inventory of bivalves and their food supply in the Indian River, Brevard County, Florida final report

[From the U.S. Government Printing Office, www.gpo.gov]

AN INVENTORY OF BIVALVES AND THEIR FOOD SUPPLY
IN THE INDIAN RIVER, BREVARD COUNTY, FLORIDA

Final Report Submitted to the
revard Coun ater Resources Department
and the
Brevard County Board of County Commissioners

Forrest E. Dierberg John H. Ryther
Co-Principal Investigator Co-Principal Investigator

Constantine Triantafyllidis R.,Leroy Creswell and
Graduate Research Assistant Thomas A. DeBusk
Research Associates

Mary A. Schilling
Research Assistant II

FLORIDA INSTITUTE OF TECHNOLOGY HARBOR BRANCH FOUNDATION, INC.
Department of Environmental Science and Engineering Division of Applied Biology
Melbourne, Florida 32901 Ft. Pierce, Florida 33450

QL
430.6 February, 1986
J58
1986

AN INVENTORY OF BIVALVES AND THEIR FOOD SUPPLY

IN THE INDIAN RIVER, BREVARD COUNTY, FLORIDA

Final Report Submitted to the
Brevard County Water Resources Department
and the
Brevard County Board of County Commissioners
Via
Ln

Forrest E. Dierberg John H. Ryther
-j Co-Principal Investigator Co-Principal Investigator

Constantine Triantafyllidis R. Leroy Creswell and
Graduate Research Assistant Thomas A. DeBusk
Research Associates

Mary A. Schilling
Research Assistant 11

FLORIDA INSTITUTE OF TECHNOLOGY HARBOR BRANCH FOUNDATION, INC.
Department of Environmental Science and Engineering Division of Applied Biology
Melbourne, Florida 32901 Ft. Pierce, Florida 33450

February, 1986

TABLE OF CONTENTS
Page'

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . .
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . v
LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . I
METHODOLOGY . * , * * * , * , * * * , * * , * * * * * * , , ,* , * , I
Shellfish Populations . . . . . . . . . . . . . . . . . . . . . . . 3
Chlorophyll a . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Salinity and Water Temperature . . . . . . . . . . . . . . . . . . 8
Phytoplankton Species . . . . . . . . . . . . . . . . . . . . . . . 8
Primary Productivity . . . . . . . . . . . . . . . . . . . . . . . 8
QUALITY ASSURANCE . . . . . . . . . . . . . . . * * * ' * * * * * * * 11
Filter Pore Size and the Effects of Grinding on the
Efficiency of the Chlorophyll a Analysis . . . . . . . . . . . . 11
Surface vs. Deep Water Chlorophyll a Concentrations . . . . . . . . 13
Sediment Pigment Concentration and gediment Density . . . . . . . . 14
The Effect of Incubation Time on 14C Uptake Rates . . . . . . . . . 18
Comparison of 14C Uptake and 02 Evolution Techniques
in Measuring Primary Productivity . . . . . . . . . . . . . . . . 20
EPA Quality Control Samples for Fluorometric.Analyses
of Chlorophyll a . . . . . . . . . . . . . . . . . . . . . . . . 21
Bivalve Taxa . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
RESULTS AND DISCUSSION . * , * , * * * * * * * * , * * * . . . . . . 23
Salinity and Temperature . . . . . . . . . . . . . . . . . . . . . 23
Chlorophyll a . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Primary Productivity . . . . . . . . . . . . . . . . . . . . . . . 31
Diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Distribution and Relative Abundance . . . . . . . . . . . . . . . . 37
Population Size Structure . . . . . . . . . . . . . . . . . . . . . 41
Allometric Relationships . . . . . . . . . . . . ... . . . . . . . 45
Bivalve Biomass . . . . . * * , * * * * * * * , * * * * * , , 45
The Relationship of Food Su*pply' to Bivalve Production . . . . . . . 53
Literature Review on Bivalves of the Indian River Lagoon . . . . . . 57
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

APPENDIX A: ANNOTATED BIBLIOGRAPHY ON BIVALVES AND
PHYTOPLANKTON OF THE INDIAN RIVER ESTUARY

APPENDIX B: NUMBERS ACCORDING TO SIZE CLASS (mm SHELL LENGTH)
OF MERCENARIA MERCENARIA AND MULINIA LATERALIS
COLLECTED ALONG TRANSECTS A, B, C D IN THE
GRANT, MELBOURNE, AND MERRITT ISLAND AREAS OF
THE INDIAN RIVER LAGOON.

EXECUTIVE SUMMARY

1. An extensive literature review covering the years between 1973-81 revealed
a lower population of hard clams (Mercenaria mercenaria) and higher bivalve
diversity than what was found in this investigation.

2. Ninety-eight percent of the bivalves collected, sorted, identified, and
measured from 110 stations along 12 transects in the Indian River lagoon between
April and July 1985 were Mulinia lateralis (coot clam). The next most abundant
bivalve was Mercenaria mercenaria, comprising one percent of the total number.
However, because of its small size (0.5 in., shell length), the coot clam
contributed only 36 percent of the weight to the bivalve community; the hard
clam's contribution was 64 percent. Overall, only nine species of bivalves were
collected.

3. Recruitment of juvenile hard clams in the Grant area was 31 individuals/m2.
Low recruitment at Melbourne and Merritt Island locations (1.0-3.4
individuals/m2) suggests that those areas will not provide large numbers of
harvestable clams. -

4. The population of harvestable clams (>1.75 in. in length) at Grant (5.5
individuals/m2) is considerably lower than the juveniles, probably because of
commercial harvesting; slightly lower numbers of legal sized harvestable cl s
were found at Melbourne (4 individuals/m2). The waters of Merritt Island
contained only 1.9 legal sized clams per m2.
5. The number of individual coot clams (Mulinia lateralis) were larie for the
Melbourne and Merritt Island areas (2,484 and 3,165 individuals per m ) where
comparably sized "seed" hard clams were low.

6. Dry weight meat biomass, obtained from shell length-dry meat weight
regression relationships of subsamples of coot and hard clams, was significantly
different among the three collection areas for either coot or hard clams.
However, when the biomass of all species were summed at each sampling site,
there were no significant differencesbetween the sampling sites in total
bivalve biomass, which ranged from 8.8 to 13.7 g dry meat wt. per m2.

7. Chlorophyll a concentrations and primary productivity rates indicated food
production in the estuary was less than the amounts necessary to sustain the
bivalve community based on maximum filtration rates, indicating food may be a
limiting resource.

8. Based on a bi-monthly sampling schedule from October 1984 through October
1985, phytoplankton standing stock was approximately 30% lower at Grant than at
Melbourne. Likewise, primary productivity (monthly measurements) was 40% lower
at Grant than at Melbourne. For both chlorophyll a and primary productivity
average values, the differences between Grant and-Melbourne were statistically
significant. Annual chlorophyll a averages from 1980-1984 collected by Brevard

County were not'significantly different between stations at Grant and Melbourne
(except 1982); nor was the average for 1984 statistically higher than the 1980
average at either site. This indicates chlorophyll a concentrations in the river
did not increase during this period. Both chlorophyll a concentration and
'
primary productivity in the Indian River estuary are extremely high when
compared to other estuarine systems.

ACKNOWLEDGMENTS

We would like to thank Conrad White and Bob Day of the Brevard County

Environmental Services Division for supplying benthic, chlorophyll a, and

salinity data for areas of the estuary which were not sampled during this

research. Paul Jensen instructed in the 14r
,analysis. Mark Castro and Larry

Pollack assisted in the field work; Simone Triantafyllidis helped in sorting

shellfish. R. Tucker Abbot contributed his expert taxonomic skills to some of

the more problematic bivalves. Stimulating conversations with Mark Berrigan

of the Florida Department of Natural Resources on shellfish biology and

ecology provided the impetus for the design of the bivalve field census. The

administrative skills of Steve Kintner of the Brevard County Water Resources

Department allowed the co-principal investigators to focus more on the

research effort. John Schneider, Chief of the Bureau of Marine Resource

Regulation and Development, Florida Department of Natural Resources, provided

an invaluable service by excluding the sites at Melbourne and Merritt Island

from relaying for the duration of the study. Finally, Betty Fink contributed

to the typing and word processing of this final report.

Preparation of this Final Report was primarily supported by a grant from

the U.S. Office of Ocean and Coastal Resource Management, National

Oceanographic and Atmospheric Administration,, and Florida Department of

Environmental Regulation, Office of Coastal Zone Management, through the

Coastal Zone Management Act of 1972 as amended.

LIST OF FIGURES
Page

Figure 1. Location of the four bivalve sampling transects (A, B, C and D)
at each of the three areas in the Indian River: Merritt Island
(upper left), Melbourne (upper right), and Grant (bottom). . . 4

Figure 2. Airlift suction dredge . . . . . . . . . . . . . . . . . . . . . 6

Figure 3. Monthly concentrations of chlorophyll a in the Indian River
lagoon at Melbourne (closed circles) and Grant (open circles)
between 1980 and 1985 (data provided by Conrad White and
Bob Day of Brevard County Water Resources Dept.) . . . . . . 28
Figure 4. Mean chlorophyll a concentrations (mg m-3) +1 S.E. along
transects at Melbourne (closed circles) and Grant
(open circles). . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 5. Differences in size (length)-frequency distributions of
Mercenaria mercenaria from the Indian River at the Merritt
Island, Melbourne, and Grant sampling sites. The vertical
dashed line represents the shell length equal to the minimum
legal width of 7/8 inch across the hinge allowed by Florida
statue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 6. Regression relationship [Wl = a (L)b] between total wet weight
(Wl, gm) to shell length (L, mm) for 50 hard clams (Mercenaria
mercenaria) collected from three areas in the Indian River
between April and July, 1985 . . . . . . . . . . . . . . . . . . . 46
Figure 7. Regression relationship IW2 = a (L)b] between dry meat weight
(W2,mg) to shell length (L, mm) for 50 hard clams (Mercenaria
mercenaria) collected from three areas in the Indian River
between April and July, 1985 . . . . . . . . ... . ... . . . . . 47
Figure 8. Regression relationship [Wl = a (L)b] between total wet weight
(WI, mg) to shell length (L, mm) for 40 coot clams (Mulinia
lateralis) collected from three areas in the Indian River between 48
April and July, 1985 . . . . . . . . . . . . . . . . . . . . . .
Figure 9. Regression relationship IW2 = a (L)b] between dry meat weight
(W2, mg) to shell length (L, mm) for 40 coot clams (Mulinia
lateralis) collected from three areas in the Indian River between
April and July, 1985 . . . . . . . . . . . . . . . . . . . . . . 49

Figure 10. Standing crop for hard clams, Mercenaria mercenaria, and coot
clams, Mulinia lateralis, and the total for the two species at
three sites in.-the Indian River lagoon in Brevard County,
Florida, during 1985 . . . . . . . . . . . . . . . . . . . . . . 51

LIST OF TABLES Page

Table 1. Effect of phytoplankton grinding on chlorophyll a extraction . . . 12

Table 2. Standing crop (chlorophyll a concentrations) of the Indian
River lagoon phytoplankton 3f two size classes: greater than
0. 45 m and 0.45 m to 0.1 m . . . . . . . . . . . . . . . . . . 13

Table 3. Chlorophyll a concentrations of shallow (0.1 m) and deep
(1.4 m) waters at individual sampling sites in the Indian
River lagoon . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 4. Photosynthetic pigment concentrations in the sediment (wt/wt)
and water (wt/vol) at two locations in the Indian River lagoon
on 28 February 1985 . . . . . . . . . . . . . . . . . . . . . . . . 16

Table 5. Phytoplankton production over a 4 hour period in 300 mL glass
bottles as measured using one hour (1+1+1+1), two hour (2+2)
and four hour (4) incubation times . . . . . . . . . . . . . . . . 19

