, J.E., 1964. "Contributions to the Biology of th.e Queen Conch Strombus g igas,` Balletin of Marine 178 I I I Redding, M.J., November 1973. Aesthetics In Environmental Planning. U.S. Environmental Protection Agency, 600/5-73-009. Basic, well organized, thoughtful and systematic study sug- gesting alternative methodologies and implementation strategies for adding aesthetic concepts to public and private sector planning. Appendix con- tains useful examples of enviornmen- tal planning done by various federal agencies that incorporate attention to aesthetic impacts. * Reynolds, J.R., August 1970. Preliminary Study of Sewage Disposal Practices in Areas Not Served by the Public Sewage System of Charlotte Amalie, St. Thomas, Virgin Islands. Prepared for Virgin Islands Department of Health, Division of Environmental Health by Caribbean Research insti- tute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 6). Historical value only. Needs updating. Present practices apparent- ly are more effective and less sub- ject to personnel failures, due to training programs for sewage plant operators. See also Shatrosky re- ference. * Robas, A.K., December 1970. South Florida's Mangrove-Bordered Estuaries: Their Role in Sport and Commercial Fish Production. University of Mii-ami Sea Grant information Bulletin No. 4. Useful background study for under- standing role of Virgin Islands mangrove areas as nursery for local fish species. ** Robinson, A.H., August 1973. Natural Ver- sus Visitor-Related Damage to Shallow Water Corals: Recommendations for Visitor Management and the,Design of Underwater Nature Trails in the Vir- gin Islands. National Park Service, St. John, Virgin Islands. Technical report sumiaary of damage based on outside literature and NationalPark Service staff observation. Fuller visitor impact data is expected in future; in the interim, some general- izations are made concerning visitor management. Describes in detail reef corals of present and natural damage. Finds visitor damage minimal but feels future management needed. ** Robinson, T.M., et al, 1973. water Re- cords of the Virgin Islands, 1962- 1969. U.S. Geological Survey. Covers surface-water, quality of water and ground water records of Virgin Islands (stream flow, chemical and physical characteristics of water and ground water levels). * Robinson, T.M. , 1971. Earthquake-Accelerat- ed Decline of Water Level in an Obser- vation Well in St. Thomas, Virgin Is- lands. U.S. Geological Survey, Pro- fessional Paper 750-B, in Geological Survey Research, pp. B252-B253. Des- cribes increased rate of water level decline in a well near Turpentine Run following a 4.7 Richter shock centered about 30 miles north of St. Thomas at 60 kilometer depth. * I I I I I I I I I I I I 179 a Robinson, T.M., 1972. Ground Water in Central St. Croix, U.S. Virgin Is- lands. U.S. Department of the In- terior, Geological Survey, in coop- eration with the Government of the Virgin Islands (Caribbean District open file report). Data from 237 wells including complete chemical analyses of water quality. Avail- able water in aquifer would require desalting by electrodialysis for poor quality water or distillation. Robinson, T., et al, 1970. Magens Bay Master Plan. Consulting report pre- pared by Design Collaborative, St. Thomas, for the Magens Bay Beach Commission, St. Thomas. Includes excellent summary of biological and hydrological features of the asso- ciated watershed, salt pond, man- grove, beach and bay area. Has use- ful base line information for fu- ture planning and management. Site specific. ** Rundel, P.W., 1974. An Annotated Biblio- graphy of West Indian Plant Ecology. Published for the Island Resources Foundation, St. Thomas by the Virgin Islands Department of Conservation and Cultural Affairs, Division of Libraries and Museums. Result of Foundation sponsored research. Pri- marily useful as a research refer- ence