:final report for contract period 18 November 1981 through 30 November 1983/Barbara A. Harris ... [et al.] Harris, Barbara A. Florida.Marine Research Laboratories. Coastal Zone Information Center (CZIC) St. Petersburg, FL:Florida Dept. of Natural Resources, Bureau of Marine Research, Marine Research Laboratories,1983 Fisheries Florida. Estuaries Florida. Estuarine fisheries Florida. Fishes Habitat Florida. I U. S. DEPARTMENT . '", ;'<F N0A- COASTAL SERVICES :.'r , 2234 SOUTH HOBSOr. . f, CHARLESTON , SC ".'" - '' ASSESSMENT OF FISHERIES HABITAT: CHARLOTTE HARBOR AND LAKE WORTH, FLORIDA Final Report for contract period 18 November 1981 throuqh 30 November 1983 Barbara A. Harris, Kenneth D. Haddad, Karen A. Steidinger, and James A. Huff Florida Department of Natural Resources Bureau of Marine Research Marine Research Laboratories St. Petersburg, FL November 1983 3?Property of CSC Library I a This project was supported by a grant from the Florida Office of Coastal ' rp-r- Management, Department of Environmental Requlation, with funds provided by rem the United States Office of Ocean and Coastal Resource Management, NOAA, under the Coastal Zone Management Act of 1972, as amended. CONTENTS Contents Acknowledgements I. Introduction and Rationale 1 II. Estuaries A. Description 9 B. Importance of Estuaries as Nursery Grounds 13 C. Estuarine Habitat Components 15 1. Mangroves 16 2. Seagrass Beds 21 3. Salt Marshes 25 4. Mud Flats 29 5. Oyster Reefs 30 6. Unvegetated Subtidal Bottom Areas 32 7. Water Column 33 D. Estuarine Food Web 35 III. Adjacent Land Use and Habitat Alteration A. Estuarine Limitations 39 B. Perturbations 43 IV. Restoration 51 A. Seagrass Restoration 52 B. Mangrove Restoration 57 C. Salt Marsh Restoration 61 D. Miscellaneous Restoration Techniques 64 V. Linking Juvenile Fish to Estuaries A. Species Found in Estuaries 69 B. Diet Analyses 75 C. Stable Isotope Analyses 80 D. Correlations Between Fisheries Yield and Habitat Type 83 E. Correlations Between Declines in Fisheries Yield and Wetlands Destruction 85 1. Life History Studies Red drum (Sciaenops ocellatus) 86 Spotted seatrout (Cynoscion nebulosus) 88 Black mullet (Mugil cephalisT 91 Blue crab (Callinectes sapidus) 92 Pink shrimp (Penaeus duorarum) 94 2. Fisheries Statistics: l950-1981 97 Charlotte Harbor 101 Lake Worth 106 VI. Land Use and Vegetation Maps of Charlotte Harbor and Lake Worth: Historical and Recent 111 A. Background 111 B. Problems and Recommendations 112 C. Description of Map Products 115 D. Acreage Values - Charlotte Harbor 1. General Site Description 119 2. General Acreage Values 123 ACKNOWLEDGEMENTS We express much gratitude to many people who provided assistance during this project, particularly to those who helped formulate ideas on a project to assess fisheries habitat loss during discussions as far back as 1980. We thank NASA Earth Resources Laboratory personnel for initial training in ELAS and for answering the many questions concerning the development of the Marine Resources Geobased Information System. We thank Fred Calder and Dave Worley (DER) for providing valuable advice and support in developing the successful grant application. Jim Stoutamire (DER) did much to facilitate the completion of this report by providinq expeditious contract guidance. Thanks also to Roy Williams and Mark Leiby for their help with fisheries data; to Ann Marshall of Lee County's Marine Extension Office, Roger Clark and William Sheftal of DNR Bureau of Land Manaqemnent, Steve Travis of DNR Bureau of Parks and Recreation, and Stewart Bradow of DER for their help in field sampling; to Mike Sprague for the use of SEAS' boats; to Robin Lewis of Mangrove Systems, Inc. for use of his data in our presentations; to Mark Moffler for his excellent drawings of seagrasses; to David Crewz for his drafting and drawings of mangroves; to Warren Clary of DOT for providing computer training; to Mary Krost and library staff for providing much assistance; to Winnie Sue Moravec and Jeff Brown for folding maps and binding the report, to DNR's Division of Recreation and Parks for the use of their white printer; to Alonzo Felder for drafting numerous graphs; and, finally, to Margie Myers for typing this report. I . INTRODUCTION AND RATIONALE Estuaries are coastal embayments or lagoons where saltwater and freshwater interact. They are among the most productive ecosystems on Earth because of this interaction and their relative shallowness compared to open seas. Estuaries provide food and shelter for a multitude of living resources such as fishes and crustaceans. Their fringing vegetation and 5 wetlands can absorb flood waters, recharge ground water, assimilate wastes and excess nutrients and, therefore, they maintain water quality, recycle 5 nutrients, and control erosion. Estuaries also have a direct aesthetic, recreational, and commercial value, exemplified by the location of urban S centers and recreational and commercial enterprises. Protection and 5 management of Florida estuaries to retain their natural functions and benefits to man is tied to efficient growth management. Nearly 70% of Florida's recreational and commercial fisheries species are dependent on estuaries during at least part of their life span, usually S in the juvenile stages prior to reaching harvest size. In Nakamura et 5 al.'s (1980) listing of recreational finfish stages found in estuaries, hle stated "In each estuarine area, the number of species was lowest for eggs, 5 second lowest for larvae, third lowest for adults, and highest for juveniles .... Thus, additional credence is provided to the importance of 5 estuaries as nursery grounds for juvenile recreational fishes...." ShrirnD and many species of juvenile fishes move out of the estuary to offshore areas to spawn or spend their adult life. They reenter the estuary as 5 eggs, larvae or juveniles. Some species, such as spotted seatrout, spend their entire life within the estuary while others move out as juveniles and come back to spawn near barrier islands or at the lower reaches of the estuary. Estuarine environments provide necessary food and protection from3 predators for these growing fishes. This dependency is one of inference based on known repeated frequencies and abundance of juveniles in bays and lagoons. Various experiments and field observations have also illustrated that shallow bay bottoms and intertidal vegetated areas provide cover and food items to a variety of animals. These estuarine and nearshore areas3 lend support and continuity to animal populations seeking refuge, but only if the estuary, as a system of structural components and interactiveU processes, maintains a healthy, dynamic state of diversity and productivity. Florida has extensive estuarine and marine coastal areas with emergent vegetation such as marsh grasses and mangroves and submergent vegetation such as seagrasses. About 430,000 acres of mangroves and an estimated3 502,000- acres of submerged vegetation exist in Florida. Sixty percent of saltwater wetlands in the United States occur in Gulf Coast states and the Gulf of Mexico supports two of the largest U.S. commercial fisheries:3 menhaden and shrimp. Amounts of emergent and submergent vegetation and freshwater flow have been associated statistically with shrimp and fish3 yield in some areas. The estuary is a multi-dimensional and multi-structured habitat forI living resources such as fishes and crustaceans. Habitat represents where an organism lives in time/space and includes bottom tyoe (e.g. vegetated), water depth, water quality, salinity, and other parameters than can change1 daily, seasonally or geographically. Habitat has vertical and horizontal vari abilIi ty. A specific species' habitat typically changes with age 21 whereby the animal moves from one area to another. The species is adapted to such change; it is part of its life history. If the habitat is removed or altered in a substantial .way, populations of that species may not survive because of stress, lack of food, or increased competition or predation. Many people interpret estuarine habitat by structural component, e.g. mangrove stands, salt marshes, seagrass beds, oyster reefs, mud flats, sand bars, or even man-made structures such as jetties. These 3 components represent shoreline and bottom type. Although certain species or assemblages may be more prevalent in these areas, "habitat" per se is temporally and spatially multi-dimensional. It varies from one species to 3 another and is defined by a multitude of parameters. It is more than a person can perceive visually from any one vantage point. * A variety of potential variables exist to determine relationships between species and habitat. For example, the U.S. Fish and Wildlife Service (USFWS) and others have identified availability of food items at different ages, spawning season and area, age at spawning, transport of eggs and larvae, larval recruitment and its area and timing, salinity and 3 temperature tolerances, substrate type, presence and abundance of predators, water quality, available cover, and other habitat and species 3 variables. Resource partitioning among different species as juveniles or adults can involve different temporal and spatial distributions by age and feeding habits. Differences in feeding apparatuses, digestive systems, and 3 feeding habits can lessen direct competition for available resources and allow species to co-exist. To develop Habitat Suitability Indices 3 (models), USFWS has used ranges and means of salinity, turbidity, depth, * 3 dissolved oxygen, and temperature, water color, bottom type, sediments, and diversity or amount of cover. The index is thought to have a relationship to "habitat" carrying capacity, but values only suggest whether one area is more or less suitable than another. Since the 1950's, Florida's population has soared. With people came development, agriculture, urbanization, and industrialization. Such3 development has destroyed or altered coastal habitats and wetlands. These events have led to loss of productive vegetation and cover, loss of openI bay areas, alteration of freshwater flow patterns, pollution of rivers and estuaries, and other perturbations. The direct loss of estuarine shoreline and bottom habitat componentsI such as saltmarshes, mangroves, and seagrasses has been dramatic, particularly adjacent to urban areas. Such direct loss has resulted from dredging and filling, channelization, ditching, and mosquito impoundments. For example, Lewis (1979) documented a 44% loss of mangroves on theI southern shore of Hillsborough County and estimated an 81% loss of seagrasses in Tampa Bay. Frayer et al. (1982) estimated that over one- third of the United States losses in coastal wetlands due to urbanizationI occurred in Florida. According to other projections, 215,000 additional acres will be lost due to development during 1980-2000. Direct loss of habitat components leads to loss of nursery habitat, increased suspended loads, increased erosion, and decreased water quality. One of the most dramatic examples of impact involves mosquito impoundments where salt tolerant vegetation dies, poor water quality causes physiological stress, and diverse fish assemblages are reduced to only a few tolerant speciesI lower in the food chain (Harrington and Harrinqton, 1982). When one 41 impoundment was opened, it became revegetated and fish diversity increased (Gilmore et al. 1982). This example points out that although habitat components may be lost through removal or die offs, the habitat itself merely changes; it has gone from a healthy environment with biotic diversity and richness to one that supports fewer, less desirable species. It then is the alteration of habitat that impedes the function and efficiency of the system through shifts in species composition and loss of certain populations. Alteration of freshwater flow to coastal areas has severely impacted estuarine systems. Alterations have occurred in timing, amount, quality, and direction of freshwater discharge. Such alterations through water retention areas, canalization, irrigation, and programmed releases can increase or decrease estuarine salinity regimes and stress populations, affect available dissolved oxygen, and affect the delivery and type of nutrients and food particles. Modification of estuarine circulation patterns through altered freshwater flow, channelization, dredge and fill, bridges, and spoil banks can create poor flushing and exchange of water in shallow areas and lead to a condition of excess nutrients and monospecific algal blooms (eutrophication). Other sources that can alter the quality and quantity of estuarine habitats are point and nonpoint source pollutants, e.g. sewage, land runoff, industrial wastes, pesticide spraying, mining, toxic chemical spills, etc. Often these impacts are accumulative. Pollutants in the water column may be barely detectable, yet they can be magnified in the sediments through settling, adsorbtion, flocculation, and high residency. They can, therefore, impact the system because the bottom and water are coupled through biological, physical and chemical interactions. Even 5 though estuaries are dynamic systems adjusted to wide fluctuations, major3 acute or chronic stresses or impacts will alter the systems and the life it supports.I Amounts of emergent and submergent vegetation and freshwater flow have been associated statistically with fisheries yield in some areas, yet mostU perceived fisheries declines are based on user group observations and/or reduced commercial landings, not on documented catch-per-unit effort decreases. Sports fishermen and commercial fishermen have both complained of reduced resource availability and have attributed it to a variety of causes, but mainly to overfishinq and/or habitat alteration. However,3 without adequate fisheries statistics to determine total fishing mortality and population dynamics, catch-per-unit effort and total populationI abundance cannot be determined for such multispecies fisheries (>1001 species of interest in Florida marine waters). Correlation of fisheries decline with habitat component loss is also difficult because of problems with available fisheries statistics and lack of current quantification for carrying capacity of different habitat components or ecosystems. CarryingI capacity itself is difficult to define and characterize, much less quantify, because it involves both benthic and pelagic environments, their structure, quantity and quality. It represents how much biomass of a3 specific species or multiple species can be supported in a specified time- space relationship. Carrying capacity can differ between salt-narshes, and vegetated bay bottoms; it could vary between two seagrass beds in, two different parts of the same estuary. Florida is currently the second fastest growing state in the nation3 with 17.4 million residents projected for the year 2000. Over 60% of the 1000 new residents per day will locate along the coast; today, over 73% of3 6 Florida's residents already live in coastal counties. Decisions and implementation of actions in the next few years will determine how Florida's estuaries survive and in turn whether they will support living resources as we know them now, and whether they will retain any aesthetic and recreational appeal and value. This is a critical period in Florida's history, one requiring farsighted management and legislation. First we must understand what an estuary is, how it functions, and why it is necessary to maintain it as a system. Only if we recognize and accept the values of individual estuaries can we manage them properly. The Department of Natural Resources, as well as many others, recognizes that habitat alteration is a significant factor affecting fisheries yield. Therefore, the Department has made a long term commitment through various research projects and legislative requests to pursue documentation of such alterations, their effects on resource availability and yield, the development of a more comprehensive fisheries statistics program, restoration and enhancement techniques, and a program to purchase sensitive lands. Concurrently with development of mitigation, restoration and creation of estuarine habitat and the establishment of preserves and sanctuaries, we need to: 1) conduct long term multidisciplinary system studies, 2) conduct trend analyses by inventorying estuarine resources and changes therein over time, and 3) inform and educate the public on the function and importance of estuaries. This Coastal Management oroject entitled "Assessment of Fishery Habitat Loss, Use of a Coastal Geographic Digital Data Base and Establishment of a Geobased Information System' addressed trend analyses over time to correlate changes in habitat components, such as mangroves and seagrasses, with changes in fisheries * 7 yield using aerial photography and commercial landings by individual system, i.e. the Charlotte Harbor System and the Lake Worth System. The continuance of the program in 1983-85 addresses trend analyses for U additional systems and public education. 8 I Estuaries Idacent Land Use and Habitat Alteration Restoration II. ESTUARIES II 1 A. DESCRIPTION U Estuaries and lagoons constitute 80-90% of the Atlantic and Gulf 3 coasts of the continental United States (Lauff 1967). Pritchard (1967) provided the most widely accepted defiinition of an estuary: "a semi- 3 enclosed coastal body of water which has a free connection with the open sea and within which sea water is measurably diluted with fresh water derived from land dra inage." This fresh water is introduced as river flow, 3 stream flow, or overland sheet flow, with resulting estuarine waters known as "brackish." Lankford (1977) described a coastal lagoon as "a coastal 3 zone depression below MHHW (mean high high waves) having permanent or ephemeral communications with the sea, but protected from the sea by some type of barrier." Estuaries are characteri zed by constant and variable changes. Tides daily influence water depth, salinity regimes, and the presence or absence of water in very shallow zones. Heavy rainfall introduces for short time periods large amounts of fresh water. Dry spells cause estuarine waters to 3 become more saline. Wind mixes the water. Estuaries are capable of withstanding these wide ranges in environmental parameters - conditions that normally would collapse other ecosystems. These variabilities are the 3 driving forces of estuaries. 'Without them, the system would not be an estuary. 5 Day and Yanez-Arancibia (1982) describe the physical traits of estuaries: 9 I1. They are semi-enclosed yet connected to the sea. This partial envelopment provides a buffer from oceanic effects. 2. They receive input from a freshwater source. The amount of fresh- water varies from very low during periods of extreme drought to high after storms or seasons of heavy rainfall. Dissolved andI suspended materials and nutrients also enter the system via fresh- water inflow. 3. Tides influence the circulation pattern of estuaries and are important in physical, chemical, and biological interactions Tidal action allows the mixing of fresh and salt water and plays a3 major role in exporting and importing material from and into the estuary. 4. Estuaries are shallow. Surface turbulence, such as wind and3 waves, affects the bottom as well as the surface. 5. Estuaries have complex water circulation patterns, influenced by3 winds, tides, river currents, and the qeormorphology of the basin. 6. Relatively rapid geomnorphological changes occur in estuaries be-I cause powerful physical energies resuspend and move sediments. This characteristic is exemplified in Florida by the change in shape and location of some barrier islands and the natural con-3 struction of new islands or channels during severe storms. Whittaker (1975) found that estuaries, in comparison to several other ecosystem types, are one of the most highly productive systems on Earth (Table 1). Estuaries are characterized by high rates of primary and secondary production because of their rich nutrient supplies, efficient 10 Table 1. NET PRIMARY PRODUCTION OF MAJOR ECOSYSTEMS (After Whittaker 19/b5) Ecosystem Net Primary Production (g/m2/yr dry weight) Normal range Mean Lake and stream 100-1500 500 Swamp and marsh 800-4000 2000 Tropical forest 1000-5000 2000 Boreal forest 400-2000 800 Woodland and shrubland 200-1200 600 Savanna 200-2000 700 Temperate grassland 150-1500 500 Tundra and alpine 10-400 140 Desert scrub 10-250 70 Extreme desert, rock and ice 0-10 3 Agricultural land 100-4000 650 Open ocean 2-400 125 Continental shelf 200-600 350 Attached algae and estuaries 500-4000 2000 conservation, and the occurrence of several different types of primary producers (Day and Yanez-Arancibia 1982). Estuaries are also ecologically complex, not because of a high species diversity (species diversity is actually quite low in estuaries), but because of the variety of environ- mental factors, habitat types, and highly complex food webs. Although estuaries are dynamic, transient, and variable, they are remarkably stable as an ecosystem. Margalef (1968) explains that ecological stability evolves in two different ways: (1) a system evolves under constant conditions and develops a steady state and thus stability, or (2) a system evolves under variable conditions and develops mechanisms to adapt to the variability. Estuaries undoubtedly developed via the second method. Estuarine biota have developed physiological and behavorial patterns to adapt to their fluctuating environment (Day and Yanez-Arancibia 1982). Organisms that successfully dwell within the dynamic estuarine system must be tolerant of change (Beal 1980). Probably the single most renowned function of estuaries is their role as nursery grounds for growing fish, shrimp, and shellfish. Because of their high productivity, large food supply, diversity of cover, and shallow, calm waters, estuaries serve as prime nurseries for many species. This aspect will be discussed in detail in the next section. High productivity of coastal offshore waters may result from the existence of estuaries. Odum (1980) explained that most fertile coastal zones receive nutrients either from deep water upwelling or from shallow water outwelling with areas such as reefs, banks, seagrass beds, algal mats, and salt marshes being the prime contributors. In Florida, mangroves 12 would also contribute nutrients. Odum (1980) stated that outwelling is likely a periodic or seasonal occurrence, associated with high spring tides and storms. Turner et al. (1979) found that offshore productivity and densities of zooplankton, fish eggs, and fish larvae were strongly coupled with the extent and productivities of local estuaries. They concluded that the influence of estuaries on continental shelf ecology was extensive. II B. IMPORTANCE OF ESTUARIES AS NURSERY GROUNDS According to life history studies, very few marine species of recreational and commercial value utilize the shallow coastal waters of estuaries as spawning areas. However, estuaries are used extensively as nursery grounds. Most finfishes and crustaceans migrate offshore to spawn. The eggs are usually planktonic, developing into larvae that depend on currents and tides to transport them toward shore. As post larvae, they enter the estuary, and spend their juvenile existance in close association with the estuarine system (Odum and Smith 1981). Some species grow within the estuary for several years while others remain there for life. Numerous authors such as Nakamura et al. (1980) and Odum and Smith (1981) have noted the importance of estuaries as nursery grounds. Joseph (1973) described nursery grounds as areas that (1) are physio- logically suitable in terms of chemical and physical features, (2) provide an abundant food supply, and (3) provide some degree of protection from predators. Chemical and physical parameters include water depth, tempera- ture, salinity, turbidity, and tidal and wave action. Climatic features such as rainfall, cold spells, and wind coupled with tidal action may be 13 the most influencing factors on depth, temperature, and salinity, irrespective of human influence. Because juveniles are more tolerant of wide ranges in environmental variabilities than their adult counterparts,I changes in depth, temperature, and salinity serve as protective mechanisms for the juveniles by forcing out adults during periods of (for them)I intolerable conditions. Seagrasses as well as mangrove roots and salt marsh stalks mitigate predation by providing hiding places, as well as baffles for waves and currents (Orth 1977). Beal (1980) summarized the nursery aspect by stating that because the estuary is dynamic, species that dwell there must be tolerant of change. This is certainly true for juvenile fish and shrimp. Margalef (1963) suggested that unpredictable environments character-I ized by high abiotic stress maintain both a high resource standing crop and low utilization by endemic species. Miller and Dunn (1980) applied this concept to estuaries: an outside population whose early life stages are3 spent in estuaries to exploit the food source will profit by this strategy.I Miller and Dunn (1980) summarized the general features of feeding relationships of estuarine juvenile fish assemblages: 1. Flexibility of feeding habits in time/space3 2. Omnivory 3. Sharing a common pool of resources among species5 4. Exploitation of food chains at different levels by the same speciesI 5. Ontogenetic changes in diet with rapid growth5 6. Short food chains based on detritus/algal feeders. 14 The most important feeding characteristic is likely the first: the ability to switch prey items in accordance with food availability, commonly termed the generalist strategy. Miller and Dunn (1980) point out that prey items undergo rapid and unpredictable changes in distribution and abundance in response to abiotid stresses. For example, after a heavy rain, the sudden presence of freshwater due to increased river flow, terrestrial run-off, and the rain itself would probably produce a period of hyposaline turbid conditions. This situation might present the juvenile population with a new supply of food items. The generalist feeding strategy then gives juvenile species a selective advantage over species that have restricted diets. II C. ESTUARINE HABITAT COMPONENTS Florida estuaries are composed of six structural components or habitat types: mangroves, seagrass beds, salt marshes, intertidal mudflats, unvegetated subtidal bottoms, and oyster bars. Overlying all six is the water column. In the intertidal zone, salt marshes and mangroves occur high with mudflats and oyster bars found low. Seagrass beds grow in the shallow subtidal zone. Unvegetated subtidal bottom occurs at depths below the seagrass zone and within seagrass beds. The water column overlies all the habitats during high tides and covers only the subtidal areas during low tides. Sections II C1 through II C7 describe these seven areas in greater detail. 15 II C 1. MANGROVES Mangroves in Florida extend from the Keys to approximately 30°N latitude on both coasts. Three species of mangroves are found in Florida (Figure 1): Red mangroves (Rhizophora mangle) are easily identified by their prop roots. Reds generally grow nearest to the shoreline. Black mangroves (Avicennia germinans) have characteristic small verticle root offshoots, called pneumatophores, attached to the underground roots and arising from the substrate. Blacks commonly grow higher in the intertidal zone than reds. White mangroves (Laguncularia racemosa) have a diffuse below-ground root system with verticle, bulbous knee-like projections arising from the roots. Whites generally occur much higher than reds or blacks, out of the intertidal zone, in areas affected only by extreme tides. Odum et al. (1982) describe four factors that determine mangrove distribution and extent of development: 1. Climate - since mangroves are a tropical species, they do not tolerate temperatures below freezing for any length of time. 2. Saltwater - most mangroves are able to grow without difficulty in pure freshwater habitats. However, they are faculative halo- phytes; salinity acts as a competitive excluder to other vascular plants. 3. Tidal fluctuation - tides serve as subsidies to mangrove systems (a) The constant alternation of standing water and then no water 16 BLACK MANGROVE WHITE MANGROVE RED MANGROVE - -I HIGH TIDE LOW TIDE Figure 1. A stylized view of Florida mangroves. 17 and fluctuations in salinity reduces competition from other vascular plants. (b) In some areas, tides carry salt water high into the estuary against the outgoing flow of freshwater, allowingI the establishment of mangroves well inland. Tides also transport nutrients into mangroves, and export organic carbon, reducedI sulphur compounds, propagules (seeds), and detritus. 4. Substrate and wave energy - the most productive mangrove systems develop on substrates of anaerobic fine-grained muds composed of silt, clay, and a large percentage of organic matter, with very little wave energy.I Lugo and Snedeker (1974) described six major mangrove forest communi- ties (Figure 2): the overwash mangrove forest, fringe mangrove forest, riverine mangrove forest, basin mangrove forest, hammock forest, and scrubI or dwarf forest. Each type embodies its own characteristic variables, ranges, and differences such as soil type, soil depth, flushing rates, primary production, rate of litter decomposition, and nutrient recycling rates.I Mangroves are considered one of the Earth's most productive systems (Odum et a]. 1982; see Table 2). Productivity of the three snecies vary (Odum et a]. 1982); red mangrove has the highest net productivity, black has intermediate values, and white retains the lowest, assuming the plant inhabit the zones for which they are best adapted and that these areas ar devoid of strong limiting factors. Odum et a] (1982) additionally noted that reds experience a decreasing gross productivity with increasing salinity while the productivity for blacks and whites increases to a certain extent with increasing salinity. 18 (I) OVERWASH FOREST (2) FRINGE FOREST (3) RIVERINE FOREST (4) BASIN FOREST (5) HAMMOCK FOREST (6) SCRUB FOREST Figure 2. The six mangrove communities (redrawn from Odum et al. 1982, after Lugo and Snedaker 1974). 19 Table 2. NET PRIMARY PRODUCTION OF HABITAT COMPONENTS Average NP Range NoI Habitat (gC/m /day) (gC/m2/day) Source Mangroves (all species) 5.3 1.0 - 12.6 Odum et al. 1982 Seagrasses (Syringodium, 1.0 - 4.0 0.5 - 16.0 Zieman 1982 Halodule, and Thalassia) Salt marsh 4.2 0.8 - 8.2 Durako et al. 1983 Mud flat 0.5 - Pomeroy 1959 Water column (phytoplankton) 0.9 --- Thayer and Ustach 1981 The estuarine system can benefit by the presence of mangroves. The aerial root system, especially the red mangrove prop roots, provides a substrate for algae attachment and serves as a protected habitat for nursery-stage fish, crustaceans, and shellfish. These intricate root systems also play an important part in substrate stabilization; their presence retards erosion. Litter fall also can be important, forming the basis of a mangrove-detritus food web, providing a supply of food to many organisms. Mangroves cleanse inflowing water and aid in nutrient cycling. Nitrogen, phosphorus, heavy metals, and more are removed from the water by the combined activities of prop roots, prop root algae, associated sedi- ments, and the multitude of invertebrates and microorganisms present in the system (Odum et al. 1982). Nutrient import, originating mostly from upland and terrestrial sources, is either reduced by faunal species and exported, or it becomes mangrove or algal biomass. Low nutrient import 20 results in low storage, low biomass, low productivity and small export, whereas the outcome of high nutrient import is high storage, high biomass, high productivity, and moderate export (Odum et al. 1982). II C 2. SEAGRASS BEDS Seven species of seagrasses inhabit Florida waters (Figure 3). Turtle grass (Thalassia testudinum) is the most abundant of the seagrasses with ribbon-like leaves from 2 to 35 cm in length and 2 to 12 mm in width. The tips of the leaves are rounded. Thalassia is capable of forming extensive beds. Shoal grass (Halodule wrightii) is generally accepted as the most tolerant of all the seagrasses to temperature and salinity changes (cf. Zieman, 1982). Leaves are flat and are from 10 to 20 cm long and 3 mm wide. Leaf tips have 2 to 3 points. Shoal qrass, too, is capable of forming extensive beds. Manatee grass (Syringodium filiforme) is usually found amongst other species, or in small dense patches. Leaves are cylindrical from 1.0 to 1.5 mm in diameter; length is variable. Three species of Halophila are sparsely distributed (Zieman 1982). Leaves are ovate from 10 to 30 mm long. Halophila engelmannii has 4 to 8 leaves on the end of a stem 2 to 4 cm long. Halophila decipens and H. johnsonii have paired leaves arising from a single rhizome node. Halophila decipens differs from H. johnsonii in that the latter lacks root hairs, and veins emerge from the midrib at 45° angles rather than 60° angles of the former. Widgeon grass (Ruppia maritima) occurs in both fresh and salt water environments. In saline systems, Ruppia is found primarily in areas of reduced salinity (Zieman 1982), but it also inhabits and reproduces 21 4 2 I. Thalassia testudinum 2. Syringodium filiforme 3. Halodule wrightii 6 i 4. Halophila engelmannii 5. Halophila johnsonii 7 6. Ruppia maritima a i A 7. Halophila deci pi ens Figure 3. Seagrasses of Florida. 22 sexually in sites with salinities as high as 380/oo (M. Moffler, personal communication). Seagrasses perform many significant functions in estuarine systems. (1) Since leaf growth is generally >5mm per day, and the typical lifetime of a single Thalassia leaf is 30-60 days, seagrasses provide a tremendous food source to herbivores, such as sea turtles and manatees, and detriti- vores (Zieman 1982). In addition, exportation of living and detrital material provides energy to areas quite remote from the source grass beds (Zieman 1981). (2) In addition to their abundant food supply, seagrass beds provide shelter, i.e. places to hide for young stages of numerous fish, crustaceans and shellfish. The presence of seaqrasses is essential to the occurrence and growth of many species of marine life (Zieman 1982). Seagrasses also provide a surface for attachment for sessile epiphytes. (3) Seagrass systems stabilize sediments; the leaves provide a baffle for waves and currents and roots and rhizomes bind the sediments, thereby retarding erosion (Zieman 1982). (4) Seagrasses aid in the cycling of nitrogen by transporting it from the sediments into their leaf structure, then into the environment via herbivory or as detritus (Zieman 1982). In viewing seagrass systems with a holistic approach, they may be classified as ecosystems of high diversity. Seagrass meadows provide a habitat for numerous organisms. Kikuchi and Peres (1977) described the biota that inhabit seagrass beds: 1. Species living on or near the leaves, including epiphytes, micro and meiofauna, sessile fauna, mobile creeping and walking fauna, and swimming epifauna. 2. Species attached to stems and rhizomes. 23 3. Mobile species living under the leaf canopy (permanent residents, seasonal residents, visitors, and occasional migrants). 4. Infaunal species (found in unvegetated parts as well). Added to this list are nektonic species living within and above the blades. Brooke (1978) found 38 to 80 species were represented within five Thalassia meadows (blade density >3,000 blades/m2) in south Florida; abundance varied from 292 to 10,644 individuals/m2. Seagrass blades create a surface on which epiphytes can attach. After a leaf emerges, it remains "clean" for a period of time (Zieman 1982). As they grow, they become heavily colonized, more so at the tips than at the bases. Harlin (1980) compiled a species list of the microalgae, macroalgae, and animals that have utilized seagrasses for attachment. Because the majority of seagrass consumers (turtles and manatees excluded) do not possess a gut flora to digest structural cellulose, their nutrition is derived from seagrass cell contents and attached epiphytes. Epiphytized blades thus provide a more valuable food source to most consumers than clean blades. Seagrasses probably are more important to the food web as detritus than as a source for direct herbivory. Physical breakdown of detritus occurs through the activities of crabs, shrimp, and amphipods. During decomposition, particles become smaller and provide a larger surface area for colonizers such as bacteria, fungi, and other microorganisms. Detritus is an important food source for deposit feeders, providing polychaetes, amphipods, isopods, ophiuroids, some gastropods, and mullet with much of their nutrition (Zieman 1982). Detritivores assimilate plant compounds with <5% efficiency as opposed to 50-100% efficiency at assimilatinq associated microflora (Zieman 1982). 