Table 6. A comparison of primary productivity by Indian River
phytoplankton as measured by the 14C uptake and the 02
evolution techniques . . . . . . . . . . . . . . . . . . . . . . . 21

Table 7 . Salinity along two transacts in the Indian River. W, C, and E
designate the west, central, and east stations, respectively. 24

Table 8. Water temperature along two transacts in the Indian River.
W, C, and E designate the west, central, and east stations,
respectively . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Table 9. Chlorophyll a concentrations along two transacts in the Indian
River, Florida. W, C, and E designate the west., central, and
east stations, respectively . . . . . . . . . . . . . . . . . . . 26

Table 10. Annual mean (+I s.d.) chlorophyll a concentrations for station
I10 at Melbourne and station Ill at Grant from 1980 to 1984.
Data provided by Conrad White and Bob Day of the Brevard County
Water Resources Division . . . . . . . . . . . . . . . . . . . . . 30

Table 11. Depth integrated phytoplankton productivity at two sites in the
Indian River. Both morning and afternoon incubations were
conducted at each site, except on 15 October 1985 when one-six
hour incubation elapsed both morning and afternoon times . . . . . 32

Table 12. Phytoplankton productivity at two sites in the Indian River
lagoon. Values represent average carbon uptake (mg C m-3h-1)
+1 s.d. in a 3 hr in situ incubation during morning and
afternoon incubations for surface (0.25 m depth) and subsurface
(1.4 m depth) waters . . . . . . . . . . . . . . . . . . . . . . . 33

Table 13. Daily phytoplankton productivity (g C/m2-day) at two Page
sites in the Indian River . . . . . . . . . . . . . . . . . . . . 35

Table 14. Total number of individuals for each bivalve species
collected at 110 stations (sampling area was 1/4 M2 at
each station) at the Grant, Melbourne, and Merritt Island
sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Table 15. Density of the hard clam, Mercenaria mercenaria, collected
from three areas in the Indian River lagoon in Brevard
County, Florida. Four transects, each consisting of 7 to
11 sampling stations, were sampled from each-area . . . . . . . . 40

Table 16. Abundance of the coot clam, Mulinia lateralis, sampled from
three areas of the Indian River lagoon in Brevard County,
Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table 17. Biomass of hard clams, Mercenaria mercenaria, sampled from
three areas of the Indian River lagoon in Brevard County,
Florida. Dry meat weight values were calculated from a shell
length: dry meat weight relationship derived from individuals
ranging from 2.8-100.0 mm total shell length (see Figure 7) . . . 30

Table 18. Biomass of coot clams, Mulinia lateralis, sampled from three
areas of the Indian River lagoon in Brevard County, Florida.
Dry meat weight values were calculated from a shell length:
dry meat weight relationship derived from individuals ranging
from 2.8-20.0 mm total shell length (see Figure 9) . . . . . . . . 52

Table 19. Biomass of hard clams, Mercenaria mercenaria, and coot clams,
Mulinia lateralis, sampled from three areas of the Indian River
lagoon in Brevard County, Florida. Dry meat weight values were
calculated from a shell length: dry meat relationship derived for
each species (see Figures 7 and 9) . . . . . . . . . . . . . . . . 54

Vii

INTRODUCTION

The Indian River is a barrier island lagoon which extends 150 miles along

the east coast of Florida. This lagoon supports dense populations of

shellfish: hard clam (Mercenaria mercenaria) landings from the Brevard County

section of the estuary were reported by the National Marine Fisheries Service

to be over 90% of the total harvest for the state in 1984, which was 1.7

million pounds of clam meats valued at $6.1 million (dockside value of $3.59

per pound of meat). Since Florida harvests 13% of the nation's total,

clamming is clearly an economically important industry to Brevard County.

Several other species of bivalves, although not utilized commercially,

reportedly occur in even greater numbers.

In 1978, clam mortality rates increased because of unknown reasons,

resulting in poor commercial harvests until the summer of 1982, when an

explosion in the hard clam population occurred. With the decline in the

oyster and blue crab industries, along with the steady growth in the numbers

of commercial shellfishermen, competition for the remaining commercially

important shellfish, the hard clam, has occurred. In a Brevard County Clam

Industry Workshop held on September 7, 1985 and sponsored by the Brevard

County Sea Grant Extension Program, concern of the attendees focused on the

problems affecting the future of the clamming industry. These problems

include a lack of information concerning the biology and ecology of clams, the

effects of pollution and increased fishing pressure on the resource, and

enforcement of current laws relating to harvesting and certification of

shellfish dealers. Partial results of this research dealing with the clam

population we re presented at that workshop. In 1914 the Marine Fisheries

Commission, which is composed of Governor-appointed representatives from

commercial and sport fisheries, the scientific community, and conservation

groups, and whose task is to formulate policy on marine resources, set 7/8"

across the hinge as the minimum size limitation on harvested clams.

With the accelerating interest in the management of the clam fishery in

the Indian River, a scientific basis for formulating policy is needed. The

answers to fundamental questions, such as what types and numbers of shellfish

presently occupy the river bottom, are unknown or exist in a diverse array of

fragmented and unpublished literature. Another, more germane (from the

standpoint of formulating a sound management program) question is: does

competition for food by non-commercial shellfish influence the production of

commercial shellfish?

The primary purpose of this research was to provide data that will lead

to a better understanding of the biology and ecology of the hard clam in the

Indian River. This information is essential in the formulation of a

management plan for the shellfish industry in Brevard County, and could be

used by responsible policy-formulating parties such as the Marine Fisheries

Commission. The end product of the project is an inventory according to

numbers, sizes and densities of the dominant commercial and non-commercial

bivalve shellfish in the Indian River in southern and central Brevard County.

In addition, a thorough search of relevant unpublished reports, theses, or

population censuses was completed. Because the food source of shellfish is of.

paramount importance in determining the capacity of the estuary to support the

maximum number of hard clams, phytoplankton standing crop and primary

productivity was routinely assayed at bi-weekly and monthly intervals,

respectively.

METHOLOGY

Shellfish Populations

Sixteen benthic transects across the lagoon were established in

the sites adjacent to Grant, Melbourne and Merritt Island (Fig. 1).

The Grant site represented a conditionally approved area with a

history of heavy clam harvesting; the Melbourne location was in closed

(restricted) waters and had some relaying associated with it; the

third section in closed waters with little harvesting activity was

located between Channel Markers 99 and 100 south of the Pineda

Causeway. Initially, only the Grant and Melbourne sites were to be

sampled, with the Melbourne site serving as a control (unharvested)

area for comparison with shellfish populations from heavily harvested

Grant area. However, relaying activity by commercial fishermen from

the closed waters at the Melbourne site became prevalent beginning in

December, 1984, violating our conditions of a non-harvested site.

After petitioning the Department of Natural Resources, Bureau of

Marine Resource Regulation and Development, for two exclusion zones

(one at the Melbourne site and the other near the Pineda Causeway),

the Department excluded the two areas from all future relay permits

beginning February 20, 1985.

Four transects were sampled at stations of 200 m intervals at

each site, producing 8 to 11 sampling stations along each transect.

Transects were sampled on a fixed rotating basis: Transect A was

sampled first at all sites beginning with the Grant site and ending

with the Merritt Island site, then Transect B. etc. Shellfish

sampling commenced on April and ended July, 1985.

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Figure I.' Location of 'the four bivalve sampling transects (A, C and D) at each of
the three areas in the Indian River: Merritt Island (upper left), Melbourne
(upper righl), and Grant (bottom).

A 1/4 m2 open-ended drum with a 10 cm wide fluorescent strip and

a bevelled edge was pushed to a depth of 10 cm into the sediment.

Bottom substrate along with shellfish were collected with an airlift

(suction) dredge (Fig. 2) with the assistance of SCUBA equipped

divers. The hydraulic suction dredge operates by a Briggs and

Stratton 5 h.p. gasoline engine attached to a pump'which generated a

water flow through the intake. The outflow passes through a long

hose leading to a suction control valve which regulates the force of

water transmitted to a reduction nozzle in the suction head, which

according to the Venturi principle, the flow of the water is

accelerated and the pressure below the nozzle falls creating suction

on the suction hose. Consequently, a sample is airlifted through the

hose and collected into a 2 mm mesh bag, This technique has been

reported to be nearly 100% efficient and was not size selective for

Mercenaria mercenaria >5 mm long (Peterson et al. 1983). All samples

were stored frozen prior to analysis. Sorting of the benthos samples

was done by sieving them through a 2.8 mm screen sieve (U.S. Standard

No. 7) and collecting the bivalves from the shell fragments and

debris. The screen size above was chosen as appropriate considering

the number and size of the samples, but still allowed a realistic

sieving time.

All live shellfish retained by the 2.8 mm mesh sieve were

identified using Abbott (1974), Lindner (1975), and The Audubon

Society (1981). They were then enumerated and measured along the

longest anteroposterior axis to the nearest 1.15 mm using vernier

SUCTION
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VALVE
Pump
Ar' and motor

Suction head with
Wlecting bag UdiKfian noxxit

SUCTION (FLEX)
ROSE
Intake

Figure 2,- Airlift suction dredge.

calipers. The total wet weight of subsets of approximately five

Mercenaria and 20 Mulinia clam s from each 10 mm incremented size

range (10 and two size classes for Mercenaria and Mulinia,

respectively) were determined prior to drying the meat at 800C to

determine shell length-dry weight relationships. The total dry meat

weight for each size class was determined from the total individuals

and median length of each size class.as predicted by the regression

equations of the log transformed data from the measured subset.

Non-linear regression and one-way ANOVA analyses were performed on a

PRIME computer using a MINITAB program.

Chlorophyll a

Phytoplankton sampling was initiated in the Indian River lagoon

along two east-west transects, one in open water, the other in waters

closed to shellfishing. The "open water" transect was adjacent to

Channel Marker 28, between the towns of Grant and Valkaria. The

transect in closed water is approximately 1500 m south of the

Melbourne Beach municipal pier at the Melbourne site. Water samples

were collected semi-monthly from the eastern, center, and western

sections of each transect. Two hundred and fifty ml of water were

filtered through a 0.45 4m cellulose nitrate filter. Two drops of a

saturated MgC03 solution was added during filtering to inhibit

chlorophyll degradation. The filter plus retentate was placed in a

vial containing 10 mL of 90% acetone, and held in the dark at OOC for

12-18 hr. The vials were then centrifuged, the supernatant collected

and adjusted to a volume of 10 mL, and fluorescence measured on a

Turner fluorometer. Each reading was corrected for phaeophytin

concentration.

Salinity and Water Temperature

Water temperature and salinity were measured at the six stations

in the lagoon at the time of each chlorophyll a water sampling.

Phytoplankton Species

Unconcentrated phytoplankton from the center station at each

transect was preserved with buffered formalin at a 4% final

concentration. The samples, collected semi-monthly are archived so

that identifications can be made if additional monies or assistance
become available. Primary Productivity

Monthly measurements of phytoplankton productivity were

conducted beginning in November. Water samples from the central

stations along each transect were collected from two depths (0.25 m

and,'.0'.25 m) at Grant and three depths at Melbourne (0.4 m, 1.4 m, and

2.5 m). The 2.5 m depth for Melbourne was not included until af ter

the March sampling trip. These waters were placed in triplicate

(surface waters) or duplicate (subsurface waters) light and dark
glass bottles (300 ml), inoculated with 2.5 pcurie NaH14 C03, and

incubated for 2-4 hours at their respective depths (0.25 and 1.4 m).

At the end of the incubation period, the sample bottles were placed

in a dark cooler on ice. A 250 ml aliquot of water from each bottle

was filtered through a 0.45 m filter within one hour. The filters

were transported to the laboratory, fumed over concentrated HU to

remove unincorporated NaHC03, and placed in vials containing 10 ml of

Amersham scintillation cocktail. Samples were counted with a Searle

Mark III LSC at a counting efficiency >80%. Available inorganic

carbon in the water at each site was estimated from total alkalinity,

PH, salinity and temperature measurements (Strickland and Parsons

1972).