guide. Shatrosky, E.L., vanEepoel, R.P. and Grigg, D.I., October 1972. Operating Characteristics of Package Sewage Plants on St. Thomas, Virgin Islands, January-June 1972. Prepared for Virgin Islands Department of Health, Division of Environmental Health by the Caribbean Research In- stitute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 20). Continues analyses of 19 plants. Consummation of three prior reports. Principally of historical value. * Smith, F.G.W., 1971. Atlantic Reef Corals. university of Miami Press. Technical reference for coral identification. * Smith, J.W., 1974. Growth Studies on Gorgonian Octocorals (abstract only). Proceedings of the Florida Keys Coral Reef Workshop. State of Florida, Department of Natural Re- sources, Coastal Coordinating Council. Average growth rate for seven species of gorgonians, measured over thirteen months was 4.1 centimeters/year. Range for individuals was 2.4 to 5.5 centi- meters/year. Studies at Key West. Ranges similar to those ifl Jamaica and Dry Tortugas. * Sorensen, J. and Demers, M., 1973. Coastal Zone Bibliography: Citations to Docu- ments on Planning, Resources Manage- ment and Impact Assessment. Sea Grant Publication No. 8, University of Cali- fornia, La Jolla, California. Standard bibliographical reference. ** Stephens, W.M., 1963. Mangroves: Trees That Make Land. Smithsonian Institution, i10 I I I I I I I I I I I I I I Washington, D.C. Reprint from Smith- sonian Report for 1962, pp. 491-496. Brief popular account of natural pro- cesses anid value cf mangroves. * Stott, S., 1974. Economics of Conch (Strombus gigas) on St. Thomas, Virgin Islands. Unpublished survey by Island Resources Foundation, St. Thomas. Of limited value to planner. ~ Stursa, M.L., December 1974. Florida Keys Coral Reef Workshop, Proceedings. Sponsored by Florida Coastal Coor- dinating Council,. State of Florida, Department of Natural Resources. Practical, management oriented report with some discussion of 'stress, tol- erance and mortality, and research needs. *** Sverdrup, H.U., Johnson, MoW. and Fleming, R.H., 1942. The Oceans. Prentice Hall, Inc., Englewood. Standard reference work. * Swingle, W.E., Dammann, A.E., and Yntema, JoA., 1969, Survey of the Commercial Fishery of the Virgin Islands of the United States- Proceedings of the Twenty-second Annual Session, Gulf and Caribbean Fisheries Institute, 26, pp. 110-121. University of Miami, Rosenstiel School of Marine and At- mospheric Sciences. Summary of in- formation available in Dammann (1969) on Virgin Islands commercial fisheries. Tabb, D.C., 1967. Report of Investiga- tion: The Biological and Ecological Effects of Dredging for Sand in the Water and Brewers Bay Areas of St. Thomas, Virgin Islands. University of Miiami, Institute of Marine Sciences. Consulting Report prepared for Office of the Governor, Government of the U.S. Virgin Islands. Very general appraisal based on brief site ob- servations (apparently of shorelines only). Recommends allowing dredging of Brewers Bay. List of some or- ganisms observed in rocky shoreline habitat. * Tabb, D.C. and Michel, J.F., 1968. A Study of the Biological and Coastal Engineering Aspects of the Proposed Jet Airstrip at Jersey Bay, St. Thomras, U.S. Virgin Islands. Part I: Biological Considerations. Univer- sity of Miami, Institute of Marine Sciences. Contains valuable base line data; otherwise useful only as an historical document. See also Michel and Tabb, 1968 for Part II. * Thompson, J.R., 1973. Ecological Effects of Offshore Dredging and Beach Nour- ishment: A Review. Miscellaneous Paper No. 1-73, U.S. Army Corps of Engineers, Washington, D.C. Fine annotated bib- liographic review article written for both the specialist and the layman/ planner. Extensive sumamary of eco- logical processes intruded upon by dredging. **** I81 I a Towle, E.L., 1973. Environmental Management of Island Based Ocean Engineering Pro- jects. Paper presented at the