24 II C 3. SALT MARSHES Salt marshes are herbaceous plant communities in northern Florida intertidal zones that are periodically tidally flooded by salt or brackish water. They predominate over mangroves (39% more acreage) as the most abundant plant community of Florida's intertidal zone (Coastal Coordinating Council 1973). They are replaced by mangroves as the dominate vegetation south of Cape Kennedy and Tarpon Springs (Odum et al. 1982); marshes in this southern region generally serve as a transitional zone between the mangroves and fresh water marshes (McNulty et al. 1972). Smooth cordgrass (Spartina alterniflora) dominates Florida's east coast marsh vegetation (Durako et al. 1983). Along the southeast tip of Florida, black needle rush, (Juncus roemarianus) exists in large marsh areas in association with mangroves (Eleuterius 1976). Juncus also occurs in large stands from Tarpon Springs to Apalachicola Bay. The Florida panhandle has very little salt marsh. Juncus produces plant biomass continuously whereas Spartina grows in the spring with a general dieback in the winter (Turner 1976). No two marshes are alike and variations in productivity (Table 2) reflect complex interactions between light energy, temperature, tidal subsidy, nutrient availability and other factors. Kruczynski et al. (1978) reported that net aerial primary production of Juncus was highest in the low marsh decreasing landward to about 30% of the low marsh value in the high marsh. They also found the same to be true for Spartina; production decreased landward to less than 20% in the high marsh of the original value in the low marsh. Detrital material is the end result of 90% of the net production of 25 salt marshes (de la Cruz 1973). The export of detritus has historically been believed to be the most important contribution of salt marshes to the estuarine system. Studies have provided evidence that energy was being exported because production values were consistently higher than the sum of the losses due to respiration, grazing, and the accumulation of organic sediments within the marsh (Durako et al. 1983). Studies that measure amounts of carbon or organic matter entering and departing salt marshes showed both a net export to the estuary and a net import. Other studies however, demonstrated that salt marshes may retain and utilize their own production (Durako et al. 1983). Animal production is high in salt marsh systems. Subrahmanyam et al. (1976) found densities of marsh invertebrates to be 540 individuals/m2 for a Juncus low marsh and 381 individuals/m2 for the high marsh. Proximity of the marsh to tidal waters or frequency of tidal inundation may be the determining factor of organism density in salt marshes (Day et al. 1973). Day et al. (1973) also reported that animal diversity within the marsh is lower than values of adjacent open water areas, however, he found that animal biomass was higher. Zimmerman (in prep.) found shrimp densities of 11 shrimp/m2 within a Spartina marsh as opposed to 1.5 shrimp/m2 in non- vegetated sites. Like seagrass and mangrove systems, salt marshes provide a concentra- tion of high quality food for estuarine animals in addition to a conducive environment for early life stages. Park and Batie (1979) describe four additional functions for salt marshes: 1) tertiary sewage treatment, 2) fundamental part of nutrient cycles, 3) long-term accumulators of non- point source pollution, and 4) short term pollutant buffers. 26 Releasing primary treated sewage into marshes introduces large amounts of organic matter into a system already high in organic detritus and can reduce the oxygen content. of the water to unfavorable levels. Eutrophication can easily result. On the other hand, marshes are capable of assimilating secondary-treated sewage into their biological systems without added stress. Secondary treatment of sewage wastes is a relatively inexpensive process when done by sewage treatment plants. Tertiary treatment, however, is quite costly. By introducing secondary-treated sewage into marshes, marshes can then become a site of free tertiary treat- ment (Gosselink et a]. 1974). * Salt marshes share in the nitrogen and phosphorus cycle; salt marsh systems break down particulate organic nitrogen and phosphorus, exporting them in dissolved forms (Park and Batie 1979). This reaction increases estuarine productivity since estuarine biota are better able to assimilate dissolved -organics. As runoff, with its various types of associated non-point source pollution, moves through salt marshes, its velocity is reduced. This * causes suspended particles to settle out and become part of the sediment. If these particles remain permanently deposited, the following may result (Park and Batie 1979): 1. reduction in turbidity. 2. reduction of sediment in main part of the estuary. 3. reduction of eutrophication due to adsorption of nutrients to sedi ments. * 4. reduction of toxic materials due to adsorption of pesticides and heavy metals to sediments. In addition, the toxins may become 27 buried or decomposed. I Salt marshes are capable of acting as short-term pollution buffers by stretching out the time frame of pollutant loading during periods of heavy I rainfall. Without wetlands, run-off would enter the estuary directly, I however, by first flowing through the marsh, the length of time for estuaries to receive run-off increases (Figure 4). This may not decrease the total amount of pollution entering the estuary, but it would decrease the amount per unit of time. I <t< without wetlands| 0 _j I -withou wetlands TIME Figure 4. Rate of pollution loading to the receiving water body (after Park and Batie 1979). _J z o2 ' 0 To T, 2 TIME Figure 4. Rate of pollution loading to the receiving waterbody (after Park and Batie 1979).I 28I I I C 4. MUD FLATS Petersen (1981) defines mud flats as "any unvegetated shoreline of a sound, lagoon, estuary, or river mouth that becomes exposed by lower tides." Because of their barren appearance, at least in contrast to sea- grasses and salt marshes, they are perceived to be insignificant in their contribution to the gross primary production of the estuary. They function, however, to produce not macrophytes, but rather microscopic benthic algae. Diatoms, dinoflagellates, filamentous green algae, and blue-green algae compose the primary producers of mud flats, and are observed as a discoloration of the sediment. Turnover is rapid, but productivity rates are less than half that of salt marsh and seagrass systems (Table 2), however, the crop is in a form readily useable by consumers. Many herbivores and deposit feeding invertebrates consume the benthic algae of mud flats. Benthic infauna are the primary inhabitants of mud flats during low tide when the flats are exposed. Numerous species of birds extensively utilize this habitat as feeding grounds during daylight hours. However, during high tides and especially at night, crabs, shrimp, and fish become the major consumers. Summerson (1980; cited by Petersen 1981) found that crabs and bottom-feeding fishes are more evenly distributed over vegetated and unvegetated bottoms during the night. During daylight, however, seagrass beds contain far higher numbers of fishes, crabs, and shrimp (Petersen 1981). In addition to their value as a food producer, mud flats also serve as 29 a site for detrital breakdown. Currents and tides carry plant debris from the source habitat to the mud flat. During low tide, much debris is available to fiddler crabs,, amphipods, and other detritivores that physically break it down. Through these processes, a substantial amount of production of other habitats is made available to mud flat consumers (Petersen 1981). II C 5. OYSTER REEFS1 Oyster reefs are defined as "the natural structures found between the tide lines that are composed of oyster shell, live oysters, and other organisms that are discreet, contiguous, and clearly distinguishable (during ebb tide) from scattered oysters in marshes and mud flats, and from wave-formed shell windrows." (Bahr and Lanier 1981). Oyster reefs in Florida are composed of the American oyster (Crassostrea virginica) that range from 20°N to 54°N latitude. The oyster is a typical estuarine inhabitant, tolerating broad limits of salinity, temperature, turbidity, and oxygen content. Because oysters are gregarious, they tend to form mounds ranging in size from scattered clumps to huge solid masses. The middle section of the intertidal zone affords the best habitat for oyster reef development; the lower zone subjects oysters to increased predation. A typical reef is composed of three horizons. The upper layer (5- 10cm) dries out during low tide, hosts a film of algae, and is colored a ISummarized from Bahr and Lanier (1981). 30 pale greenish grey. The mid layer remains moist and lacks an algal film. A thin layer of detritus covers each shell and is colored reddish-brown. The lower layer is composed' of non-living shells that are buried in anerobic sediments. Of the upper and mid layers together, approximately 61% by volume consists of living oysters, 21% consists of dead shells, and 18% consists of silt, clay, and non-oyster macro-fauna. In theory, oyster reefs benefit estuaries by influencing physical and hydrological regimes. Oyster reefs dampen current velocities, undoubtedly for small areas, perhaps influencing the entire estuary. A slower current allows for settlement of particulate matter, thereby, decreasing turbidity. Within natural systems, where hard substrate is rather limited, oysters provide a much needed habitat for algae and animals that require hard surfaces for attachment. In fact, every square meter of oyster reef provides at least 50 square meters of available hard surface. The irregular surface, filled with nooks and crannies, serves as shelter for motile invertebrates and, during high tides, for small fish. Oyster reef communities are composed primarily of suspension and deposit-feeding macrofaunal species. The community consists of various mud crabs, polychaetes, barnacles, other macrofauna, protozoa, metazoa, and bacteria. Oysters themselves serve as food for various boring sponges and the American oystercatcher, one of their major predators. Overall, this macro-faunal community more importantly serves to assimilate carbon derived from phytoplankton and detritus than it contributes to the food web. Because many oyster reefs are intertidal or shallow subtidal, they exist constantly at or near their stress tolerance threshold. Further disturbance may destroy an entire reef community (Table 3). 31 Table 3. GENERAL EFFECTS OF MAN-INDUCED STRESS ON OYSTERS (from Bahr and Lanier 1981) Stress Detectable Effects 1) Sedimentation Burial and anoxia of adult oysters 2) Salinity increase over Increased predation and/or fouling ambient concentrations 3) Oxygen depletion in Toxic effects of blue qreen algae bottom water and other algae; excess particulate (Eutrophication) organic carbon 4) Chemical Pollutants Sublethal effects, increased mor- tality, reduced resistance to natural stress, subtle changes in entire community, reduced gametogenesis 5) Physical effects of Impairment of feeding mechanism oil-type pollutants 6) Thermal loading Decreased community diversity, increased respiratory cost 7) Overharvesting Depletion of breeding stock and culch and decrease in bottom stability 8) Loss of wetlands Loss of wetland-water interface prime reef habitat, decline of primary pro- duction II C 6. UNVEGETATED SUBTIDAL BOTTOM AREAS Located below the photic zone or scattered throughout the estuary are areas of unvegetated subtidal bottom. Large patches (>3m) of bare bottom occur naturally in the photic zone due probably to high enerqy circulation patterns. Large bar-type bare sites may serve to lessen wave surges and current velocities, providing calmer areas behind the bar. Natural defoli- 32 ation may result from herbivore feeding behaviors such as those described by Bjorndal (1980) for green turtles (Chelonia mydas) and by Packard (1981) concerning West Indian manatees (Trichechus manatus). Reasons for the natural existence of small patches of bare sand within expansive grass flats remain questionable. Blowouts, or bare sites within beds that con- sistently reject seagrass growth, may result because of high energy patterns such as eddies that occur continuously at that particular location (Durako, M., personal communication). Cryptic behavior of cownose rays have caused total removal of Zostera communities (Orth 1977). Many areas where underlying rock layers protrude through the bottom surface are unsupportive of seagrasses and macro algal beds (personal observation). Though reasons for their presence must exist, small sites of unvege- tated subtidal bottom probably are not very productive. Orth (1977) de- scribed sediment stability within these bare sites: storm activities pro- duced sand ripples and erosion of <20cm in the bare areas whereas the adjacent Zostera community indicated no evidence of instability. Orth concludes that this instability accounts for the lack of species and individuals in this habitat. Human-induced defoliations are numerous and include activities such as motor boat propeller cuts, disposal of heated effluent, turbidity, physical removal, and hiqh energy circulation patterns; these are discussed in greater detail in section IVB. 3 I C 7. WATER COLUMN Overlying parts or all of the six other estuarine habitats is the water column. Several variables and, especially, the interactions between 33 the variables, cause the estuarine water column to exhibit differing physiochemical characteristics. Depending on the time of year, time of day, weather, tide and circulation patterns, the water column may be extremely saline or fresh, clear or turbid, warm or cold, deep or shallow, and calm or turbulent. Further, it is capable of existinq in any combina- tion of these features. The water column is the medium through which most marine fauna travel and feed. It is dynamic and organisms living within it must be tolerant of change. As the tide comes in, meroplanktonic stages entering the estuary can rise to the top of the water column and profit by the free ride to safer territory. High tide also creates a feeding habitat for larger predators by deepening those areas that physically excluded them during low tide. Receding tides, in a sense, "cleanse" the estuary by removing nutrients that may eventually serve as a food source for offshore systems. Phytoplankters are the primary producers of the water column. Compared with seagrasses, mangroves, and salt marshes, productivity values for phytoplankton are minimal (Table 2), however, phytoplankton productivity is not limited to shallow areas (as are seagrasses) or shorelines (as are marshes and mangroves). Instead, these organisms are capable of reproducing in the photic zone over the total area of the system. Further, phytoplankton exist in a state readily available to consumers. In other words, phytoplankton need not pass through the many steps of the vascular plant detrital food web before consumption by "higher" organisms. Although the vascular plant detrital food chain may be most important in estuaries, phytoplankters are essential components in the food chain supporting zooplankton and larval fishes. Larval fish consume zooplankton, and 34 zooplankton can consume detritus, however, almost all detrital consumers include at least 10 to 20% fresh algal cells in their diet (Odum 1970). II D. ESTUARINE FOOD WEB The trophic structure of estuaries features different sources of primary production, numerous generalist feeders, and an intricate food web (Day and Yanez-Arancibia 1982). Zieman (1982) listed the main sources of primary production: 1. Macrophytes - seagrasses, mangroves, macroalgae, and marsh grasses 2. Benthic microalgae - benthic and epiphytic diatoms, dinoflagel- lates, filamentous green and blue green algae 3. Phytoplankton A diverse set of consumers contribute to the food web. An organism rarely fits exclusively into one category or level due to changing food habits resulting from age, time of year, and food availability (Odum and Heald 1972; Day and Yanez-Arancibia 1982). Juvenile fish, for example, switch prey items as they grow. Following is a list of estuarine consumers (Day and Yanez-Arancibia 1982): 1. First order consumers - pure herbivores, detritivores, and ominni- vores; includes most zooplankton, filter feeders, fishes such as mullets and menhaden, benthic deposit feeders, shrimps, crabs, and most other fauna of wetlands. 2. Second order consumers - organisms that consume mostly first order consumers and also small amounts of plant material and detritus; fishes consuming zooplankton (anchovies and sardines, for ex- 35 ample), demersal fishes (such as croaker and catfish), other crabs, and starfish. 3. Third order consumers - exclusively carnivorous organisms that prey on first and second order consumers; many larger fishes and birds. Two basic food chains exist within the estuary: the grazing food chain and the detrital food chain. Interactions between these two create the complex food web of the estuary. The grazing food chain is basically: primary producers -- herbivores -+ carnivores -> bacteria. The detrital food chain is basically: detritus - bacteria -> detritus feeders -> carnivores bacteria. The detrital chain is considered by many researchers to be the most important of the two food chains (see Day and Yanez-Arancibia 1982). The process is based, obviously, not on living primary production, but on dead material. After a mangrove leaf, Juncus shoot, Spartina shoot, or seagrass blade breaks off from its host plant, physical breakdown occurs immediately. The material is shredded into smaller fragments by crabs and amphipods and quickly becomes colonized by bacteria, fungi, and microalgae. These decomposers are considered rich sources of vitamins and proteins, greatly increasing the food value of the material. Heald and Odum (1970) found that broken-down particles after 12 months contained 22% more protein as compared to a protein content of 6% when they were still intact. Net nutrient value is much higher for detritus materials than for the plant material alone. In addition, this rich source of food decomposes slowly, insuring a continuous production of food. Mann (1972; cited by Day and 36 Yanez-Arancibia 1982) states that the detrital colonizers are the actual food source; the plant material passes through the gut systems of detrital feeders almost unaltered. Eighty to ninety percent of the nutrition of several species of crustaceans, polychaetes, insect larvae, and small fishes is derived from detritus (Robas 1970). Detritus feeders are consumed by over 60 species of juvenile fishes that live in the estuary during at least parts of their lives (Robas 1970). However, no estuarine food web is completely dependent upon vascular plant detritus, in fact, according to Odum (1970), detritus consumers appear unable to grow and successfully reproduce when consuming solely detritus. He adds that at least 10 to 20% algal cells in the form of diatoms or filamentous and blue-green algae are included in the diets of almost all detrital consumers. 37 38 III. ADJACENT LAND USE AND HABITAT ALTERATION III A. ESTUARINE LIMITATIONS As discussed in Section II A, estuaries are extremely interactive, highly dynamic ecosystems. However, even though estuarine biota are quite capable of withstanding frequent environmental changes, they do have limitations. In this section these boundaries will be described as well as how they are exceeded and the resulting effects on estuarine habitats. Odum and Copeland (1969) described three main energy types that dominate estuarine systems: 1. Light energy activates the process of photosynthesis and is the primary source of the estuarine food web. 2. Organic fuels constitute a second energy source. Incoming nutri- ents flowing through the estuarine habitats "fertilize" the system resulting in an increase in vascular plants and algae. 3. Mechanical energy, such as waves, wind, river and stream flow, and tides serve as energy subsidies and are responsible for many interactions that occur in the estuary. A reduction in light energy, as might occur if estuarine waters became turbid, would greatly affect the seagrass system. Copeland (1965) tested the effect of light reductions by lowering the input of sunlight from 1500 to 200 foot candles on a simulated seagrass community. The community, pre- viously dominated by Thalassia, soon became a blue-green algae community. After stabilization, however, the productivity of the two community types became equivalent. But, considering that blue-green algae is consumed successfully by only a few species (Copeland 1965), as opposed to Thalassia 39 leaves and detritus that are consumed by numerous species, Thalassia communities are much more useful, both as a food source and as a hiding habi tat. Lessening the amounts of incoming organic fuels (commonly derived from freshwater sources such as rivers and terrestrial run-off) would decreaseI the biomass of all the systems - mangroves, salt marshes, seagrasses, and phytoplankton. However, an overabundance of nutrients precedes eutrophi- cation. In response to increased nutrients, productivity increases resulting in an increase in detrital material, but the amount of energy required to breakdown this material has not changed. The system becomesI eutrophicated and consists of sediments and a water column devoid of oxygen. Vascular plants die and the system begins to cease functioning. Mechanical energies within the estuary are numerous, and their importance cannot be overemphasized. For example, tides and freshwater inflows are responsible for the chemical properties of the water. If tidesI were restricted from the estuary, freshwater would predominate and the system would drastically change from a euryhaline system to a fresh system.I Decrease in freshwater flows would cause an increase in salinity. The numbers of molluscs, crustaceans, and fishes would rise, but the subtle qualities of the estuary would be lost, especially its value as a protective nursery ground. Consistent high levels of dissolved oxygen do not occur in estuaries,I due mostly to the large volume of organic matter in the surface sediments and water column (Odum 1970). In fact, many estuaries possess a value wellI below the standard of 4.0 mg 02 per liter water established for polluted estuaries by the National Technical Advisory Committee in their 1968 report 40 on water quality criteria to the Secretary of the Interior (Odum 1970). Odum (1970) theorized that since estuaries already exist in a borderline condition, a decrease in dissolved oxygen content is capable of causing mass mortalities. He further states that any process that suspends oxidizable sediments also reduces the oxygen concentration of estuarine water to a level unfit for normal biota. An example of this occurs frequently in an unpolluted Everglades estuary during rainy season: l arge volumes of cold rainwater sink to the bottom causing resuspension of detrital materials. Oxygen is depleted and marine animal mortalities U follow. Although estuarine biota are capable of withstanding drastic tempera- ture fluctuations, they cannot deal with continuous heat or cold. Severe cold spells cause adult fish to migrate to offshore warmer waters, and freezes destroy mangroves. Many resi dent speci es of tropi cal areas are surviving within a few degrees of their upper lethal limit (Lindall 1973). Fishes rarely survive temperatures of 38'C, and waters typically exceeding 350C would probably not support a large or diverse fish population (Carr and Giese] 1975). Effects of excessive heat from natural sources have not been reported, but effects of heated effluent from power plants have been we]lI documented. Roessler and Zieman (1969) found adverse effects from effluent emerging from Turkey Point Power Plant in southern Biscayne. Bay; nearly all biota within 125 acres nearest the outfall were destroyed or greatly reduced. By comparing two thermally-influenced creeks to an ambient temperature creek, Carr and Giese] (1975) found a higher fish density during summer months in the ambient creek. In addition, Juveniles of species of commercial and recreational importance were 3 to 10 times 41 greater in biomass and numbers in the ambient creek than in the thermally affected creeks. Two extremely important, but not easily defined, parameters that greatly influence the effects of various perturbations, are time and multiple interactions. The estuary apparently can cope with literallyI almost any major alterations, but for only relatively short periods of time. For example, seagrasses will not be detrimentally affected by turbidity if the condition exists for merely a week. But further periods of inundation may result in reduction of photosynthesis and decreased production. Synergistic or multiple interactions are those perturbations that occur coincidentally with others. It is often difficult to separate the effects of single disturbances when another, or others, are present as well. Using the seagrass community again as a hypothetical example, turbidity, excessive freshwater, and above normal nutrient levels are simultaneously introduced into the seagrasses due to heavy rains and river flooding. Two months later, after the system returned to normalI conditions, the seagrasses are thinner and less dense with fewer faunal inhabitants. It would be difficult to pinpoint any single variable for the results. In summary, a reduction of light energy or a reduction or over- abundance of organic fuels and mechanical energy, excessive changes in chemical properties (oxygen and salinity) and temperature, or a combination of any or all, since all variables are interrelated, may result in decreased production. Lowered productivity is realized through the food chain and the outcome is lower yields in fish stocks. 42 III B. PERTURBATIONS Probably the greatest single disturbance that causes irreversible damage in the shortest period of time is physical removal of parts or all of the estuarine habitats. Destruction of this type often occurs on a large-scale and includes activities such as channel dredging, dredge and fill, shell-mining, and various sorts of shoreline modifications. Small scale perturbations that directly and physically destroy habitat are produced from activities such as motorboat cuts and clam digging. Anything that exceeds estuarine limitations, as discussed in the previous section, H either destroys habitat or reduces productivity; these disturbances may include the introduction into the estuary of power plant effluent, storm water run-off, industrial discharges, mosquito impoundments and vessel discharges (gas and oil). Channel Dredging Because estuarine habitats are relatively shallow and typically link the oceanic waters to the mainland, they pose transportation difficulties to large vessels and even small boats. To alleviate this problem, channels are cut into the sediment, providing deep areas for easy access through the shallow zone. Odum (1970) explains that the dredging process would cause * minimal damage if properly engineered; only the actual area containing the navigation channel should be altered. However, Odum describes the continu- al adverse effects resulting from the "hydraulic dredge cycle". Material dredged from channels is typically dumped as nearby spoil banks. A s the spoil banks erode, dredged material is transported back into the channel, necessitating re-dredging. Turbidity and destruction of circulation patterns are often unavoidable by-products. Lindall and Saloman (1977) 43 reported outcomes of channel dredging that are significant to fishery resources. Physical loss of aquatic habitat by creation of spoil islands, segmentation and isolation of' parts of the estuary, alteration of tidal exchange and circulation patterns, increased turbidity, and destruction of submergent and emergent vegetation are some of these significant problems. Mosquito Impoundments and Ditches Mosquitoes, as adults, pose a threat to the health and sanity of people and yet, as larvae, serve as food for juvenile fishes. Unfortu-. nately, both mosquitoes and humans wish to occupy the same coastal areas -- humans, because of the aesthetic qualities, and mosquitoes because of theirU need for moist, exposed soil on which to lay eggs. Higher intertidal salt marsh and mangrove areas provide exceptional habitat on which mosquitoes lay eggs. To help eradicate mosquitoes, a dike is built around the system or channels are dug through it. Dikes serve to retain water within the system while canals dry it out. They change an occasionally-flooded area to one continuously flooded or to one persistently dry. Diking and channelization remove the influence of tides and the inflow of terrestrial freshwater and, therefore, a part of the nutrient import. Estuarine fauna are no longer capable of moving into and out of the site, and its import- ance as habitat for growing fishes and shellfish is destroyed. Harringtonj and Harrington (1982) reported that during a few months following impound- ment of a salt marsh community in Indian River County, nearly all theI vegetation died and juvenile fish that originally used the site previous to impoundment disappeared as well. Of 16 species found before impoundment, only five remained after impoundment (Harrington and Harrington 1982, 1961.) GilImore et al . (1982) found a total of 12 species within the 44I Harrington's impounded site as compared to 41 species in an impounded site that was reopened to tidal influence via a single 80 cm culvert. Power Plants To cool the operating system of electrical generating power plants, water is essential. Placement of a power plant adjacent to an estuary provides easy access to a direct source of required cooling water. After the water is used, it is deposited back into the estuary. The foremost perturbation the power plant provides to the estuary is the direct destruction of shoreline habitat, usually mangroves and marsh, to build the plant. Three additional problems are as follows: 1. Impingement - organisms can get trapped on screens that filter the intake water. 2. Entrainment - organisms of the intake water that pass through the filter system can be killed or damaged by the turbulent and pressurized process of the cooling system. 3. Thermal effects - the impact of thermal pollution depends on several variables - discharge volume, average and maximum tempera- ture elevations, characteristics of plume dispersion, and hydro- graphy of receiving waters. In addition to the reports discussed in Part I of this section, another investigation found that thermal effects from a coal-fired power plant destroyed 200 acres of seagrasses and lowered the diversity of invertebrates to 40% of 3 their original value (Blake et a]. 1976). Sewage Di sposal 3 "The greatest direct threat to the clear productive waters of the Charlotte Harbor area is inadequately treated and improperly disposed * 45 domestic wastes" (U.S. Department of the Interior, Bureau of Land Management, 1978). As described in Section III, estuaries provide an ideal site for the disposal of secondary-treated sewage. However, the addition of primary-treated sewage contains more nutrients than the system can properly handle. A study of Hillsborough Bay found progressive eutrophi- cation after years of receiving primary treatment (Federal Water Pollution Control Administration, 1969). Water quality was lower as compared to all other parts of Tampa Bay; measurements of dissolved oxygen were low, coli- form bacteria surpassed safe levels, sediments became anoxic, and frequent noxious algal fish kills and blooms occurred. In addition, diversity and abundance of macroinvertebrates were lowered (Taylor et al. 1970). Canals and Canal Developments During the 1950's and 1960's, demand for waterfront property in the southern half of Florida was immense. Developers met this need by extensively exploiting the coastline. Available shoreline was limited, so developers planned communities around networks of branching canals, maximizing the amount of waterfront property to land configuration. Some of these canal systems extend inland over thousands of acres. Morris (1981) distinguishes three basic designs of waterfront canals: 1. Bay-fill or finger-fill canals: those constructed below mean low tide by dredging and filling shallow bay bottoms. 2. Intertidal developments: those constructed by dredge-and-fill between mean low and mean high water, typically in mangroves, salt marshes, bays, estuaries, lakes, or other wetlands. 3. Inland or upland canals: those developed by excavating land above mean high tide and connecting the canals to natural channels, 46 lakes, rivers, bays, or other natural or artificial waterways. In the past, canal developments were usually constructed by dredging out the channels, first, and depositing the dredged material behind bulkheads, or seawalls, elevating the land surface to meet State criteria for hurricane tide and flood protection (Morris 1981). During construc- j tion, mangroves, seagrasses, and trees were removed from the dredge location, and the fill material covered vegetation located in the landfill sites, often destroying estuaring nursery sites over vast areas. Lindall and Saloman (1977) determined that 23,521 acres of Florida estuaries have U been filled, the majority for housing developments and industrial real estate. Three major deleterious effects of canal developments are apparent, * irrespective of less obvious concurrent impacts: 1. The immediate destruction of habitat at the construction site. 2. The presence of seawalls at the land/water interface, eliminating critical habitat for the development of estuarine shoreline vege- tation. This, in turn, eradicates nursery habitat, as well as a * cleansing site for incoming water. 3.' The inability of circulation patterns to adequately flush the waters and carry undesirable pollutants to the receiving water body, and/or maintain a sufficient concentration of dissolved oxygen throughout the water column of the entire canal network. 3 Fortunately, the direct causes of water degradation within canal systems were clear. The documentation of canal problems resulted in restrictive legislation, causing a si gni f icant decrease- in canal construction. However, canal developments continue to be permitted. 