Phytoplankton productivity was calculated using the expression:

mg C M-3 h-1 (R)(W)(1.05)/(R)(N) (1)

where R = dpm's counted (dark blank subtracted)
W = total available inorganic C per m-3.
1.05 = preferential uptake factor 12C:14C.

R = dpm's added as inoculum.

N = incubation time in hours.

Total solar insolation at the water's surface was estimated

using an Epply pyroheliometer located at the HBF laboratory, which is

50 km south of the experimental site.

Morning and afternoon productivity incubations (ca 3-4 hr each)

were conducted on each sampling date in order to provide a direct

measurement of carbon fixation during the bulk of the daylight hours.

The coefficient of variation for 84 separate primary productivity

incubations (each incubation in either duplicate or triplicate)

ranged from 0 to 14.4Z with an average of 13.97, A ratio of incident

solar radiation during the incubations (Iexp) to total daily
insolation (Itot) was calculated from an intergrated record of

incident solar radiation measured with an Epply pyroheliometer.

pyroheliometer. Daily productivity was obtained by multiplying the
ratio Itot/Iexp by the quantity of carbon fixed during the

experimental period, assuming a linear relationship between incident

solar radiation and carbon uptake by phytoplankton in the water.

Measurements of carbon fixed per unit volume of water were

converted to integrated water column (areal) rates as follows. At

Grant,, the 1.5 m deep water column was partitioned into two equal

sections, 0.75 m in depth. Carbon fixation (PS) measured at a depth

of 0.25 m was chosen to represent average productivity in the top

section of the water column, while carbon fixation (Pb) measured at a

depth of 1.4 m was used to represent average productivity of the
bottom of the water column. Areal fixation (i.e., mg C m-2 hr-1) was

thus calculated as (Ps + Pb) (0.75 m), with Ps and Pb expressed in mg
C M-2 hr-1. At the deeper (3 m) Melbourne site, the water column was

partitioned into three sections: 0-1 m, 1-2 m, and 2-3 m (for April

to October). Average carbon fixation in the surface section was

estimated with bottles incubated at 0.25 m (Ps); carbon fixation in

the middle section was estimated with bottles incubated at 1.4 m

(Pm), and carbon fixation in the bottom section was estimated with

bottles incubated at 2.5 m (Pb). The integrated water column rates

at Melbourne were thus calculated by the expression (Ps + Pm + Pb)

QUALITY ASSURANCE

This section presents the results of seven separate plankton

experiments designed to test extraction efficiency, spatial and

temporal variability, instrument calibration, and primary

productivity methodology.

Filter Pore Size and the Effects of Grinding on the Efficiency

of the Chlorophyll a Analysis

Two short-term experiments were conducted to determine whether

improvements on the filtration and extraction techniques for

phytoplankton could be made. In the first experiment, a grinding

step was added to the procedure in order to determine whether we

were obtaining "complete" chlorophyll a removal from the

phytoplankton. Triplicate one liter samples were collected from two

stations in the river. Separate 250 ml aliquots from each bottle

were filtered. One set of filters was ground for two minutes (in

90% acetone) using a hand operated glass tissue homogenizer. The

companion set of filters was not ground. Both sets of filters were

placed in the dark for 12 hours for further extraction.

Fluorescence of the extracts was determined as described above,

Grinding neither increased chlorophyll a yields, nor improved the

precision of the method (Table 1). Although grinding is typically

recommended for chlorophyll a analyses when short (ca. I hr)

extraction times are utilized, it does not appear necessary with the

12-18 hr extraction period as used in this study.

Table 1. Effect of phytoplankton grinding on chlorophyll a
extraction. Six aliquots were taken from each sample; three were
ground following filtration.

SAMPLE GROUND NOT GROUND

........ chlorophyll a, (mg M-3 ), X (s.d.), n=3 .....

1 72.3 (8.4) 73.2 (8.0)

81.7 (3.6) 77.6 (4.1)

A second experiment was conducted to determine whether small

phytoplankton, in the size range 0.45 to 0.1 um, contribute

substantially to total chlorophyll a concentrations in the lagoon,

and are not part of the retentate trapped on the 0.45 um filter

routinely used in this study. Four 250 ml aliquots of river water

were filtered first through a 0.45 um filter, and then through a 0.1

um cellulose nitrate filter. Chlorophyll a was extracted from

filters using 90% acetone, and fluorescence was measured as

described above. Phytoplankton larger than 0.45 um were found to

comprise the bulk of the microalgal standing crop in the water

column at both sites in the Indian River lagoon (Table 2).

Phytoplankton in the size class of 0.45 um were responsible for only

0.3 - 0.5% of the total chlorophyll a concentration in these waters.

Table 1. Standing crop (chlorophyll a concentrations) of Indian
River lagoon phytoplankton of two size classes: greater than 0.45
um and 0.45 to 0.1 um.

SAMPLE > 0.45 um 0.45 -0.1 um

........ chlorophyll a (mg m-3 ) .......

Ia 19.5 0.06

b 30.3 0.08

IIa 7.2 0.04

b 6.4 0.03

Surface vs. Deep Water Chlorophyll a Concentrations

On eight occasions between November 1984 and March 1985,

shallow (0.1 m) and deep (1.4 m) water samples were collected from

the central station of either the Palm Bay or Grant transects.

Chlorophyll a concentrations were determined by fluarometry, and

differences in shallow water and deep water pigment concentrations

were evaluated using a t-test of paired comparisons.

No difference (P = 0.20) was found between chlorophyll a

concentrations of shallow (0.1 m) and deep (1.4 m) waters at

individual sampling sites during this study (Table 3). Because

similar pigment concentrations were found with depth under a range

of wind conditions, and at both high and low pigment concentrations,

we conclude that the Indian River lagoon at these sites is

vertically well mixed during the fall and winter months.

Table 3. Chlorophyll a concentrations of shallow (0.1 m) and deep
(1.4 m) waters at individual sampling sites in the Indian River
lagoon. Samples were collected between 14 November 1984 and 12
March 1985 at both Grant and Melbourne sites.

DEPTH
0.1 .m....... chlorophyll a (mg M-3) ........ 1.4. m

17.3 18.7

7.8 6.6

67.9 66.6

25.4 28.1

15.6 15.0

19.7 10.7

15.5 15.1

18.8 10.7

Sediment Pigment Concentration and Sediment Density

Sediments at Grant and Melbourne were compare d with respect to

pigment concentrations and densities. On 28 February

1985, seven sediment cores (3.8 cm diamter X 20 cm deep) were

collected from the central station of each transect, placed on ice,

and transported to the laboratory. Each core was extruded and the

top 1 cm removed with a knife. For three of the cores from each

site, this fraction was dried (48 h at 700 C) and weighed for the

determination of sediment bulk density. Each of the remaining four

core fractions was ground for one minute in a mortar containing 10

ml of 107 acetone and two drops saturated MgC03 solution. The

sediment-acetone slurries were poured into wide mouth plastic tubes,

which were then held in the dark at 00 C for 18 hours. The

fluorescence of a 5.0 ml aliquot from each tube was measured on a

Turner fluorometer. Chlorophyll a and pheophytin concentrations

were calculated according to Strickland and Parsons (1972).

Grant an& Melboune lagoon bottom sediments differed markedly in

physical and chemical characteristics. Melbourne sediments were
unconsolidated and silty (0.7 + 0.5 g cm-3 bulk density), whereas

the sediment at Grant consisted primarily of sand particles (1.8 +
0.2 g cm-3). Chlorophyll a and pigment degradation product

(pheopigment) concentrations in the sediment were seven times higher

at Grant than at Melbourne (Table 4). The sediment at the shallower

Grant site is well within the euphotic zone (bottom light intensity

is ca. 107 of surface light intensity), so it is possible that

benthic microalgae account for a portion of the high sediment

pigment levels at this site. Benthic diatoms, for example, commonly

occur in sandy sediments in temperate estuaries (Tietjen, 1968).

However, the live chlorophyll a to total pigment ratio in the Grant

sediments was quite low, and did not differ from that at the Melbourne

site (Table 4).

Unlike the sediments, the bulk of the photosynthetic pigments

in the water column consisted of "live" chlorophyll a (Table 4).

The higher water column chlorophyll levels at Melbourne, expressed

both in concentration (wt/vol) units and as per unit area of river

Table 4. Photosynthetic pigment concentrations in the sediment
(wt/wt) and water (wt/vol) at two locations in the Indian River
lagoon on 28 February 1985.

SEDIMENT! WATER-2

Grant Melbourne Grant Melbourne

... pigment (ug/g) ... ... pigment (ug/1) ...

Chlorophyll a 0.27 (0.07) 0.04 (0.03) 5.2 (1.3) 20.7 (3.6)

Pheophytin 2.63 (0.81) 0.34 (0.10) 2.0 (0.5) 6.5 (1.8)

Total Pigment 2.90 (0.85) 0.38 (0.12) 7.2 (1-8) 27.1 (5.4)

----------- %------------- --------- % -----------

Chl a/Total 9.4 (2.4) 8.4 (5.6) 72.8 (0.2) 76.3 (1.8)
Pigment --- pigment (mg/m2)--- --- pigment (mg/m2)---

Chlorophyll a 4.9 0.3 7.3 62.1

Total Pigment 52.2 2.6 10.1 81.3

1x, (s.d.), n 4
2x, (s.d.), n 2

surface (wt/area)(Table 4), suggests that phytoplankton (and hence,

pigment) deposition at this site is greater than at Grant. The

resulting lower sediment pigment levels at Melbourne indicates that

the deposited material decomposes at this location more rapidly.

The Effect of Incubation Time on 14C Uptake Rates

Phytoplankton productivity estimates by the 14C technique are

typically conducted with waters incubated in small glass or

polycarbonate bottles for a period of time ranging from I to 24

hours. Long incubation times (e.g., sunrise to sunset) have the

advantage of permitting direct measurement of daily phytoplankton

production (Williams et al.1983). However, many investigators have

observed that the enclosure of algae in small static volumes for

long time periods does not provide a true measure of in situ C

fixation, since interference from pH drift, carbon depletion,

bacterial proliferation on the bottle walls, and even changes in

algal species composition can occur.

On 20 December 1984, a study was conducted to determine whether
the 4 hour 14C incubations, as utilized in this study, were subject

to "bottle effects". Carbon fixation rates of phytoplankton in

lagoon waters over a 4 hr period were measured using a 4 hr

incubation period and two lesser timed incubation periods, which

when added, each totaled 4 hrs of incubation. One set of three 300

ml glass bottles was filled with Indian River water, inoculated
with 2.5 @icurie NaH14 C03, and placed at a depth of 0.25 m in a

concrete tank containing 700 L of lagoon water. These bottles

were incubated from 1100 to 1500 h. The same 4 hr incubation was

accomplished with lagoon water contained in another two sets of

bottles (3 per set) incubated 2 hr each, from 1100-1300 h and

1300-1500 h. An additional four sets of bottles (3 per set) were

incubated over the same 4 hr period, at one set per hour. The

contents of all bottles were filtered immediately upon removal from

the water. Light bottle carbon fixation rates, alkalinity and

chlorophyll a of the river water was measured by methods previously

described. Corrections for dark bottle carbon uptake were not made,

but were assumed from prior experience to be slight (ca. 5% of total

C fixed). Differences in total quantity of carbon fixed over the 4

hr period using the three incubation times were tested for

statistical significance using a one-way ANOVA.

Carbon fixation over a 4 hour period was found to be slightly

higher with one, 4 hour and two, 2 hour incubation times than with

four, 1 hr incubations (Table 5). These differences, however, were

not significant (P = 0.15). Hence, the 3 - 4 hour long morning and
afternoon 14C incubations in the present study are probably not

subject to deleterious '.'bottle effects".