Third Technical Session of the First Carib- bean Oceaneering Conference in San Juan, Puerto Rico, sponsored by Inter- American University. Also, Island Re- sources Foundation, St. Thomas, Occa- sional Paper No. 5. Critical analysis of St. John based Tektite undersea habitat project with special refer- ence to local application problems and relevance to local research needs. ~** Towle, E.L., 1973. The Role of the Travel- Tourism Industry In international Ma- rine Recreation Development. PresentEd at Ninth Annual Marine Technology Soci- ety Conference, Washington, D.C. Also, Island Resources Foundation, St. Thomas, Occasional Paper No. 19. Background for recreation planning, stressing need for educational dimension. * Towle, E.L. and Hanif, M., 1973. National Parks in the Caribbean Area. Paper presented to the Conference on Science and Man in the Americas, Mexico City. Also, Island Resources Foundation, St. Thomas, Occasional Paper No. 2. * Towle, E.L., Marx, R., and Tyson, G.F., 1976 (revised edition) . Shipwrecks of the Virgin Islands (1523-1900) . Island Resources Foundation Monograph, St. Thomas. Most comprehensive listing available. Includes U.S. and British Virgin Islands. ** U.S. Government, Department of Agriculture, Virgin Islands Soil and Water Conserva- tion District, 1971. Environmental Pro- tection Handbook: A Guide to Assist in the implementation of the Environmental Protection Act of the United States vir- gin Islands. Kingshill, St. Croix. Standards and specifications for soil erosion control, slope control prac- tices, water conservation, for persons applying for Virgin Islands "Earth Change" permits. Includes seven page glossary. See latest edition. ** U.S. Government, Department of the Army, Corps of Engineers, 1975. Flood Plain Information, Tidal Areas St. Thomas, St. Croix and St. John, U.S. Virgin Islands. Office of the Governor of the U.S. Virgin Islands, Virgin Is- lands Planning Office. Provides (1) historical data on hurricanes and re- lated flooding and (2) future flooding predictions for major storms of 100 year frequency plus worst possible flood plates are fold out maps of coastline showing areas of expected flooding. *** U.S. Government, Department of the inter- ior, Bureau of Outdoor Recreation, 1970. Islands of America. Excellent inventory of the island resources of the United States with a plan for an island heritage trust. ~** U.S. Government, Department of the Inter- ior, Federal Water Pollution Control Administration, 1967. Biological As- pects of Marine Water Quality, St. 182 a I I College of the Virgin Islands, St. Thomas (Water Pollution Report No. 2). A controversial study with some continuing instructive value on how not to dredge close inshore and why. ** vanEepoel, R.P. and Grigg, D.I., January 1970. Survey of the Ecology and Water Quality of Lindberg Bay, St. Thomas. Prepared for the Virgin Is- lands Department of Health, Division of Environmental Health by Caribbean Research Institute, College of the Virgn Islands, St. Thomas (Water Pollution Report No. 4). Base line value (see other parallel studies of dredged and stressed sites in Cruz, Water, Benner, Vessup and Brewers Bays and Christiansted harbor). ** vanEepoel, R.P. , et al, 1971. Notes On Some Oceanographic Marine Factors in the U.S. Virgin Islands. Prepared for Virgin Islands Water and Power Authority by Caribbean Research In- stitute, College of the Virgin Islands, St. Thomas. Institute Special Publi- cation No. 2. Despite the title, this is a report on the definition of a suitable medium depth route for a submarine electric (40 megawatt) cable linking St. Croix and St. Thomas. Contains useful oceanographic data summaries and bathymetric gra- phics on the submarine features be- tween the two islands separated by a relatively deep trench except to the Thomas, St. Croix and St. John, U.S. Virgin Islands. Historical value only. * U.S. Government, Naval