47 Perhaps these developers can follow the less negative approach to canal design as devised by Morris (1981) and discussed in Section IV D. Of course, the best approach is to completely ban the construction of canals. Stormwater Run-off When rainfall occurs, much of the water perculates through the ground. It is cleansed by the soil and lower rock layers and enters the groundwater system. When rainwater falls on land it can enter the estuary via rivers and streams as terrestrial run-off, relatively clean but full of nutrients. The remainder enters the estuary via storm pipes asI run-off from roads, lawns, parking lots, and agricultural cropland. This run-off may contain pollutants such as pesticides, gasoline, oil, heavy metals, and fine particles of rubber and asbestos. Odum (1970) termed the influence of these pollutants "sub-lethal effects", and described it as a poorly understood occurrence. Butler (1966) has shown that widespread pesticide pollution significantly decreases the production of estuarine fish and shellfish. Anderson and Peterson (1969) discovered that sublethal concentrations of DOT prevented the establishment of a visual conditioned avoidance response in some fish and also affected the thermal acclimation mechanisin. Industri al Di scharge In Florida, phosphate is the prevalent mineral extracted from theI ground. Phosphate plants, like power plants, require a cooling system that utilizes water, therefore, Florida phosphate plants typically are found on rivers or on estuarine shorelines. Upchurch et al. (1976) found that effluent from a phosphate processing plant in Hillsborough Bay was heated 48I to 18'C above ambient water temperatures, contained much fluoride, and was a ci dic. The discharge caused the disappearance of all animals within 61 hectares, and diversity and abundance were low where organisms did occur. Phosphate strip mining and processing plants established far upstream affect the estuary. Though outflow water temperatures have probably cooled by the time they reach the estuary, the chemical contaminants would no doubt be sustained within the outflow. Miscellaneous Activities Numerous additional activities that affect estuarine production continuously occur. Vessels, whether they are large, small, commercial, or recreational, release gas and oil into the water. Larger vessels are capable of producing wakes that may disturb quiet areas and cause detri- mental affects such as stripping newly established vegetation from the sediments. Motorboat scars within seagrass meadows persist for years (Zieman 1976). The construction and placement of causeways and bridges destroys habitat of the immediate site. After stabilization, however, estuarine vegetation may sometimes return depending on boat activity, wave action, turbidity, and other factors influencing reestablishment. Cause- ways additionally alter circulation patterns that can severely affect some areas. Oil spills can cause extensive damage. Oyster shell dredging * creates temporary turbid conditions within approximately 30 meters of the site, in addition to a reduced organic content within the sediment, a 40% loss in species, a 66% loss in abundance, and an 87% loss in biomass. Within six to 12 months, however, these parameters can become naturally restored to pre-dredge conditions (Conner and Simon 1979). 49 Cumulative Effects The health and well being of estuaries is based not on an impact of a solitary activity, but rather on the accumulated effects of all activities,I since the whole estuarine system is interrelated and interactive. Estevas (1981) states: "In Coastal Ecosystem Management, Clark (1977) names or dis-I cusses nearly 100 activities with adverse estuarine impact. The permutations of just those activities possibly relevant to south- west Florida estuaries all profoundly numerous, and of inestimableI impact due to the many variables involved. This does not mean, however, that cumulative impacts cannot be anticipated, identified, or managed. For all purposes, recent efforts to protect Charlotte Harbor by its designation as a complex of aquatic preserves, and possibly as an area of critical state concern, represents the emergence of public concern for cumulative (additive and inter- active) effects (CHPRMC, 1980)." 50 IV. RESTORATION Estuarine shorelines and, nearby shallow waters provide the perfect ecological environment for salt marshes, mangroves, and seagrasses, however, this same shoreline aesthetically appeals to many humans as well. Unfortunately, in many areas of Florida, humans who dwell along shorelines do not want to coexist with native habitats. Instead, they live on shoreline habitat restructured by developers. An anonymous author once woe No thought has been given to the fact that the highly- touted offshore fishing in this area of retirement homes is directly related to the very mangrove swamps being destroyed to make homes for the fishermen. Present knowledge linking the estuarine system to such important U entities as growth and survival of juvenile fish and shellfish, shoreline stabilization, water quality, and food production has led scientists into the complex realm of habitat restoration. Of course, the simplest and most 3 inexpensive "method" is preservation, in other words, absolutely no adverse effects due to development shall occur. For areas already destroyed, preservation is of course, impossible; only future development can employ this procedure. Next to preservation is conservation -- if a project must be constructed at a specific location resulting in damage to natural 3 systems, then the construction process should cause the least possible deleterious effects. Mitigation is also a choice, but still results in destruction of habitat in trade for preservation or re-establishment of another site. This section addresses (1) post-development sites devoid of native vegetation, where vegetative restoration is indeed a possibility, and (2) miscellaneous restorative and pre-development concerns such as spoil island configuration, bulkhead alternatives, and rational canal design. Various techniques of restoration are discussed, and those with best results will be delineated. The reader should always keep in mind that each restoration site is unique with different flow patterns and water regimes, varying sediment compositions, and other parameters. Restorative capacity is, therefore, peculiar to each site where restoration has or will occur. IV A. SEAGRASS RESTORATION The major methods of reestablishing a seagrass population are seed cultivation or transplantation of plugs, turfs, or sprigs, possibly apply- ing hormone treatments executed at different times of the year. The dis- cussion is limited to reports of seagrasses that occur in Florida waters. Plugs: A plug of seagrass is composed of seagrass blades, roots, and rhizomes with attached sediment. A plug is removed from the transplant site with a shovel or post hole digger and transported intact to the recipient site. A hole is dug into which the plug is placed; an anchor or sediment cover holds it in place. Plugs are typically spaced one meter apart. Disadvantages to this system are the damages it induces to the donor site, the substantial time and labor requirements, and the slowness of regrowth, especially of Thalassia (Godcharles 1971). Kelly et al. (1971) was unsuccessful in applying this technique to Thalassia in Boca Ciega Bay. Van Breedveld (1976), however, had 100% survival of Syringodium in Tampa Bay by using a post hole digger and planting in rows in early spring. Lewis and Phillips (1980) planted plugs in a small borrow area of the Florida Keys that had silted in with fine calcareous sand and silt. 52 They had 35% survival for Syringodium and 37% for Thalassia; Halodule plugs, however, failed. Turfs: A turf is a large clump of sediment with seagrasses. A turf is removed from the donor site and placed into a shallow trench at the recipient site. Disadvantages are the same as described for plugs. Phillips (1974) had no success with Thalassia in Tampa Bay, probably because of erosion by currents, but Halodule exhibited some success. Van Breedveld (1975) concluded that turf transplants are most preferable. He suggested that the clumps be planted in rows, spaced 30 cm apart in favorable substrates, and closer in unfavorable substrates with donor sediment in between. Sprigs: Sprigs are single "plants" composed of the blades, short shoot, roots, and maybe the rhizomes, but no sediment. The donor site is affected less deleteriously, but stress on the plant itself might be much greater. Kelly et al. (1971) planted sprigs of Thalassia without rhizomes in Boca Ciega Bay; 11 of 60 plants survived. Lewis and Phillips (1980) reported a failure of nearly 100% of Thalassia, Halodule, and Syringodium using springs in a borrow area of the Florida Keys. Seeds: Thorhaug (1974) gathered Thalassia fruits from Caribbean beds and immediately separated the seeds. The seeds were transported under recirculating sea water and planted in the denuded Turkey Point Power Plant discharge canal in Biscayne Bay. After 2.5 years, the transplant site was moderately dense. After 4 years, blade density was 2000/rn2 as compared with 2295/m2 at a control site. Lewis and Phillips (1980) reported nearly 100% failure of planting Thalassia seeds and seedlings in a silted-in borrow area created by dredging. 53 Durako and Moffler (1981) reported 100% success in planting laboratory seedlings in peat pellets (compressed dehydrated peat containing low grade fertilizer); plants exhibited, healthy leaf growth after 3 months, and maintained good health in situ for over 6 months. The transplant site however, presented unsuitable growth parameters of high sedimentation and turbidity, therefore, field results were inconclusive. Durako and Moffler (1981) described several physiological variables that must be considered when choosing seed stock for restoration projects: When considering seed stock for mitigation projects, the possibility of genetic fixing in local strains may be im- portant (Odum, 1971). Geographically separated T. testudi- num populations exhibit ecoplastic limits that are adaptive To-local conditions (McMillan, 1978, 1979; McMillan and Phillips, 1979). Response to the influence of habitat in- clude variation in leaf length and width (Phillips, 1960; Zieman, 1974) and variable reproductive patterns (Grey and Moffler, 1978; Moffler and Durako, unpublished data). In this regard, transplanting seeds or seedlings from remote locations may result in failure or poor success since they lack this factor compensation. The possibility of pathogen introduction utilizing nonlocal seeds also suggests that indigenous seed stock would be preferable for revegetation projects. An important consideration for seagrass restoration projects is the feasibility for growth at the recipient site. Thorhaug (1980) planted seedlings in 4 types of high stress environments in Biscayne Bay: areas of submerged dredge spoil, bottoms damaged by sewage pollution, areas of high tidal currents, and areas of shifting sand. Low survival occurred in areas of strong tidal currents, those with wave action from boats, and the dredge spoil site that was experiencing erosion and sediment shifting. Suitable sites for seedling growth included areas of low energy with peaty bottoms consisting of sandy, consolidated sediments. 54 Miscellaneous Techniques: Fonseca et al. (1979) removed Halodule (and Zostera) from donor beds and rapidly transported them to a processing area. Terminal shoots were separated'and woven into pre-cut biodegradable 20 x 20 cm mesh paper, with 15 shoots per O.04m2 mesh. The squares were placed 1 m apart in a 6 x 6 m plot and attached to the substrate with sharp pins. The logic behind this complex technique is a compromise between recovery time and cost: revegetating only a small portion of the damaged area to an advanced stage of succession. Though apparently successful, it is time consuming, costly, and labor intensive. Hormone treatments (mostly the use of Naphthalene Acetic Acid -NAA) appear to exhibit no consistent results. In his work with pluq and sprig transplants, Van Breedveld (1975, 1976) reported no advantages from using hormone treatments. Thorhaug (1974), however, found that seeds soaked in NAA solution appeared to increase root propagation. Kelly et al. (1971) reported 100% success in transplanting sprigs without rhizomes that were first dipped into NAA solution previous to planting. Whether the success- ful attempts were due to hormone treatment or to other parameters such as viability of the recipient site and the restoration technique itself remains questionable. The season in which restoration is attempted may play an important role in successful projects. Saurs (1981) and Van Breedveld (1975) suggest early spring as optimal for planting since seagrasses exist in a semi- dormant state during this time. Saurs (1981) also emphasized that historical changes must also be considered, i.e., if seagrasses are disappearing within an area, restoration may prove useless. Disturbance to the system is causing their demise and any restorative attempts may fail. 55 In summary, investigators must choose between several alternatives before attempting restoration of a seagrass bed. Selection concerning which restoration techniques to use, when to plant, the use or disuse of a hormone treatment, cost considerations, and, most important, the receptivity of the recipient site must all be considered. A final option regards which species to place into the new site. Often, the system has changed extensively and new growth of the original species may not be feasible. Thorhaug (1980) noted that some investigators plant Halodule because it grows faster, however, she argues against this reasoning because Halodule might not support a faunal system as large or diverse as those maintained by Thalassia beds, nor does it apparently function to stabilize sediments as well. Lewis and Phillips (1980) suggest that Thalassia exists as the climax species in an ecological succession with Halodule and Syringodium; Halodule roots are shallow and it grows quickly, Syringodium has deeper roots and grows slower than Halodule, and Thalassia has the deepest roots and grows the slowest of all three. Reasons describing why one site is better suited than another for a particular species are multitudinous, and basically unknown (M. Durako, personal communication). The reader is referred to Coastal Engineering Technical Aid No. 30-2 (Phillips, 1980) and a bibliography on seagrass planting and propagation techniques (Knight et al. 1980) prepared for the U.S. Army, Corps of Engineers, Coastal Engineering Research Center, for more information regarding seagrass restoration. 56 IV B. MANGROVE RESTORATION Lewis (1981) described some of the major reasons for the recent in- creased interest in mangrove restoration: (1) the value of mangrove forests has been realized and documented; (2) large-scale losses of mangroves have occurred; and (3) legal authority has been granted to regulatory agencies to control destruction of mangroves through develop- ment and to establish fines, replanting requirements, and other mitigation procedures. Teas (1980) describes one goal for mangrove restoration: to develop a functional, diverse ecosystem as rapidly as possible. He suggests (1981) several short cuts that rapidly establish a mature system. Dense planting and planting larger trees help accelerate development. Faster growth is achieved with fertilizer treatments. Large block plantings as opposed to scattered plantings are favored since larger forests harbor a more diverse fauna. If the site is distant from other mangroves, introducing inverte- brates, algae, and other fauna could accelerate development (Teas 1980). Substrate stabilization appears to be one of the most important functions of mangroves. Since black mangroves form dense root mats, they may serve as better stabilizers than red mangroves (Savage 1972; Carlton 1974). White mangroves also grow dense root mats; they, too, can stabilize substrate (Teas 1981). Lewis and Dunstan (1975) suggested achievement of rapid stabilization by first planting Spartina alterniflora and then planting mangroves within the Spartina. Pulver (1975) suggested plantinq mangroves in greater densities, then allowing natural overcrowding and competition or artificial thinning to occur. 57 Four basic methods of mangrove reestablishment have been applied: planting of propagules, planting nursery-grown seedlings, transplanting from field stocks, and air layering. These methods are herein described as well as some common decisions and problems encountered in the field. Planting propagules: This method simply involves collecting propa- gules and placing them into the substrate at the restoration site. Most restoration failures of planting seeds or seedlings appear to occur due to high wave energy. This form of stress physically undermines and removes plant material before it becomes established (Hoffman et al., in prep.). Natural high wave energy is caused by strong winds, but boat wakes constitute an induced stress, especially in well-used recreation areas. Teas et al. (1975) planted 178 young Rhizophora seedlings on a St. Lucie River site that was subjected to waves from boat traffic; after 7 months, there were no survivors. However, a nearby low energy site had a dense growth of mangroves after 5 years (Teas et al. 1975). After plant- ing 60,000 Rhizophora propagules on a low energy site in Charlotte Harbor, the same authors reported 85 to 90% survival after one year. Teas (1977) reported 100% survival after 5 months of small pot-grown mangroves of all species planted along a low energy canal. The establishment of a "rocky" berm in areas prone to high wave energy in order to absorb destructive water movements are sometimes used; this berm should be high enough to inhibit waves, but porous enough to allow tidal infiltration. If planted or growing too low in the tidal zone, mangroves are subject "Sphaeroma disease." Sphaeroma terebrans is an isopod parasite that bores into mangrove roots and stems, weakening them and making them more vulnerable to adverse effects of wave stress. Hannan (1975) reported that 58 all mangroves planted 10 cm too low in the tidal zone were killed by Sphaeroma, but trees planted above this level were not attacked. Nursery-grown mangroves: -This method involves the growth of mangroves in an artificial environment and transplanting them to restorative sites. Evans et al. (1978) described how several methods of treatment affected growth and survival of mangrove seeds. Mulched soils (50% grass clippings/50% soil) enhanced growth rates of red and black mangroves, but had no effect on survival of reds and an undetermined effect on survival of blacks. Salt additions increased survival for both reds and blacks but was ineffective on growth rate. Fertilizers showed no effect for red mangroves, but were detrimental to blacks. Various watering schedules did not affect red mangroves, but blacks exhibited greater survival after one watering per week. These authors suggested that black mangrove seeds, prior to planting, be soaked until their seed coats fall off and roots start growing. Transplanting mangroves: This method involves the removal of plants from a donor site and replanting them at a recipient site. Pulver (1976) developed guidelines for transplanting mangroves: (1) The top and side branches should be pruned to approximately 2/3 of the original length. (2) A root ball diameter about 112 the original tree height should be retained. (3) At the recipient site, when replacing soil in the hole, the root ball should be watered and pushed down to insure a seal between it and the sides of the hole. (4) The plant should be placed at about the same substrate 59 depth and the same tidal elevation as the original source site. (5) Plants should not be placed into unstable substrates. Hoffman and Rogers (1980) successfully applied these methods but without initial pruning. They reported 73.3% success after 13 months for transplanting red and black mangroves on a dredge spoil island in Tampa Bay on an area of low wave energy and proper elevation. Hannan (1975) transplanted 4-year old root balled red mangroves at or above mid-tide range in the Jensen Beach area; after 13 months, 85 to 100% survived. Teas (1977) transplanted 14 black mangroves and white mangroves that were previously root-pruned and top-pruned at the time of translocation; after 6 months, all were dead. Teas attributes these losses not to pruning, but to improper handling. Mangrove Air Layering: Air layering serves as an untried method of restoration. Short sections of bark and phloem are stripped to the cambiam and wrapped with Sphagnum moss and aluminum foil to retain moisture. Roots soon emerge from the "layers". To form new trees, stems may be cut under- neath the layers and planted at a new location. Carlton and Moffler (1978) observed root growth 5 to 6 months following layering with 39% success for red mangroves, 35% for white mangroves, and 6% for black mangroves. Further investigations by the Department of Natural Resources (DNR) Bureau of Marine Research indicate that root growth requires 4-6 months with success rates of 87.5% for whites, 60.4% for reds, and 12.5% for black mangroves (D. Crewz, personal communication). Investigators at DNR suggest that air layering be performed just before the rainy season to take advantage of higher humidities and temperatures, however, they warn that 60 too much water may lead to fungal/bacterial infection. Air layering provides larger planting material without the labor-intensive costs of growing nursery plants or the-loss of plants from source sites associated with transplanting. Addi ti onallIy, air layering allows for phenotypic selection for specific traits (D. Crewz, personal communication). In summary, restoration of mangrove stands and even the introduction of mangroves into new sites is highly feasible. Planting in recipient sites of low wave energy and fairly stable substrate appears to enhance survival. Berms or another method of lowering wave stress can be placed at sites of high wave energy. All four methods of restoration exhibit successful results when guidelines are properly followed. Fehri ng et al . (1979) stress the importance of community acceptance and assistance with projects at or near developed areas. They further point out that most of the habitat restoration projects are run by government agencies - these U projects are assured of long-term commitments in most cases. Developers, too should be responsible for long-term commitments, i.e., successful re- establishment and not just initial plantings. IV C. SALT MARSH RESTORATION As with seagrasses and mangroves, the importance of marsh vegetation is well-known and documented. Present salt marshes occupy calm waters subject to tidal influences; restored marshes prefer the same habitat. In planning for a restored site with the ultimate veqetative composition in mind, Hunt (1979) suggested that investigators first observe the species composition of nearby marshes (if any) occurring at the same elevations as the site to be restored. Local species may be more likely to invade and 3 61 colonize the area. Like mangroves, salt marsh revegetation has incorpo- rated three methods: planting seeds and transplanting field and nursery stock. Seeds: If water levels maintain relatively shallow depths during the time of seed germination and establishment or the site is located in the upper portion of the tidal zone, revegetation by seeds may have positive results; tidal action may otherwise dislodge seeds (Hunt 1979). Darovec et al. (1975) recommended collecting cord grass seeds at least 3.Om from the seaward edge of the marsh. Woodhouse et al. (1972) describe the proper techniques of handling seeds and Darovec et al. (1975) summarized these procedures: seeds should be stored in seawater between 1.7-3.3°C for two to four months. Seeds planted in vivo require 6 to 25mm substrate over them to prevent being washed away. Transplants: Depending on the species, various harvest methods have been suggested for different types of marsh vegetation. 15cm plugs of Spartina alterniflora and S. patens should be removed from a mature marsh in random locations, however, Juncus stock should be removed from one site since the plant is easily destroyed by human traffic (Hoffman et al, in prep.). Plugs of Spartina can be planted intact, or separated into individual stalks, which reduces collection labor since one plug supplies many stalks (Hoffman et al., in press). Removing the top 1/3 of Juncus shoots reduces aerial transpiration and allows greater ease in handling (Hoffman et al., in press). If high tide covers the cut top, survival is reduced (Coultas, 1980). Some important techniques for transplanting are described by Darovec et al. (1975): 1. "Transplants should be removed beyond 15 ft. from the 62 seaward edge of the marsh, taken in alternating square yards in checkerboard array. Three to five plants should remain in the center of each thinned square yard." 2. "Cordgrass and needlerush should be removed by shovel. To minimize erosion, holes should be refilled with soil rinsed from plant roots. Bare root plantings will work satisfactorily if plants are kept moist and are not ex- posed to direct sunlight. When transportation is involved, roots can be kept in buckets of seawater or in wet burlap sacks." 3. "Marsh transplanting should be done in winter and early spring, preferably after the coastal storm season." 4. "Salt marsh plants should be planted in rows paralleling the shoreline, cordgrass nearest the shoreline, plants 18-24 inches apart." Coultas (1980) recommended that transplants with one or more buds be used since these will produce more leaves and a greater height. He also noted that "Rootone" (a commercial growth regulator) produces deleterious effects. Hoffman and Rogers (1980) performed an S. alterniflora restoration project on dredge material in Hillsborough Bay. Plugs of S. alterniflora were planted on a 1.64 ha. site of low wave energy and a favorable tide regime. The 12cm plugs were placed one meter apart (center to center) in rows two meters apart. After 14 months, 93.4% survived. Hunt (1979) reported that sprigs of Spartina alterniflora grew well when planted 0.3, 63 0. 6, and O. 9m apart, but I1.8 and 2. 7m spaci ngs resul ted i n poor survi val. Spartina patens, however, grew best at spacings of 1.8 and 2.7m (Hunt 1979) . Hunt additionally found that seeds grew with greater success than spri gs. IV D. MISCELLANEOUS RESTORATION TECHNIQUESI Spoil Island Configuration: The initial formation and subsequent maintenance of ship and boat channels requires huge amounts of sediments to be dredged up. The sediments are typically dumped as random piles or spoilI islands, adjacent to the channel sites, sometimes without regard to island configuration in relation to current flow and ensuing erosion. Many times, these islands quickly erode back into the channel necessitating further dredging. In Tampa Bay, for example, three spoil islands were created in 1931. By 1957, two islands had completely eroded away. However, the remaining island shifted continuously, and finally stabilized forming a horseshoe shape with distinct arms. By 1966, one arm was shortened and curved around forming a lagoon. A mixed mangrove habitat became established and by 1979 the island served as a nesting site for 13 species of birds. Lewis and Dunstan (1974) suggested several methods to correctly configure inevitable spoil islands. These suggestions were recommended forI a proposed Tampa Bay harbor deepening project, but can also be applied to other proposed channel sites as well. The overall shape of the new spoil island should describe a three-to-one ratio of length to width. Stabili- zation can be achieved more quickly through the establishment of oyster 64 U reefs and vegetation such as mangroves. An artificial reef composed of surplus construction materials can be built to minimize wave action and protect the shoreline. Bulkhead Alternatives: Seawalls not only deprive the estuary of the important shallow intertidal gradient between dry land and water, but they also provide residents with an impersonal and false view of the natural world. There are less obtrusive methods of changing or creating shoreline to allow man to live adjacent to water. One method is to leave the natural vegetation and allow the mangroves and salt marsh to control erosion, a task for which they were so well designed. Houses built on stilts elevate * their residents and provide not only a scenic view over the natural shoreline vegetation, but also assurance against storm and hurricane tides. The natural shoreline additionally provides habitat for numerous birds, fish, and invertebrates. Depending -on the shoreline width, it may also help cleanse water flowing through it. A second method is to build a low wall of rip-rap. Rip-rap, with its wealth of crevices, holes, and surface area, provides a habitat for algae and invertebrates. It may also provide protection for inqrowing mangove seedlings and other shoreline vegetation. It is relatively inexpensive and extremely strong and stable. Depending on the material used to create the rip-rap wall, it can also be aesthetically appealing. Rational Canal Design: The early approach to canal designing was to maximize waterfront property in relation to shoreline -space. Traditional desiqns provided little potential for effective flushing. This most always leads to water quality and biological degradation. However, Morris (1981) states that on 65 a day to day basis, small amplitude tides, supplemented by periodic winds, in most cases provides enough energy for flushing, if the canal was designed properly. Obtaining the required energy, as Morris continues, canI be accomplished by (1) eliminating unnecessary energy losses due to mechanical reasons such as right-angle bends, deep holes, and culverts and biological inbalances such as the absence of natural filtering action and nutrient uptake provided by vegetation and aquatic organisms, and (2) utilizing open channels to optimize mixing. A good example of rational canal designing is demonstrated by a canal network currently under construction along the intracoastal waterway south of Jupiter, Florida. The site includes (Morris 1981): meandering channels large areas of intertidal channelsI sloping, vegetated banks elimination of dead ends increased tidal prism freshwater flow over salinity structuresI more uniform change in section through tidal entrances natural preserves set aside along the water The rational approach to canal design includes common sense planning, in-depth data collection, the correct application of physical chemical biological and ecological principles, and the use of judgement. The method cannot guarantee that a given design will function as planned,I but it will provide the kind of guidance needed for environmentally compatible development. Water Quality Improvements: Indirect problems, in many cases, causes the disappearance ofI estuarine vegetation, especially seagrasses. Poor water quality such as high levels of organics and/or pollutants, high turbidity, and poor .66 circulation oftentimes is the cause. Restoring vegetative habitats, especially seagrasses, in an area of poor water quality, would probably result in a failed attempt., Several methods exist to improve water quality; these, of course, depend on the type of water quality perturbation pasting at the site. Improving sewage treatment and wastes released into the estuary would lessen the amount of introduced nutrients, this reducing the process of eutrophi cati on. To induce better circulation in areas where circulation has been moderated or terminated, one-way tidegates, cuts, and/or culverts can be installed. Treatment of point and non-point sources of pollution, especially stormwater run-off, would decrease the amount of chemicals and toxins that are released into the estuary. These ideas represent only a few options that exist to improve water quality of damaged estuaries. 6 68 I II * Linking Juvenile Fish to Estuaries U I11111 iith IAIIL II III·k IA r V. LINKING JUVENILE FISHERIES SPECIES TO ESTUARIES V A. SPECIES FOUND IN ESTUARIES Many investigators have produced rather extensive juvenile species lists for estuarine environments in Florida alone. Among them are Reid (1954) and Kilby (1955) who listed species from Cedar Key; Harrington and Harrington (1961) who recorded species from Indian River; Tabb and Manning (1961) who listed species of Florida Bay; Springer and Woodburn (1960) and Sykes and Finucane (1966) who listed fishes of Tampa Bay; and Odum and Heald (1972) who recorded species from North River estuary. While species lists represent single point-in-time presence of juvenile fish in estuaries, studies of age and growth can document longer- term presence. An example of this concept is a two year age and growth project currently underway by DNR Bureau of Marine Research. The project involves bimonthly collections of juvenile trout, drum, and related species from various sites in the Tampa Bay estuary. Sites include seagrass beds, sandy bottoms, and back water sites with generally turbid water and muddy bottoms. Collections at these sites have yielded progressively larger juvenile fish of the same species, indicating that these fish live and grow within the estuarine system. In addition, this study will document growth rates, site preference, and arrival time of new post-larvae that indirectly indicates spawning times of adults. Table 4 lists the recreational and commercial fishes of Florida. Robins et al. (1980) provided the scientific and common names. Commercial species are defined as those recorded in Florida Landings (Florida 69 Table 4. FLORIDA RECREATIONAL AND COMMERCIAL SPECIES ESTUARINE-j RECREATIONAL COMMERCIAL FAMILY/SPECIES DEPENDENT EAST WEST EAST WEST Carcharhinidae - requiem sharks (Carcharhinus spp.) + X X X X Sphyrnidae - hammerhead sharks Hammerheads, bonnethead (Sphyrna spp.) + X X X X Acipenseridae - sturgeons Atlantic sturgeon (Acipenser o. oxyrhynchus) X X Gulf sturgeon (Acipenser oxyrhynchus desotoi) X X Shortnose sturgeon (Acipenser brevirostrum) X X Albulidae - bonefishes Bonefish (Albula vulpes) + X X Elopidae - tarpons Ladyfish, Tenpounder (Elops saurus) + X X Tarpon (Megalops atlantica-)a + X X Clupeidae - herrings Alabama shad (Alosa alabamae) + X Alewife (Alosa pseudoharengus) + X X American shad (Alosa sapidissima) + X X Atlantic thread herring (Opisthonema oglinum) - X Atlantic menhaden (Brevoortia tyrannus) + X Gulf menhaden (Brevoortia patronus) + X Spanish sardines (Sardinella aurita) X X Ariidea - sea catfishes Gafftopsail catfish (Bagre marinus) + X X X X Sea catfish (Arius fel6s)- + X X X X Exocoetidae - flying fishes Ballyhoo (Hemiramphus brasiliensis) X X Carangidae - jacks and pompanos Blue runner (Caranx crysos) + X X X X Cigarfish, scad (Decapterus spp.) X X Crevalle jack (Caranx hippos) + X X X X Florida pompano (Trachinotus carolinus) + X X X X Greater amberjack (Seriola dumerili) - X X X X Permit (Trachinotus falcatus) + X X X X Centropomidae - snooks Snook (Centropomus pectinatus) + X X Coryphaenidae - dolphins Dolphin (Coryphaena hippurus) X x X X X 70 Table 4. FLORIDA RECREATIONAL AND COMMERCIAL SPECIES (Continued) IESIUARINE-I RECREATIONALI COMMERCIAL FAMILY/SPECIES DEPENDENT EAST WEST EAST WEST Ephippidae - spadefishes Atlantic spadefish (Chaetodipterus faber) + X X Gerreidae - mojarras Spotfin mojarra (Eucinostomus argentus) + X X X X Striped mojarra (Diapterus plumieri) + X X Yellowfin mojarra-,-sa-nd-per-ch-,-go-atfish (Gerres cinereus)X X Silver jenny (Eucinosou ua + X X X X Haemulidae - grunts Pigfish (Orthopristis chrysoptera) + X X X X Tomtate (Haemulon aurolineatum) + X X White grunt (Haemulon plumieri)+X X X X I Istiophoridae - billfishes Blue marlin (Makaira nigricans) - X X X X Sailfish (Istio-phorus platypterus) - X X White marlin (letrapturus lbidT u) - X x x x Labridae - wrasses Hogfish (Lachnolaimus maximus) X x X I Lobotidae -trpeal Tripletail (Lobotes surinamensis) + X X X X E Lutjanidae - Snappers Cubera snapper (Lutjanus cyanopterus) + X x x x Lane snapper (Lutjanus synagris) + X X X X Mangrove (Gray) npe7Ltau griseus) + X X X X Mutton snapper (Lutjanus analis) + X X X X Red snapper (Lutjanus campechanus) + X x X X Vermillion snapper (RiomboplTTe-saurorubens) - X X X X Yellowtail snapper (Ocyurus chrys u-rus)-y X X X X Mal acanthi dae - til1efi shes 3 Ti lefish (Lopholatilus chamaeleonticeps) X X Mugilidae - mullets Black mullet (Mugil cephalus) + x x x x Fantail mullet (Mugil trichodon) + X X Silver, white muTT-ef(7u-g- I curema) + X x I Percichthyidae - temperate basses Striped bass (Morone saxatilis) + X X I Pomacanthidae - angelfishes Angelfish (H-olacanthus or Pomacanthus spp.) X X * 71 Table 4. FLORIDA RECREATIONAL AND COMMERCIAL SPECIES (Continued)3 IESTUARINE-1 RECREATIONAL I COMMERCIALj I FAMILY/SPECIES IDEPENDENT I EAST WEST I EAST WEST Pomatomidae - bluefishes Bluefish (Pomatomus saltatrix) + X X X X3 Rachycentridae - cobi asI Cobia (Rachycentron canadum) x x x x Sciaenidae - drums Atlantic croaker (Micropogon undulatus) + X X X X Black drum (Pagna rms + X X X X Grey seatrouFi§inrgls + X XI King whitingsotenkgfh (Menti ci rrhus americanus) + X X X X Red drum (Sciaenops ocellatus) I + X X X Sand seatro-ut (Cyno scion arenarius) + x x x Silver perch (Bairdiella chrysura) + X X Spot (Leiostomus xanthuru sT7 + x x x xI Spotted seatrout (Cy nosci on nebulosus) + X X X X White, silver seatrout Cynosc-ion n'othus)-X X X X Scombridae - mackerels and tunasI Bigeye tuna (Thunnus obesus) -x x Blackfin tuna (Thunnus atlanticus) -X X Bluefin tuna (Thu nnus-thynnus)IIIII Little tunny (Euthynnus alletteratus) x X X X Skipjack tuna (Luthynnus pelarnis) - X X X X Frigate mackerel-T(Auxi s th-azar-d) - X X X X Ki ng mac kerelI ( Sco mberomo-ru-sc cava]lla) + X X X X Spanish mackerel (Scomberomorus maculatus) + X I X X Serranidae - sea bassesI I II I Bank sea bass (Centropristis ocyurus) 1 X I Ix Black sea bass (Centropri sti s stri ata)-X X X Gag grouper (Mycteroperca micr-o7e p-1s7 +X X XX I I Jewfish (Epinephelus itajara) + X X X X Red grouper (Epi nephelus mono ) + X X X X Rock sea bass (Centropr-is-t-i-s--piladelphica) + X X Southern sea bass (Centropristis melana) x x Warsaw (Epinephelus nigritus) - X X X X Jparidae - porgiesI Pinfish (Lagodon rhomboides) + X X Scup (Stenotomus chrysops) X x X Sheepshead (Archosarqus probatocephalus) + X X X X White snapper, porgy (Calamus spp.) X X X x X 72 Table 4. FLORIDA RECREATIONAL AND COMMERCIAL SPECIES (Continued) IESTUARINE-I RECREATIONALI COMMERCIAL FAMILY/SPECIES DEPENDENT EAST WEST EAST WEST Sphyraenidae - barracudas Great barracuda (Sphyraena barracuda) + X X X X Guaguanche (Sphyraena guaguancho) + X X X X Xiphiidae - swordfishes Swordfish (Xiphias gladius) X X X X Bothidae - lefteye flounders Gulf flounder (Paralichthys albigutta) + X X Southern flounder (Paralichthys lethostigma) + X X X X Summer flounder (Paralichthys dentatus) + X X Balistidae - leatherjackets Triggerfish (Balistes capriscus) + X X X X Tetraodontidae - puffers Southern puffer (Sphoeroides nephelus) + X X CRUSTACEANS, SPONGES, AND MOLLUSKS Spongiidae - sponges Glove sponge (Spongia spp.) + X X Grass sponge (Spongia graminea) + X X Sheepswool sponge (Hippiospongia lachne) + X X Yellow sponge (Spongia zimocca) + X X Loliginidae: Squid (Loligo plei) - X X Strombidae: Conch (Strombus gigas) + X X X X Ostreidae: Oyster (Crassostrea virginica) + X X X X Pectinidae: Scallops (Argopectin irradians) + X X X X Veneridae: Clam (Mercenaria mercenaria) + X X X X Penaeidae: Brown shrimp (Penaeus aztecus) + X X X X Pink shrimp (Penaeus duorarum) + x X X X White shrimp (Penaeus setiferus) + X X X X Sicyoniidae: Rock shrimp (Sicyonia brevirostris) + X X X X Palinuridae: Spiny lobster (Panulirus argus) + X X X X Portunidae: Blue crab (Callinectes sapidus) + X X X X Xanthidae: Stone crab (Menippe mercenaria) + X X X X 73 Department of Natural Resources, 1978). Considering that certain species may or may not be regarded as recreational, dependi ng on the fi sherman, recreational species are here defined as any fish caught and kept byI saltwater anglers, all fish currently listed as a Florida record catch (a co-sponsored DNR/IGFA project in developmental stages), and all species pursued by sports fishermen. Species designated as non-food fishes (typically bait fish) are included only as commercial species. Of 108 total species, 89 are caught commercially (85 on the east coast, 83 on the west coast), and 88 represent the recreational catch (84 on the east coast, 83 on the west coast).I Table 4 also indicates which species reside in estuaries during someI time in their lives. This information is based on literature citations that indicate the presence within an estuary of any sub-adult stage of the species listed. 