Table 5. Phytoplankton production over a 4 hour period in 300 ml
glass bottles as measured using one hour (I + I + I + 1), two hour
(2 + 2) and four hour (4) incubation times.

Incubation time Incubations/4 hr. Carbon fixed/4 hr periodl
(hr.) -------- mg: C/M3 ---------

1 4 23.7 (1.2)

2 2 25.1 (0.6)

4 1 25.2 (0.7)
------------------------------------------------------------
1 x, (s.d.) n = 3

Comparison' of 14C Uptake and 02 Evolution Techniques in Measuring
Primary Productivity

An experiment was conducted to compare phytoplankton
productivity measured by the 14C technique with net and gross

productivity as measured by the 02 evolution technique. Coincident
with the morning 14C incub@ations on 8 January and 30 July 1985,

oxygen changes in duplicate bottles containing Grant and Melbourne

waters were measured using the Winkler method (APHA, 1971). Net
primary production (as mg 02 m- 3 hr-I ) was calculated from the

change in oxygen concentration in the light bottles during the

incubation period. Respiratory oxygen consumption (measured in dark

bottles) was added to light bottle oxygen changes to provide a

measure of gross primary production. Oxygen evolution rates were

converted to carbon uptake rates by multiplying by the factor 0.3 ug

C fixed/1.0 ug 02 evolved (Ryther 1956), which accounts for the

difference in atomic (molecular) weights of C and 02, and assumes a

photosynthetic quotient of 1.25.

The comparison between productivity measured by the 02
evolution and 14C uptake techniques in this study showed that the

latter method more closely approximates "net" than "gross"

productivity (Table 6), a finding in agreement with most previous

studies (Ryther 1956).

Table 6. A comparison of ductivity by Indian River
primary ro
phytoplankton as measured by the @4C uptake and the 02 evolution
techniques.

DATE LOCATION 14 C METHOD 22 METHOD

Net Gross

----- Productivity (mg Cm-3 hr-1 ) ----

01/08/85 Grant 79.6 + 9.2 105 + 10 111 + 3

Melbourne 67.6 + 14 60 81

07/30/85 Grant 181 + 14 195 + 22 234 + 29

Melbourne 230 + 19 103 + 11 114 + 13

The 02 evolution technique should not be use in either

ultra-oligotrophic waters, because of the method's low sensitivity
[3 mg C m-3 hr-1 I (Riley and Chester 1971), or in grossly

eutrophic waters, because of interference from high bacterial

respiration. With the exception of Melbourne on 30 July 1985,

Indian River phytoplankton productivity appears to be in a range

which can be accurately measured by the simpler and less expensive

02 evolution technique.

EPA Quality Control Samples
For Fluorometric Analyses of Chlorophyll a

Reference samples for chlorophyll a obtained from EPA were used

for instrument calibration and verification of the calibration. The

'Icheck solution" containing 16.7 ug/L of chlorophyll a and -0.1 ug/L

pheophytin a measured 17.1 ug chlorophyll a and 0.5 ug pheophytin a

per L, well within the confidence limits stated by EPA; agreement

was within 98% for the chlorophyll a solution.

Bivalve Taxa

Bivalves whose appropriate taxonomic position was uncertain

were identified with the help of R. Tucker Abbott, a noted

malacologist.

RESULTS AND DISCUSSION

Salinity and Temperature

Salinities at Grant were greater than at Melbourne (Table 7) because of

the closer proximity of Grant to an ocean inlet and the more numerous

freshwater inputs in the Melbourne area. At Grant, salinities ranged from

150/oo (immediately after the Thanksgiving Day storm) to 360/oo with a mean of

25.80/oo (s.d. + 6.20/oo); the range was 130/oo to 280/oo at Melbourne and a

mean of 22.3% (s.d. + 4.3). Unlike salinity, water temperature did not differ

between the two sampling areas (Table 8). The minimum water temperature was

110C on 11 January 1985; the highest was 32.50C on 30 July 1985.

Chlorophyll a

The annual average chlorophyll a concentration 1 s.d.) was roughly 30%
lower at the Grant site (21.1 + 21.7 mg M-3) than at Melbourne (29.4 + 20.0 mg
M-3); the difference was significant (p<0.05). Chlorophyll a concentrations of
the water at the Melbourne site ranged from 6.7 to 108 mg m-3, whereas

chlorophyll a concentrations at the Grant site exhibited a slightly narrower
range (4.3 to 99 mg m-3) (Table 9). Wide variation among the east and west

edge and one center sampling station within each site occurred on some sampling

occasions (Table 9). However, over the entire study year, there were no

statistically significant differences among sampling sites within each

transect.

The Environmental Resources Division of Brevard County has collected

monthly chlorophyll a data at numerous stations in the Indian River lagoon

since 1980. Two of these stations, one at Channel Marker 14 (near Turkey

Creek, in Melbourne) and the other at Channel Marker 32 (near Grant), are close

Table 7. Salinity along two transects in the Indian River. W, C, and E designate
the west, central, and east stations, respectively.

DATE GRANT MELBOURNE
W C E W C E

................. Salinity (ppt) ....................

10/18/84 23 23 23 20r 20 19

10/31/84 26 26 26 20 20 20

11/14/84 18.5 18.5 17.5 17 18 17

11/28/84 15 15 16 14 14 13

12/11/84 18.5 18.5 18.5 20 20 20

12/27/84 22 21 21 17 18 17

01/08/85 22 22.5 22 21.5 20 20

01/24/85 20 19.5 19.5 19 19 19

02/14/85 22 20 20 17 17 21

02/28/85 25 23. - 21 23 22

03/12/85 34 34 35 27 26 27

03/28/85 35 34 35 27 26 27

04/18/85 25 24 24 17 25 24

05/02/85 35 35 27 35 24 25

05/16/85 36 34 36 27 28 26

06/06/85 30 30 30 24 24 24

06/20/85 30 29 29 27 26 24

07/02/85 33 34 33 26 26 26

07/30/85 30 29 30 28 29 28

08/16/85 32 31 32 27 26 27

09/03/35 25 26 26 22 21 24

09/24/85 15 22 23 22 21 20

10/15/85 - 21 - - 19 -

Table 1, Water temperature along two transects in the Indian River, W, C, and E
designate the west, central, and east stations, respectively.

DATE GRANT MELBOURNE
W C E W C E
................. Temperature 0C....................

10/18/84 27 27 27 27 27 27

10/31/84 25 25 25 25 25 25

11/14J84 19 19 19 19 19 19

11/23/84 22 22 22 22 22 22

12/11/84 17.5 17.5 18 17 17 17

12/27/84 23 23 23 23 22 22

01/08/85 16.5 16 16 16 16 16

01/24/85 11 11 11 11 11 11

02/14/85 13 12.5 12.5 13 13 12

02/28/85 22 22 22 22 21.5 21.5

03/12/85 23.5 23 23 23.5 23 23

03/23/85 20.5 21 21 20.5 20 20

04/18/85 24 23 24 24 23 23

05/02/85 25 25 25 25 24 25

05/16/85 28 28 28 28 28 29

06/06/85 29 29 29 29 29 20,

06/20/85 30 30.5 30.5 30.5 30.5 30

07/Q2/85 30 29.5 30 29.5 29.5 29.15

07/30/85 31.5 32.5 32 32 31.5 32

08/16/85 30 29.5 30 29.5 30 29-50

09/03/35 30 29 29 29 29 29

09/24/85 28 23 28 28 27.5 27

10/15/65 - 27 - - 28 -

Table 1, Chlorophyll a concentrations along two transects in the Indian River,
Florida. W, C, and E designate the west, central, and east stations,
respectively.

DATE GRANT MELBOURNE
W C E W C E

1 -3
............. chlorophyll a, mg m ....................

10/18/84 11.1 12.0 10.9 30.3 24.2 27.0

10/31/84 22.4 20.9 26.9 48.7 50.9 63.9

11/14/84 19.8 25.4 24.3 37.4 67.9 35.8

11/28/84 99.2 73.2 89.2 67.2 77.6 70.4

12/11/84 6.4 7.8 7.1 13.6 17.3 10.2

12/27/84 8.6 6.8 5.9 31.4 24.9 16.1

01/08/85 14.7 15.3 13.5 15.6 16.1 10.4

01/24/35 34.0 46.4 64.5 72.4 56.0 60.0

02/14/85 7.7 13.4 13.6 13.5 16.0 9.5

02/28/85 6.1 4.3 8.1 18.1 23.2 -

03/12/85 20.2 15.5 15.5 18.1 15.6 35.6

03/28/85 14.9 13.1 12.6 17.6 5.4 16.6

04/18/85 9.6 13.4 8.3 29.2 32.5 30.5

05/02/85 6.3 11.2 6.7 14.9 11.2 11.2

05/16/85 11.0 14.4 13.9 32.7 18.3 26.0

06/06/85 15.5 16.1 19.8 19.3 12.8 19.3

06/20/85 55.4 79.6 55.4 79.4 108.3 62.6

071102/85 17.1 18.2 15.0 17.1 19.3 12.8

07/30/85 20.3 19.0 20.1 14.4 12.3 19.5

08/16/85 17.7 17.7 16.1 20.3 9.1 6.7

09/03/85 17.4 17..4 18.5 40.6 23.0 23.8

09/24/85 9.1 18.7 15.0 18.5 23.0 i9.8

10/15/35 - 9.9 - - 20.3

to the transects selected for phytoplankton and bivalve inventories in this

study. Their data for these sites show seasonal variations in chlorophyll a,

with maxima occurring between June and December (Fig. 3). These trends are

similar to those found to date in the present study (except for January).

Mahoney and Gibson (1983) attributed such pulses in chlorophyll a in the Indian

River lagoon to heavy rainfall events, and the associated release of

nutrient-laden fresh waters to the lagoon from nearby agricultural operations

and urban areas. While this may be the causative reason for some of the

phytoplankton maxima observed in our study, it does not explain all of the

phytoplankton,peaks. The maxima associated with the 28 November 1984 and 20

June 1985 sampling dates (Fig. 4) were preceded by 5.64 and 3.31 inches of

rain, respectively, eight days before sampling (F. Doehring, pers. commun.;

rainfall data collected at the Port Malabar sewage treatment plant, which is

approximately mid-way between the two transects). However, the chlorophyll a

peak on 24 January 1985 was not associated with any major rainfall events, nor

did the heavy rain (6.2 inches from 18 to 21 September 1985) produce high

chlorophyll a concentrations preceding 24 September 1985 sampling date.

Relative to previous studies in the Indian River region, the average
chlorophyll a concentrations of 21 to 29 mg m-3 found in the present study are

high. Mahoney and Gibson (1983) reported average chlorophyll a concentrations
in the Vero Beach area of 4.0 mg M-3 during the months October through

December. Mean annual chlorophyll a concentrations reported in the Brevard
County study ranged from 9 to 26 mg m-3 (Table 10), and the statistically

insignificant between-site differences (except for 1982) for annual chlorophyll

45-

35-

CV)
30-
E

Cn j
25- it
0
co

Z 20-

9
2
15

10
6L

5
'd

JJJA-LLLL" L A II
1980 1981 1982 1983 1984 1985
YEAR

Figure 3. Monthly con'centrations of chlorophyll 4 in the Indian River lagoon at Melbourne (closed circles)
and Grant (open circles) between 1980 and 1985 (data provided by Conrad White and Bob Day of
0

Brevard County Water Resources Dept.

90-

80-

70-

50- 1

co I

0 40-

30-

IItI
20-

NOV DEC JAN FES MAR APR MAY JUN JUL AUG SEP OCT

M 0 N T H
Figure 4. mean chlorophyll a concentrations (mg m-3 +1 S.E. along transects
'T

at Melbourne (clo-sed circles) and Grant (open circles).