Oceanographic Office, 1963. Oceanographic Atlas of the North Atlantic Ocean, Sec- tion IV, Sea and Swell. Standard reference. * U.S. Government, Naval Oceanographic Office, 1963. Sailing Directions for the West Indies, vol. II, H.O. Publication 22. Standard reference with detailed descrip- tions of physical features of Vir- gin Islands coastlines. * University of Texas (Austin), Division of Natural Resources and the En- vironment, 1973. The Management of Bay and Estuarine Systems in the Texas Coastal Zone. Prepared for Office of the Governor, State of Texas. Describes coastal eco- system units of Texas. Gives their attributes, beneficial and detri- mental uses and inherent factors influencing uses. Many of these ecosystems are locally comparable. Useful document for planning insights. *** vanEepoel, R.P., November 1969. Report on Effects of Dredging in Water Bay, St. Thomas. Prepared for Vir- gin Islands Department of Health, Division of Environmental Health by Caribbean Reserach Institute, I I I I I I I I I I I I 183 a Virgin Islands Government, Department of Conservation and Cultural Affairs, Division of Planning, 1974. Vi-rgin islands Comprehensive Outdoor Rec- reation Plan, Executive Summiary. Contains useful tabular data on the recreational value, size, and accessibility of offshore c'ays, is- land wide recreational demand fac- tors, and maps of facilities and sites. * Virgin islands Government, Department of Health, Division of Environmental Health, 1971. A Report on the Environ- ment Surrounding the Hess-Har'vey Alumnina Plants on St. Croix. In-house Report. Air, water and marine bio- logical observations. Description of industrial plants' processes. Mostly qualitative descriptions of environ- mental impacts associated with.plants' construction and operation. * Virgin Islands Government, Planning Board, September 1967. Conservation of Beachies: A Study of Problems, Needed Policies, Resources and Actions Re- quired of Private Enterprise, Citi- zens, and the Government of the U- nited States Virgin Islands, revised draft. St. Thomas, Virgin Islands and Cambridge, Massachusetts; report pre- pared by Reginald Isaa cs. Study of beach problems, government policies and proposed management planning from 1967 vantage point. * Weaver, J.D., editor, 1960. Transactions eastward where a route appeared feasible. *** vanEepoel, R.P., et al, June 1971. Water ouality and _Sediments of Lind- bergh Bay, St. Thomas. Prepared for Virgin Islands Department of Health, Division of Environmen-tal Health by the Caribbean Research Institute, College of the Virgin islands, St. Thomas (Water Pollution Report No. 11) . Hiistorical and technical value with observations on the still de- pauperate dredge hole and marginal recolonization. * Veri, A.~R,, et al, 1973. Rookery Bay Land Use Studies. Envi-ronmental Planning Strategies for the Development of a mangrove Shoreline, Study No. 2: The Resource Buffer Plan, A Concep- tual Land Use Study. The Conserva- tion Foundation, Washington, D.C. -Very useful segment of a larger set of studies. Excellent methodolo- gy. Virgin Islands Government, Department of Conservation and Cultural Affairs, Division of Natural Resources Man- agement, 1975. Virgin Islands Water Quality Monitoring, 1970-75. Ex- cellent Departmental report sum- maarizing statistical data and pro- blems of island growth and pollution, pollution monitoring and abatement programs, and improvements in water quality. All Virgin Islands waters now meet Virgin Islands water quality standards. ** 1 84 U I I impacts and means to alleviate im- pacts, particularly oil spill pre- vention alternatives.* White, G.F. and Haas, J.E., 1974. Assess- ment of Research on Natural Hazards. Massachusetts Institute of Technology Publication, Cambridge, Massachusetts. Scholarly review of methodology espe- cially relevant to the Virgin Islands for hurricane, flooding and earthquake disaster planning. Most up to date study available covering national responses, acceptable levels of risk and adjustment choices in public de- cision making and planning fcr hazard prone areas. *** Wilcher, R., 1974. A Characterization of Sedimentary Facies Relationships of Salt River, Sto Croix, U.S. Virgin Islands. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Reports. Useful background data on a critical unique area. * Wdst, G., 1964. Stratification and Circu- lation in the Antillean-Caribbean Basins. Part 1: Spreading and Mixing of the Water Types, with an Oceano- graphic Atlas, Columbia University Press, London. Technical treatment of Caribbean oceanography. * Yokel, B.J., 1975. Rookery Bay Land Use Studies. Environmental Planning Stra- tegies for the Development of a Man- grove Shoreline, Study No. 5: Estua- rine Biology. The Conservation Founda- of Caribbean Geological Conference, Mayaguez, Puerto Rico, January 4-9, 1959. Published by the University of Puerto Rico, Mayaguez, Puerto Rico. Technical report on scholarly papers and abstracts, some bearing up- on the Virgin Islands. Background use only. * Weil, S. and Otsoka, C., 1974. Salt Ri- ver Mlangroves - A Preliminary Study. West Indies Laboratory, Fairleigh Dickinson University, St. Croix. Open File Student Reports. Useful background information on a unique area. , Westermann, J.H. , 1952. Conservation in the Caribbean. Foundation for Scien- tific Research in Surinam and the Netherlands Antilles, Utrecht, Netherlands, Publication No. 7. Reviews conservation problems and programs in Caribbean islands. Discusses regional problems in agriculture, soil, water and wild- life conservation. Reviews con- temporary views on the population problem. * Weston, R.Fo., Inc., 1975. Environmental Assessment Study for a Two Hundred Thousand BPCD Refinery, St. Croix, U.S. Virgin Islands. West Chester, Pennsylvania. Prepared for the Vir- gin Islands Refinery Corporation. Detailed study of area background setting (socio-economic, land use, natural areas, landmarks, climate, oceanography, ecology), expected I I I I I I I I I I I I 185 tion, Washington, D.C. Excellent presentation on the biological pro- cesses operative in a mangrove la- goonal system similar to those in the Virgin Islands. *** Zube, E.H., January 1968. The Islands: Selected Resources of the United States Virgin Islands and Their Relationship to Recreation, Tourism and Open Space. University of Massachusetts, Department of Land- scape Architecture. Prepared for the U.S. Department of the Interior. Provides basic resource inventory data for governmental agencies. A general, short-term production emphasizing open space systems. 186 SUPPLMIViENITAL 131BLiOGRA.PBA�YP' I port of sand. ** Grigg, D.I. and vanEepoel, R.P., 1970. The Status of the Marine Environment at Water Bay, St. Thomas. Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 7). Useful base line information concerning a contro- versial dredging project and its im- pact on coastal processes at Water Bay. * Grigg, D.I., vanEepoel, R.P., and Brody, R.W., 1970. Water Quality and the Marine Environment of Vessup Bay, St. Thomas. Caribbean Research In- stitute, College of the Virgin Is- lands, St. Thomas (Water Pollution Report No. 8). The only study of this site. Useful base line data. * Hackley-Master Science Seminar, March 1973. An Ecological Survey of Great St. JamesF U.S. Virgin Islands. Tarrytown and Dobbs Ferry, New York. A marginal quality survey by secondary school students. Should be used with extreme caution. * Kimmelman, B., et al, 1974. Studies In Environment: Outdoor Recreation and the Environment, Volume 5. Socio- economic Environmental Studies Series, Office of Research and Development, U.S. Environmental Protection Agency, Washington, D.C. The section on coastal areas provides a useful evai- uation methodology. ** I Bristol, Childs, Crowder and Associates, Inc., February ].975. Proposed Master Plan