71.9% (n=64) of the commercial species and 73.9% (n=65) of the recreational species dwell in estuaries at least as pre-adults. Of theI total commercial and recreational species, 68.5% (n=74) use estuaries as nursery grounds. These amounts are significant, especially considering the importance of fishing industries in Florida. Adding to this information is the report by McHugh (1976) who estimated, using 1970 statistics, that 98% by weight of all Gulf of Mexico landings areI estuari ne-dependent. Unfortunately, the simple presence of young stages within an estuary is not enough proof of the use of estuaries as nursery grounds. A link must be established. Several methods exist to define this link. Direct evidence can be attained by diet analyses and feeding studies. Indirect 741 evidence is provided by stable isotope analyses, correlations between fisheries yield and habitat type, and correlations between declines in fisheries yield and wetlands, destruction. V B. DIET ANALYSES Many researchers have examined gut contents to determine diet. Table 5 lists some recreational and commercial juvenile estuarine fishes along with items found in their digestive tracts. An attempt was made to include only fishes reported as less than or equal to 100mm in length, regardless of species, to insure juvenile age class. Food items found most commonly (composing over 50% of the gut content) are underlined. Three obvious conclusions can be drawn from the table: (1) juvenile fish utilize several food sources, (2) differing species share common food sources, and (3) diets change as fish grow. These conclusions emphasize four (#1, #3, #4 and #5) of Miller and Dunn's (1980) features of juvenile fish feeding relationships as discussed in the previous section. The most common food items found in digestive tracts of the majority of species are copepods, shrimp, mysids, amphipods, fish, and polychaetes. A subsequent food chain study would require a diet analysis of each of these animal groups. However, within each group, no single feedinq strategy exists, especially for those groups occupying the sub-tropical shoreline waters of Florida. Within the polychaete group, for example, omnivores, herbivores, deposit feeders, carnivores, and detritivores are found, each consuming a wide variety of food items. Diet studies of these groups are feasible and certainly important, but must be very specific. 75 Table 5. DIET ANALYSES OF SOME PRE-ADULT RECREATIONAL AND COMMERCIAL ESTUARINE FISH Species Size (mm) Code for Food1 Reference2 Ladyfish 19-38' 120,132 106 Atlantic thread herring 21-40 230 14 Juvenile 300 6 >40 120,140,131,230 14 Sea catfish small 620,160,100 90 Crevalle jack 79 600 61 Permit 15-20 140,135 14 15-44 160,420,221 38 26-35 610 14 >35 900 14 50-100 180,200 38 Silver jenny 11-15 120 14 16-39 120,911 14 19-70 160,120,400 102 >35 911 14 Striped mojarra 35-172 140,160,410 106 Pigfish 12-15 120,110,210 60 16-20 T2U 14 21-30 120,135 and/or 140,630 14 31-40 T357 and/or 140,911,120 14 40-100 160,135,133,200,911 60 41-55 911,135 and/or 140,160,120,630 14 56-80 T,911,134,630,210,120 14 White grunt 21-35 120,140 or 135,500 14 36-40 TT4 or 135,120 14 Black mullet Juvenile 500,510 61 Atlantic croaker 10-39 911,400,160,120 130 10-49 O-T,700,500,510 61 17-42 200,110,120,911,600 156 <39 120,100 133 40-49 121,120,141,100 133 40-89 TT1,400,160,120,500,140,135 130 50-59 100,141,120 133 50-124 510,500,300,700,600 61 60-79 121,141,120,100 133 80-99 120,100,911,141 133 1Code list located on page 2Numbers refer to references listed in Section X. 76 Table 5. DIET ANALYSES OF SOME PRE-ADULT RECREATIONAL AND COMMERCIAL ESTUARINE FISH (continued) Species Size (mm) Code for Food Reference Grey seatrout 30-49 121,100,141 133 50-99 141,911,100 133 Red drum 0-19 120,140 4 20-39 140,120,160 4 40-49 T6O,140,600 4 50-69 60,160,911 4 70-99 176, 911,133,600,511,512 Sand seatrout 10-39 140,120,135,600 130 40-99 6TU,140,135,300 61,130 Silver perch 6-30 120,630,600,135 or 140,160, 14,60,90, n1l =I70,140,911 106 23-63 130,140,410,160,610 90 25-50 140,135,133 60 25-99 135,120,160,200,911,600,100 122 30-39 1T2T -i 133 31-35 120,135 and/or 140 14 36-70 T37,120,160,100 14 40-69 T1T,121,100 133 50-80 140,135,161,911 60 60-82 140 156 70-99 141,100 133 Larval 120,630 102 Spot <25 120,110 60 Post-larval 120 70 15-100 500,200,910,100 60 20-69 911,500,120,920,140,220,400 130 40-99 700,500,510 61 50-99 120,121 133 Spotted seatrout 20-100 120,140,138 97 20-130 600,135 and/or 140,120,160 14 25-150 140,137 133 40-99 600,300,700,800,500,510 61 68-122 14-,160,410,138,610 102 Pinfish 10-30 120,160,135 and/or 140,1100, -11,100 14 15-50 135,160,120 122 31-65 160,1100,911,135 and/or 140 14 39-61 222,140,160,223 106 40-99 700,500,800,600 61 51-100 120,135,510,160,200,133,600, 122 1400 66-90 135 and/or 140,1100,600,500 14 <76 1200,100,911,2000 53 Post-larval 120 70 77 Table 5. DIET ANALYSES OF SOME PRE-ADULT RECREATIONAL AND COMMERCIAL tL5UAKINL Il5H (continued) Species Size (mm) Code for Food Reference Sheepshead <40 120,160,410,140,1300,200 106 Southern puffer 6-25 500,300,911,210,133,135 14 78 DIET CODE LIST 100 Crustaceans 110 Ostracods 120 Copepods 121 Pseudodiaptomus coronatus 130 Decapods 131 Megalops larvae 132 Crab zooae 133 Crabs 134 Xanthid crabs 135 Shrimp 136 Post larval shrimp 137 Penaeid shrimp 138 Cariddean shrimp 140 Mysids 141 Neomysis americana 150 Isopods 160 Amphipods 161 Gammarid amphipods 170 Cladocereans 180 Larger crustaceans 200 Mollusks 210 Gastropods 220 Bivalves 221 Donax variabilis 222 Brachidontes exustus 223 Congeria leucophaeta (now called Mytilopsis leucophaeta) 230 Veliger larvae 300 Zooplankton 400 Insect larvae 410 Chironomids 420 Larval and adult Dipteran insects 500 Detritus 510 Organic matter 511 Animal remains 300 Zooplankton: mostly cope- 512 Fecal pellets pods, mysids, larval 600 Fish penaeid shrimp 610 Small fish 700 Micro-invertebrates: small 620 Fish eggs bivalves, isopods, 630 Fish larvae amphipods, small 700 Micro-invertebrates crabs, chironomid 800 Larger invertebrates larvae 900 Benthic invertebrates 800 Larger invertebrates: mud 910 Annelids crabs, blue crabs, 911 Polychaetes shrimp spp. 920 Nematodes 500 Detritus: decaying marsh 1000 Vegetation grasses, phyto- 1100 Epiphytes plankton, zooplank- 1200 Diatoms ton, micro-benthic 1300 Algae animals 1400 Plant debris 2000 Chordates 79 Since most sources of Table 5 reported food items as groups, i.e. copepods and polychaetes, without knowing the exact species serving as food items, no conclusions can be drawn. However, using gut analyses to link seagrasses and mangroves to juvenile fishes has potential, although available knowledge about different trophic levels and their food items does not provide enough information to concretely link juvenile species to primary producers. V C. STABLE ISOTOPE ANALYSES Carbon, the element upon which all life is based, occurs on Earth in three isotopic forms (12C, 13C, and 14C), and all prove useful in scientific investigations. Radioactive 14C, due to its inherent instabil- ity and, therefore, its rate of decay, provides an extremely valuable tool for dating fossils. 12C and 13C occur as stable isotopes. Because the two isotopes react at different rates during photosynthesis, every primary producer embodies a certain ratio of the two isotopes, specific to the plant or plant group. The ratio, known as the relative 13C content (613C ), is determined by the equati on 12 1 C/ C sample - 1) 3 C standard in which the standard refers to the PDB marine carbonate standard (Craig, 1953). 613C is typically measured in parts per million (0/00). Because the standard has a higher ratio than almost all other carbon-based materials, most materials have negative values. C3 plants (those that 8O convert carbon dioxide to a 3-carbon molecule) possess 613C values between about -21 and -340/oo (Wong and Sacket 1978; Sacket, in press). C4 plants (those that convert carbon dioxide to a 4-carbon compound) maintain values of approximately -6 to -19°/oo (Smith and Epstein 1971). An interesting fact about 613C is that the ratio is maintained through the food chain. In other words, whereas primary producers fix 13C/12C into their biomass through photosynthesis, secondary consumers maintain the ratios of plants they eat. Subsequently, tertiary consumers maintain the ratio of their prey. The theory for the estuarine system follows that pre- adult fishes, existing as top carnivores (irrespective of larger fish and birds), should maintain 613C values identical to seagrasses and mangroves, if these two primary producers do indeed serve as important food sources for the estuarine system. Although the first measurements of 13C were made in 1939 (Nier and Gulbransen 1939), the concept of ratio maintenance through the food chain is relatively new, and very little work has been done to date in this realm of research. A significant point is that 613C is a function of an animal's history - it provides data of feeding behaviors over time, averaging out seasonality and food availability. In comparison, gut analyses provides data for only a single point in time. Haines and Montague (1979) recognized two significant criteria for using 13C/12C ratios to analyze food chains: (1) definite ratios must exist for food sources alternate to those under investigation, and (2) the ratio must be maintained through the food chain. Fry and Parker (1979) noted that previous studies have indicated that animals possess a 13C value very near the value of their diets, however, metabolism may affect the value + 2% between individuals or species (Minson et al. 1975; DeNiro 81 and Epstein 1978). No 613C studies for Lake Worth or Charlotte Harbor have been reported; however, Fry and Parker (1979)and Fry et al. (1977) investigated the Upper Laguna Madre seagrass ecosystem in Texas. The dominant seagrass at the site was Halodule wrightii with smaller areas of Thalassia testudinum and Halophila engelmanni. By comparing 613C values of fish, shrimp, and invertebrates of the seagrass system to the same species offshore, they found that benthic plants heavily influenced the carbon flow. Results from another study by Fry et al. (1982) of a Caribbean seagrass bed and coral reef suggested that benthic plants contribute 48-76% of the carbon in fish generally greater than 40mm in length. Thayer et al. (unpublished) found that deposit feeders and herbivorous invertebrates living on eelgrass blades near Beaufort, N.C. obtained about 60% of their carbon from seagrasses. In the same study, seagrasses provided omnivorous inverte- brates and fishes 45% of their carbon. Nitrogen and sulfur also are used as tracers in food web studies. Both elements have two major stable isotopes: 15N and 14N, and 32S and 34S. Joseph Zieman (Department of Environmental Science, University of Virginia, Charlottesville, VA) is currently analyzing juvenile shrimp of south Florida estuaries using carbon, nitrogen, and sulphur. Other than this study, little work has been done using tracer methods in Florida estuaries, however, the papers reported here certainly support the use of these methods as an effective tool in tracing estuarine food webs. Such tracer studies could determine the significance of different vegetation components within major estuarine systems, e.g. Charlotte Harbor and Tampa Bay. These studies could partition out the contributions of manqrove 82 detritus, seagrasses, and phytoplankton in disturbed versus relatively undisturbed systems. V D. CORRELATIONS BETWEEN FISHERIES YIELD AND HABITAT TYPE Amounts of emergent and submergent vegetation and freshwater flow have been associated statistically with fisheries yield in some areas. For example, Turner (1977) related shrimp yield to acreage of marsh and sub- merged grassbeds as did Barrett and Gillespie (1973) who demonstrated a positive correlation between brown shrimp landings in Louisiana and marsh acreage with salinities above 100/oo. More recently, Zimmerman et al. (1984) showed that juvenile brown shrimp in Texas were more abundant in salt marsh areas than in nonvegetated areas. The association between faunal abundance and marine vegetation is not limited to shrimp. Macalaster (1982) showed that fish were more diverse and abundant at vegetated sites than nonvegetated sites in the Chesapeake Bay and that a decline in submerged grasses affected fisheries yield. Weinstein and Brooks (1983) determined fish species and abundance differ- ences between a tidal creek and an adjacent seagrass bed and although both areas harbored wide ranging species, the seagrass area had hiqher diver- sity. As Weinstein and Brooks pointed out, the specifics of habitat selec- tion and utilization are not well documented, yet we accept the theory of estuaries as nursery ground habitat based on occurrence, distribution, abundance, and gut contents of those fisheries species studied. Yokel (1975) reported that crustacean abundance was 3.9 times larger within seagrass beds and algal mats than on nearby unvegetated bottoms. 83 Densities of fishes in south Florida estuaries and lagoons were found generally higher within grass beds as opposed to adjacent non-vegetated habitats (cf. Zieman 1982; Figure 5). In addition to these reports, other studies have shown that in Thalassia beds, areas of greater plant biomass contained both a higher diversity and a greater abundance of epibenthic invertebrates than areas of lesser biomass (Heck and Orth 1980). An extremely important point is that the presence of seagrasses is critical to the presence of many other plant and animal species living within the system. In other words, if all seagrass blades were removed, much of the epibenthic faunal community would probably vanish as well. Zieman (1982) notes that "there are few other systems which are so dominated and controlled by a sinqle species...". In summary, areas containing seagrasses are inhabited by a greater abundance Fish w' 75 Invertebrates z 50- I-. HEAVY THIN SAND, MUD, SEAGRASS SEAGRASS SHELL SAND, Halodule 8 Thalassia Halodule SHELL Figure 5. Relative abundance of some faunal communities within seagrass beds and within adjacent non-vegetated sites. (Redrawn from Zieman 1982, after Yokel 1975). 84 of organisms than unvegetated sites, and abundance appears to be directly related to seagrass density. V E. CORRELATIONS BETWEEN DECLINES IN FISHERIES YIELD AND WETLANDS DESTRUCTION Since the literature well-documents the importance of estuaries as nursery grounds, it is obvious that as estuarine habitat disappears, a 3 decline in associated fisheries also should occur. Lindall and Saloman (1977) warned that "man's physical and chemical alterations of gulf * estuaries are threatening the continued production of its fisheries resources." However, they could not quantify the impact. 3 Two methods exist to quantify the relationship between fisheries habitat alteration and associated fisheries decline. One method is to determine carry capacities of the various habitats. In theory, carrying * capacity would describe the amount of fisheries species and individuals that an area of habi tat can support. As fi sheri es habi tat is altered or destroyed, the quantity of fisheries it supports can be predicted to be destroyed as well. In practice, however, ways to determine carrying .1 capacity *are basically unknown and are under investigation. A second method i s to relate catch statistics of estuarine-dependent species to declines in estuarine habitat over a period of time. Assuming 3 that catch effort has remained stable, that catch efforts occur at habitat carrying capacity, and that all life history stages of a species is known, 3 this method should reflect a change in fisheries relative to changes and alterations in habitat. To test this theory, five estuarine-dependent 85 species were chosen as target groups: red drum (Sciaenops ocellatus), spotted seatrout (Cynoscion nebulosus), black mullet (Mugil cephalus), blue crab (Callinectes sapidus), and pink shrimp (Penaeus duorarum). Fisheries statistics, though improper and inadequate as will be described in Section V E 2, of these five species were obtained for the two study sites, Charlotte Harbor and Lake Worth. V E i. LIFE HISTORY STUDIES RED DRUM (Sciaenops ocellatus)l Red drum spends its juvenile and early subadult stages within estuaries. Some adult populations live exclusively in the Gulf while others live in estuaries. Red drum's range extends from Buzzards Bay, Massachusetts to Key West, Florida on the Atlantic Coast and throughout the Gulf of Mexico to at least as far south as Taxpan, Mexico on the Gulf Coast. Shrimp, crab and fish primarily comprise the diet of the adult red drum. The literature also reports annelids, echinoderms, and bryozoans as food items; these probably are ingested only incidentally. Florida red drum spawn offshore in fall, reportedly near passes and channels. Fecundity estimates for artificially conditioned and spawned red drum are 2 x 104 to 2 x 106 eggs per spawn. Fecundity of wild fish from Texas ranges from 0.5 x 106 to 3.5 x 106 eggs per fish. Tidal currents carry larvae through inlets and passes into estuarine areas where they settle out among 1Summarized from Perret et al. (1980) 86 the aquatic vegetation until they are strong enough to swim. In Florida, the smallest larval fishes (5-7mm) were always found in shallow areas in or near the Gulf. In Mississippi- abundant juvenile red drum are found at the perimeter of marshes. In Florida, young fish are found in protected waters with grassy or slightly muddy bottoms that are not affected by tides. Following spawning, red drum appear to spend more time in offshore waters and less time in estuaries. Growth of the small fishes is rapid, and continues to be rapid during the first year. A study of 106 juveniles collected from Everglades National Park found growth rates of about 20mm per month. Results from * tagging studies in Florida indicated that growth is not constant throughout the year; fish exhibit a growth lag in spring, a rapid growth in summer and a slight lag at the end of summer. Food density and larval stock density influence growth as demonstrated in studies in mariculture systems. For their first winter, many red drum ranging from 50 to 150mm move to 3 the deeper areas of estuaries. A gradual movement of fishes into the Gulf during colder weather and a definite movement back into the estuary in early spring occurs after the first year. No apparent seasonal movement of juveniles into the Gulf is known. As sub-adults, they move offshore prior to maturation and spawning. Red drum are euryhaline and eurythermal. Although they are found in salinities from 0 to 500/00, they appear to prefer an optimum range of 3 30-350/oo. A direct relationship between size and salinity generally occurs with smaller fish prefering low salinities and larger fish favoring 3 higher salinities. Red drum also have the ability to tolerate a wide range of temperature. Although they are found in temperatures ranging from 2- 87 31.8°C, red drum are sensitive to rapid and sustained lows in water temperature. In Florida, winter produces the greatest availability of red drum, whereas in Texas, Louisiana, and Mississippi, the greatest numbers occur in fall. SPOTTED SEATROUT (Cynoscion nebulosus)l The spotted seatrout is a species that spends all of its life within the estuary. Primarily found in large areas of quiet brackish water with extensive submerged vegetation, the species ranges from Cape Cod to Mexico. Reflecting the mottled appearance of seagrasses, the spotted seatrout's body is silvery with numerous dark spots on the sides and on the dorsal and caudal fins. The world record catch was a 7.3kg fish taken in Virginia; Florida's state record is a 7kg fish. Feeding habits of the spotted seatrout change as the fish grows. Postlarval seatrout feed on larval shrimp, copepods, small fish, and crabs. They also prey on their own species. Copepods, mysids, penaeid shrimp, and carridean shrimp comprise the diet of juveniles. Fish become an increas- ingly important food item during the adult stage. Adult diets most often consist of black mullet (Mugil cephalus), anchovies (Anchoa spp), pinfish (Lagoden rhomboides), mojarras (Eucinostomus sp.), sheepshead minnows (Cyprinodon variegatos), and penaeid shrimp (Penaeus sp.). It appears that any preference for food items is more a function of food availability than 1Summarized from Lorio and Perret (1980) 88 of selectivity. This theory is exemplified by studies that found that shrimp and fish were equally present in gut contents during May, June, and July, when shrimp are most abundant in the area. The spawning season of spotted seatrout in the Gulf is generally from February through October. In Florida, spawning occurs from April through September, peaking in late May/early June. Ripe fish occur all year in Florida Bay, the southern limit of the species range, with a major peak occurring in May and a lesser peak in September. Spawning takes place at night and is believed to occur in the deeper channels and holes adjacent to grassy bays and flats. Some spawning may also take place in the tidal portions of estuaries and also outside the estuary. Fecundity estimates range from 15,000 to 150,000 eggs per spawn. Larval spotted seatrout grow from 1.5mm at hatching to about 4.5mm in 15 days. Rapid growth continues to about 13cm by the first winter and about 24cm by the second winter. Growth lessens or ceases during winter due probably to decreased metabolism and cessation of feeding activities at lower temperatures. The most rapid growth occurs in July and August. Longevity for spotted seatrout appears to be about 8 or 9 years. Growth rates are density dependent, and may vary from one population to another. Growth of spotted seatrout in five different estuaries along the Florida coast occurred at different rates. Because seatrout popula- tions from given estuaries exhibit differing growth characteristics, each estuary and its population of spotted seatrout should be considered as a separate stock. Spotted seatrout are not considered a migratory species since they seldom move more than 48.3km from their tagging site and very few leaving 89 their natal estuary. Movement patterns appear to be associated with temperature, avoidance of fresh water, spawning, feeding, and protection. Winter habitat throughout- the species' range extends farther offshore and at greater depths. Optimum temperatures in Florida are 15 to 27°C. Temperatures below 7 to 9°C force spotted seatrout to enter ocean inlets or live offshore along the beach area for brief periods of time. However, just as they move to deeper water to escape cold water, seatrout also travel to deeper water to escape intolerable warm water. Spotted seatrout is a euryhaline species sometimes found in fresh- water and in hypersaline water of 750/o0. Normal salinity fluctuation of 5 to 300/0o is important to all productive seatrout populations, however, sudden changes in salinity may cause mass migration or mortali- ties. Peak spawning occurs at 30 to 350/oo, but no spawning has been reported to take place when salinity exceeded 450/00. Spotted seatrout are found along their range within clear to very turbid waters. The only documented negative effect of turbidity occurred in Florida Bay following Hurricane Donna when turbulent water stirred up the sandy bottom causing packing of the fishes' gill chambers and mortality. Within the food web of the estuary, the spotted seatrout represents a top carnivore, in fact in many estuaries the only carnivore present in numbers. All other aquatic orqanisms, either directly or indirectly, can serve as food. Because of this, the general health of the estuary must be maintained to insure healthy populations of spotted seatrout. 90 BLACK MULLET (Mugil cephalus)1 Black mullet represents a species that spends most of its life within the estuary except during times of seasonal migration, annual spawning, and during very young stages. Also known as striped mullet, black mullet are found throughout in coastal waters and estuaries the tropics and subtropics. Adult and juvenile black mullet feed diurnally in bays and estuaries during high tide. Mullet feed by sucking up surface layers of muddy bottoms or by grazing on seagrasses, rocks, or other surfaces. Diatoms, dinoflagellates, copepods, plant detritus (especially attached microflora), and inorganic sediments commonly comprise their diet. When present, non- toxic plankton provides the exclusive diet. Larvae and small juveniles (2-35mm) feed on zooplankton. 1Summarized from Saltwater Fisheries Study and Advisory Council (1981) and Futch (1976). 91 Spawning takes place in Florida from October through February, peaking from November through January. Prior to spawning, mullet form large schools and migrate from the estuary to offshore waters. Along the east coast of Florida, spawning migrations move southward. The only distinct migration pattern reported for the west coast occurs from Cedar Key to Homosassa. Spawning usually occurs from 8 to 32km offshore in the Gulf of Mexico. Females produce from 1.2 - 2.7 million eggs in a single spawn, releasing them directly into the water. Accompanying males fertilize the floating, planktonic eggs. Depending on water temperature, hatching occurs 30 - 50 hours after fertilization. Hatched larvae measure 2 - 4mm, main- taining an oceanic, planktonic existence for approximately 7 days. During this time, they grow to 20-30mm and migrate inshore, passing through inlets into the grassy parts of estuaries. Growth rates directly correlate with water temperature and mullet from Florida mature in 1-2 years, growing to a length of 230-350mm. Black mullet live to 6-7 years and grow to about 750mm. Females typically live longer and grow larger than males. BLUE CRAB (Callinectes sapidus)l The blue crab inhabits coasts from Nova Scotia to Argentina. It is 1Summarized from Saltwater Fisheries Study and Advisory Council (1981) and Oesterling (1976). 92 found from shore to approximately 90 meters in depth., but principally up to 35 meters. The adult blue crab is characteristically omnivorous. Live and dead fish, aquatic vegetation, clams, mussels, snails, amphipods, isopods, insects and annelid worms comprise the diet of the adult blue crab. Food j selection of larval crabs remains relatively unknown, however, laboratory larvae have been raised successfully on dinoflagellates, brine shrimp, and sea urchin eggs. Crabs at the megalops stage feed on fish, shellfish, and aquatic plants. Mating and spawning in Florida occur year-round, except in northern Florida waters when the water temperatures drop below 15.6'C. Female blue crabs mate only once per lifetime, during the molt from juvenile to adult. Prior to this transition, the female will move to less saline brackish waters, of 8-l80/oo salinity. She will then pair with a male and will be carried, or cradled, underneath the male. While in this cradled position, the female completes her final molt into the adult. At this time, while in the soft inter-molt stage, copulation (lasting several hours) takes place. The male transfers his sperm to the female, of which she stores in seminal receptacles within her body. The sperm are able to live in this condition for about one year. After copulation, the male still cradles the female beneath him until her new shell hardens, then he * releases her. After mating, females migrate to nearshore high salinity waters 3 (>250/o0) at the mouths of estuaries to spawn. Spawning typically occurs I - 9 months subsequent to mating, with peak spawning in April and June. Females spawn at least twice, each time laying 700,000 - 2 million eggs. Classically, females follow a general latitudinal onshore/offshore 93 migration pattern. On Florida's Gulf coast, however, a tagging study conducted by DNR Bureau of Marine Research found that females migrate longitudinally, sometimes travelling over 640 km. Females carry their eggs for 7-14 days in the offshore waters until they hatch into a zoea larvae stage. Dependent upon temperature and salinity, the seven zoea stages develop for 31-49 days, leading a planktonic existence. The following megalops stage has both planktonic and benthic features. By utilizing tidal currents, the megalops enter the estuary and molt into the first crab stage. Grass beds and a variety of shallow water areas provide habitats for growing crabs. Adult size (>120mm) is achieved within 12-14 months and 18-20 molts. Movement to deeper water occurs with increasing size. After reaching adult size, crabs live about one more year. PINK SHRIMP (Penaeus duorarum)l Pink shrimp range from lower Chesapeake Bay to south Florida on the Atlantic coast, throughout the Gulf of Mexico, and on the Bermuda coast. The greatest abundance of pink shrimp occurs along coastlines characterized by shallow bays and estuaries and where the continental shelf is broad and shallow. Optimum habitat varies with age; shallow, quiet, clear water with seagrass growth is preferred by young shrimp while adults live in the 1Summarized from Costello and Allen (1970) unless otherwise noted. 94 deeper offshore bottom areas with no seagrasses. Pink shrimp spawn offshore and year round. Females release fertilized microscopic eggs into the water; the eggs then sink to the bottom. After hatching, the larvae are planktonic and are transported landward, apparent- ly floating with currents. Three to five weeks are believed to pass before the 8mm postlarvae enter the estuaries. Mortality rates for shrimp larvae are estimated as 17% per day; extremely few make it to the estuaries. Post- larvae enter the south Florida estuaries throughout the year but are least abundant during the winter. When shrimp reach approximately 10mm, they become benthic, concentrating within shallow seagrasses, and developino into juveniles. Densities may exceed 32 individuals per m2 within the sub- sequent two to four months. Shrimp grow rapidly, reaching commercially acceptable size within a few months. As they grow and mature, most shrimp gradually emigrate offshore into deeper, higher salinity water. Size at emigration averages 90-100mm. A few, however, remain in the estuaries after becoming adults. Eighty-three weeks is the estimated average maximum age. Most shrimp that develop within the estuarine waters of southwestern Florida are captured either in the Dry Tortugas or Sanibel shrimping grounds. However, most offshore waters adjacent to south Florida contain maturing and adult pink shrimp, sometimes in depths to 110 meters. But much of the bottom is too rough for conventional trawling gear; a rela- tively smooth sandy bottom underlies the Sanbibel, Tortugas, and Hawk Channel grounds where most large pink shrimp are taken commercially (Costello and Allen 1966). 95 Spawning and distribution of shrimp populations may be determined by temperature and salinity. On the Tortugas grounds, shrimp spawn in waters of 19.6°-30.6°C, with highest activity coinciding with highest bottom temperatures. A rising temperature may trigger spawning activity. Preference for various salinity regimes vary with shrimp size and geographic area. Young shrimp can survive for a short time at low salinities. In the Florida Bay area, postlarvae were caught at salinities from 12-43°/oo, juveniles at 0-470/oo, and adults at 25- 450/oo. The Tortugas grounds, have salinities of 36-380/oo. Water that is mostly turbid generally harbors the largest concentra- tions of young shrimp per unit area. Kutkuhn (1966) suggested that since more detrital material is suspended, a greater food source and protective cover is created. Juvenile and estuarine-dwelling adult pink shrimp are omnivorous bottom feeders, feeding primarily in shallow waters within seagrass beds. Crustaceans and polychaetes comprise the main food source of juveniles in south Florida, with no difference seasonally or with shrimp size. Stomach contents from juvenile and adult shrimp from Tampa Bay, Florida indicated indiscriminate feeding behaviors; diets consisted of sand, debris, algae, diatoms, seagrass particles, dinoflagellates, foraminiferans, nematodes, polychates, ostracods, copepods, mysids, isopods, amphipods, caridean shrimp, caridean eggs, mollusks, and fish scales. Most feeding occurs at night, though some takes place during daytime under turbid conditions. 