Table 10. Annual mean (+ 1 s.d.) chlorophyll a concentrations for Station 1 10 at
Melbourne and7Station 1 11 at Grant7from 1980 to 1985. Data provided
by Conrad White and Bob Day of the Brevard County Water Resources Division.

1980 1981 1982 1983 1984

Melbourne 16 + 2 14 + 6 26 + 9 13 + 7 12 + 9

n = 10 n = 12 n = 12 n = 12 n = 11

Grant 16 + 10 18 + 7 14 + 5 12 + 7 0 + 6

n 9 n 12 n__=-. 12. n 12 n 12

a concentrations in the Brevard County study is contrary to the significant

differences of our 1985 data. Higher chlorophyll a concentrations would be

expected in Melbourne because of its proximity to several sewage treatment

outfalls and urban runoff.

There is no trend of increasing chlorophyll a concentrations in the lagoon

from 1980 to 1984 since there was not a significant difference between

chlorophyll a levels between those two years at the Melbourne station. At

Grant the chlorophyll a concentration was actually significantly lower in 1984

than 1980.

Boynton et al (1982) reported that annual mean chlorophyll a
concentrations in 39 estuaries ranged from near zero to 24 mg m-3, with the
majority (34 out of 39 estuaries) 15 mg m-3 or less. Based on our data,

chlorophyll a concentrations in the Indian River lagoon are thus high compared

to other estuarine systems.

Primary Productivity

Morning incubations usually yielded higher primary productivity rates than

did afternoon incubations at both sites (Table 11), probably due to the morning

incubation period being closer to mid-day than the afternoon incubation. Based

on the volumetric primary productivity rates presented in Table 12, surface

(0.25 m) and subsurface (1.4 m) waters from Melbourne had significantly higher

rates than at Grant for 18 of the 40 incubations; only two of the 40

incubations produced higher productivity rates at Grant than Melbourne. The

productivity rates for the bottom (2.5 m) waters at Melbourne (data not shown)
were. low (4.7 to 48 mg C m-3 h-1), as expected due to light limitation.
Not only was Melbourne productivity higher on a volume (m-3) basis (Table

12), but the greater"depth of the water at this site further increased the

difference between Melbourne and Grant productivity on an areal basis (e.g.,

Table 11. Depth integrated phytoplankton productivity at two sites in the
Indian River. Both morning and afternoon incubations were conducted
at each site, except on 15 October 1985 when one-six hour incubation
elapsed both morning and afternoon times.

DATE MELBOURNE GRANT

a.m. ' P.m. a.m. p.m.
--------- Productivity (mg C M_ 2 hr-1)--------

11/14/84 186.0 - 88.7 -

12/11/84 77.8 92.9 21.6 16.9

01/08/85 133.4 122.9 97.7 90.4

02/14/85 193.6 165.2 67.6 116.0

03/12/85 137.0 112.2 91.8 51.1

04/18/85 207.4 161.4 71.3 48.4

05/16/85 91.8 74.3 29.7 28.8

06/20/85 371.8 121.5 348.7 96.0

07/30/85 374.2 147.5 212.3 27.9

09/03/85 230.0 433.6 258.5 312.0

10/15/85 419.6 215.3

Table 12. Phytoplankton productivity at two sites in the Indian River lagoon. Values represent average carbon
uptake (mg C ni-311-1) + I s.d. in a 3 hr in situ incubation during morning and afternoon incubations
for surface (0.25 m depth) and subsurface (1.4 in depth) waters.

Melbotirne- Melbourne Crant Crant
Silyface Subsurface Surface Subsurface

Date a.m. p.m. a.m. p. m. a.m. p.m. a.m. p.m.

11/ 4/84 118.3 + 27.3 46.3 + 26.3 --- 85.7 + 19.6 --- 32.5 + 0.0

12/11/84 44.0 + 1.4 52.0 + 1.7 25.8 + 3.4 31.5 + 0.4 15.9 + 1.5 13.9 + 0.3 13.0 + 1.1 8.7 + 0.1

LO
01/08/85 67.6 + 2.4 63.4 + 9.4 53.4 + 2.1 48.0 + 1.1 79.6 + 9.2 55.5 + 2.5 50.6 + 7.8 27.5 + 3.6

02/14/85 108.3 + .22.3 88.5 + 14.9 65.7 + 35.6 60.7 + 2.5 56.4 + 8.4 95.6 + 14.0 33.7 + 10.8 59.1 + 8.7

03/12/85 77.7 + 11.5 71.9 + 5.9 45.2 + 1.4 13.0 + 2.2 93.5 + 9.7 52.0 + 6.4 28.9 + 4.5 16.1 + 2.3

04/18/85 140.4 + 17.6 100.4 + 1.9 70.1 + 33.5 32.9 + 18.6 69.8 + 5.3 29.8 + 2.3 45.2 + 1.1 14.7 + 1.8

05/16/85 61.2 + 4.9 43.7 + 4.2 30.9 + 1.1 20.9 + 1.2 22.0 + 5.6 20.8 + 2.3 24.7 + 0.8 10.7 + 1.2

06/20/85 132.0 + 0.9 108.1 + 0.9 204J + 0.4 12.0 + 0.4 302.3 + 42.8 117.2 + 41.0 162.6 + 10.2

07/30/85 229.8 + 18.6 139.3 + 1.8 1.11.5 + 3.3 2.9 + 1.3 181.2 + 13.8 31.3 + 3.1 01.9 + 12.6 5.9 + 3.8

09/03/85 120.9 + 3.5 302.8 + 49.0 88.7 + 2.5 106.2 + 33.6 200.8 + 12.1 282.0 + 27.6 44.0 + 36.0 134.2 + 7.8

10/15/85 258.3 + 24. 0 113.2 + 1.5 4 -212.2 12.1 vp 4 74.9 19.2 10

----------- .........

Tab le 13). Light extinction measurements show that the entire water column

(3 m) at Melbourne is usually in the euphotic zone, assuming that

photosynthesis occurs down to a depth limit of 1% of surface light intensity.

The higher phytoplankton productivity (and standing crop) at the Melbourne site

may be a result of the greater nutrient loading to the lagoon at this site.
The phytoplankton productivity in the lagoon ranged from 0.16 g C/m2-day
(Grant, December) to 3.7 g C/m2-day (Melbourne, October), and averaged 1.08 and
1.85 g C/m2-day for Grant and Melbourne, respectively (Table 13). The wide

range in productivity observed in the Indian River lagoon during the 12 months

of sampling is probably typical, where fluctuations in light, temperature, and

rainfall affect primary production. The average daily primary productivity at

Melbourne was significantly higher (p<0.05) than the average productivity rate

for the waters at Grant.

The photysynthetic rates are high: the chlorophyll-normalized rates of

carbon fixation ranged from 1.1 to 21.4 (mean of 6.0) with many of the monthly

assimilation ratios comparable to maximum ones observed for cultures (Glover

1980). There were no major differences in assimilation ratios between the

Melbourne and Grant sites. The high variability in the monthly assimilation

ratios (coeff. variations of 76% and 96% for Melbourne and Grant, respectively)

over the eleven month sampling period is to be expected since assimilation

numbers vary as a function of nutrient regime, temperature, cell size, and

light history (Falkowski 1981). Boyton et al. (1982) found that the average
seasonal productivity ranged from near zero to 2.5 g C/m2-day for 45 mostly

temperate estuarine systems, with the mean of all annual average rates being
0.52 g C/m2-day. The mean primary production rates from both Grant and

Melbourne waters are well above the average for all estuaries, clearly

Table 13. Daily phytoplankton productivity at two sites in the Indian River..

DATE MELBOURNE GRANT

----- Productivity (9 C m day

11/14/84 1.55@ 0.74

12/11/84 0.70 0.16

01/08/85 1.12 0.82

02/14/85 1.50 0.77

03/12/85 1.20 0.70

04/18/85 1.86 0.61

05/16/85 0.81 0.29

06/20/85 2.67 2.37

07/30/85 2.43 1.12

09/03/85 2.79 2.41

10/15/85 3.72 1.91

indicat'ing that the Indian River lagoon is a very productive estuary. In fact,

the average daily phytoplankton production for Melbourne waters (1.85 g
C/m2-day) is the highest reported rate for any estuary; primary productivity at

Grant is only superceded by four of the 45 estuarine rates provided by Boynton

et al. (1982).

Monthly fluctuations in volumetric productivity rates for the surface

waters at the center stations of the two sampling sites appear unrelated to

changes in phytoplankton standing crop. The coefficient of determination for a

simple linear correlation between chlorophyll a and productivity at the Grant
site was low (r2 = 0.30). For Melbourne, the coefficient of determination was

zero. Chlorophyll a concentrations have been found to be a good indicator of

temporal and spatial variations-in daily photosynthetic rates in certain

freshwaters (Megard 1972) and estuaries (Boynton et al. 1982), but the

distribution of production was not similar to that of chlorophyll a in our

study.

Diversity

Only nine bivalve taxa were collected and identified during the entire

study (Table 14). with Mulinia lateralis (coot clam) making up 98 percent

(53,351 individuals) of the total number. Mercenaria mercenaria (hard clam)

was the second most abundant species (464 individuals) collected, but was

present in the bivalve community only 1 percent of the total number. This low

diversity is contrary to the higher bivalve diversity of previous mollusk work

done in the Indian River (e.g., Applied Biology, Inc. 1980; Brevard County

1975; Reish and Hallisey 1983; Virnstein et al. 1983; Y6ung and Young 1977).

Also Mercenaria mercenaria was reported in only two (Applied Biology, Inc.

1980; Virnstein et al. 1983) of the eight studies which presented a bivalve

species list (see Appendix A for annotated bibliography on bivalve and

hytoplankton of the Indian River). The higher diversities and absence of

Mercenaria mercenaria from the earlier studies may have been from: (i) a low

hard clam population and richer bivalve species present during 1973-81;

(ii) limited sampling; and/or (iii) geographical variability between sampling

locations and distribution of bivalve taxa.

Distribution and Relative Abundance

Hard clams, Mercenaria mercenaria, occurred mainly in the region near

Grant where clam harvesting has been the heaviest (Fig. 5; Table 15).
Densities averaging 36.3 per m2 (4-104 per M2) from 38 quantitative samples are

the same as the higher densities reported by Walker and Tenore (1984) for small
feeder creeks in Wassaw Sound, Georgia, and higher than the 6.4 per m2

collected at Core Sound, North Carolina (Peterson et al. 1983).

Table 14. Total number of individuals of each bivalve species collected from
110 stations (sampling area was 1/4 m2 at each station) at the

Grant, Melbourne, and Merritt Island sites.

Species Common Name Number of Individuals

Mulinia lateralis coot clam 53,351

Mercenaria mercenaria hard clam 464

Amygdalum papyrium paper mussel 152

Anomalocardia auberiana pointed venus 25

Dosinia discus disk dosinia 10

Noetia ponderosa ponderous ark 8

Parastarte triquetra brown gem clam 7

Corbula contracta contracted corbula 2

Tellina alterna alternate tellin 2

12-
11-
10-

8 MERRITT ISLAND
7
91
5
4- 1

2- 1
1- 1
I FSZ9
0

ry
LLJ 12-7

lo-
9'
MELBOURNE
D 7-
6-
5-
4'
n 3-
2-
1@ R
0_1
0

14
13
12@.
10-: 1 GRANT
9_-
8-
7-:
6-
5.:
4'
3
2
1
0
0 10 20 .30 40 50 60 70 80 90 100 110 120
TOTAL SHELL LENGTH (mm) ,

Figure 5. Differences in size (length)-frequency distributions of Mercenaria
mercenaria from the Indian River at the Merritt Island, Melbourne,
and Grant sampling sites. The vertical dashed line represen ts the
shell length equal to the minimum legal width of 7/8 inch across the
hinge allowed by Florida statute.