and Feasibility of Development of the Cruz Bay-Enighed Pond Areas, St. John, United States Virgin Is- lands. Published for the virgin Is- lands Port Authority. Coral Gables, Florida. Report has given prime consideration to St. John's natural resources and considers environ- mental impacts of its recommendations. Incorporates separation of cargo dock- ing from passenger-tourist-pleasure boat docking. * Dong, M., et al, 1973. The Role of Man Induced Stresses in the Natural Evolution of Long Reef and Chris- tiansted Harbor, St. Croix, tJ.S. Virgin Islands. West Indies Labora- tory, Fairleigh Dickinson University, St. Croix, Virgin Islands. Useful base line reference. * Environment Consultants, Inc., 1969. Beach Erosion Survey: Forrest Waldo Property, LaGrande Princess, St. Croix, Virgin Islands. Christian- sted, St. Croix. Site specific con- sulting report. * Environment Consultants, Inc., November 1969. Environmental Studcy of the Green Cay Development Property, St. Croix, U.S. Virgin Islands. Chris- tiansted, St. Croix. Site specific consultincg firm recommendations with useful base line data on beach- rock formation, wave and swell con- dition, drainage and littoral trans- I I I I I I I I I I I I 187 McGuire, J.W., 1925. Geographic Dic- tionary of the Virgin Islands of the United States. U.S. Coast and Geodetic Survey, U.S. Department of Commerce, Washington, D.C. An invaluable reference. * National Academy of Sciences, 1970. Waste Management Concepts for the Coastal Zone: Requirements for Research and Investigation. Washington, D.C. A comprehensive evaluation of the scientific and engineering aspects of coastal wastes management with special emphasis on physical processes, chemical and biological factors, and'recommended studies. Required reading. *** Onuf, C., 1973. Annotated Bibliography on the Biological and Ecological Effects of Oil Pollution in Tro- pical Waters. Office of Internation- al Programs, Smithsonian Institu- tion, Washington D.C. A very use- ful reference of a technical nature (see also Freeman, 1974). * Randall, H., 1964. A Study of the Growth and Other Aspects of the Biology of the West Indian Top- shell, Cittarium pica," Bulletin of Marine Science, vol. 14, pp. 424-443. Institute of Marine Science, University of Miami. Classic study of limited value to the planner. * Rivera, L.H., et al, 1966. Soils and Their Interpretation for Various Uses, St. Thomas, St. John, Virgin Islands. U.S. Department of Agriculture, Soil Conservation Service, Kingshill, St. Croix. Distribution and classi- fication of St. Thomas and St. John soils and their suitability and limitations for various purposes. Useful for soil runoff and erosion control. ** Rivera, L.H., et al, 1970. Soil Survey of the Virgin slands of the United States. U.S. Department of Agricul- ture, Soil Conservation Service, Kingshill, St. Croix. A summary re- port, useful for runoff assessment and as a basic study. ** Unger, I., 1966. Artificial Reefs - A Review. Special Publication No. 4, American Littoral Society, Highlands, New Jersey. A standard reference on artificial reefs including a section on the Randall installed reef at Lameshur Bay, St. John. A very use- ful summary. ** URS Madigan-Praeger, Inc., 1974. Report on Plans for Seaport Development and Relocation for the Virgin islands Port Authority. New York. Specialized study of St. Croix port facilities with reference to containerized lo- gistics, upgrading, berth utilization, cruise ship traffic and a master plan for Christiansted and Frederiksted. Very useful statistical data. * vanEepoel, R.P. and Grigg, D.I., 1970. 