96 V E 2. FISHERIES STATISTICS Catch data for the five selected species were obtained from the annual summaries of Florida Landings (Florida Department of Natural Resources, 1950-1978). National Marine Fisheries Service (Southeast Center, Miami) provided information for 1979-1981 from their computer data base. All data include only commercial catch information. Florida Landings lists commer- cial catch by county of landing (processing); study sites are, therefore, defined by the counties surrounding them: Charlotte Harbor =Charlotte and Lee Counties * Lake Worth = Palm Beach County Catch data are graphically depicted in Figure 6 through Figure 14 for Charlotte Harbor and Figure 15 through Figure 22 for Lake Worth. Each figure with "LBS CATCH" on the y-axis shows a straight horizontal line drawn through it; this line represents the 31-year average for that species for that study site. Note, too, that the y-axis scale differs for each figure. Since data for bait shrimp catch in Lake 'Worth are non-existent, Lake Worth has no figure for bait shrimp. There are five major problems associated with commercial catch data. One of the most significant difficulties concerns the location where the catch was made as opposed to the location where it was landed. Lake Worth exemplifies this problem. The use of commercial nets except cast nets in Lake Worth was banned in 1931 (Special Acts, 1931, Chapter 8796) and banned in 1955 from any inlets and in waters surrounding the inlets of Palm Beach County (Special Acts, 1955, Chapter 31137). However, Palm Beach County 97 continuously contributes catch data, albeit low amounts, for estuary- dwelling species to the landings' data base. Illegal commercial netting supposedly occurs at night in Lake Worth; this may account for some of the reported landings, since landing the catch in Palm Beach County is not illegal. Theoretically, however, unless caught legally by hook or cast net or illegally by commercial nets, landed catch in Palm Beach was harvested outside the county. This problem of where the harvest was made is typical throughout Florida's landing statistics.I The second significant problem, most critical for this study, is the absence of effort data. Catch per unit of effort would best reveal a riseI or fall in catch rate for specific sites and species. For example, Figure 8, depicting the spotted seatrout catch of Charlotte Harbor, indicates a general upward slope in landed poundage. Thi s increase may be due to the presence of more seatrout or because of a rise in the number of fishermen. Without effort data, increases and decreases in landed amounts remain un- assessable. A third consideration is that landings data exclude recreationalI fisheries which, for certain species, exceed commercial efforts. Red drum. and spotted seatrout, for example, are caught extensively by recreational fishermen. This concern is compounded by the fact that effort in recreational fishing has significantly increased in conjunction with the rise in Florida's population and tourist industry.I Fourth, si nce landings data are obtained from reports made by the commercial dealers themselves, values are only as accurate as the dealers' record; values are perhaps much higher. In addition, some commercial catch is not reported at all (e.g. live catch of blue crabs sold to restaurants. 98I Finally, landings data do not account for open and closed seasons or local laws. For example, bait shrimp has the potential to serve as an excellent indicator species of-estuarine health, since juvenile bait shrimp grow and are captured within an estuary. However, in 1976, Charlotte County, for example, banned the use of more than 1 trawl net at a time and the trawl net must be under 25' in length (Special Acts, 1976 Chapter 76- 343 as amended by Chapter 77-525). In addition, Lee County banned the practice of sweeping, dragging or hauling any nets except hand cast nets or bait nets; bait nets must not exceed 100' in length, a depth greater than 6', nor a mesh size greater than 1 3/8" (Special Acts 1947, Chapter 23951, as amended by Chapters 63-1560, 69-1236 and 69-1237). These laws must certainly affect the distribution of landing statistics. Another example concerns the local laws of Palm Beach County as described in the second paragraph of this section - commercial netting, except cast netting, is banned altogether in Lake Worth. Existing problems in fisheries statistics can be resolved through establishing a State program. A memorandum of understanding with National Marine Fisheries (NMFS) has been signed by DNR to access aggregate commercial landings. A cooperataive agreement between NMFS and DNR is under consideration that will allow individual data access and eventually the acquisition of the commercial statistics program. Additionally, DNR has formulated a State marine fisheries statistics program that includes both commercial and recreational fisheries statistics. The program was designed to collect effort, area of catch, species composition and weight, gear type used, and biological data. The acquisition of such data augments historical data and will provide a more comprehensive data base necessary 99 for future management strategies and decisions. Until an improved fish- eries statistics program is established, the use of present Landings' data for comparing between site catch values and even trends over time may prove erroneous. However, because no other data exists, Landing's values remain as the only available information. 100 700 500 i 400 300 200 900 IO 0 - 950 7955 960 965 1970 975 90 't40- IY < YEAR Figure 6. Annual summaries of Florida Landings for red drum landed in the Charlotte Harbor area. Horizontal line indicates the 31 year average. IO0 - '90 - o 80 - 70- 0 195 60 1 10 'J 30 - IL. 20.+. - + - 1950 1955 1960 1965 1970 1975 1980 Figure 7. Annual summaries of Florida Landings for red drum landed in the Charlotte Harbor area over the amount landed for the west coast of Florida. 101 1500 -- 1400 - 1300 -- 1200 - 1100 - o 900-- 800 o 700 - 600 - J 500 300 - 200 - 100 : : ; : : * : : : : : : : : : - I I I , I , , , 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 8. Annual summaries of Florida Landings for spotted seatrout landed in the Charlotte Harbor area. Horizontal line indicates the 31 year average. 100 - 90 - o 80 - - 70 - U60 o 40 -- U- 30 0 20 -- 10 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 9. Annual summaries of Florida Landings for spotted seatrout landed in the Charlotte Harbor area over the amount landed for the west coast of Florida. 102 12000 - I 1000 - 10000 9000- 8000- 7000 -XCZ) < 6000 5000 4000 3000 -- 2 000 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 10. Annual summaries of Florida Landings for black mullet landed in the Charlotte Harbor area. Horizontal line indicates the 31 year average. 100 - 90- 80 -- so 0 70 7 - o 60 - 40 o 50 -- 30 LL F'- o 0 -- 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 11. Annual summaries of Florida Landings for black mullet landed in the Charlotte Harbor area over the amount landed for the west coast of Florida. 103 3000 ' 2500 -- 00 1500 landed in the Charlotte Harbor area. Horizontal line indicates the 30 year average. U 100 90 50 - 1950 955 1960 YEA 70 1975 960 Figure 12. Annual summaries of Florida Landings for blue crab landed in the Charlotte Harbor area. Horizontal line indicates the 30 year average. 600 -- 90 60-- U-U p- 70 -- I.- (2: ,. 50 -- 4,0 ---. o 30 - - IA- ,o ,t / I I I 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 13. Annual summaries of Florida Landings for blue crab landed in the Charlotte Harbor area over the amount landed for the west coast of Florida. 104 4000 - 3000 " 2000- o i 1000- 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 14. Annual summaries of Florida Landings for bait shrimp landed in the Charlotte Harbor area. Horizontal line indicates the 30 year average. 105 25146 20420 17098 6000 5000 4000 2000 I000 - ! 1950 1955 1960 1965 19 70 1975 1980 Note change in scale. YEAR Figure 15. Annual summaries of Florida Landings for red drum landed in the Lake Worth area. Horizontal line indicates the 31 year average. 100 - 90 - u 80 - U 70- 0 60 O 60 -, in . 50 - 0 40 -L 30 - 20 -- 950- 955 90 41 0 *965 197 0 1975 1980 I 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 16. Annual summaries of Florida Landings for red drum landed in the Lake Worth area over the amount landed for the east coast of Florida. 106 218587 -- 101465 -- o 50000 -- 30000 20000 10000 20000 -- 1 0000 - 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 17. Annual summaries of Florida Landings for spotted seatrout landed in the Lake Worth area. Horizontal line indicates the 31 year average. 100 -- 90-- 80-- U 70 - U) 60-- < 50-- F- 40 30 20 -- 4 0 --, - - 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 18. Annual summaries of Florida Landings for spotted seatrout landed in the Lake Worth area over the amount landed for the east coast of Florida. 107 900 -- 700 600-- 300 I- - ' 400 -- I 200 - 100 -- 1950 1955 1960 1965. 1970 1975 !980 YEAR Figure 19. Annual summaries of Florida Landings for black mullet landed in the Lake Worth area. Horizontal line indicates the 31 year average. 100 1 90 ' 80 1 70 60 - U) <I 50-- ° 40 - 30 -- 950 955 960 o965 970 5 98-- 1950 1955 1960 1965 1970 19 5 1980 YEAR Figure 20. Annual summaries of Florida Landings for black mullet landed in the Lake Worth area over the amount landed for the east coast of Florida. 108 208900 -- 6000 -- 5000 -- : 4000-- WOO u -J3000 -- _.I 2000 -' 1000 -' 1950 1955 1960 1965 1 970 1975 1980 Note change in scale YEAR Figure 21. Annual summaries of Florida Landings for blue crab landed in the Lake Worth area. Horizontal line indicates the 30 year average. 100 -- 90 80 - 70 C-, 70 -- p- 0 60 -- In hi 50-- w I 0 c 40- 0j 30-- - LL LL ° 20 -- O' 10 - 1950 1955 1960 1965 1970 1975 1980 YEAR Figure 22. Annual summaries of Florida Landings for blue crab landed in the Lake Worth area over the amount landed for the east coast of Florida. 109 110 I 110 Land Use and Vegetation Maps of Charlotte Harbor and Lake Worth: Historical and Recent VI. LAND USE AND VEGETATION MAPS OF CHARLOTTE HARBOR AND LAKE WORTH: HISTORICAL AND RECENT A primary objective of this project was to develop a digital data base of coastal/estuarine habitat components and changes from 1940-50 to the present in a quantitative and geographically specific manner. VI A. BACKGROUND The Florida Department of Transportation (DOT) Topographic Bureau was sub-contracted to provide the interpretation and mapping of historical and current land use, vegetation, and drainage patterns of the Charlotte Harbor and Lake Worth study sites. For the current interpretation of Charlotte Harbor, controlled aerial photographs (flight altitude 12,000 ft, 2658 mn) were acquired in April, 1982 at a scale of 1:24,000 (I in = 2,000 ft; lcm= 0.24 kin) utilizing a specially outfitted Rockwell Aerocommander. Positive false color infrared transparencies were produced for standard photo- interpretation utilizing stereoscopic vision equipment. Current interpre- tation for Lake Worth involved color aerials flown in 1975. Historical * interpretation involved using black and white aerial photographs taken in 1940 for Lake Worth and 1946 and 1951 for Charlotte Harbor. Interpre- tation and subsequent classification of surface features followed the scheme of Kuyper et al. (1981). Land use, vegetation, and drainage categories were then digitized into the DOT computer graphics system. Digitized geographic data were placed in a point-vector data format in this proprietary system (Friedly and Unger 1981). Output mapping products include ballpoint pen plots on drawing paper and ink plats on mylar overlays for USGS 7.5 minute quadrangles (quads) (1:24,000). Because the maps are digitized, adjacent 7.5 minute quads may be merged to produce smaller scale maps typically at 1:48,000 scale (1"=4,000', 1.0 cm=O.48km). Other products that will be available to users are maps depicting only selected land use or vegetation categories, such as seagrass and mangroves, without other features and graphics displayed. A combination of merging maps to any scale, and the selection of one class to be displayed would result, for example, in a seagrass or mangrove map of Charlotte Harbor. VI B. PROBLEMS AND RECOMMENDATIONS DOT encountered several major difficulties in the interpretation and digitization of the aerial photographs. These problems resulted in a delay in final map production. The principal problem with interpretation of aerial photographs dealt with seagrass delineations. The historical black and white photographs presented an inherent lower quality for identifying seagrasses. In addi- tion, the historical aerials were interpreted before the 1982 photographs. Because historical interpretations could not be ground truthed, a problem in the interpretation of seagrasses was not noticed until the 1982 photointerpretations were completed and comparative acreages computed. Several historical photographs were reexamined and it became apparent that general misinterpretations had occurred because of the unfamiliarity of the photointerpreter with the photographic signatures of seagrasses. The 112 recent color infrared aerials presented no such problem as the quality was exceptional for seagrass delineation. As a result of this finding, a time consuming reanalysis and digitization of the historical seagrasses was necessary. A similar problem occurred in the analysis of mangroves versus tropi- cal hammocks. The interpreters classified much of the exceptionally large mangrove fringe as tropical hammock. This problem was again due to the in- terpreter encountering new land cover signatures. Until the study site was visited, this problem was not realized. Several valuable interpretive methodologies were learned in this process: 1. Interpret the most recent aerials first. These are generally of better quality and provide the photointerpreter with a feel of the study site. This method may bias the historical interpretation, however, the bias is far outweighed by the increase in accuracy. 2. Visit the study site in the early stages of interpretation. This will eliminate obvious classification errors because of unfamiliarity with vegetation cover characteristics. 3. Complete all ground truthing effort prior to digitization. Since most photointerpreters are unfamiliar with interpreting sea- grasses, some general comments on seagrass interpretation and quantifi- cation follow: 1. Color infrared photography provides excellent seagrass mapping media in addition to the best delineation of all other emerged habitats. 2. Low tide with clear waters (generally late October through early June) provide the best imagery. 113 3. The relationship between the time of year the aerials were flown to the seasonal densities of seagrasses is under investigation (Section VIII 0). It may have some impact on total acreages or perhaps on density descriptions. 4. The 1982 aerials for Charlotte Harbor were of sufficient quality to develop a density classification system: 901 (sparse underwater vegetation) - This class was characteri zed by approximately >70% exposed sand in the actual meadow regardless of the patchiness observed within the meadow and was considered minimal as habitat cover. This category will most likely be the subject to misinterpretation particularly if seasonal differences exist.I 903 (moderate to dense underwater vegetation) - This class encompassed all contiguous meadows with approximately <30%I uniformally exposed sand. No attempt was made to develop a separate class for moderate densities because of the subjectiveness in interpretation at that level. 904 (Patchy underwater vegetation) - This category was characterized by large unvegetated patches within areas of >1m2 moderate to dense grass. The historical aerials were simply classified as seagrass in oneI category: 645(submerged aquatic vegetation) Only one classification could be interpreted due to the quality of the historical aerials and the absence of a method for ground truthing. 114 The major factor delaying map production was the digitization process. This is a time-consuming job requiring an understanding of both the subject matter and the complex digitization system. The bottleneck in the digiti- zation process occurred for two related reasons. A system software upgrade was implemented with the intent to streamline the digitization process and provide the ability to compute acreages, to merge quads and to do other needed data manipulations. The new software introduced a series of deficiencies that required extensive time for correction. This was com- pounded by a series of hardware failures. These delays created a severe backlog in the digitization process. Considering that this project was only one of many priorities for production, the order by which jobs were completed was weighed by the contractor. VI C. DESCRIPTION OF MAP PRODUCTS The photointerpretation and ditgitizations were based on the U.S. Geological Survey 7.5 minute by 7.5 minute quadrangle (quad) grids depicted in Figure 23 for Charlotte Harbor and Figure 24 for Lake Worth. The quads are individually named both numerically and with a common descriptor. The common descriptor names have been used throuqhout this discussion. Included in the map pockets of this report are several maps to pro- vide examples and references of the map products available and used in the report. They are as follows: Map 1. Drainage Map - Historical (El Jobean) Map 2. Drainage Map - Recent (El Jobean) Map 3. Land Use and Vegetation Map - Historical (Matlacha) W EL JOB A > U N PUiA PLACI + O 16 I PORT ond BOCA M9 QQ*§4A i MOCHA GRANDE \\4b TIV;A ' i iND MiI WULFER + Figure 23. Charlotte Harbor quadrangle names and locations. 116 Iz /it RIVIERA BEACH 6BI e Feron Bt / / Okeec Southen -PALM BEACH Southern Blv - : / ' c Uninterpreted area I ; / -LAKE WORTH _804 Figure 24. Lake Worth quadrangle names and locations. 117 Map 4. Land Use and Vegetation Map - Recent (Matlacha) Map 5. Merged Land Use and Vegetation - Recent (El Jobean, Punta Gorda) Map 6. Merged Land Use and Vegetation - Recent (Placida, Port Boca Grande) Map 7. Merged Land Use and Vegetation - Recent (Punta Gorda SW, Punta Gorda SE, Bokeelia, Matlacha) Map 8. Merged Land Use and Vegetation - Recent (Captiva, Pine Island Center, Wulfert, Sanibel) Map 9. Merged Land Use and Vegetation - Recent (Fort Myers SW, Fort Myers Beach, Estero) Map 10. Land Use and Vegetation Map - Historical (Riviera Beach) Map 11. Land Use and Vegetation Map - Recent (Riviera Beach) The reader/user should note that the historical and recent maps often are not directly comparable. Due to subjectivity in photo interpretation, boundary lines are somewhat incongruous. The maps, therefore, should not be overlayed to determine temporal changes in classification boundaries except when making purely widescale, synoptic observations. Drainage Maps: Historical and recent drainage maps have been produced and are available for the Charlotte Harbor study area in quad or in merged form. Examples of these are Maps 1 and 2, depicting the historical and recent El Jobean quad. These maps provide a visual inventory for non-point source drainage pattern changes that have occurred. Acreage of a drainage system, linear miles of canals, and other drainage schematics potentially can be quantified to assess the non-point source runoff into the estuary. 118 3 Land Use and Vegetation Inventory Maps: Maps 3, 4, 10, and 11 represent the style of Land Use and Vegetation Inventory products produced for the Charlotte Harbor and Lake Worth study areas. Appendix A provides users of 3 these products with the D.O.T. classification description associated with the numerical classification codes. Maps 3 and 4 represent historical and 3 recent interpretations of the Matlacha quad with corresponding acreage values. Maps 10 and 11 provide the same format for the Riviera Beach (Lake Worth) quad. Because of the large number of individual quads (15 recent and 15 historical for Charlotte Harbor and 3 recent and 3 historical for Lake Worth), the entire set of individual interpreted quad maps could not 3 be included in this report. 3 Merged Maps: Maps 4-9 are examples of the map product created by merging adjacent individual quad maps into a scale addressing a larger area. Unfortunately, neither a classification key nor acreage values could be 3 incorporated into the merged maps. The user should refer to Appendix A where numerical classifications can be identified. VI D. CHARLOTTE HARBOR VI Dl1. GENERAL SITE DESCRIPTION 3 The Charlotte Harbor estuarine complex began to form approximately 5,000 years ago when a rise in sea level flooded the mouths of the Myakka 3 and Peace Rivers. Flooding caused sediments to be deposited in a series of deltaic formations which began the in-filling of the present estuary. 119 This process also formed the present barrier island chain which began as a spit of land north of the present Gasparilla Island. River sediments and those of the littoral drift helped create the chain of barrier islands. The resulting five major barrier islands of today (Gasparilla, Cayo Costa, North Captiva, Captiva, and Sanibel) have joined, separated into additional islands, and changed shapes continuously since their development (Herwitz 1977). "Pine Island is believed to be a remnant of the original mainland, that was isolated by a southerly shift in the river flow. Then, as sedi- ments built up at the present location of Little Pine Island and the evolving shape of Sanibel Island restricted water flow, the estuary broke through the Gulf, creating a deep channel near the present Boca Grande Pass. This pass eventually shifted to its present position (Herwitz 1977). Other passes have been opened and closed by storm events and other natural forces that are still acting on the system today. Both Cayo Costa and North Captiva Island have had new cuts through them in the last year." (Department of Natural Resources Bureau of Environmental Land Management 1983). Charlotte Harbor today (Figure 25) is approximately 56km long encompassing at least 71,680 ha of water area. Total shoreline includes 320km excluding the numerous mangrove islands. Shallow water up to M.8M predominates the estuary with natural depressions and channel margins of 1.8 to 3.7m and 3.7m or greater within channels and anchorages (Taylor 1976). Three major rivers flow into Charlotte Harbor. The Mayakka and Peace Rivers, together draining a land area of approximately 76,800ha, flow into 120 km 'Son I Lemon Bay L -o Gaspartifloa Octtle Pine North e Co.iv Coyo Costaj ,'I 1- Matlsteo Pas Figure 25. C halottlee Hror 121 sln the northwest and northeast ends of Charlotte Harbor proper (Taylor 1976). The Caloosahatchee River enters San Carlos Say, south of Charlotte Harbor proper, draining about 307,200ha of land (Taylor 1976). The watershed of all three rivers contain areas of pasture land, citrus groves, and cultivated ground. In addition, the Peace River flowsI through expansive sites of phosphate mines, while the Caloosahatchee receivyes i ndustri al and domestic wastes from the urban areas surroundi ng Fort Myers. During periods of low tide and heavy rainfall, high river flow reduces surface salinity throughout the estuary and also offshore to a distance ofI several kilometers. During high tide and low river flow, a saline wedge of bottom water has been documented to 38 miles upstream in the Caloosahatchee and well upstream in the Myakka and Peace Rivers (Taylor 1976). Aside from nutrient and waste inputs from the three river systems, Charlotte Harbor has suffered very few detrimental impacts and remainsI a relatively natural ecosystem. Beginning in 1977, the State of Florida has purchased most of the land along Charlotte Harbor's shoreline, attempt- ing to maintain a natural mangrove/marsh and, thereby, hopefully, a healthy estuary. In addition, approximately 90% of the harbor itself exists as fo ur aquatic preserves. However, behind some of this natural buffer area3 encroaches vast areas of development. "The Charlotte Harbor area has been the site of enormous subdivisionI development during the past thirty years. The General Development Corpo- ration's Port Charlotte project covers almost 200 square miles inland from Charlotte Harbor, between the Myakka and Peace Rivers. The projected population of Charlotte County, if this and the other subdivisions 122 presently platted in the county were .occupied, would be nearly 1,000,000 people. The 1980 U.S. census population for Charlotte County was 58,460. "Cape Coral, Gulf American Corporation's subdivision north of the Caloosahatchee River and east of Matlacha Pass, covers approximately 96 square miles. An estimated 400,000 people may one day inhabit that j presently incorporated city. The 1980 U.S. census population for Lee County was 205,266. The Ft. Myers-(Cape Coral)-Lee County area has been identified in a number of reports as the fastest growing area in the United States." (Department of Natural Resources Bureau of Environmental Land U Management 1983). Obviously, if wide-scale development continues with no consideration for environmental impact, Charlotte Harbor could change radically. Wang and Raney (1971) described Charlotte Harbor as one of the largest and least contaminated estuarine complexes in all of Florida. Today, Charlotte Harbor retains that image. Its unspoiled habitat houses over 40 endangered and threatened species, including at least 15 active eagle nests. In addition, the harbor's importance as a productive fisheries 5 environment, both in the past and today, is emphasized by Figures 6 through 14. Hopefully, the future will find Charlotte Harbor unchanged. VI IJ 2. GENERAL ACREAGE VALUES 5 Much change has occurred in Charlotte Harbor. Table 6 provides acreage values for ei ght general categories. The ei ght categori es are herein described. The number in parentheses following the category name is the DOT numerical classification code. Appendix A provides a complete descri pti on. 123 Table 6. CHARLOTTE HARBOR ACREAGE VALUES Level 1 Land Use name Urban Agriculture Rangeland Forestland Level 2. Land Use code 100 200 300 400 Year 1945 1982 1945 1982 1945 1982 1945 1982 USGS Quadrangle Name I El Jobean j 90 16657 1872 870 15222 2380 3586 1896 Punta Gorda SW 0 1093 0 0 6459 5128 737 2247 Placida 283 1915 0 249 3688 1464 647 1783 Bokeelia 162 1593 541 444 1477 1181 2655 1864 Port Boca Grande 299 300 0 0 360 458 229 292 Captiva 60 546 87 0 490 203 348 297 Wul fert 10 658 92 40 1045 329 461 875 Sani bel 113 3100 50 0 4456 668 494 1864 Punta Gorda 1270 16412 2336 1534 12319 1810 4106 1937 Punta Gorda SE 9 4249 454 1460 8237 1543 4341 6701 Matlacha 7 13561 1051 783 16155 866 4641 6348I Pine Island Center 1 9120 490 954 10064 1482 4159 3786 Fort Myers Beach 320 2734 855 504 4321 982 908 2221 Fort Myers SW 1006 22556 5091 3288 16086 583 5341 3472 Estero 80 1611 I 218 157 I 5840 1627 I 1930 4908 TOTAL ACRES 3710 96105 I13137 10283 I106219 20704 I 34583 40491 % TOTAL ACRES 1% 16% 2% 2% t7% 3% 6% 7%/ Acreage Change +92395 I -2854 I -85515 +5908 Percent (%) Change + 2490% I - 22 I - 81% + 17% 124 Table 6. CHARLOTTE HARBOR ACREAGE VALUES (Continued) Transportati or Level 1 Land Use name Water Wetlands Barrenland and Utilities Level i Land Use code 500 600 700 800 Year 1945 1982 1945 1982 1945 1982 1945 1982 USGS Quadrangle Name El Jobean 11231 12400 8772 6899 819 1176 178 287 Punta Gorda S.W. 17406 18191 18065 15762 2 148 21 34 Placida 33038 33711 4321 2979 447 319 170 207 Bokeelia 21126 21886 15861 15213 704 405 62 66 Port Boca Grande 41150 41354 421 98 131 77 58 49 Captiva 20426 30159 21008 11292 233 192 45 13 Wulfert 36428 37581 4311 3100 354 143 37 16 Sanibel 28795 29960 8548 6896 195 172 89 75 Punta Gorda 13876 14037 7197 3906 911 1564 531 1357 Punta Gorda S.E. 19347 19850 9456 7772 749 870 14 164 Matlacha 8462 9090 12230 10900 43 942 71 175 Pine Island Center 3598 5214 24122 21843 107 80 146 207 Fort Myers Beach 24786 25572 11371 9755 143 615 28 366 Fort Myers SW 7643 9847 6253 1844 1147 840 126 263 Estero 1487 3853 8290 5644 217 283 225 154 TOTAL ACRES 288799 312705 160226 123903 6202 7826 1801 3433 Acreage Change +23906 -36323 +1624 +1632 Percent (%) Change + 8% - 23% + 26% + 91% 125 Urban and Built Up (100) In 1944-45, the Charlotte Harbor area had 3,710 acres classified as urban. The Punta Gorda and Fort Myers SW quads comprised 61% of this total. The 1982 inventory showed 96,105 acres (a 2490% increase). Fort Myers SW experienced the greatest increase from 1,006 acres to 22,556U acres (23% of the total). Striking urban features in the Charlotte Harbor area are the massive 1960-1970's land boom development tracts where huge areas were cleared and roads were built. Few, if any, have dwellings. Most of the tracts also have canals for land drainage and harbor access. These urban tractsI (classification 192) comprise 47,298 acres (49%) of the total urban area. If these tracts alone are developed, assuming 4 dwellings/acre and 3 persons/dwelling, 567,576 new residents can impact the area with no additional land development. This would cause a significant impact on the Charlotte Harbor area if not properly planned. Agriculture (200)I As evidenced by the acreage values, agriculture is not a major industry in the Charlotte Harbor study area. The historical acreages (13,137 acres) decreased 22% to 10,283 acres at present. The bulk of this acreage is pasture land or citrus crops. Rangeland (300) Rangeland decreased 81% from 106,219 acres to 20,704 acres. The primary acreages in this category were shrub and brushland characterized by scattered pines, palmetto and grasses. These vegetation types often 126 support cattle grazing, however, this is not quantified. It may be assumed that most of the acreage loss (85,515 acres) transferred to urban gains (92,395 acres). The shrub/brushland type areas supported the greatest upland loss in the study area. Forestland (400) Forestland was the only Level I vegetation category to increase in acreage (17%) from 34,583 to 40,491 acres. The majority of forestland acreage is pine flatwoods. A large increase in exotic forestland (i.e. Brazilian pepper, Melaluca, and Australian pine) was observed during this time period. These species compete with natural rangelands, forestlands, and wetland mangroves, accounting for the greatest forest habitat altera- tion. Water (500) This category increased 8% from 288,799 acres to 312,705 acres. Most of the increase may be attributed to canals and vegetated (seagrass) bottom loss. Water comprised the major acreage of the study area. Wetlands (600) Wetlands experienced a 23% decrease in acreage from 162,226 acres to 123,903 acres. The major decrease in this category was seagrass (sub- merged aquatic vegetation). Wetlands (fishery habitats) will be discussed in detail in the following section. 127 Barrenland (700) Barrenland increased 26% from 6,202 acres to 7,826 acres. Some barrenland beach categories are important nesting habitat for terns, skimmers, and other open-ground nesting birds. Transporation (800) A 91% increase from 1,801 acres to 3,433 acres was observed in the study area. This directly reflects the increased development. Special Category (900) This category was used to record the 1982 seagrass densities and will be discussed later in the following section. The historical seagrass inventory was included under Wetlands (600) as code 645. For comparable total wetlands acreages, the 1982 900 category has been added to the 1982 600 category in Table 6. VI D 3. FISHERIES HABITAT COMPONENT ACREAGES Fisheries habitat is considered the geoqraphical, physical, chemical and biological environment in which a species can find food, cover, and re- produce during the various stages of its life cycle. A fisheries habitat component for this report is defined as a specific remotely-sensed and in- terpretable submerged or emerged vegetated or non-vegetated class. Different species at different ages can utilize many different habitat components or can be monospecific as to habitat component. Although different habitat components can be readily defined, a specific fish 128 habitat may only be determined through extensive sampling and research. This report delineates some of the habitat components currently considered important to fisheries production in general, but neglects many of the more transient components such as salinity, temperature, turbidity, etc. Some of these interpretable components include mangroves, seagrass beds, salt marshes, non-vegetated tidal flats (mud flats), and oyster reefs. They provide cover and an indirect food source for over 70% of Florida's recreational and commercial fisheries species. Table 7 provides historical * and recent acreage values for these fisheries habitat components. Mangroves (612) Section 11 C I provides a complete discussion of mangroves and can be reviewed to familiarize the reader with the role of mangroves in estuaries. Species delineation was not attempted within the mangrove category. A 10% increase, 51,524 acres to 56,631 acres, was recorded for the study area. These results are surprising because they do not follow the general trend for wetland loss. State and local regulations protecting the man- grove fringe surrounding Charlotte Harbor were enacted prior to any large- scale destruction. Consequently, very few mangrove areas have been dredged or filled and, in fact, area] coverage has increased by 5,107 acres. In- creases can be explained by natural growth. It appears that much of the mangrove increase could be related to the 8,158 acre loss of non-vegetated tidal flat. Tidal flats provide suitable locations for mangrove seedlings to take hold. If conditions are suitable for growth, new mangrove stands can be propagated. Other factors such as rising sea level, spoil island creation, marsh succession, and restoration can explain increases, but they 129 Table 7. CHARLOTTE HARBOR FISHERIES HABITAT COMPONENT ACREAGES Non-Vegetated Habitat Component Mangrove Tidal Flat Oyster Reef Saltmarsh Seagrass Year 1945 1982 1945 1982 1945 1982 1945 1982 1945 1982 USGS Quadrangle Name E1 Jobean 3433 4321 757 126 0 4 1762 1528 1632 894 Punta Gorda SW 6885 8251 2930 1079 173 28 436 169 6881 5760 Placida 1083 968 267 142 55 56 157 0 2610 1566 Bokeelia 3544 3731 52 31 0 38 29 24 12154 11367 Port Boca Grande 39 32 0 0 0 0 0 0 382 66 Captiva 1033 1121 57 0 0 2 0 7 19907 10162 Wulfert 1392 1426 0 0 0 0 0 0 2749 1674 Sanibel 3067 2943 148 3 8 10 22 0 5296 3940 Punta Gorda 4310 2799 858 95 4 5 550 140 892 772 Punta Gorda SE 2821 3502 1081 255 0 0 424 0 4246 3562 Matlacha 4243 5821 1268 51 0 8 462 0 5780 4940 Pine Island Center 8937 11291 2324 358 515 303 709 197 11462 9684 Fort Myers Beach 6032 5955 775 362 2 3 767 747 3586 2626 Fort Myers SW 1936 1190 378 53 0 0 1384 341 1465 189 Estero 2769 3280 311 168 49 31 549 394 3917 1293 TOTAL 51524 56631 11206 2723 806 488 7251 3547 82959 58495 Acreage Change +5107 -8483 -318 -3704 -24464 Percent (%) Change + 10% 76% - 39% - 51% - 29% 130 are most likely minor in this case. The only quads showing mangrove losses were Placida, Port Boca Grande, Sanibel, Punta Gorda, Ft. Myers Beach, and Ft. Myers SW. These areas lost a total of 2,581 acres of which Punta Gorda comprised 1,511 acres or 59% of the loss. Punta Gorda is one of the oldest developed areas within the * Charlotte Harbor study site and the mangrove loss can be attributed to the early waterfront development that eliminated fringing mangroves. The quads with the greatest increase in mangrove acreage were Punta Gorda SW, Matlacha, and Pine Island Center (+5,298 acres). Pine Island Center had the largest increase at 2,354 acres or 46% of the total increase. These same quads had the largest decrease in non-vegetated tidal flats (5,034 acres or 59% of the decrease). This further substantiates the hypothesis that the conversion of tidal flats was a major portion of the mangrove increase. It is apparent that the protection and preservation of mangroves in the Charlotte Harbor area has helped to stabilize the existence of this habitat component for fisheries utilization. Non-Vegetated Tidal Flat (651) Section II C 4 provides a discussion of tidal flats, i.e., mud flats. A 76% decrease in non-vegetated tidal flats (from 11,206 acres to 2,723 acres) was observed. As discussed in the preceding category, mangrove increases appear to account for loss of tidal flat. Pine Island Center experienced the largest decrease in tidal flats and the largest increase in mangroves. This is a natural loss of tidal flats and the total acreages involved account for only a small fraction of the entire area of fisheries habitat components considered. 