Table 15. Density of the hard clam, Mercenaria mercenaria, collected from three
areas in the Indian River lagoon in Brevard County, Florida. Four transects,
each transect consisting of 7 to 11 sampling stations, were sampled from each
area.

CLASSIFICATION +
SHELL LENGTH (APPROXIMATE HARD CLAM DENSITY ANALYSIS OF
(mm) SHELL LENGTH) (Individuals/m2) VARIANCE

Grant Melbourne Merritt Island

.......... + I S.E ................

2.8 - 9.9 seeds" 11.1 + 2.1 1.6 + 0.8 0.3 + 0.3 P< 0.001
10.0 - 19.9 (< 1 in.) 16.2 T 3.0 0.9 T 0.4 0.0 P< 0.001

20.0 - 29.9 "beans'l 1.6 + 0.6 0.1 + 0.1 0.3 + 0.2 P< 0.05
30.0 - 39.9 (1-1.5 in.) 1.0 + 0.6 0.3 + 0.2 0.2 + 0.1 NS

40.0 - 49.9 l'buttons" 1.8 + 0.4 0.7 + 0.6 0.4 + 0.2 NS
(1.5-2 in.)

50.0 - 59.9 "little necks" 1.8 + 0.3 1.0 + 0.2 0.6 + 0.3 P< 0.05
(2-2.5 in.)

60.0 - 69.9 "top necks" 1.6 + 0.3 1.3 + 0.4 0.7 + 0.3 NS
70.0 - 79.9 (2.5-3 in.) 0.8 + 0.3 0.7 + 0.2 0.1 + 0.1 NS

80.0 - 89.9 "cherrystones" 0.2 + 0.1 0.4 + 0.2 0.2 + 0.1 NS
(3-3.5 in.)

90.0 - 99.9 "chowders" 0.2 + 0.1 0.3 + 0.1 0.1 + 0.1 NS
(>3.5 in)

+Size classification based on a 2:1 ratio of longitudinal (i.e.,
anterior-posterior) shell length to shell thickness across the hinge as per
conversation with David Chanley, August 25, 1985,
*Probabilities of significant differences in clam density (M*- 0.05) are given
based on critical values of the F-distribution (d.f. = 2,9).
** Approximate legal minimum size for harvest (>7/8 in. across the hinge) is
longer than 44 mm total shell length.

According to Carriker (1961), a commercially exploitable density in

northern waters is 23.6 clams per m2, with dense beds yielding approximately 22
to 33 clams per m2. In comparison, for clam mariculture, 1500-3000 individuals
per m2 is considered an optimum density (M. Castagna, pers. commun., September

7, 1985). By contrast, the clam density from 38 quantitative samples taken at
Melbourne was nearly 5-fold less (average 7.4 per m2) than at Grant, and ranged
from 0 to 40 individuals per m2 (Fig. 5). Still, according to Carriker's

criterion, the clam density is sufficient to yield a commercially viable crop.

However, clams surveyed in the unharvested waters off Merritt Island (34
samples) averaged only 2.9 per m2 (range of 0 to 16 individuals per m2), and

are not dense enough to warrant commercial harvesting.

Compared to the hard clam, densities for the coot clam (Mulinia lateralis)

were considerably greater, being approximately 10-fold more numerous at Grant,

300-fold more abundant at Melbourne, and 1000-fold greater at Merritt Island

(Table 16). Significant differences in the Mulinia population existed between

Grant and Melbourne, and Grant and Merritt Island, but not between Melbourne

and Merritt Island. It is interesting that the numbers of Mulinia increased

with decreasing populations of Mercenaria among the three areas. Size-frequency

distribution is not reported for this species as its small size (<20 mm) does

not allow for such an analysis to be made.

Population Size Structure

Variation in the number of individuals among the four transects

within an area was remarkably low (e.g., coefficient of variation was 37

percent for "seeds" from Grant)(Table 15)*.* This similarity in the hard and

Table 16. Abundance of the coot clam, Mulinia lateralis, sampled from three
areas of the Indian River lagoon in Brevard County, Florida.

ANALYSIS OF
TRANSECT COOT CLAM DENSITY (Individuals/m2) VARIANCE

Grant Melbourne Merritt Island

1 216 2040 1313

2 176 3 304 .4029

3 196 2812 3696

4 292 1780 3624

X + I S.E. 220 + 25.4 2484 + 350 3165 + 624 P<0.001

*Probabilities of significant differences in clam density (a,- 0.05) are based
on critical values of the F-distribution (d.f. 2,9).

coot clam population structure among transects within an area indicated both a

uniform distribution and a thorough sampling methodology. For instance, the 4

in. harvesting depth was adequate since the number of individuals taken in

April along transect A (when the temperature was cooler and the shellfish

possibly deeper in the sediment) are not greater than they are in June

(Transect C). See Appendix B.

The mean size of clams from Grant was smaller (21 + 24 s.d. mm) than for

beds in Melbourne (44 + 39 s.d. mm) and Merritt Island (51 + 49 s.d. mm) (Table

15). Size-frequency distribution (Fig. 5) of hard clams collected at Grant,was

dominated by small clams: 85% of the total individuals sampled were less than

7/8 in. across the hinge ( 44 mm total shell length), the minimum size for

legally harvestable clams in Florida. There are two possible explanations for

the decrease in the number of clams greater than one inch at Grant: (i) the

more likely reason is that harvesting in the conditionally approved waters near

Grant has reduced the numbers of larger clams to levels similar to those areas

of the lagoon where populations are naturally lower (Fig. 5); or (ii) because

larval sets of hard clams are naturally sporadic (Hibbert 1976), unsuccessful

sets of larvae for a two-year period, or mortality of juveniles, resulted in

low numbers as the survivors grew to marketable sizes. Note the number of

"beans", an illegal size, is very low at Grant (Table 15).
Only 5.5 clams/m2 make up the legally harvestable stock at Grant,' which is
close to Carriker's (1961) minimum of 3.6 clams/m2 density necessary to

commercially harvest. Still, the legal sized clam density at Grant was the

highest of the three sections sampled in the lagoon. Melbourne and Merritt
Island had 4.0 and 1.9 legally sized clams per m2, but for all except one

(50.0-59.9 mm) of the six legal sized shell length divisions, the differences

were not statistically significant among sampling locations (Table 15).
However, the abundance of "seeds" (27 "seed" clams/m2) at Grant yielded highly

significant differences among the three harvested areas for clams in that size

range. By contrast, the numbers of "seed" clams at the Melbourne and Merritt

Island locations are considerably less than those found at Grant. indicating

recruitment failure or juvenile size-selective mortality.

Apparently the extensive harvesting pressure exerted at Grant during the

past two-three years has not deleteriously affected recruitment up to now.

Whether increasing harvesting can continue unabated without affecting the

recruitment success is uncertain. Peterson et al. (1983) believed the

relatively low numbers in the younger age classes was a result of reduced

reproductive effort caused by a reduction in the spawning population of M.

mercenaria in North Carolina through increased commercial harvest. However,

the authors readily admit that they had no way of distinguishing reduced

reproductive effort from increased mortality of larvae and early post larvae,

The "button" law of 1984, where clams 0/8 inch must be returned to insure

continued recruitment, is debatable considering the low reproductive potential

of buttons compared to larger clams and the effects of predators on the

returned, unprotected buttons. There clearly is a need for more scientific

information on the efficacy of the "button" law and the strength and nature of

spawner-recruit relationships, which is the single biggest barrier to effective

management of clams.

Allometric Relationships

The best fitted curve through all points in describing the relationship

between total wet weight and shell length, and dry meat weight and shell

length, for the two dominant marine bivalves (M. mercenaria and M. lateralis)

collected in the Indian River is a logarthmic function in the form (Hibbert

1976):

- W = a (L)b (2)

Figures 6-9 provide an estimate of length-specific biomass of the two bivalve

species, and were used to calculate total biomass of the two species.

Bivalve Biomass

Although dry meat biomass for Mercenaria was highest at Grant (mean of
9.74 g m-2), it was not significantly different from the average found at
Melbourne (mean of 8.61 g m-2) (Table 17 and Fig. 10). However, the lower

number of hard clams (and thus lower biomass) at Merritt Island resulted in
that area having a clam biomass (3.59 g m-2) that was significantly different

from that at Grant, but not Melbourne, and lead to an overall ANOVA that

produced a significant difference (P <0.05) in the hard clam biomass among all

three sampled areas.

The low number of Mulinia individuals at Grant (Table 16) translated into
a very low dry meat biomass (mean of 0.95 g m-2), which was significantly

different than the larger biomass estimates for Melbourne and Merritt Island

(Table 18), where higher numbers of Mulinia were found (Table 16). The average

biomass of the coot clam from Melbourne and Merritt Island (mean of 5.13 and
5.18 g m-2, respectively) were not significantly different from each other

(Fig. 10).

200-
- TOTAL WET WEIGHT 0.00017 (SHELL LENGTH)3-12
180- r 0.997

160-

140-

120-

100-

80-

60-

40-

20-
0@ I I0-1-90-T T I 1 1 4
0 10 20 30 40 50 60 70 80 90 100
SHELL LENGTH (MM)

Figure.6. Regression relationship [W a(L)bI between total wet weight (Wi. gm)
to shell length (L, mm) for 50 hard clams (Mercenaria mercenaria)
collected from three areas in the Indian River between April and July,
1985.

6000.-
DRY WEIGHT 0.0017 (SHELL LENGTH),3-3
5500. -@- I-
r 0.996
5000._:

4500.
40M-:
3500,7

3000.--,

Lij
4000.

1500.
CY
Q 1000.

500.

0.- -r7-r-m -r7-r-m -r-r-r-T-1 -r'-T-7 -TI-r-r-I
0 10 20 30 40 5 (1, 60 70 80 90 1 Oit-'
SHELL LENGTH (mm)

Figure 7. Regression relationship Ew 2 =a(L)bI between dry meat weight (W 2@mg)
shell length (L, mm) for 50 hard clams (Mercenaria mercenaria) collected
from three areas in the Indian River between April and July, 1985.

400 TOTAL WET WEIGHT 0.54 (SHELL LENGTH )2.54
r 0.956
350

300-

250-

200-

150-

100
0
507

0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 1.4 15
SHELL LENGTH (mm)

Figure 8. Regression relationship NW, = a(L) b between total wet weight
NP mg) to shell length (L. mm) for 40 coot clams (Mulinia
lateralis) collected from three areas in the Indian Rive'r between

April and July, 1985.

18- )2.33
- DRY MEAT WEIGHT 0.038 (SHELL LENGTH
16- 0.920

0
14-

8
<
6-

0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
SHELL LENGTH (mm)

Figure 9. Regression relationship W 2 = a(L)b between dry meat weight (W., mg)
to shell length (L, mm) for 40 coot clams (Mulinia lateralis) collected
from three areas in the Indian River between April and July, 1985.

Table 17. Biomass of hard clams, Mercenaria mercenaria, sampled from three areas
of the Indian River lagoon in Brevard County, Florida. Dry meat weight values
were calculated from a shell length: dry meat weight relationship derived from
individuals ranging from 2.8 - 100.0 mm total shell length (see Figure 7

ANALYSIS OF
11
TRANSECT DRY MEAT BIOMASS (g/m2) VARIANCE-

Grant Melbourne Merritt Island

1 8.16 10.49 4.47

2 9.80 .12.98 3.49

3 11.48 '1.94 3.92

4 9.51 9.03 2.48

1 S.E. 9.74 + 0.68 8.61 + 2.37 3.59 + 0.42 P<0.05

Probabilities of significant differences in hard clam biomass (a 0.05) are
based on critical values of the F-distributions (d.f. 2,9).