188 I I Effects of Dredging at Great Cruz Bay, St. John. Prepared for the Virgin Islands Department of Health, Division of Environmental Health by the Caribbean Research Institute, College of the Virgin Islands, St. Thomas (Water Pollution Report No. 5). historical and technical value. See other studies of Cruz Bay under Brody, et al, 1969 and Grigg and vanE l cel, 1971. ** I I I Wilbur Smith Associates, 1976. Virgin Islands Ma,s Transit Study. Columbia, South Carolina. Detailed survey and tiansit development plan, in- cluding assessments of inter- island marine transportation and coastal nodal points. Excellent data. ** Zube, E.H., ed. 1976. Studies In Land- scape Perception. Puhlication No. R-76-1 of the Institute for Man and Ihe Environment, University of Massachusetts, Amherst, Mass- achusetts. Useful for methodology. See especially the section on cross-cu ltural asrects of land- scape perception. ** "'. c .. 1 I ' "I4 , C . 1 - t '%,% I t - I ' `" d , S ? h./ ~~~4?r~~~~ i 3'.~~~ .,.3 s - CE 1, 1. 0 , ~i. I '' ' e;-,A, - ' 't, I 189 INT'Wei Accretion (shoreline) 77, 86-89 Algae 70, 86, 102-104, 110, 117 Altona Lagoon 82, 100 Aquaculture (see mariculture) Artemia (brine shrimp) 88 Bathymetry 46-49, 53, 147 Beach rock 76-77, 148 Beaches 70-83, 119, 136, 148, 152 Benner Bay (see also Jersey Bay, Mangrove Lagoon) 29 Berm (beach) 70, 86 Biochemical oxygen demand (see B.O.D.) 34, 88, 89 Bioturbation 97 Birds 62-63, 85, 88, 98, 113, 139 Black coral 118 B.O.D. (see biochemical oxyg'en demand) Brewers Bay 80 Brine shrimp (see Artemia) Cays 64, 113-116, 141, 151 Charlotte Amalie harbor 32, 79 Christiansted 9, 45, 79, 80 Ciguatera 59 Cinnamon Bay 80 Coastal zone management 129 C.O.D. (chemical oxygen demand) 34 Conch 56-57, 110, 117 Corals (see also Reefs) 70, 85, 101-107 Crabs 86 Critical areas 126-128, 154 Cruz Bay 29 Current Hole 11 Currents 5-8, 74, 96, 145 Dissolved oxygen (see water quality, and oxygen) Diversity, species 94 Drainage 132, 134, 139 Dredging 82, 136, 137 Earthquakes 50 Ecology 52-58, 88, 102, 107, 110, 113, 147-155 Ecosystems (including bibphysical rela- tionships) 64, 119-130, 134-135 Effluent discharge 106 Energy 110, 117, 134 Erosion 72, 77, 80, 82 Estuaries (see Mangroves, Lagoon, Jer- sey Bay and Salt River) Eutrophication 105 Evaporation 44, 45, 86, 88 Evapotranspiration 44 Fish and fisheries 52-63, 99, 147-148 Floods and flooding 40, 45, 88 Geology 46-51, 70-83 Gorgonians 85 Grass beds 109-112, 119, 140, 151 Grasses (marine) 82 Great Pond, St. Croix 100 Groundwater 80 Hurricanes 38-43, 77-80, 146 Hypersaline 17, 88, 97 Jersey Bay (see also Mangrove lagoon) 28- 31, 94, 98, 132 Lagoons (see Mangroves) Land crabs 86 Littoral drift 74, 78 Lobsters 54-55, 94, 99 Magens Bay 74, 82 190 I M ia nagEtr2oi1t qu id, Ii n e,s 1 31 1 343i- 2 1.2 Manglove L'age-on (sep- under ~~q�VS ~ancroves (see also Vegetation) 641, 9 2- 1,J0 1,22--132 / 138-1219, 1 49D -15 0 ',ajps arind charts (sce li-st of1 f iguLires) acr 2. cu It~itre 88 12, 117 ivk~.an namals53, 60 Mario recration(seererti) 1',arine ~ seresearch)(e YL:eteoroi-ogy 3!5, 38, 44 Nt r ets I17, 9 4'- 9 II7, 11. 13 -,v gnn d ssolc)ved 29. 31, 32 3 8 134 'P hct cs vn -- h e s i s I02 Phvtoplankton 97 a I~ ,, P oI 1' ut c.i 17-18 88,8 92, 11C0 P 5 4 Pro Losta.t Cay 8 aa f ' 441- 4 5 62 e1 41 7 te '-t or (zS'ie als I 0 i c a ]r2 ati_1 ) .0 sO~~~~-o, 1239L (~ fe alsn o oral) 1 107, T 121 - I3 L140, 152 Salinity IS, -19, 23 ,SC., 88, 937, 103 , I134 Salt ~pcnds 341, 86-91, 119, -137, 1S2 SAt River 92-96 8and production 74, 78, 102 Saxid travs-,ort 712-75- eSimdv bottoms 107-1-09, 140 Sa,mdy Point 77 Sea graos Bi-, 99g S'ea turtles (see Tur-t-les) Saa 'uLlls 79 S'e,-clai mea.surem.,.,yt~s 32-33 Sda:nenc.ati-on tsee also Siltation) 49, 70- 72, 7a; 38-q0, 92, 96, 137 SO.C, f 1 u e , 2- 3 4 3iij ta~on (see also Sediment-ation,) 45, I0) .i 0 Solid wastes 80 Sor La- fi i ng 5 2, 133 Storms .10-43 S t r 3 -15 245 Tepeatr 16 3- 17 145 Thesmodc a 30IIu , 103 11 Tid-, -1-4,1 96, 1.44q Tidal surge- 15, -145 ...0.Lr (se,e Th,r,-shold) T u rbau'' i16IyIC 17, 32, 82, 105, '112, 135 Unir'i~~ as128, 132 Vi ul a:eIa c! (e c alIs r Critical ,Un iaue)u 131 I'a v cs 1.3-1.3, 40, 50, 70,71, 79, 1'45 ~i.nds 35S-3S8 I I I I I I I I I I I I91I