131 Oyster Reefs (654) Section II C 5 discusses oyster reefs as a habitat component. The acreages observed for oyster reefs are most likely low for two reasons: (1) The reefs are often too small for photointerpretation, and (2) turbid waters often associated with these areas render the reefs difficult to remotely sense. Larger reef areas have been delineated and show a 38% de- cline from 806 to 488 acres. Punta Gorda SW (Turtle Bay) and Pine Island Center (Matlacha Pass) supported the historical highest acreages with 173 and 515 acres respectively. The recent interpretations indicate that Pine Island Center and Placida have the highest acreages, with 303 and 56 acres respectively. Reasons for loss are purely speculative but could involve overharvesting, circulation changes, and particularly salinity changes. Salt Marshes (642) Section II C 3 contains a detailed discussion on salt marshes. A 51% decrease in salt marsh acreage, from 7,521 to 3,547 acres, was observed in the study area. El Jobean comprised a historical high of 1,762 acres (24% of the total) and also contains the highest recent acreage of 1,528 acres or 43% of the total. Punta Gorda, Punta Gorda SE, Matlacha, and Pine Island Center, and Fort Myers SW incurred the greatest losses (as much as 100%) accounting for 77% of the salt marsh loss. The loss of salt marshes can be directly attributed to the major land developments. Although these developments did not always directly destroy the marshes, they apparently indirectly destroyed them by canalization. The digging and networking of canals (see Drainage Maps 1 and 2 for visual impact) in order to drain the low-lying uplands has apparently served to 132 divert the natural flow of freshwater away from the salt marshes. This would cause saltwater intrusion allowing mangroves to outcompete and succeed the marsh habitat. This succession is well documented in four quads: Punta Gorda, Punta Gorda SE, Matlacha, and Pine Island Center. The direct loss (removal) of salt marshes could be catastrophic to many organisms, but the impact caused by succession from saltmarsh to mangroves is unknown. The major losses occurred where there was relatively low marsh acreage originally. The greatest acreage of salt marshes occurred up the Myakka and Peace Rivers, out of the study area. Succession from marsh to mangrove may be immaterial at least to fisheries species, however, it is certainly significant to the above water community, such as birds, and also to the benthic infauna. Seagrasses (645 historical; 901, 903, 904 recent) A complete discussion on seagrasses is found in Section II B. Also Section II C 2 should be consulted in reference to problems encountered in mapping seagrasses (specifically the historical photointerpretation). The level of accuracy in delineating historical extent of seagrasses cannot be assessed by groundtruthing. The fact that they are submerged introduces an optical variation not found in emergent vegetation and can affect the interpretation. The 1982 photointerpretations, however, were of exceptional quality and extensively groundtruthed; we are quite confident in their accuracy. A 29% decrease in seagrass, from 82,959 acres to 58,495 acres, was observed between 1944 and 1982. This is substantial and surprising since the Charlotte Harbor estuary is perceived as an area of little detrimental 133 impact. Virtually every quad experienced decreases in seagrass acreages. The largest loss occurred in the Captiva quad with a 9,745 acre loss or 40% of the total Charlotte Harbor seagrass decline. The adjacent Wulfert, Sanibel, and Pine Island Center quads also accrued substantial losses; these four quads comprise Pine Island Sound and account for 57% of the total loss in seagrasses. Several factors that most likely account for the loss of seagrasses in this specific area. When reviewing nautical charts of Pine Island Sound, a subjective analysis of tidal circulation can be made by observing topographic patterns. A shallow bar extending entirely across Pine Island Sound (<5 ft depth) is a prominent feature and was apparently the location of the first channel dredging operation (sometime before 1948) in the area. Deeper tidal channels (8-15 ft) existed on both sides of the bar. It was likely that this bar area represented a tidal node. During an ebb tide, flow occurred to the north above the bar and to the south below the bar. Coastal Engineering Laboratory (1958, c.f. Esteves 1981) determined the tidal node to be just to the north and south of Redfish Pass, substanti- ating the implication that the shallow bar historically delineated the tidal node. In the early 1960's, several major alterations to the Pine Island Sound area occurred that appear to have dramatically affected the ecosystem. (1) The Intracoastal Waterway was dredged through Pine Island Sound and up the Caloosahatchee River, (2) The Sanibel Causeway was con- structed across San Carlo Bay. Even before 1960, the Caloosahatchee River was channelized to Lake Okeechobee and lock systems were installed. Prior to these alterations, Pine Island Sound was under oceanic in- 134 fluence, with sponges, some corals, Thalassia and other higher salinity species growing within the Sound (Art Marshal, personal communication). Esteves et a]. (1981) presented excerpts from a U.S.F.W.S. report to the U.S. Army Corp. of Engineers on the construction of the Sanibel Causeway: The U.S. Fish and Wildlife Service has reviewed the application of the Board of Lee County Commissioners, Fort Myers, Florida, for a Department of the Army permit (Bridges 1057) to construct a causeway with three bridges across San Carlos Bay so as to connect Sanibel Island with the mainland at Punta Rassa in Lee County, Florida. The project as proposed would adversely affect the fish and wildlife resources of the area in two dif- ferent ways. One of these would be the effect of dredging and filling. The bottom plant and animal communities in the areas to be filled would be per- manently destroyed. The communities in the areas to be dredged would be destroyed at least temporarily and permanently if frequent maintenance dredging were required Such reduction in bottom communities would have the effect of reducing important fish populations to some degree. A second effect of the project, and a much more damag- ing one, would result from reduced salinities in lower Pine Island Sound, San Carlos Bay, Matlacha Pass, and the lower estuary of the Caloosahatchee River. With lowering of the salinity, changes in the biota would result. As a particular example, the scallop beds of lower Pine Island Sound might very well be eliminated, inasmuch as these mollusks reqiuire salinities of better than 20 parts per thousand. In more complex fashion, the abundance of some of the brackish and marine fishes in the area would be reduced. The above report was very prophetic. After causeway construction in 1962, the area went from a major scallop producer in Florida (as great as 180,000 lbs/yr) to no scallop population by 1964. Circulation alterations caused by the causeway diverting flow into Pine Island Sound from the Caloosahatchee River were probably the primary reasons for the scallop * loss. 135 The effects on seagrass communities are as apparent as that on the scallops, perhaps compounded by dredging for the Intercoastal Waterway. The 13,936 acre seagrass loss in the four mid and lower Pine Island SoundI quads primarily occurred in the deeper portions of the water (>3 ft). With the described construction projects the location of the tidal node has most likely been artificially destroyed or dramatically shifted. Thi s may be explained if the causeway is considered a dam impeding the outflow of freshwater from the Caloosahatchee. This would create a high pressure at the low end of the sound inducing a net flow of freshwater up Matlacha Pass and Pine Island Sound. The tannins and particulates associated with theI freshwater would increase turbidity and consequently reduce water clarity.3 Compounded by direct destruction and reintroduction of fine sediments into the environment by dredging, a decrease in seagrasses would be expected and3 has certainly occurred. Although exact explanations cannot account for seagrass losses in other portions of the study area, some analogies may be implied. Primary seagrass loss has been in the deeper portions of the Harbor, at the fring- ing bars, and in lagoonal-type areas. Very little direct destruction has3 occurred. It is likely that overall changes in drainage patterns and introduction of sewage pollutants and storm water runoff has served to3 increase the suspended load in the Harbor. The loss of natural filtration of nutrients also has probably increased the phytoplankton production. AllI of these factors would synergistically act to increase turbidity in the Harbor and eliminate seagrass meadows in the deeper waters. Whether the loss is continuing is unknown and can only be assessed3 through periodic monitoring and mapping. The predominant grass beds are 136 located in the very shallow waters behind protective sandbars. if circulation patterns change and bars are altered, additional losses may be expected. If turbidities increase, the seagrass meadows will exist only in 3 the shallowest waters. The long term alteration of this fisheries habitat component may one 3 day have a pronounced effect on fisheries of the area. With every new canal, lawn, road, storm pipe, sewage treatment facility, septic tank, etc., additional nutrients and particulates are introduced into the system. This can potentially increase turbidity and alter water quality to an extent that further losses may occur. In addition, as the human 3 population increases, boating pressure and propeller damage to the shallower seagrass beds will occur. On-site management of this habitat 3 component, which the Department of Natural Resources Aquatic Preserve Program provides in Charlotte Harbor, is important. However, concurrent upland management must occur also. Unlike for mangroves and other emergent 3 vegetation types, seagrasses are not readily observable and, unfortunately, management considerations typically have not applied to seagrasses. This 3 trend is changing, but further research must be conducted on declining seagrass populations to determine exact causative factors of loss and 3 determine the best possible approaches for management. This should not preclude effective management today. 3 VI D 4. COMPARISON BETWEEN FISHERIES STATISTICS AND HABITAT ALTERATION 3 At the onset of this project it was realized that the available commerci al fi sheri es stati sti cs as landings data were inadequate for a 3 137 confident comparison to habitat alterations and loss (see Section VI 8). At this point, in the total scope of the project, a comparative analysis will not be attempted. Certain subjective comparisons can be made such as5 the total loss of the scallop industry discussed in Section VI D 3, but quantitative analysis is not possible. We have documented the areal extentI and location of many of the fisheries habitat components and have docu- mented their alterations over a 35-40 year period. Florida is attempting to develop a State fisheries statistics program in cooperation with NMFS which will provide the proper data needed for area-specific commercial catch and effort data, as well as recreational data.5 Section V E 2 presents existing fisheries statistics for the Charlotte Harbor area. The general trend for the target species is for increases in landings. But we do not know how much effort (man hours, number of trips,5 length of trips, etc.) was required per pound landed to assess if this reflects an increase, decrease, or stability in the total population. However, the trends are evident and may prove beneficial for comparative purposes.I With this in consideration, a future report (CM-69) will compare habitat component alterations and fisheries statistics of Charlotte Harbor and Tampa Bay. This comparative analysis will provide a basis for manage- ment decisions even though the results may be subjective in their presen- tation. We can logically deduce that loss of fisheries habitat will eventually result in changes in fisheries yield. Loss in habitat components may be a direct or indirect cause and, thus, a direct or in - direct measure of fisheries population changes. Only continued research on the entire life hi stories of the species in different areas will provide the direct or synergistic relationships to the habitats in which they live. 138 VI E. LAKE WORTH U VI E 1. GENERAL SITE DESCRIPTION As sea levels declined following the Ice Age, Lake Worth, then a j saltwater lagoon, became elevated above sea level and became a predomi- nately freshwater system. Extreme high tides and waves, high freshwater, and storms occasionally breached the thin eastern rock and sand ridge (now the island of Palm Beach) that separated Lake Worth from the Atlantic Ocean, forming natural inlets. These inlets were unstable and closed spontaneously within a short period of time, returning the system to freshwater. A sand ridge immediately west of Lake Worth separated the lake from the mainland. This ridge ran continuously from the Hillsborough River north to the Loxahatchee River where it then turned east, connecting to the eastern sand-rock ridge. The ridge was bordered on the north and west by a 3 system of lakes and sawgrass sloughs. By 1845, two islands in Lake Worth existed naturally: Big Munyon Island and Hypoluxo Island. Vast freshwater marshes surrounded the lake and freshwater grassbeds grew within. In the 1860's, the first manmade inlet to the Atlantic Ocean was excavated north of the present site of the North Palm Beach inlet, but it soon closed naturally. In 1877, a relatively stable inlet was cut through a section of the eastern ridge that stood 25 feet above sea level. A rapid 3 conversion took place changing the freshwater system to a saltwater environment. Beach sand swept in through tidal action smothering the 3 bottom vegetation and benthic organisms, replacing them with organic muds. By the late 1800's, mangroves replaced the freshwater marshes. 139 The area's resident population was approximately 1,000 persons in 1894. During the 1890's, resort developers began filling the wetland edges of Lake Worth . At the same time, the East Coast Canal Company finished dredging a navigational canal, now part of the Intracoastal Waterway, that extended from the north end of Lake Worth through the northern sand ridgeI and sawgrass sloughs to the Jupiter Inlet. Water that had previously flowed from portions of the mainland inland to the Jupiter Inlet was now directed south into Lake Worth, thus increasing the organic load of the Ilake. In the early 1900's, the Intracoastal Waterway was completed from the south end of Lake Worth to Biscayne Bay.I By 1915, the Port of Palm Beach created an inlet 4' deep at the north end of Lake Worth. Dredge and fill activities replaced more and more acres of mangroves in the 1920's. By 1925, 4 additional alterations were com- pleted. (1) The North Lake Worth inlet was deepened to 16' and bulkheaded. Peanut Island was created by the dumping of dredge spoil during creation of North Lake Worth Inlet. (2) The South Lake Worth inlet was constructed to help flush Lake Worth, however, tidal action increased sand deposition intoI Lake Worth. (3) The West Palm Beach Canal was completed by the EvergladesI Drainage District (EDO), connecting Lake Okeechobee to the Atlantic Ocean. This canal functioned for drainage and transportation and was provided with two water control structures, one at Lake Okeechobee and the other on the coast at the fresh and salt water interface. (4) Part of the naturalI sawgrass slough system of the mainland was impounded and inflow was diverted into Clear Lake and Lake Mangoni a to serve as a water supply for the cities of West Palm Beach and Palm Beach. Resident population at this time was approximately 30,000. 140 The West Palm Beach Canal and alteration of the mainland drainage pattern greatly affected urbanization. Prior to these changes, settlement occurred primarily on the island of Palm Beach and along the high and dry sand ridge bordering Lake Worth. Now, however, drainage made available much more l and f or development. Urbanization and agriculture quickly spread west, placing additional pressures on surface waters of the area, including Lake Worth. By 1950, resident population of West Palm Beach increased to over 43,000. The entire urban development at that time was discharging 10 million gallons of raw sewage daily directly into Lake Worth or through septic tanks into ground waters. Already, much of Lake Worth shoreline had been dredged, filled, and bulkheaded. The cumulative effect of 5 interior drainage, agricultural and urban runoff, sewage disposal, and shoreline development peaked in the early 1950's. Concurrently the cost of waterfront property skyrocketed. In 1959, Munyon Island was significantly enlarged by deposition of dredge spoil. In 1967 North Palm Beach Inlet was further dredged to 35'. By 1972, almost the entire Lake Worth shoreline 5 was urbanized with half the shoreline bulkheaded. Figure 26 describes Lake Worth. Between 1950 and the present, several steps to improve the lake have been taken. Dredge and fill and bulkhead operations have been prohibited. By mid-1960, 70% of the urban population was served by sewage treatment facilities. A massive cleanup occurred through the 1970's resulting i11 all sewage receiving secondary treatment prior to disposal. 5 Today, Lake Worth receives saltwater input from the intracoastal waterways and from the two inlets directly opening Lake Worth to the 5 141 · .; .,'... . ': · ·'4 Intracooastal waterway Munyon Islands ':: 4 ' C17 Canal * g fPeanut Island il, T -----North Lake Worth Inlet * .: ,.w,.. - ' .. eF3 3 km N ·- - - Loke Worth K. ,i C51 Canal Atlantic Ocean C16 Canal Hypoluxo Island Beercan Island .... ----South Lake Worth Inlet Intracoastal waterway Figure 26. Lake Worth.. 142 Atlantic. Freshwater input arrives from 7 sources with the C-51 canal being the major source of freshwater and a major source of nutrients and pollutants (Table 8). Table 8. SOURCES OF FRESHWATER FLOWING INTO LAKE WORTH SOURCE % OF TOTAL FRESHWATER INPUT C-17 canal 12.1% C-51 canal 49.7% (75% flows north, 25% flows south) C-16 canal 10.7% WPB Sewage Treatment Plant 1.3% Boynton Sewage Treatment Plant 0.3% Surface runoff 4.1% Groundwater discharge 22.3% In summary, Lake Worth naturally evolved from a saltwater lagoon to a fresh-water lake. Man-made changes modified the lake into an estuarine lagoon. Though it is not feasible to return Lake Worth to its original freshwater condition, it is desirable to maintain the lake as a productive estuary. 143 VI E 2. GENERAL ACREAGE VALUES Several inconsistencies exist with the interpretation of the threeI Lake Worth quads that did not occur with any of the Charlotte Harbor quads. The Lake Worth study site did not extend entirely to the western boundaries of the three quads; it stopped approximately 1.5 km east of the western edge (See Figure 24). However, the contractor continued interpretation to the western boundary on the 1975 Riviera Beach quad. Since the extended interpretation also included acreage values, only those categories that are not included within the 1.5 km interpretation extension are accurate forI comparing the historical and recent Riviera Beach quads. These include only marine waters and marine wetlands. However, all categories were compared between historical and recent interpretation of the other two Lake Worth quads. Also the Atlantic Ocean was classified as "Bays and Estuaries" on both the historical and recent Lake Worth quad maps. Another interpretation error is the delineation of reefs for all 1940 quads but not for the 1975 quads. Reviewing the 1975 aerial photographs and ground truthing revealed that these reefs still exist.I Table 9 lists the eight general categories and their associated historical and recent acreage values. Since seagrasses. were classified as a special category (900) for the recent interpretation, these values were added to the recent wetlands' values (600). Historically, seagrasses wereI classified under the wetlands category. The following paragraphs describe the Level I acreage changes. The numbers in parentheses following the category name relate to the interpretation index numbers as found on the maps. 144 Table 9. LAKE WORTH ACREAGE VALUES Level 1 Land Use name Urban Agriculture Rangeland Forestland Level 1 Land Use code 100 200 300 400 Year 1940 1975 T940 IT T-40T75 T940 T975 USGS Quadrangle Name Riviera Beach 5274 15499 1217 1440 15408 2015 3493 4204 Palm Beach 8788 16910 525 427 6599 427 809 1326 Lake Worth 3490 14500 4340 1633 4663 1324 5566 2201 TOTAL ACRES 17552 46909 6082 3500 26670 3766 9868 7731 Acreage Change1 +19132 -2805 -9511 -2848 Percent (%) Change1 + 159% - 58% - 84% - 45% Transportation Level 1 Land Use name Water Wetlands Barrenland and Utilities Level 1 Land Use code 500 600 700 800 Year 1940 1975 1940 1975 1940 1975 1940 1975 USGS Quadrangle Name Riviera Beach 31255 16168 13863 1226 896 1060 732 1001 Palm Beach 13740 15962 5691 212 461 111 658 2676 Lake Worth 15307 16911 4733 373 420 838 211 1147 TOTAL ACRES 60302 49041 24287 1811 1777 2009 1601 4824 Acreage Change1 +3826 -22476 + 68 +2956 Percent (%) Change1 + 13% - 93% + 08% + 341% 1The Riviera Beach quad acreage values are not included in these totals since different size areas were photointerpreted for that quad. 145 Urban (100)1 Urban area increased 159%, from 12,278 acres to 31,410 acres. The Palm Beach quad nearly doubled in urban area while the Lake Worth quad quadrupled. The majority of the urban category is residential housing. Since much of the area immediately surrounding Lake Worth was already urbanized by 1940, much of this increase occurred farther inland. Agriculture (200)1 Agriculture land decreased by 3,805 acres, a 58% decrease. The Lake Worth quad experienced 97% of this loss accounting for 2,707 acres. Most of the lost agricultural land was replaced by urban area and occurred inland from Lake Worth. Rangeland (300)1 Rangeland decreased by 84%, a loss of 9,511 acres. This rangeland was converted into urban area and, like the agriculture class above, occurred inland of Lake Worth. Forestland (400)1 Forestland lost 2,848 acres, a decrease of 45%. This value does not reflect a true loss of natural forestland because it includes acreage increases of exotic species. These increases include 1,514 acres of Brazilian Pepper, 331 acres of Melaleuca, and 215 acres of Australian Pine. 'Does not include acreage data from the Riviera Beach quad. 146 Conversely, natural pine flatwoods lost 3,680 acres, a decline of 76%. In addition, sandpine scrub, one of Florida's most unique natural upland habitats, lost 511 acres, an 85% decline. Water (500)1 Water area increased 13%, a gain of 3,826 acres. Most, if not all, of this increase can be explained by the loss of acreage from the seagrass category. Wetlands (600)1 Wetlands experienced an overall decrease of 22,476 acres, a decline of 93%. Wet prairies and freshwater marsh lost 7,017 acres, a 97% decline. Marine wetlands will be discussed in detail in the followinq section. Barrenland (700)1 Barrenland increased by 8%, a gain of 68 acres. These lands were generally the result of land clearing and other construction activities. Transportation and Utilities (800)1 This category increased 341%, from 867 acres to 3,823 acres. Much of the increase can be explained by the addition of Interstate 95 and expansion of West Palm Beach International Airport. In addition, several other factors, such as bus terminals and sewage treatment plants, have increased the acreage value for this category. 1Does not include acreage data from the Riviera Beach quad. 147 VI E 3. FISHERIES HABITAT COMPONENT ACREAGES Section VI 0 3 defines ,fisheries habitat components. Table 110 provides historical and recent acreage values for fisheries habitat in Lake Worth. Acreage values for the Riviera Beach quad can be included within this sectio Olsi nce the i nterpretati on error does not include marine wetlands. Mangroves (612)I Mangroves lost 1,881 acres, a decrease of 87%. Mangroves appear to be replaced by Australian Pines and urbanization in the form of seawalls andI resi denti al and commerci al housi ng. The remai ni ng 276 acres of mangroves occur in very small scattered areas and are now protected by strict regulations. Non-Vegetated Tidal Flat (651)1 Mudflats apparently did not exist either historically or presently within the Lake Worth study site. Oyster Reefs (654) Oyster reefs did not exist either historically or presently within the Lake Worth study site. Saltmarshes (642)1 Only one site of saltmarsh occurred historically within the study si te, which was located in the Riviera Beach quad. All 130 acres of this marsh was replaced by residential area and a small lake. Some tropical 148 Table 10. LAKE WORTH FISHERIES HABITAT COMPONENT ACREAGES Habitat Component Non-Vegetated Mangrove Tidal Flat Oyster Reef Saltmarsh Seagrass Year 1940 1975 1940 1975 1940 140 975 1940 1975 USGS Quadrangle Name Riviera Beach 1667 112 0 0 0 0 130 0 1995 152 Palm Beach 66 46 0 0 0 0 0 0 1014 0 Lake Worth 424 118 0 0 0 0 130 0 1262 9 TOTAL ACRES 17552 46909 0 0 0 0 130 0 4271 161 Acreage Change - 1881 - 130 -4110 Percent (%) Change - 87% - 100% - 96% 149 hammock also occurred there possibly as a result of natural succession but more likely a result of residential trees planting. Seagrasses (645 historical; 901, 903, 904 recent) Due to the poor quality of photography (for seagrass interpretation) in the Lake Worth study area, it has been determined that a historical comparison is of unacceptable accuracy. Because of the long term turbidity patterns in Lake Worth, even the recent photography was difficult to interpret and much of the seagrass delineation was provided to the contractor through ground truth efforts and personal communication. The only substantial seagrass bed found in Lake Worth was north of Palm Beach Inlet adjacent to John MacArther State Recreation Area. This seagrass bed consisted of primarily Halodule and Thalassia. During the ground truth efforts, the Thalassia was found to be highly reproductive with large accumulations of viable seeds. This is of important consequence for future restoration work in the Lake Worth area. Some recollective communication with early researchers in the Lake Worth area has provided some understanding of seagrass populations. Dr. Gilbert Voss (personal communication) stated that seagrasses within Lake Worth historically existed only near the inlets and were never very abundant. In addition, Dr. Voss stated that no seagrasses ever existed within mid Lake Worth; he described this area as a "big mud hole." Seasonal and short term variations most likely occur, however, it is probable that seagrass populations have remained relatively unchanged over the past 40 years. 150 VI E 4. COMPARISON BETWEEN FISHERIES STATISTICS AND HABITAT ALTERATION Since commercial fisheries statistics were inadequate in general and grossly inaccurate for the Lake Worth Study site (see Section V E 2), and because the acreage values for the seagrass category are questionable, no attempt was made to compare wetland loss to fisheries decline. Observing the commercial catch values in 1951 (Fig. 15 through 22), however, shows that before regulations were enacted that banned all net fishing other than cast nets in Lake Worth, a large commercial fishing industry existed in the area. As discussed in Section V E 2, the catch may not have come from Lake Worth. The data presents only the county in which the catch was landed. Much of the catch may well have come from the Loxahatchee estuary. Unfortunately, no data are available to clarify this discrepancy. Until fisheries statistics are improved to include effort data and knowledge of where the catch was made, no conclusions can be drawn to associ ate habitat alteration to fisheries decline. 5 152 152 Marine Resources Geobased Information System VII. MARINE RESOURCES GEOBASED INFORMATION SYSTEM VII A. DESCRIPTION A Marine Resources Geobased Information System (MRGIS) has been installed at the Florida Department of Natural Resources Bureau of Marine Research (BMR) in St. Petersburg, Florida. The MRGIS is designed for processing, analyzing, and integrating satellite data and other digital data from a grid system with a variety of environmental and socioeconomic data for resource analyses and applications modeling. The MRGIS will be used primarily as a research tool for coastal zone resource management and for integrating coastal zone data bases. The system is a research prototype for the State of Florida and is being used to demonstrate regional and state-wide applications. The MRGIS was developed at the BMR with the following reasoning: 1. BMR has actively pursued research with satellite imagery since the early 1970's and has participated in field experiments with NASA, testing prototype sensors and applications of these sensors. 2. Scientists from BMR represented DNR on the LANDSAT Evaluation Committee and, thus, the integration of the MRGIS as a prototype for a statewide research system was consistent with the intent of the committee. 3. BMR had the capability of assessing hardware and software required to develop the MRGIS and was current with the latest technology in the field by close association with NASA. 4. BMR Scientists had been trained on Earth Resources Laboratory Applications System (ELAS) software and were computer-oriented. 153 This permitted the purchase, installation, and use of the system without additional staffing. 5. Habitat loss is of critical concern to the State of Florida andI the MRGIS provides an exemplary too] to establish a digital data base for coastal habitats. Since the MRGIS was the prototype for a State of Florida research system, extreme caution was required in hardware configuration. With the assistance of NASA Earth Resource Laboratory personnel, specific hardware configurations to meet general budgetary constraints were developed. At that time bid specifications were developed. Si nce the i ntent was toI establish a turnkey system that would use ELAS as the operating software, a major requirement to the vendor was the installation of ELAS on the model they bid. In addition, specific hardware requirements to ensure expand- ability and state of the art technology were included to maintain the potential for future systems development.I The image processor and display was purchased as a sole source item because the software driver and interface to the mainframe were available and ELAS was designed with I/O commands specific to the processor. Soft- ware and hardware development would have been necessary if any other approach had been taken. The mainframe hardware (Fig. 27) consists of a 512 kilobyte core memory and peripheral storage and retrieval devices. The image processingI system (Fig. 28) is interfaced to the mainframe and is capable of image and graphics display. The system configuration was designed by NASA Earth Resources Laboratory (ERL) to satisfy requirements of the Earth Resources Laboratory Applications Software (ELAS). 154 32/27 3510 3025 3025 CENTRAL FLOATING MEMORY MEMORY PROCESSING APOINT MODULE MODULE UNIT ACCELERATOR SELBUS 9203 8000 9131 9020- CRT INPUT/OUTPUT HIGH LSTP CR T PROCESSOR SPEED DATA I INTERFACE I SEE FIG. I MPBUS I 8030 8oo I 9 CONTROLLER IjCONTROLLER 8 LINE TA LPFDC I IOPDC ASYNC TAPE DRIV 8580 o IPS I I DP 800/1600 t 8310 GRS232 '8310 300 LPM I PRINTER I DISK DRIVE MODEL W/8317 300 MB 9 2 03 9568 IREMOVABL I CRT L _ I MODEL I L 8144 Figure 27. MRGIS mainframe and peripheral hardware. 155 GOULD SELBUS 9131 HIGH SPEED DATA INTERFACE HSD COMTAL CONT- I 3 INTERFACE IMAGE RESOURCES VIDEOPRINT 3M COMTAL CT-8H MODEL 5300 8000-30SER 512 x 512 4 x 5 INSTA PRINT IMAGE PROCESSOR HIGH RESOLUTION OR COLOR MONITOR 35 MM EXPOSURE 3 REFRESH MEMORY 19" DIAGONAL HARDCOPY OUTPUT |TRACK BALL LCONTROL LER Figure 28. MRGIS graphics hardware. 156 ---- C3 -- --- --- - The software (Fig. 29) installed on the MRGIS consists of three levels: I 1. System Software - machine-specific operating software for primary level communication. 2. FORTRAN, Symbolic Debugger, Scientific Run Time Library - Proqram- ing language and programing aids. 3. Application Software - ELAS, Coastal Zone Color Scanner, and any other level two programs. The principal applications software installed on the system is ELAS. This software was sponsored and developed by the Earth Resources Labora- tory (ERL) of the National Space Technology Laboratories (NSTL) of the National Aeronautics and Space Administration (NASA). ELAS software development began in the early 1970's. The initial work was directed towards supervised classification of LANDSAT and aircraft data. Develop- ment progressed with the addition of the capability to geographically reference the data to the Universal Transverse Mercator (UTM) grid. Also, the data processing approach was changed from batch to interactive process- ing. A data base program was added to allow the storage of numerous para- meters, (i.e.) LANDSAT classifications, soil types, rainfall, elevation, per-cent slope, slope length, aspect, ownership, oceanographic variables, etc., by a selectable cell size. This permits manipulation of these parameters through selectable application algorithms to produce resource management information. The ELAS software is divided into two components, the operatino sub- system and the applications modules. The operating subsystem is FORTRAN- based and uses some machine-dependent routines for INPUT/OUTPUT and control functions. 157 GOULD SYSTEMS MPX 32 OPERATING SYSTEMS PROGRAMMING SUPPORT SOFTWARE FORTRAN 77+ SYMBOLIC DEBUGGER SCTIENTIFIC RUNTIME LIBRARY FISHERIES STATISTICS SOFTWARE DEVELOPMENT EARTH RESOURCES LABORATORY APPLICATIONS SOFTWARE COASTAL ZONE COLOR SCANNER IMAGERY ANALYSIS SOFTWARE Figure 29. HRGIS software configuration. 158 The applications modules are written in FORTRAN, utilizing the operat- ing subsystem for the machine dependent functions. The application modules exist generally as FORTRAN overlays or subroutines. Depending an the application, needed modules are called or released by the operating sub- system. Approximately 133 processing modules now exist within the ELAS package. A complete description of ELAS is documented by Junkin et al. (1980). The usefulness of information derived from LANDSAT multispectral scanner data has been recognized by state agencies primarily as a result of the Florida LANDSAT Demonstration Project (Brannan et al. 1981). That pro- ject was developed in conjunction with the NASA Earth Resources Laboratory Regional Applications Program and the Florida LANOSAT Evaluation Committee. VII B. LANDSAT IMAGERY ANALYSIS OF CHARLOTTE HARBOR General LANDSAT vegetation cover classifications have been developed for the Charlotte Harbor area. Development of these classifications represents the initial phase of the MRGIS operational development. These initial classifications are at Level I/Level II resolutions and stati sti - cal accuracies of the classifications have not yet been developed. As we gain better familiarity with ELAS, it is certain that classifications will be greatly enhanced and specific analysis techniques relative to the infor- mation desired will be refined. A stepwise progression to provide a general understanding of the process in developing these classifications, including observations and comments for this report, follows: 159 1. LANDSAT: When utilizing LANDSAT data it is important to under- stand physical processes of data acquisition. The LANDSAT program was initiated in 1972 and data are available from 1972 to the present. This report utilizes data collected by the multispectral scanner (MSS) located on board all four LANDSAT satellites launched since 1972. The satellites were launched into a polar sun-synchronous orbit at an altitude of 920km and pass over a given area every 18 days. The MSS has a ground resolution of one pixel (equal to 80m2 or 1.1 acres) and measures average reflectence of the pixel in four wavelength bands (0.5-0.6, 0.6-0.7, 0.7-0.8 and 0.8-1.1 nanometers). Each LANDSAT scene (fixed image) covers an area approximately 183 x 183km (115 x 115 statute miles). These data are relayed to earth stations and radiometric and geometric corrections are made by computer. The raw data, in several forms, are then available for purchase (currently through NOAA) as computer compatible tapes. LANDSAT 4 contains the MSS and a new Thematic Mapper (TM) sensor with coverage every 16 days and a lower orbit. The TM measures seven wavelength bands and has a ground resolution of 1/4 acre. These data are not yet available. One TM scene has been installed on the MRGIS and initial review suggests a tremendous increase in the ability to resolve fisheries habitat. TM data will be compared to MSS and aerial photography in detail in subsequent reports. 