16-
:= TOTAL BIOMASS
147

10.:
7-
8-:

0-
C-4

Q)
16,
14 MULINIA LATERALIS
E 12-:

10--:

8-:
LLJ 6-:
4-:

0
16, MERCENARIA MERCENARIA
14

12-:
10-:

8--

6--

4-z

0 . . .................... ...........
GRANT MELBOURNE MERRFFT IS

Figure 10. Standing crop for hard clams, Mercenaria mercenaria, and coot clams,
Mulinia lateralis, and the total for the two species at three sites
in the Indian River lagoon in Brevard County, Florida, during 1985.
F

Table 18. Biomass of coot clams, Mulinia lateralis, sampled from three areas of
the Indian River lagoon in Brevard County, Florida. Dry meat weight values were
calculated from a shell length: dry meat weight relationship derived from
individuals ranging from 2.8 -20.0 mm total shell length (see Figure 9).

ANALYSIS OF
TRANSECT DRY MEAT BIOMASS (g/m2) VARIANCE

Grant Melbourne Merritt Island

1 1.04 3.37 2.15

2 1.06 5.99 6.55

3 0.78 6.02 6.00

4 0.94 5.12 6.03

+ I S.E. 0.95 + 0.006 5.13 + 0.62 5.18 + 1.02 P< 0.005

Probabilities of significant differences in biomass (a 0.05) are based on
critical values of the F-distribution (d.f. 2,9).

When taken together, the total dry meat biomass of the two dominant

bivalves were not significantly different (P < 0.10) among the three sampling

areas (Table 19), suggesting that a maximum sustainable yield for filter
feeding bivalves of 8.8 to 13.7 g dry meat weight m-2 (Fig. 10) prevailed in

the Indian River estuary adjacent to central and south Brevard County in 1985.

The Relationship of Food Supply to Bivalve Production

An often overlooked limiting factor in accounting for the abundance of

shellfish is their food supply, which is probably more critical during their

larval stages than during their adult life. A way to assess the availability of

food to the bivalve community is to divide the net primary productivity rate (g
C/m2-day) at each location by the respective bivalve standing stock (g dry meat
wt/m2) to produce the mg C of phytoplankton made available as a food source per

g dry meat of bivalve per day. This can then be compared to Tenore and

Dunstan's (1973) regression relationship between food concentration (ug C/L)

and absolute feeding rate measured for Mercenaria having an average shell

length of 45.4 mm.. Although particulate organic carbon was not measured in our

investigation, an estimate can be made based on chlorophyll a concentrations

and the ratio of 35:1 for phytoplanktonic particulate carbon to chlorophyll a

(Ryther and Menzel 1965). Considering that measured chlorophyll.a

concentrations for the Melbourne and Grant transects averaged 29.4 and 21.1 mg
M-3 respectively, living phytoplankton particulate carbon would be 1,029 and

738 ug C/L.

With an average phytoplanktonic carbon at Melbourne of 1,029 ug/L, a

feeding rate of 25.2 mg C/g dry meat/day at 200C for Mercenaria would be

predicted according to Tenore and Dunstan's regression analysis. However, the

size classes of most of the bivalves collected in the Indian River were

Table 19. Biomass of hard clams, Mercenaria mercenaria, and coot clams, Mulinia
lateralis, sampled from thee areas of the Indian River lagoon in Brevard County,
Florida. Dry meat weight values were calculated.from a shell length: dry meat
weight relationship derived for each species (see Figures 7 and 9).

ANALYSIS OF
TRANSECT DRY MEAT BIOMASS (g/m2) VARIANCE

Grant Melbourne Merritt Island

1 9.21 13.86 6.62

2 10.86 18.95 10.03

3 12.26 7.96 9.91

4 10.44 14.15 8.50

+ 1 S.E. 10.69 + 0.63 13.73 + 0.22 8.77 + 0.80 P<0.10 (N$)

Probabilities of significant differences in hard clam biomass (a 0.05) are
based on critical values of the F-distributions (d.f. 2,9).

considerably less than the size class (45.4 mm shell length) used by Tenore and

Dunstan (1973). Smaller size classes for Mulinia and Mercenaria would mean the

filtration (feeding) rates for Indian River bivalves were higher on a g dry

meat wt basis than the rates used by Tenore and Dunstan. Using Hibbert's (1977)

empirical relationship between Mercenaria filtration rate and shell length, a

filtration rate for the Mercenaria population used by Tenore and Dunstan can be

compared to the rates obtained in our study based on the average shell lengths

measured for Mulinia (7.7 mm, 5.6 mm, and 5.0 mm for Grant, Melbourne, and

Merritt Island, respectively) and Mercenaria (20.7 mm, 44.5 mm, and 50.5 mm for

Grant, Melbourne, and Merritt Island, respectively). In addition, knowledge of

what proportion of the total bivalve biomass was comprised by each species at

each sampling area permits a weighted (according to size and relative biomass

abundances) filtration rate for the bivalve community to be computed.

For Melbourne, the maximum feeding rate would be 14.4 X higher (i.e., 364

g C/g dry meat/day) than the feeding rate reported by Tenore and Dunstan (25.2
mMg C/g dry meat/day). When this rate is compared to the amount of

phytoplankton carbon made available daily per g dry meat wt of bivalve at the
Melbourne section (1.85 g C/m2-day t 13.7 g dry meat/m2 = 135 mg C/g dry

meat/ day), only 37 percent of the amount of food is being produced than what is

required by the bivalve community. This assumes Mulinia lateralis feeds at a

similar rate as does Mercenaria mercenaria in the same size class. If the

lowest daily primary productivity rate (0.7 g C/m2-day) of the year (in
December 1984) and its associated chlorophyll a concentration (13.7 mg m-3) is

used as a "worst case" example, then 51 mg C/g dry meat/day is available to the

bivalves, which is still less than 30 percent of what the maximum feeding rate

(125 mg C/g dry meat/day) would be required for a food concentration of 480 ug
C/L (= 13.7 mg chl a m-3).

An average phytoplanktonic carbon concentration of 738 ug/L at Grant

resulted in an absolute feeding rate of 8.1 X the 16.4 mg C/g dry meat/day

reported by Tenore and Dunstan at this food concentration, When compared to the
daily produced food available for bivalve grazing (1.08 g C/m2-day i 10.7 g dry
meat/m2) of 101 mg C/g dry meat/day, primary productivity at Grant produces 76

percent of the daily maximum requirement of food for the bivalve community.
Again, if the lowest recorded primary productivity rate (O.i6 g C/m2-day in
November) and its associated chlorophyll a concentration (7.1 mg m-3) is used,

then primary production (15 mg C/g dry meat/day) furnishes the amount of food

required by Mercenaria (15 mg C/g dry meat/day) at a food concentration of 248
ug C/L (= 7.1 mg m-3 of chlorophyll a).

It appears that the primary productivity rates at Grant and Melbourne are

inadequate to sustain the filter feeding bivalve biomass based on maximum

fil,tration rates. However, the grazing rates for the bivalve community is

probably less than maximum, meaning the measured primary productivity is

meeting the food requirements of the existing standing stock. If primary

productivity rates were to increase, a higher bivalve standing stock may be

possible. Thus the quantity of food could be limiting to the bivalve community,

even though the abundant phytoplankton productivity of the estuary is part of

the reason why growth rates and standing stocks of bivalves are high.

There is also a quality aspect to the food resources. Calabrese and Davis

(1970) found food requirements for hard clam larvae to differ under different

environmental conditions. Although the composition of the phytoplankton

community during this investigation is unknown, the almost negligible

information on what species of pla.nkter is best for larval growth at given

temperatures, salinities, and larval stages would have precluded any meaningful

interpretation of phytoplankton species data.

Literature Review on Bivalves of the Indian River Lagoon

An annotated bibliography found in Appendix A of this report on bivalves

and phytoplankton of the Indian River represe nts, an exhaustive search of

published and unpublished reports as well as interviews with several

scientists. The bibliographic entries are summarized according to emphases

chosen by ourselves. Thus methodology, phytoplankton standing crops and rates

of production, bivalve species lists and densities, and conclusions are

highlighted in the annotations.

Several recurrent ecological observations/principles were noted during the

course of the literature search:

1) greater numbers of bivalves (both species diversity and total

individuals) are found in seagrass beds than in bare sand substrate.

2) most unpredictable (i.e., stressed)-environments is caused by low

dissolve d oxygen, and leads to less species and total individuals.

3) deposit feeders such as polychaetes can exclude suspension feeders

like bivalves.

4) the most common bivalve taxa in decreasing order of numbers were:

Tellina sp., Mulinia lateralis, Brachidontes exustus, Corbula sp., Tagelus

divisus, Chione sp., Macoma sp., Nucula proxima, Parastarte triquetra, Musculus

lateralis, Anadara transversa. Bbarbatia domingensis, Amygdalum papyrium,

Anomalocardia cuneimeris, Laevicardium sp. Most of the dominant taxa were

c
posed of small individuals, some of which can grow in dense clusters (>1,000
om

individuals/m2 according to data taken by Brevard County). As previo*usly

discussed, only two of the eight studies which presented bivalve species lists

reported Mercenaria mercenaria. Another major difference between our study and

previous inventories is the minor numbers for Tellina found by us (Table 14).

whereas it was the most common bivalve found in the other studies. This could

be due to the close morphological appearances of Tellina and Mulinia lateralis,

which was 98 percent of the total bivalve number in our study.

None of the previously published or unpublished studies on the Indian

River concentrated exclusively on the bivalve population; all examined the

macrobenthic community, which includes polychaetes, sipunculans, gastropods,

nemertineans, crustacea, and echinoderms in addition to bivalves. Thus the

investigations were confined to ecological studies within the macrobenthic

faunal community: competitive exclusion between suspension feeders and deposit

feeders (Thomas 1974; Weiderhold 1976) or how environmentally unpredictable

habitats affect community structure (Grizzle 1979; Young and Young 1977). Most

of the studies were quantitative to the point of listing numbers of individuals

collected (but not dry or wet weights). Only two studies (Virnstein et al.

1983; Young and Young 1977) addressed the interaction of the benthic

macroinvertebrate community with other trophic levels; no study looked at

benthic-pelagic coupling of nutrients and/or carbon.

REFERENCES

Abbott, R.T., 1974. American Seashells. The Marine Mollusca of the Atlantic
and Pacific Coasts of North America, 2nd ed. Van Nostrand Reinhold
Company, New York.

A.P.H.A. 1971. Standard Methods for the Examination of Water and Wastewater.
Am. Public Health Assoc., New York, N.Y. 864 pp.

Applied Biology, Inc. 1980. Biological and Environmental Studies at the
Florida Power and Light Company Cape Canaveral Plant and the Orlando
Utilities Commission Indian River Plant. Volume 2. 641 Dekalb Industrial
Way, Atlanta, GA.

The Audubon Society. 198t. Guide to North American Seashells. Alfred A.
Knopf, New York.

Boynton, W.R., W.M. Kemp, and C.W. Keefe. 1982. A comparative analysis of
nutrients and other factors influencing estuarine phytoplankton
production. In: V.S. Kennedy (ed.), Estuarine Comparisons. Academic
Press.

Brevard County Environmental Engineering Dept. (Mr. Conrad White, pers.
commun.). 1975-1981.

Calabrese, A., and H.C. Davis. 1970. Tolerances and requirements of embryos
and larvae of bivalve molluscus. Helgolander wiss. Meeresunters.
20:553-564.

Carriker, M.R. 1961. Interrelation of functional morphology, behavior, and
autecology in early stages of the bivale Mercenaria mercenaria. J. Elisha
Mitchell Sci. Soc. 776:168-241.

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Plankton Res. 4:203-216.

Glover, H.E. 1980. Assimilation numbers in cultures of marine phytoplankton.
J. Plankton Res. 2:69-79.

Grizzle, R.E. 1979. A preliminary investigation of the effects of enrichment
on the macrobenthos in an east-central Florida lagoon. Florida Scient.
42:33-42.