2. Acquiring data: Data are ordered on computer compatible tapes from data centers located in several cities across the U.S. Prior to ordering a scene it is important to know the percent cloud cover over the area of interest. Usually, the best imagery has less than 20% cloud cover. In addition, the type of information to be extracted from the data should 160 be considered before or dering data. If, for example, the prime interest is seagrasses, late fall to early spring (when the water is clearer) at low tides provides the best data. 'If the interest is in deciduous forests then a multitemporal analysis from summer (when leaves are present) and winter (when leaves are absent) would provide the best data sources. It is advised that the scene be personally scrutenized through microfiche or hardcopy prior to purchase. 3. Processing: Raw computer compatible tape (CCT) imagery consists of four data channels for each scene. The data consist of a numerical value between 0 and 255 representing an average relative reflectance value for each of the four spectral bands of each pixel. The raw data, therefore, can potentially contain four of (256)4 possible values for each pi xel. ELAS contai ns numerous stati sti cal packages which can be used to transform the raw data into a managable data set, a necessary step in developing a vegetative and land use classification. By usi ng one or two of the statistical classifiers, less than 62 classes will be developed based upon the statistical boundaries set by the investigator. At this point, the investigator evaluates the classes broken out by the processing techniques and assigns them a land cover type such as mangroves, pines or hardwoods. During this interactive process, some classes may be lumped and others may be further statistically evaluated. 4. Charlotte Harbor: The Charlotte Harbor study area required two scenes of data, Upper and Lower Charlotte Harbor (Fig. 30 and 31). Upper Charlotte Harbor (Fig. 30) was developed from an August 22, 1980 scene. Originally, 54 classes were developed for this image, however, they have been combined to present nine final classes and are defined as follows: 3 161 Impacted/Cleared refers primarily to areas undergoing development. The land has been cleared and has very little vegetation. The primary component of the soil is sand and the reflectence values are high. Some naturally occurring saltbarrens may be found within this category. Impacted/Urban are areas which are composed primarily of buildings such as downtown areas or dense suburban areas, or any recent housing developments with little vegetation. Impacted/Vegetated are areas comprised primarily of cleared land which has revegetated and exists in various stages of succession. The majority of lands in this class were cleared, platted and installed with roads during the 1960's - 1970's land boom period. This class also includes crop and pasture land and housing developments that are typically older and lushly vegetated. The Palmetto Scrub/Pine Scrub/Tropicals refers to the predominant natural vegetation types in a particular scene. Palmetto and pine scrub contain from 0-30% pine with palmetto the predominant vegeta- tion. These areas are typically on high ground that is rarely flooded. Tropical vegetation (generally non-native introduced species) were lumped into this class and consists of very small areas. The type of tropicals included are primarily woody tree species such as eucalyptus and members of the fig family. Palmetto/Marsh/Mangrove classes were combined to present a subarborial vegetation which is either seasonally or tidally wet. This refers to vegetation types less than 3m in height. The palmetto areas in this class have <30% pine and are seasonally wet with a high water table. 162 0;>00-40 --' ---- a,- V:4f' 4- f f - Sf--- 00, 000 00 ." ,g}6 ...... a s*, lO T PM p *54z" Figure 30 GeneralLANDSAT cassificaion of Uper Charltte HarbI SE _Ii i w l Figure 30. General LANDSAT classification of Upper Charlotte Harbor. - - -- -- - - -- - - - ---- I - - 0 0 Figure 31. General LArND$AT classification of Lower Charlotte Ha'bor. r:" '""- "| - -. Figure l1 *eea LADA clsiiaino oe hrot abr The marsh areas consist of Juncus, Spartina and other fresh and brackish water species. The mangroves included in this class are generally stunted and sparse. Batis, Salicornia and other salt- tolerant species coinhabit these areas. The Mangrove/Pine/Hardwood class is also characterized by seasonal or tidal inundation. This vegetation class typically has a dense canopy and is >3 m in height. The mangroves are typically so dense that little water is reflected through the canopy. The pine areas have a 30-60% canopy cover and usually have an understory of palmetto. These pine flatwoods are seasonally wet although the pines individu- ally inhabit the higher ground. The deciduous hardwoods inhabit pri- marily bottom lands associated with the rivers and their tributaries that comprise the Charlotte Harbor watershed. These hardwoods are generally composed of cypress, sweetgum, oaks, bays, and others. The Shallow/Turbid Water class represents those waters usually <3m in depth and either have a bottom reflectance or are turbid. Deep Water refers to those waters >3m and are less influenced by bottom reflectance. Figure 32, entitled Punta Gorda SW, is a section of the Upper Charlotte Harbor satellite image. This imaqe has been corrected from spacecraft coordinates to Universal Transverse Meridian (UTM) grid coordinates. The conversion results in a north-south orientation of the image, comparable to available aerial photography and map products. Figure 30 covers the same area as a quad map (7.5 x 7.5 minutes) and is, therefore, compatible to the photointerpretation of the Punta Gorda SW quad. A seperate set of statistics was developed for this image with 50 167 original land cover classes. Again, many of the classes were combined, but in this case the final classification is more specific in vegetation type. In addition to land cover classes, several Indian mounds and bald eagle nesting sites have been integrated into this image. The first two classes are identical to the Upper Charlotte Harbor classification description. There are no urban areas in this image. Palmetto Scrub refers to those areas with <30% pine and a palmetto understory. These areas range from 90% palmetto to a mixture of palmetto, xeric grasses, wax myrtle, and other subarboreal vegetation. Pine scrub consists of >30% pine and generally has a palmetto under- story. Fresh/Brackish Marsh consists primarily of Juncus, Spartina and Typha in areas of low salinity. Also included in this class are large sites of Batis and Salicornia. These areas were typically found in the center of mangrove islands or in supratidal areas with dead or stunted and sparse mangroves. Mangrove Predominant contains red, black and white mangroves. Quite often man-impacted mangroves were interspersed with Brazilian pepper. Vegetated Saltern or Tidal Flats primarily refers to the fringe areas separating mangroves from palmetto and pine scrub habitats. Vegeta- tion on these flats is patchy in nature and consists of grasses, palmetto, mangroves and succulents tolerant to extreme wet and dry periods. The barren areas are both organic and inorganic in nature. Lower Charlotte Harbor (Fig. 31) represents a December 8, 1980 scene. Originally, 43 classes were developed for the image but have been combined to a final 10 classes. 168 Figure 32. Detailed LANDSAT classification of the Punta Gorea SW quad. Figure 32. Detailed LANDSAT classification of the Punta Gorta SW quad. The classification scheme for this image is comparable to the Upper Charlotte Harbor image with one exception. Since this was a winter scene, the water was clear and submerged seagrasses were statistically separable The two seagrass classes represent moderate or dense meadows versus sparse or patchy meadows. The above classifications (Fig. 30-32) are initial work products and represent a stage in the development of the MRGIS. The Charlotte Harbor area is being used as a training exercise to demonstrate the potential of the MRGIS. Aerial photographs and associated digitized photointerpreta- tions are being used to develop an accuracy assessment and comparison of the aerials and LANDSAT images. The Punta Gorda SW image (Fig. 32) has been analyzed and ground truthed for comparison to the Punta Gorda SW digitized quad map (Map 7). Although the statistics for the image may not yet be the best for all the classes, a comparison of mangrove acreages has been made. The image contains 8,486 acres of mangroves while the photo- interpreted quad contains 8,251 acres. This demonstrates a very close agreement but can be misleading. For example, while the geographical locations of the mangroves are very similar, some areas on the image that depict mangrove are not found on the photointerpreted quad and vice-versa. These differences are being addressed in a detailed, and eventually a statistical, manner which will allow us to proceed to other areas of the state with a developed level of accuracy. VII C. ADDITIONAL USES OF THE MRGIS The MRGIS is now being utilized in several other areas of research. 1. Coastal Zone Color Scanner (CZCS): In conjunction with the Gulf 171 States Marine Fisheries Commission SEAMAP program, we have installed additional software into ELAS capable of analyzing imagery from the CZCS on board the Nimbus 7 satellite.' The software was provided by the National Marine Fisheries Service and is used to measure chlorophyll concentrations and turbidity in coastal and ocean waters. CZCS data will be analyzed in conjunction with ichthyoplankton surveys being made on the west Florida Shelf. This will aid in determining larval fish distribution and recruit- ment. We will be developing a CZCS analysis program to research migration patterns of pelagic/coastal species such as mackerel. We will be cooperat- ing with University of Miami personnel in using CZCS imagery in conjunction with swordfish research. The BMR has been using CZCS imagery in Red Tide research and this will continue. With the CZCS capability now operating on the MRGIS, numerous other requests and discussion from state, university and federal organiza- tions have been enacted and it is assured the CZCS will greatly enhance our understanding of the coastal environment. 2. LANDSAT: The DNR Bureau of Aquatic Plants is currently working with the MRGIS to assess its use in monitoring the spread of aquatic weeds in Florida. We are working with the DNR Bureau of Environmental Land Management to inventory Florida's aquatic preserves. We will also be working with Rookery Bay National Estuarine Sanctuary to provide an inventory of the sanctuary and the surrounding areas. LANDSAT can also be applied to red tide research. The dinoflagellate Ptychodiscus brevis is responsible for massive fish kills and neurotoxic shellfish poisoning. Figure 30 is the first LANDSAT image to document a 172 Florida west coast toxic dinoflagellate bloom and possibly the first LANDSAT image, world wide, to ever document a toxic dinoflagellate bloom. This type of imagery can provide the scientific investigator and resource manager with information pertinent to the development and dynamics of a bloom simply unattainable by conventional shipboard measurements. As visiting scientists and resource managers are introduced to the technology of the MRGIS, immediate applications are conceived. This is a relatively new technology that has not been adequately transferred to scientists and/or resource managers. The MRGIS is bridging the gap. VIID. GROUND TRUTHING Ground truthing started in August 1982 and will continue for this phase of the project through early 1984. Initial ground truthing served two major purposes and currently serves two additional intentions. Initial ground truthing efforts: 1. DNR personnel assisted DOT in verifying their photointerpretation of Charlotte Harbor aerial photography. This involved visiting specific sites in question by the interpretors and identifying the vegetation. Representative areas of numerous vegetation types were visited, including coastal habitats such as seagrasses and mangroves. 2. DNR personnel, assisted by a DER staff member and the Lee County Marine Extension Agent, ground truthed several seagrass areas to verify DOT's system of classifying seagrasses. The original classification delineated four categories: sparse, moderate, 173 dense, and patchy. Ten transects were assessed for spatial distribution of seagrasses. These initial observations suggested that the classification system be altered to three designates: sparse, moderate-dense, and patchy. Current ground truthing efforts: 1. When using remotely-sensed imagery it is important to understand seasonal density changes in vegetation resulting from leaf drop and leaf growth to allow multitemporal analysis. Five of ten original preliminary transect sites were chosen for quarterly investigations of seagrass density over one year. Each sampling period and station requires measurements of several parameters. Currently, measurements are taken only for the dominant seagrass, Thalassia testudinum. (1) Seagrass density is determined by counting the number of short shoots per 1/16 meter quadrats. An average value is calculated and extrapolated resulting with an average value per square meter. (2) Random seagrass short shoots are measured to determine number of blades and blade length and width. (3) Water temperature and salinity are recorded. (4) If drift algae is present, random samples using the 1/16m quadrat are taken. The algae is dried and an average dry weight per square meter is determined. A similar study will proceed for the Tampa Bay study (CM 69). Data from Charlotte Harbor and Tampa Bay will be analyzed to determine a method to seasonally assess seagrasses using remote sensing techniques. 2. Statistical analyses of Landsat images sometimes delineate certain 174 areas as being different from sites that are actually of the same classification. Conversely, analyses also classify very different areas as being the same. Ground truthing may clarify these questionable sites. These preliminary observations will greatly facilitate future analyses involving Landsat images of other sites of coastal Florida. 7 I. 176 Appendices Glossary * Literaturature Cited BG.GDG IIGOD IG VIII. APPENDICES VIII A. Appendix A The following is a general description of the classification scheme used on the map products. It is reproduced from Kuyper et al. (1981). 177 SECTION I General Description The definitions which follow will provide understanding of what is included in each category at Levels I, II and III. The This land use, vegetation cover and land form classification definitions are largely based on U.S.G.S publications referenced system is arranged in hierarchical levels with each level in this report. containing land information of increasing specificity. LEVEL I This class of data is very general in nature. It can be obtained from remote sensing satellite imagery with supplemental information. Level I would normally be used for very large areas, statewide or larger, mapped typically at a scale of 1:1,000,000 or 1:500,000. At these scales, one inch equals 16 miles or one inch equals eight miles, (1 centimeter per S kilometer), respectively. LEVEL II This class of data is more specific than Level I. Level II data is normally obtained from high altitude imagery (40,000 to 60,000 feet), supplemented by satellite imagery and other materials such as topographic maps. Mapping typically might be at a scale of 1:100,000 or one inch equals 8,333 feet (1 centir-eter per 1 kilometer). LEVEL III This class of data usually is obtained from medium altitude photography flown between 10,00C and 40,000 feet. The mapping scale typically is 1:24,000, or one inch equals 2,000 feet (1 centimeter per 0.24 kilometer). LEVEL IV This more specific class of data is obtained from low altitude photography flown below 10,000 feet. In comparison with the above mentioned levels, Level IV typically might be mapped at a scale of 1:6000, or one inch equals 500 feet (1 centireter per 0.06 kilometer). Scope and Use The Florida Land Use, Cover and Land Form Classification System is an important step toward the development of a geographic data based information system. It serves to reduce a large amount of prirmary data (such as remote sensing imagery or field survey records) to a more understandable, smaller amount of secondary data (such as a land use map). The system also provides a useful structure of land concepts of properties. Yet, it does not collect or analyze inferration or offer conclusions. 178 100 URPAN OR BUILT-UP residential units may be found on military bases in the form of barracks, apartments, dormitories or homes; and on college and Urban or Built-up land consists of areas of intensive use, university campuses, in the form of apartments and dormitories with much of the land covered by structures. Included in this in close proximity to instructional buildings. Agricultural category are cities, towns, villages, strip developments along field operations and resort facilities commonly provide highways, and such areas as those occupied by mills, shopping temporary lodging for their employees and these areas would be centers, industrial and commercial complexes, and institutions classified under Agriculture, and Commercial and Services respec- that may, in some instances, be isolated from urban areas. tively. As developrment progresses, small blocks of land of less 110 Residential, Low Density (less than two dwelling intensive or nonconforming use ray be isolated in the midst of units per acre] built-up areas and will generally be included in this category. Agricultural, forest, or water areas on the fringe of urban and 111 Single Family Units built-up areas will not be included except where they are part of low-density urban development. 112 Mobile Home Units The Urban or Built-up category takes precedence over others 113 Mixed Units when the criteria for more than one category are met. For example, residential areas that have sufficient tree cover to 119 Low Density, Under Construction meet Forestland Upland criteria will still be classified as Residential in the Urban or Built-up category. 120 Residential, Medium Density [two-five dwelling units per acre] 110 Residential 121 Single Family Unit Residential land uses range from high-density urban housing to low-density areas with relatively few dwelling units 122 Mobile Home Units per gross acre. The variation extends from the multi-family apartments generally found in larger urban centers to those 123 Mixed Units [fixed and mobile home units] *Note 1 single-family houses sometimes having lot sizes of more than one acre. 129 Medium Density, Under Construction Areas of sparse residential land use (generally less 130 Residential, High Density than one dwelling unit per five acres), such as farmsteads, will be included in other categories to which they relate. However, 131 Single Unit [six and over dwelling units per rural residential and recreational type subdivisions will be acrel included in the Residential category since the land is almost totally committed to residential use, even though it may have 132 Mobile Home Units [more than six dwelling units forest or range types. per acre] In most instances the boundary will be clear when new 133 Multiple Dwelling Units, Low Rise [two stories or housing developments abut clearly defined agricultural areas. lessl conversly, the residential boundary may be vague and difficult to discern when residential development is sporadic and occurs 134 Multiple Dwelling Units, High Rise [three stories in smaller isolated units, develeped over an extended Feriod of or more] time in areas with rixed or less intensive uses. A careful evaluation of density and the overall relationship of the area 135 Mixed Units [fixed and mobile home units] Note 1 to the total urLan cromplex must bhe made. 139 High Density, Under Construction Oter land use cteg-cries ray ermrace areas that meet the Residential category recu:rrent. Often Fuch residential 1 4 Commercial and Services sections are an integral rc .ent of the cat'gory with which they .. ae as s E tociatedC an t; l b e inoe wthi thath .th.v are assoc;dted and 'hou ld be incl u e d within th.at Commercial areas are predoirinantly connected with the ca tmguory. For exam: Ile, inr the Init tutionalI category, sale of products and services. This category is composed of a 179 large ,number of individual types of commercial land use, often 145 Tourist Services occurring as a complex mixture of uses. This category includes all those facilities that can be The Commercial and Services category includes the main identified in support of a motel and hotel facility. building plus secondary structures and integral areas assigned to support the base unit. Included are sheds, warehouses, 146 Oil and Gas Storage [except those areas associated office buildings, driveways, parking lots, and landscaped areas. with industrial use or manufacturing] Other types of commercial areas include shopping This category identifies storage facilities used in the centers and commercial strip developments. These areas have retail and wholesale sales of these specific products. The Port distinctive patterns and are easily identifiable. Frequently, Everglades facility in Fort Lauderdale would be a typical individual houses and other urban uses may be found in example. commercial areas. These uses are not delineated, unless they cannot be plotted into categorized cell size of at least one 147 Mixed Commercial and Service *Note 1 acre at Level III, in .hich case the Mixed category should be used. 148 Cemeteries Another commercial use that is not easily identifiable 149 Commercial or Service Under Construction is the commercial resort. These businesses cater to vacationing patrons and contain associated recreational facilities such as 150 Industrial swimming pools and ball courts. The Industrial category embraces those land uses where 141 Retail Sales and Services manufacturing, assembly, or processing of products is accomplished. Industrial areas include a wide array of The area of Retail Sales and Service is primarily industrial types ranging from light manufacturing and industrial devoted to sale of products and the services. This category parks to heavy manufacturing plants. Included are facilities will be comprised of elements of central business districts, for administration and research, assembly, storage and shopping centers, and office buildings, with associated warehousing, shipping, and associated parking lots and grounds. buildings, driveways and parking lots, etc. Typical examples of industrial types found in Florida 142 Wholesale Sales and Service [except warehousing are pulp, or lumber mills, oil refineries with tank farms, associated with industrial use] chemical plants and brickmaking plants. Stockpiles of raw materials, larger power sources, and solid waste products This element represents primarily structures identified disposal areas are visible industrial categories and are easily by size, shape, and adjacent features. Normally, structures are identified on conventional aerial photography. large and of boxlike shape, designed to hold large quantities of products. Included in this category are open storage areas that 151 Food Processing can be identified as being in use or the result of supplemental data to support this classification. Citrus processing plants, sugar refineries, and seafood packaging plants are typical of this category. 143 Professional Services 152 Timber Processing This category is unique: associated elements with the pri:.e structure, along with supplemental data, are the major Plywood manufacturing, woodchip plants, and saw mills keys to category identification and location. The typical use are the prime components in this category. would be lawyers, doctors, consulting firms, etc. 153 Mineral Processing 144 Cultural and Entertainment Refining of basic earth materials such as Koalin, This category includes theatres, museums, open air phosphates, heavy metals (Titanium, Zircon concentrates) is theatres (such as rotion pictures and those for theatrical accomplished in Florida and the facilities for processing these performances). Pecreational facilities such as skating rinks materials are located near the mining operations. and tennis courts are not included in this category. 180 154 Oil and Gas Processing 161 Strip Mines This category includes production of jet fuel, The mining method used in this category is easily processing and recycling used petroleum products, also other identified by its land scarring, either in pit form or in Iona products such as asphalt and liquid gases, as well as the trenches, with tailings along the trenching operation. classic petroleum product, gasoline. 162 Sand and Gravel Pits 155 Other Light Industrial The category of Sand and Gravel Pits will be relatively Steel fabrication, small boat manufacturing, electronic small in area size when compared to the category of strip mining manufacturing and assembly plants are typical light industry operations. These pits are used primarily to support facilities. construction activities. 156 Other Heavy Industrial 163 Rock Quarries Major ship repair, ship building, and large lumber This category identifies the excavation of building mills can be placed in this category. In some instances mineral materials that can be found in part in the St. Augustine, extraction can also be assigned here if the facility is B rooksville and Ft. Myers areas. Equipment used in this processing a final and finished product. category is the major identifying feature. 159 Industrial Under Construction 164 Oil and Gas Fields 160 Extractive These are petroleum products sources and are found in the Sunnyland and Jay areas. No processing facilities are found Extractive lands encompass both surface and subsurface near these fields. The primary distinguishing feature will be mining operations. Included are sand, gravel and clay pits, the well head sites, some pumping facilities, and small storage phosphate mines, limestone quarries, plus oil and gas wells. tank facilities. The recognition of these activities on the landscape varies from the unmistakable giant pit mines covering vast areas, to oil 165 Abandoned mine and Fields wells which cover only a few square feet. Obviously, uniform identification of all these diverse extractive uses with their 166 Reclaimed Land varied degrees of photographic expression is extremely difficult from remote sensing data alone. Industrial complexes, where the This category primarily identifies phosphate mining extracted material is refined, packaged, or further processed, areas that are being restored. are included in this category. 167 Holding Ponds Abandoned or inactive mining operations are a part of the Extractive category until revegetation occurs. Flooded pits 170 Institutional and quarries, which may be part of a mining operation, will be included in this category. Educational, religious, health and military facilities are typical components of this category. Included within a The presence of water bodies does not necessarily mean particular institutional unit are all buildings, grounds and inactive or unused extractive areas. Ponds or lakes are often parking lots that compose the facility. Those areas not parkAreas of tailings specifically related to the purposes of the institution should an integral part of an extractive operation.Araofting and abar.doned pits and quarries way r era in recoulzable for a be excluded. For example, agricultural areas not specifically long time. These areas ray be barren for decades after associated with correctional, educational or religious deposition. During the interval from discontinued use until institutions are placed in the appropriate agricultural revegetation occurs, the parcel will he retained in the categories. Extractive catecory. Educational institutions encompass all levels of public and private schools, colleges, universities, training centers, etc. The entire areas of buildings, campus open space, dormitories, recreational facilities and parking are included when identifiable. 181 military facilities have a wide variety of conditions 180 Recreational including training camps, missile sites, etc. Administration, storage, repair, security and other functional military Recreational areas are those areas whose phys icalI buildings, plus the practice ranges, storage areas, equipment structure indicates that active user-oriented recreation is or stcrage lots and buffer zones compose the institutional military could be occurring within the given physical area. This facilities. Aux ilIiary land uses, particularly residential, category would include golf courses, parks, swimming beaches and commercial, and other supporting uses located on a military shores, marinas, fairgrounds, etc. (Note: Swimming beaches are base, are included in the Institutional category. identifiable by such features as bath houses, picnic areas, service stands and large parking lots adjacent to the beach 171 Educational Facilities areas). In order to make this recreational determination, supplemental information may be required. This category includes all facilities, such as parking lots, stadiums, all buildings and any other features that can be 181 Swimming Beach related to the facility. 182 Golf Courses 172 Religious 183 Race Tracks [horse, dog, car, motorcycle) All buildings that can be related to this category are included. many religious facilities have schools and day care 184 marinas and Fish Camps centers within their prcperty. 8PakZo 173 military 186 Community Recreational Facilities All buildings and grounds that compose the facility are included, along with auxiliary land uses, particularly 18 7 Stadiums [Those facilities not associated with high residential services and other supporting land uses. schools, colleges or universities.] 174 Medical and Health Care 188 Historical Sites [Prehistoric or historic) All buildings and grounds that con-pose the facility are 189 Other Recreational [riding stables, go-cart tracks, included. skeet ranges, etc.] 175 Governmental 190 Open Land identifiable buildings and facilities are included, and This includes undeveloped land within urban areas, and supplemental data is used to identify this category. inactive land with street patterns but without structures. Open Land normally does not exhibit any structures or any indication 176 correctional of intended use. Often, urban inactive land may be in a transitional state and ultimately will be developed into one of This facility normally is confined, with multiple fence the typical urban land uses, although at the time of the structure. All structures and grounds are included that are inventory, the intended use is impossible to determine. known to be associated with this category, either by the interpretation process or as the result of supplemental data 191 Undeveloped Land within urban areas support. 192 Inactive Land with street pattern but without 177 Social and Services srcue This category is to list facilities which are unique in 193 Urban Land in transition without positive indicators structure and location. Suppler ental data is required for of intended activity identification; e.g., Elks Club, Masonic Lodge, V.F.W., etc. 194 Other Open Land 179 institutional Under Construction 182 -Note Mixed 200 AGRICULTURE I. This category is used where no single use pre- dominates. When more than one-third intermixture of another use in a broad sense, agricultural land may be defined as or uses occurs, the specific classification is changed to those lands which are cultivated to produce crops and Mixed. But, where the sum of the intermixture Is less than livestock. The sub-categories of Agriculture are; Cropland, one-third, it is mapped as the dominant land use. Pastureland, Orchards, Groves (except Citrus), Vineyards, Nurseries, Ornamental Horticulture Areas, Citrus Groves, The Mixed category includes developments along Confined Feeding Operations, specialty Farms, and Other transportation routes and in cities, towns, and built-up areas Agriculture. where separate land uses cannot be individually mapped. Residential, commercial, industrial and occasionally other land 210 Cropland and Pastureland uses will be included. ___ 2. Abandoned or not in use This includes agricultural land which is managed for the production of row or field crops, and improved, unimproved Any land use classification that is confirmed as and woodland pasture. abandoned or not in use will be preceded, in the numerical Cropland and Pastureland include: identifier, by a zero ";i.e., 0175. 1. Cropland harvested or land from which crops are harvested, other than tree and bush crops, and horticultural crops. 2. Cropland used only for pasture or pasture in rotation with crops. 3. Pastureland used more or less permanently for that purpose. Numerous variables must be recognized in identifying crop and pasture uses of land in different parts of Florida. Field size and shape are highly variable depending upon topographic conditions, as well as soil types, sizes of farms, kinds of crops and pastures, capital investment, labor availability, and other conditions. In Florida, supplemental irrigation of cropland and pastureland by use of overhead sprinklers can be detected from photography where distinctive circular patterns are created. Drainage or water control on land used for cropland and pastureland at times creates a recognizable pattern that may be helpful in identifying this type of land use from photography. The duration of crop growth in the field may be rather limited. A false impression of non-agricultural use in a field may result if the conditions of temporary inactivity are not recognized. However, this can be substantiated by field checking. Pastures may he drained and/or irrigated lands. Where the management objective is to establish or maintain stands of grasses, such as bahia, pangola or bermuda grass, either alone or in mixtures with white clover or other legumes, land can he 183 categorized as pastures regardless of treatment. Much of the 222 Fruit Orchards [Peaches are an example of a crop type permanent" pastures occur on land which usually is not tilled which is typical for this category) or used a s cropland. Topographically rough land, stream floodplains, wooded areas, and wetlands often may be used for 223 other Groves [Pecan, avocado, coconut, mango, etc.) pasture more or less permanently. If specific crop type can he determined from aerial 211 Improved Pasture photography, Level TV classification will be used; e-g., 2231 - Pecan Grove. This category in most cases is composed of land which has been cleared, tilled, reseeded with specific grass types and 230 Feeding Operations periodically improved with brush control and fertilizer application. Water ponds, troughs, feed bunkers, and in some Feeding operations are specialized, livestock cases, cow trails are evident. production enterprises which include beef cattle feedlots, dairy operations with confined feeding, large poultry farms and hog 212 Unimproved Pasture feedlots. These operations have large animal populations restricted to relatively small areas. This restriction results This category includes cleared land with major stands in a concentration of waste material that is an environmental of trees and brush where native grasses have been allowed to concern. The attendant waste disposal problems justify a develop. Normally, this land will not be managed with brush separate category for these relatively small areas. Some control and fertilizer application. operations are located near urban areas to take advantage of proximity to transportation facilities and processing plants. 213 Woodland Pasture 2 31 Cattle This is an area where forestlanda are used as pasture. Strong evidence of cattle activity, such as trails to feed 232 Poultry bunkers, salt licks and watering areas, is required. in some cases, detection of cattle in the area will be the clue used to. 2 33 Hogs iaentify this category. When supplemental data is available, this will be used along with verification during field checks. 240 Nurseries and Vineyards 214 Row Crops This category is composed of nurseries, floricultural areas, and seed-and-sod areas used perennially and generally not Corn, tomatoes, potatoes, and beans are typical row rotated with other uses. crops found in Florida. Rows remain well defined even after crops have been harvested. 241 Tree Nursery 215 Field Crops Areas in this category are not associated with the timber industry; trees primarily are ornamentals. Wheat, oats, hay and grasses are the primary types identified as field crops. some problems may occur in 242 Sod Farms identification of field crops, and field checks are necessary in many cases, especially when crop growth is in the early stages. This category is unique, requiring the crop to be in harvest stages for detection. Supplemental data can be used for 220 Tree Crops the Identification of this specific category. Orchards and groves generally occur in areas possessing 243 Orniasentals [perennial] a specific combination of soil qualities and climatological factors. Water bodies, which moderate the effects of short This category is defined as plants or shrubs grown for duration temperature fluctuations, often are in close proximity decorative effects. to these types of farming. Site selection for air drainage on sloping land also may be important. 221 Citrus Groves Icrange, grapefruit, tangerine, etc.) 184 244 Vineyards 300 RANGELAND This category is defined as land devoted to cultivating Historically, Rangeland has been defined as land where grape vines. the potential natural vegetation is predominantly grasses, grasslike plants, forbs, or shrubs, and is capable of being 245 Floriculture [annual] grazed. Management practices may include brush control, regulation of grazing intensity, and season of use. If This category is defined as the cultivation of flowers revegetated to improve the forage cover, it is managed like (decorative flowering plants.) native vegetation. Generally, this land is not fertilized, cultivated, or irrigated. 246 Timber Nursery The definition of Rangeland used in the CONSERVATION Areas in this category are associated with the timber NEEDS INVENTORY by the U.S. Departments of Agriculture and industry. Tree seedlings (primarily pine) are grown for Interior is used in This classification scheme and describes the forestation of timber sites, natural potential (climax) plant cover as being composed of principally native grasses, forbs, and shrubs valuable for 250 Specialty Farms forage. This category includes Grassland, Shrub and Brushland, and Mixed Rangeland. Specialty farms include a variety of special or unique farming activities such as thoroughbred horse farms, dog kennels 310 Herbaceous and aquaculture. This category includes prairie grasses which occur on 251 Horse Farms the upland margins of the wetland zone and may be periodically inundated by water. Generally, it is the marginal area between This category defines farms which breed and train marsh and upland forested areas. These grasslands are generally horses for sport uses in racing, riding and harness racing. treeless, but in wet areas would have many types of soils resulting in a variety of vegetation types dominated by grasses 252 Dairy sedges, rushes and other herbs, while dryer grass areas would be dominated by wire grasses with some saw palmetto present. This is a commercial establishment which processes and distributes milk and milk products. 320 Shrub and Brushland 253 Kennels This category includes saw palmettos, gallberry, wax myrtle, coastal scrub, and other shrubs and brush. Generally, In this category, specific uses of dogs are not saw palmetto is the most prevalent plant cover intermixed with a defined. In most cases it will require ground "truthing" on an wide variety of other scrub forest plants such as scrub oaks, extensive basis by visiting each site. sand pines, as well as various types of short grasses. Coastal scrub vegetation would include pioneer herbs and shrubs composed 254 Aquaculture [Fish farms] of such typical plants as sea purslane, sea grapes, sea oats, without any one of these types being dominant. The definition of this category is the culture of marine or aquatic species under either natural or artificial 321 Palmetto Prairies conditions. These are areas in which saw palmetto (Serenoa repens) 259 Other is the most dominant vegetation. Common associates of saw palmetto in this cover type are: fetterbush, tar flower, 260 Other Open Lands [Rural] gallberry, wire grass and brown grasses. This cover type is usually found on seldom flooded dry sand areas. These treeless This category includes those lands whose intended usage areas are often similar to the pine flatwoods, but without the cannot be determined. pines. 322 Coastal Scrub 400 FORESTLAND This scrub category represents a conglomeration of species found in the coastal zone. A few of the more common Forestland includes uplands, basically the drier areas, components are saw palmetto, sand live oak, myrtle oak, yaupon, which have a tree crown density (crown closure of 10 percent or railroad vine, bay bean, sea oats, sea purslane, sea grape, more), and are dominated by trees and other woody vegetation. spanish bayonet and prickly pear. This cover type is generally found in dune and white sand areas. Lands from which trees have been removed to less than 10 percent crown closure, but which have not been developed for 329 Other Shrubs and Brssh other use, are also included in this category. For example, lands on which there are rotation cycles, involving This category includes other shrubs and brush cover clear-cutting and block planting, are part of the forestland types not previously mentioned. classification. 330 Mixed Rangeland Since most naturally seeded forestlands are composed of a mixture of species, for purposes of classification a minimum When more than one-third intermixture of either of 66 2/3 percent stand dominance (by crown area measurement) of grassland or shrub-brushland range species occurs, the specific one species or species groups is necessary for inclusion into classification is changed to Mixed Rangeland. Where the separate categories. Less than 66 2/3 percent stand dominance intermixture is less than one-third, it is classified as the of one species or species groups is considered to be a mixed dominant type of Rangeland, whether Grassland, of Shrub and category. It should be noted that classification is based on Brushland categories. overstory species composition, as interpreted from aerial photo- graphy. Forestlands are classified as follows: 410 Coniferous Forest A Coniferous Forest is a forested area having a dominant tree crown that is of coniferous species and is a result of natural seeding. 411 Pine Flatwoods [undifferentiated] This is a forested area dominated by longleaf pine on the drier sites, and slash and/or longleaf pine on the wetter areas. Common understory associates are saw palmetto, wiregrass, wax myrtle, fetterbush, and gallberry. 412 Longleaf-Xeric Oak This forest type is dominated by longleaf pine. Common understory associates are bluejack oak, turkey oak, and sand post oak. 413 Sand Pine Scrub This forested area occurs on excessively drained sands, often associated with former dune areas. The dominant overstory tree is sand pine. Common understory trees are myrtle oak, sand live oak, and chapman oak. 186 -_ '__mm - - - _- - _mm mm mm 414 Australian Pine 426 Tropical Hammock This is not a true pine; the species is commonly found This is a cover type also referred to as a coastal in almost pure stands with little or no understory vegetation. hammock. Common components of this cover type include gumbo limbo, mastic, stoppers, wild lime, strangler fig, lancewood, 415 Longleaf-Upland Oak poison wood, sea grape, marl berry, and wild tamarind. This forest type is dominated 'by an overstory of 427 Dpland Temperate Hammock longleaf pine and upland oak, commonly live oak or laurel oak. This is a cover type in which live oak is pure or 419 Other Pine predominant. Common associates are sweetgum, southern magnolia, holly and laurel oak. This category is composed of other coniferous cover types not previously mentioned. 428 Cabbage Palm 420 Hardwood Forest This is a cover type in which cabbage palm is pure or predominant. Associates are southern red cedar, southern A Hardwood Forest is a forested area having a dominant magnolia, live oak, sand live oak with smaller quantities of tree crown that is of hardwood species and is a result of laurel oak, red maple, redbay and holly. natural seeding. 429 Wax Myrtle-Willow 421 Xeric Oak This is a cover type in which wax myrtle -and/or willow This forest area is dominated by xeric oak generally is pure or predominant. It is often an indicator of a disturbed located on well-drained upland sands. Typical species include site and is commonly found on moist ground. bluejack oak, turkey oak, and sand post oak. 430 Hardwoods Forest Continued 422 Brazilian Pepper 431 Beech-Magnolia This cover type frequently occurs in dense pure stands often excluding understory vegetation. It is generally andicator species of this forest type, indicator of a disturbed site. although it may not be the most abundant. Southern magnolia and a great variety of other moist site hardwoods occur in this 423 Oak-Pine -Hickory forest with common associates including sweetgum, blackgum, yellow poplar, southern red oak, white oak, white ash and This is a mixed forest type in which no one species is hickories. consistently dominant. Major components of this cover type are southern red oak, post oak, black oak, shortleaf pine, loblolly 432 Sand Live Oak pine, mockernut hickory and dogwood. Sand live oak predominates in this cover type. 424 Melaleuca Associates are cabbage palm, southern red cedar and southern magnolia with smaller quantities of chapman oak, myrtle oak, red This species occurs in almost pure stands. It is an maple, redbay, and holly. This cover type is generally found on extremely aggressive competitor, often taking over a site, old coastal dune and white sand areas. forming a dense impenetrable stand. Melaleuca generally is an indicator of a disturbed site. 438 Mised Hardwood 42 5 Teimperate Ham m ock This is a mixed hardwood forest type in which no one species achieves 66 2/3 percent composition by crown area This is a cover type also referred to as a low measurement. hammock. Cormon ccrponents of this cover type include cabbage palm, caks (centrally live oak), red-hay, swentbay, yaupon and cedar. 187 439 500 WATER 439 Other Hardwood This category includes other hardwood cover types not The delineation of water areas depends on the scale and resolution characteristics of the remote-sensor photography user pr evi ousl1y mentioned. for interpretation. One definition of water bodies, provided by 440 Tree Plantations the Bureau of Census, includes all areas within the land mass of the United States that are predominately or persistently water 441 Coniferous covered, provided that, if linear, they are at least 1/8 mile (660 feet or 200 meters) wide, and if extended, cover at least These areas are forests created as a result of planting 40 acres (16 hectares). coniferous seedling stock or by direct seeding methods. Defining water boundaries at Level III, minimum size 442 Hardwood has been established to less than 10 acres. In some instances, water bodies of one acre will be plotted and identified. Water These areas are forests created as a result of planting bodies or those portions of the water body having emergent hardwood seedling stock or by direct seeding methods. vegetation are placed in the Wetland category. 443 Regeneration Area 510 Streams and Waterways Regeneration areas are forestlands where clearcutting This category includes rivers, creeks, canals, and and block plant timber management practices are in evidence and other linear water bodies. Where the water course is where it is evident that the intended future use will not be in interrupted by a control structure, the impounded area will be another land use category. This category also includes areas of placed in the Reservoirs category. site preparation and planting. The boundary between streams and lakes, reservoirs, or 444 Experimental Tree Farms the ocean is the straight line across the mouth of the stream, unless the mouth is more than one mile (1.85 kilometers) wide. These areas are devoted to testing'-the growth response In that case, the rule given under Bays and Estuaries is of different forest tree species to various experimental followed. silvicultural treatments. 520 Lakes The Lakes category includes inland water bodies, but excludes reservoirs. Islands within lakes that are too small to delineate will be included in the water area. The delineation of a lake will be based on the size of the water body at the time the remote-sensor data is acquired. 521 Lakes larger than 500 acres (202 hectares) 522 Lakes larger than 100 acres (400 hectares) but less than 500 acres 523 Lakes less than 100 acres but greater than 10 acres (4 hectares) 524 Lakes less than 10 acres which are dominant features 530 Reservoirs Reservoirs are artificial impoundments of water. They are used for irrigation, flood control, municipal water supplies, recreation, or hydro-electric power generation. Dams, 188 levees, other water control structures, or the excavation itself, usually will be evident to aid the identification. 600 WETLANDS 531 Reservoirs larger than 500 acres Wetlands are those areas where the water table is at, 532 Reservoirs larger than 100 acres but less than 500 near, or above the land surface for a significant part of most 532Reservoirslargerthan acres bu t lyears. The hydrologic regime is such that aquatic or acres hydrophytic vegetation usually is established, although alluvial 533 Reservoirs larger than 10 acres but less than 100 and tidal flats may b e nonvegetated. wetlands are frequently 533 Reservoirs larger than 10 acres bu t l e ss than 100 associated with topographic lows. Examples of wetlands include smarshes, mudflats, emergent vegetation areas, and swamps. 540 Bays and Estuaries Shallow water areas with submerged aquatic vegetation are classed as Water and are not included in the Wetlands category. Bays and estuaries are inlets or arms of the sea that Extensive parts of some river floodplains qualify as extend into the land and, as such, are properly classified in Etnse s o oe rielan we as this system only when they are included within the land mass of etlands. These do not include agriculture land where seasonal Florida. wetness or short-term flooding may provide an important component of the total annual soil moisture necessary for crop In order that this land mass area be commensurate with production. But, uncultivated wetlands yielding products such the area of the United States used in compiling census as wood, or grazed by livestock, are retained in the Wetlands stharaoftheUitdSaeusedincomiln caegory. statistics, the convention used by the Bureau of the Census in category. setting the outer limits of the United States has been followed. Where bays and estuaries are between 1 and 10 Wetlands areas drained for any purpose belong to other nautical miles (1.85 and 18.5 kilometers) in width, the outer land use categories, whether they be Agriculture, Rangeland, limit of the United States will be a straight line connecting Forested Uplands, or Urban or Built-up. When the drainage is the headlands, except where the indentation of the embayment is discontinued and such use ceases, classification reverts to so shallow that the water area would be less than the area of a Wetlands after characteristic vegetation is reestablished. semicircle drawn with this straight line as the diameter. In Wetlands managed for wildlife purposes may show short-term that event, the coastline itself would form the outer limit of changes in vegetation type and wetness condition as different the United States. management practices are used, but are properly classified Wetlands. Embayments less than one nautical mile in width are classed as Streams and Canals. Embayments or portions of 610 Hardwood Forest embayments more than 10 nautical miles (18.5 kilometers) in Wetland-Hardwood Forest areas are those wetlands which width are not considered included within the land mass. Wetland-Hardwood Forest areas are those wetlands which meet the crown closure requirements for the Hardwood Forest and 541 Opening directly into the Gulf or Atlantic Ocean are a result of natural seeding. These wetland trees are found both in salt and freshwater areas. 542 Not opening directly into the Gulf or Atlantic Ocean 611 Bay Swamp 550 Major Springs -550 Major Springs This category is composed of dominant trees such as The natural phenomena known as springs can easily be loblolly bay, sweetbay, redbay and slash pine. Large gallberry, identified as points of origin of a water source. In many fetterbush, wax myrtle and titi are the understory vegetation. instances, major springs such as Silver Springs and Homosassa Springs can readily be identified' by the associated 612 Mangrove Swamp recreational-commercial enterprises in the adjacent area. This category is composed of red or black mangrove 560 Slough Waters which is pure or predominant. The chief associates are white mangrove, buttonwood, cabbage palm and sea grape. Slocghs are c,.Lnels of slow roving water in the coacstal zarshland. The term also refers to "backwater sloughs", those rnarrcw, often sta.narnt Iodies of water found near inland rivers. 189 613 Gum Swamp 623 Atlantic White Cedar This category is composed of swamp tupelo or water In this category, atlantic white cedar is the indicator tupelo which is pure or predominant. Associated species are species although it may not always be the most abundant. Common bald cypress and a great number of wet site hardwoods, with wide associates are slash pine, cypress, swamp tupelo, sweetbay, variation in composition. redbay, loblolly bay, black titi and red maple. 614 Titi Swamp 630 Forested-Mixed This category is composed of black titi and cyrilla This is a mixed wetland, hardwood coniferous forest which are predominant. Associated species are bays, cypress, type in which neither hardwood nor coniferous species achieves swamp tupelo, and a great number of wet site hardwoods. 66 2/3 percent stand composition, by crown area measurement. 615 Stream and Lake Swamp 640 Vegetated Non-Forested This category is also referred. to as bottomland or Wetland-vegetated, non-forested lands are found in stream hardwoods, and cover type is found on river, creek and seasonably flooded basins, meadows, and marshes. Wetlands are lake overflow areas. It is a conglomeration of species, of usually confined to relatively level areas. This category does which some of the more common components are: pond cypress, not include areas whose tree cover meets the crown cover bald cypress, red raple, river birch, water oak, sweetgum, threshold for the forested categories. When the forested crown willow, swamp tupelo, okeechee tupelo, water hickory, water ash, cover is less than the threshold for Wetland Forest or is and buttonbush. non-woody, it will be included in this category. Sawgrass and cattail are predominant communities in freshwater marshes, while 616 Inland Ponds and Sloughs spartina and needlerush are the predominant saltwater marsh communities. This category is found in depressions or drainage areas not associated with streams or lakes. One of the following 641 Freshwater Marsh species will generally predominate in these communities: pond cypress, swamp tupelo, water tupelo, titi or willow. In this category, these communities will have pre- dominantly one or more of the following species: 620 Coniferous Forest Sawgrass and Cattail, Bulrush and Maidencane Wetland-Coniferous Forest areas are wetlands which meet Marshes the crown closure requirements for the Coniferous forest and are a result of natural seeding. These species are commonly found Sawgrass - (Cladium jamaicensis) in the interior wetlands in such places as river flood plains, Arrowhead - (Sagittaria sp.) bogs, bayheads, and sloughs. Maidencane - (Panicum hemitomon) Cattail - (Typha domingensis, T. latifolia, T. 621 Cypress angustifolia) Pickerel Weed - (Pontederia lanceolata, P. cordata) This category is composed of pond cypress or bald Buttonbush - (Cephalanthus occidentalis) cypress which is pure or predominant. In the case of pond Spartina - (Spartina bakeri) cypress, common associates are swamp tupelo, slash pine, and Switchgrass - (Panicum virgatum) black titi. In the case of bald cypress, common associates are Bulrush - (Scirpus americanus, S. validus, S. water tupelo, swamp cottonwood, red maple, american elm, pumpkin robustus) ash, carolina ash, overcup oak, and water hickory. Bald cypress water lily - (Nymphea sp.) may be associated with laurel oak, sweetgum and sweetbay on less Bladderwort - (Utricularia sp.) moist sites. Needlerush - (Juncus effusus) Common Reed - (Phragmites communis [australis)) 622 Pond Pine 6411 Sawgrass (Cladium jamaicensis) This catecory is crrosed of fond pine which is pure or rrecr.inant. The nancr associate is titi. Minor associates are 6412 Cattail (Typha sp.) sweetbay, lblolly lay, rcdbay and "wamp tupelo. 190 - _- _ _- _---- m - - 642 Saltwater Marsh 644 Emergent Aquatic Vegetation In this category, these communities will have This category includes floating vegetation and/or predominantly one or more of the following species: aquatic vegetation that is found partially or completely above the surface of the water. S__artina and Needlerush Marshes 6441 Water Lettuce - (Pistia stratiotes) Cordgrasses Cordgrasses - (Spartina alterniflora, S. 6442 Spatterdock - (Nuphar sp.) cynosuroides, S. patens, S. spartinae) Needlerush - (Juncus roemerianus) 6443 Water Hyacinth - (Eichhornia sp.) Seashore Saltgrass - (Distichlis spicata) Saltwort - (Batis maritima) 5444 Duckweed - (Lemna sp.) Glassworts -(Salicornia sp.) Fringerush - (Finbristylis castanea) 645 Submergent Aquatic Vegetation Salt Dropseed - (Sporobolus virginicus) Seaside Daisy - (Borrichia frutescens) This category is composed of those aquatic species Salt Jointgrass - (Paspalum vaginatum) found growing completely below the surface of the water. 6421 Cordgrass (Spartina) 650 Non-Vegetated Vegetation association is the same as listed in 642 Wetland non-vegetated areas are those areas where (Saltwater Marsh) classification. However, dominant vegetation vegetation may be lacking due to the erosional effects of wind is one of the following: (Spartina alterniflora, S. and water transporting the surface material so rapidly that cynosuroides, S. patens or S. spartinae). plant establishment is curtailed. Also, submerged or saturated materials often develop toxic conditions of extreme acidity from 6422 Needlerush (Juncus) sulfur generation. Tidal flats, shorelines and intermittent ponds are a main component of this category. Vegetation association is the same as listed in 642 (Saltwater Marsh) classification. However, dominant vegetation 651 Tidal Flats is (Juncus roemerianus). This category is composed of that portion of the shore 643 Wet Prairies environment protected from wave action, as in estuaries, comprised primarily of muds drained by tidal channels. An This category is composed of dominantly grassy important characteristic of the tidal flat environment is its vegetation of wet soils, usually distinguished from marshes by alternate submergence and subaerial exposure during the tidal having less water and shorter herbage. These communities will cycle. have predominantly one or more of the following species: 652 Shoreline Maidencane - (Panicum hemitomon) C.Drigrasses - (Spartina bakeri, S. patens) This category is usually defined as the line where land F ikerushes - (Eleocharis sp.) and water meet. Shorelines are formed mainly by marine or Eeach Pushes - (Rhynchospora sp.) biological agents like coral reefs, barrier beaches, and St. Jchns Wort - (Hypericum sp.) marshes. (The shore is defined as the zone from low tide to the Sliderlily - (Hyrenocallis palmeri) farthest point on land where waves transport sands.) Swar-plily - (Crinum americanum) Yellow-eyed Grass - (Xeric ambigua) 653 Intermittent Pond Whitetop Sedge - (Dichromrena colorata) This category is defined as a waterbody which exists usually only during a portion of the year. Its existence relies on water received from direct precipitation, runoff or spring flow. 191 700 BARREN LAND 741 Rural land in transition without positive indicators of intended activity Barren land has very little or no vegetation and 742 Borrow Areas limrited ability to support life. In general, it is an area with only soil, sand or rocks. Vegetation, if present, is very 743 Spoil Areas widelf spaced and scrubby. However, land also may be temporarily barren due to man's activities. Generally, this 744 Fill Areas [highways-railways] land is included in another land use category. Vast areas of agricultural land are temporarily without vegetation cover due to tillage practices, and areas of extractive and industrial land use have dumps for wastes and tailings. Barren Land categories are Beaches (areas exhibitinglittle or no evidence of human encroachment), Sand Other Than Beach, Exposed Rock, Disturbed Lands. 710 Beaches Other Than Swimming Beaches Beaches are constantly affected by wave and tidal action. The fine clays and silts are washed away leaving sand. However, in protected bay and marsh areas, fine soil particles from surface drainage waters may settle out. The beach areas also are subject to water and wind erosion. Differing beach dimensions are due to factors such as tides, soil material size, water level and wave energy, all of which vary. When a stable surface is observed inland, as another land use occurs and erosion effects of water and wind decrease, the beach category is then terminated. 720 Sand Other Than Beaches Sand other than beaches is composed primarily of dunes. These are of aeolian origin composed of sand grains downwind from a natural source of sand. Dune sizes vary greatly, with diameters ranging from a few feet to more than several hundred. Their heights also vary and their shapes display considerable variety. When the dunes are the major feature, shore and strand lines, coastal plains, river flood plains, and deltas are secondary. 730 Exposed Rock Exposed rock areas consist of exposed bedrock and other accumulation of rocks lacking vegetative cover. Exposed bedrock, when weathered, ray be urvegetated due to fine soil removal by water or wind erosion. 740 Disturbed Lands Disturbed lands are te areas that have been changed due to man's activities, other than rining activities. In Florida, these areas ray be rather extensive aid often arpear outside of urban areas. 192 800 TRANSPORTATION, COMMUNICATION AND UTILITIES 820 Communications Airwave communications, radar and television antennas 810 Transportation with associated structures are typical major types that will be identified, when stations are associated with a commercial or Transportation facilities are used for the movement of governmental facility, they will be included in that specific people and goods; therefore, they are major influences on land category when located within the bounds of the specific facility and many land use boundaries are outlined by them. and will not be listed as a separate element. Highways are easily identifiable on medium altitude 821 Transmission Towers [microwave are typical in this photography. Highways include areas used for interchanges, category] limited access rights-of-way, and service facilities. The center median, pavement and sizable buffer zone should be B 22 Communication Facilities [includes transmitter included even if exact boundaries cannot be detected. stations, telephone exchanges, antenna farms, etc.] The Transportation category encompasses rail-oriented 829 Communication Facilities Under Construction facilities including stations, round-houses, repair and switching yards, and related areas. Airport facilities include 830 Utilities runways, intervening land, terminals, service buildings, navigation aids, fuel storage, parking lots and a limited buffer Utilities usually include power generating facilities, zone, and fall within the Transportation category. water treatment plants and their related functions, such as transmission lines for the electric power facilities, and Transportation areas also em.b race ports, docks, aeration fields for the sewer treatment sites. Small facilities shipyards, dry docks, locks and watercourse control structures or those associated with an industrial, commercial or extractive designed for transportation purposes. The docks and ports land use, are included within the larger category. include buildings, piers, parking lots and adjacent water utilized by ships in the loading or unloading of cargo or 831 Electrical Power Facilities passengers. Locks, in addition to the actual structure, include the control buildings, power supply buildings, docks and This category includes hydropower, thermal, nuclear, surrounding supporting land use, i.e. parking lots and green gas turbine plants, transformer yards, sub-stations. areas. 832 Electrical Power Transmission Lines 811 Airports 833 Water Supply Plants [including pumping stations] 812 Railroads This category includes treatment plants, settling 813 Bus and Truck Terminals basins, water storage towers and well fields. 814 Major Highways 834 Sewage Treatment 815 Port Facilities This category is composed of all related facilities such as aeration fields, digesters, etc. 86 Canal and Locks 835 Solid Waste Disposal 817 Oil, Water, or Gas Long Distance Transmission Lines This category is composed of controlled and managed 818 Auto Parking Facilities (when not directly related to s olid waste fields, non-permitted solid waste disposal sites, other land use) etc. 819 Transrortation Faciliris Under Construction 839 Utilities Under Construction 193 900 This section is reserved for special classification This category is used primarily for specific topics to be addressed for a specific user requirement of those land uses and land comrer which require identification at Level III or IV. e.g. Marine grasses - dense - medium - sparse 194 IX. GLOSSARY abiotic - any inorganic part of the environment. amphipod - small macroscopic crustacean; body is laterally compressed. anaerobic - a condition associated with absence of free oxygen in the environment. benthic - living on the bottom. brackish water - water that has a salt content intermediate between fresh water the sea. coastal wetland - land where the water table is at or near the surface or the land is covered by shallow water or tidally influenced. community - all the plants and animals of an area (or volume) which form a interactive assemblage. crustacean - a class of animals that have a hard outer shell; includes shrimp, crabs, lobsters. detritus - particles of non-living organic matter, usually in various stages of decomposition. dike - a dam or embankment erected to prevent flooding of a lowland area. dredge spoil - sediment material removed from a wetland bottom during dredging operations. ecosystem - the community and its non-living environment, considered collectively. epibenthic - living on the surface of bottom. epiphyte - plant or animal attached to a plant, typically not a parasitic relationship. euryhaline - able to tolerate wide variation of salinity regimes. 195 facultative halophyte - able to live under freshwater and saltwater influences but living mostly under saltwater influence due to exclusion of other species. finfish - sharks, rays, and bony fishes. fishery - the complex of interactions within and between the population s) of fish being harvested, the population s) of fishermen, and the environments of each.I food chain - the series of nutritional steps through which food passes from plants to herbivores to carnivores; also the nutritional steps in- volved in parasite and microbial (decomposer) chains. food web - the interlocking pattern formed by parallel and cross connectingI food chains. habitat - the natural environment in which an organism lives. habitat component - a specific part, be it organic, inorganic, chemical,I or environmental, of an organism' s environment. hectare - a measure of area equal to 2.47 acres.I infauna - animals living within the sediment. isopod - small macroscopic crustacean; body is flattened. life history - the series of stages through which an organism passes during its entire lifetime. macrophytes - plants larger than microscopic size. meiofauna - microscopic and small macroscopic animals living on the bottom. meroplankton - larval plankton 15-20 rmm in size.I nekton - macroscopic swimming animals that can freely regulate their dis- tribution against movements of water masses. non-point source pollution - pollution originating from non-localized sources such as storm drains. 1961 nutrient - an organic or inorganic chemical substance required for the growth and reproduction of organisms. omnivorous - eating a diet of both plants and animals. pelagic -living offshore. photic zone - surface zone of sea or lake sufficiently illuminated for * photosynthesis. photosynthesis - the chemical processes through which green plants manu- facture organic molecules from inorganic using sunlight as an energy source. plankton -aquatic organisms that cannot freely regulate their distribution against movements of water masses; includes microscopic plants (phyto- plankton) and microscopic animals (zooplankton). 3 point source pollution - pollution originating from known, localized sources. polychaete - a marine worm. productivity -the rate of production of organic matter by living organisms (i.e., the amount per unit time). * recruitment -the process of addition of animals to a population. Typically, the term is used to describe when, or how large fishes are when they first enter a fishery. rhizome -a horizontal underground stern. riprap -rock, stone, or other rough material placed on stream banks, dam faces, and other structures to protect against erosion by the water. sediment load - all particulate material (inorganic or organic) suspended 3 in or transported downstream by water (may include clay, silt, sand, organic detritus, etc.). 197 sedimentation - the settling out of suspended matter from the water to the bottom. sessile - attached to a substrate; non-motile. shellfish - oysters, clams, scallops, and conch. species - a group of populations in which the organisms reproduce and main - tain separateness, genetically.1 species diversity - the variety of types of organisms present in an area. stress - a strain or pressure applied to an organism (or group of organi sms) by an unfavorable or stress-producing factor. tidal node - the area of no current velocity where an incoming tide meetsI from opposite directions or from which an outgoing tide recedes in opposite di recti ons. trophic level - one of the several levels of a food chain; plants constitute the primary level, herbivores the second level, and carnivores the third and remaining levels. turbidity - the condition of water resulting from the presence of suspended material, often expressed as interference with light transmission.I 198 X. 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