Heffernan, J.H., and R.A. Gibson. 1983. A comparison of primary production
rates in Indian River, Florida seagrass systems. Florida Scient.
46:295-306.

Hibbert, C.J. 1976. Biomass and production of a bivalve community on an
intertidal mud flat. J. Exp. Mar. Biol. Ecol. 25:249-261.

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an intertidal mud flat. Mar. Biol. 44:77-84.

Lindner, G. 1975. Field Guide to Seasheils of the World. Van Nostrand
Reinhold Company, New York.

Mahoney, R.K., and R.A. Gibson. 1983. Phytoplankton ecology of the Indian
River near Vero Beach, Florida. Florida Sci. 46:212-232.

Megard, R.O. 1972. Phytoplankton, photosynthesis, and phosphorus in Lake
Minnetonka, Minnesota. Limnol. Oceanog. 17:68-87.

Peterson, C.H., P.B. Duncan, H.C. Summerson, and G.W. Safrit, Jr. 1983. A
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population along the southeastern United States. Fishery Bull.
81:765-779.

Reish, D.J., and M.L. Hallisey. 1983. A check-list of the benthic
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Riley J.P., and R. Chester. 1971. Introduction to Marine Chemistry. Academic
Press, London and New York.

Ryther, J.H. 1956. The measurement of primary production. Limnol. Oceanog.
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Ryther, J.H., and D.W. Menzel. 1965. On the production, composition, and
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Strickland, J.D.H., and T.R. Parsons. 1972. A Practical Handbook of Seawater
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Thomas, J.R. 1974. Benthic species diversity and environmental stability in
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Limnol. Oceanog. 13:189-192.

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hard clam, Mercenaria mercenaria,,in Wassaw Sound, Georgia. Estuaries
7:19-27.

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the northern Indian River, Florida. M.S. Thesis. Florida Institute of
Technology, Melbourne.
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Comparison of I and 02 measurements of phytoplankton production in
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South CaroTina Press, Columbia.

APPENDIX A

ANNOTATED BIBLIOGRAPHY

BIVALVES AND PHYTOPLANKTON

ON THE

INDIAN RIVER ESTUARY

Applied Biology, Inc. 1980. Biological and Environmental Studies at the

Florida Power and Light Company Cape Canaveral Plant and the Orlando

Utilities Commission Indian River Plant. Volume 2. 641 D eKalb Industrial

Way, Atlanta, GA.

Quarterly sampling from December 1978 to September 1979 at 48 stations

near Titusville by box coring (15 cm, x 15 cm x 15 cm). Four replicates per
station with each replicate core halved and then pooled (=0.05 m2 ).

The fauna was dominated by eurytopic and opportunistic species. The most

common species in all vegetated habitats was a mussel, Brachidontes exustus.,

while in unvegetated habitats an ostracod, Parasterope pollex, was most common.

Manatee grass supported the richest fauna followed by, in descending order,

the shoal grass, drift algae, channel and sand habitats. Although manatee grass

supported the greatest number of species per unit area, drift algae supported the

highest total number of species and over-all species 'richness. Because drift

algae was much more abundant then either of the grasses . it is probably the

primary vegetation habitat for benthic macroinverteb rates. Although different

habitats shared many species in common, shifts in the relative commonness of

spe-cies with habitat caused the community structure of each habitat to be unique.

The most distinct habitat in terms of species composition was the channel.

No north-south gradient in the distribution of the fauna was observed, but

the east shore generally supported a richer fauna than the west shore. The

difference between the shores was a natural phenomenon unrelated to power plant

operation, Channel communities, in the Cocoa Pool were characterized by low

diversity, species density, and faunal density. Areas within the Canaveral Pool

were typically equivalent to, or richer than, areas within the Titusville and

Cocoa Pools. Broad spatial variation in the fauna may largely reflect spatial

variation in the nature of the substratum.

Impacts of the discharge plumes on species diversity, species evenness,

species density, faunal density, and biomass were moderate and were spatially

restricted. Species diversity was most affected by discharge plumes. Impacts

on diversity were noted over the broadest area in June but were more intensive,

over a smaller area, in December. A worst-case areal extent for plume impacts

on diversity, as indicated by June data, was 245 ha. In cooler months (December,

March and September) the maximum area impacted was considerably smaller, about

142 ha. Impacts were never pervasive within affected areas and, at times,

relatively high diversities were observed within 100 m of the discharges. For

channel communities, species diversity, species density, and faunal density were

not adversely affected by the discharge plumes. Thus, adverse impacts apparently

did not extend beyond the 6-ft depth contour.

Impact on faunal density was limited to a much smaller area than impact on

diversity. The maximum areal extent for impact on faunal density was about 142

ha. Natural variation in biomass was so great that no zone of impact could be

delineated. The spatial variation in faunal density and biomass suggests that

comined effects between the two plant discharges, which were limited to a moderate

depression of species diversity at certain stations, were of little eco logical

significance.

The distributions of the most co n species substantiated the limited

extent of discharge plume effects. For most of these species, population densities

in areas exposed to the discharges were not signficantly different from densities

in areas not exposed to the discharges. All species whose population densities

were affected by the discharges exhibited significantly altered densities only in

the immediate vicinity or the discharges. In the area on the west shore where

combined effects between the discharges might be expected, no species examined

shcwed significantly altered density.

Bivalves found: Abundance (units unknown)

Amyszdalum Papyrium 3093

Anadara transversa 51

Anomalocardia alberiana 884

Brachidontes exustus 690011

Chione cancellata 195

Cyrtopleura costata 2

Laevicardium mortoni 394

Lyonsia hyalina 176

Macoma brevifrcns 10

Macoma tenta 2

Mercenaria sp.
6

Mulinia lateralis 13037

Musculus lateralis 3

Mysella planulata 3620

Nucula proxima 162

Parastarte triquetra 1132

Parvilucina multilineata 28

Tagelus divisus 241

Tellina sybaritica 6

Tellina tampaensis 1309

Tellina versicolor 269

2. Brevard County Environmental Engine'ering Dept. (Mr. Conrad White, per. com.).

1975-1981.

The most complete data onshellfish populations for the Indian River estuary

are quarterly and yearly samples taken since 1975 (1975-1981 period had shellfish

identified) by Brevard County Environmental Engineering Department. Mr. Conrad

White kindly provided the following data an the County's shellfish program. Two

shallow water stations sampled yearly are (i) Sebastian River confluence with

Indian River, and (ii) north of the SR 528 bridge; four shallow water stations

sampled quarterly are: (i) Mosquito Lagoon; (ii) Titusville; (iii) Banana River;

and (iv) Malabar. Various sampling devices were used, including Petersen, Pcnar,

and Smith-McIntyre types.

Station 110 : Banana River north of S, R, 121 between 4th and Ith p ower poles

east of west shore. Water Depth 2.0 m. Petersen (0.1 m, 3 replicates and

composited.

S2ecies No. Individuals m7

2/15/77

Amygdalum. papyrium, 3

Brachidontes exustus 3

Laevicardium !2- 17

Mulinia lateralis 7

Tellina U. A 10

217/78

Anomalocardia auberiana 50

Laevicardium, mortoni 3

Mulinia mortoni 30

Parvilucina multilineata 3

Tellina.@2. A 106

Tellina sp. E 10

Spe cies No. Individuals /m,

6/17/80 (3 replicates taken with modified Smith-McIntyre dredge)

Amygdalum papyrium 20

Anomalocardi-a c,,neimeris 10

Brachidontes exustus 360

Tellina versicolor 20

Tellina sp. B 10

Thracia sp. 1 60

Station .0874: Mosquito Lagoon, 125-150 ft. east of CM 41. Water Depth 1.0 m.
Petersen (0.1 m@). 3 replicates and composited.
Species No. Individuals/m 2

2/25/78

Mulinia lateralis 43

Nucula proxima 7

Tellina sp. A 23

Unidentified 3

2/13/78

None found

2/13/79

No species data

6/26/80 (Modified Smith-McIntyre dredge): 1 sample)

Brachidontes exustus 2

Tagelus divisns 2

9/13/82 (Modified Smith-McIntyre dredge: 1 sample)
Species No. of individuals/m 2

Amygdalum. papyrium, 4

Anomalocardia cuneimeris 20'

Brachidcntes exustus 1

Nucula, proxima. 2

Mulinia, lateralis 12

Telling sp. B 3

Venus juvenile 1

Station .0876: Titusville west of CM 30. Water Depth 2.5 m. Petersen (0.1

3 replicates and composited.

Species No. of Individuals/m

2/25/77

Nucula, proxima, 13

Telling sp. A 3

Unidentifted 67

2/13/78

Anomalocardia auberiana, 67

Brachidontes exustus 3

Mulinia lateralis 76

Nucula proxima 23

Telling. sp. a 33

Telling sp. E 13

6/16/80 (Modified Smith-McIntyre dredge: 3 replicates)

Mulinia, lateralis 150

Nucula proxima 10

Unidentified 60

9/14/82 (Grissile/Stigner: O.lm 2 1 sample)

Species No. of Individuals m

Mulinia lateralis 30

Station .0878: Malabar 200-250 yds east of CM- 20 (CM 21 and 22 in line, and

CH 23 in line with large white billboard on U.S. 1). Water depth 2.3 m.
Petersen (0.1 m2). 3 replicates and composited.
Species No. of Individuals/m2

1/31/78

Mulinia lateralis 3,333

Unidentified 10

8/26/80 (Modified Ponar: 3 replicates)

Amygdalum papyrium 28

Anadara transversa 14

Mercenaria campechiensis 14

Rangia cuneata 126

Station 1331: Confluence of Indian and Sebastian River5 100 ft. east of CM 61
Water depth 2.4 m. Petersen dredge (0.1 ft 2). 3 replicates.
11/14/73 'Species No. of Individuals/m2

Arca ap. A 14

Arca sp. B 4

Astarte nana 4

Chione sp. 22

Corhula caribaea 4

Corbula sp. A 7

Corbula sp.

Station .0335 (continued)

2
Species No. of Individuals/m

Donax sp. 220

Eucrassatella speciosa 4

Macoma sp. 54

Unidentififed Sp. A 18

Unidentified sp. B 68

Unidentified sp. C 11

Unidentified sp. D 4

Unidentififed sp. E 4

Unidentified sp. F 14

Tagelus divisus 4

1/16/74 (611 square Ponar dredge: 3 replicates)

Astarte sp. 56

Chione sp. 42

Donax sp. 695

Macoma, sp. 83

musculus 14

Tagelus divisus 14

Unidentified sp. A 445

Unidentified sp. B 139

Unidentified sp. C 28

Unidentified sp. E 14

5/l/74 (Petit Ponar- 3 replicates)

Arca sp. 14

Anoria simplex 14

Chione sp. 70

Donax sp. 14

5/l/74 Station .0335 (continued)

2
Species No. of Individuals/m

Sphenia antillensis 83

Tagelus divisus 28

Unidentified sp. A 681

Uaidentififed sp. B 70

Unidentified sp. C 14

7/17/74 (Petit Ponar: 3 replicates)

Arca sp. 14

Anomia simplex 56

Chione sp. 14

Corbula sp. A 112

Corbula sp. B 42

Donax sp. 14

Sphenia antillensis 154

Tellina sp. 70

Venus 14

11/6/74 (Petit Ponar: 3 replicates)

Donax sp. 306

Macoma sp. A. 778

Macoma sp. B 83

Tellina sp. 288

Venus sp. k 83

Venus sp. B 28

2/5/75 (Petit Ponar: 3 replicates)
Species No. of Indivi duals /M2

Macoma sp. 1 336

Macoma ap, 1 168

Sphenia antillensis 28

Telling sp. 1 168

Tellina sp. 2 14

5/21/75 0-mar dredge: 3 replicates)

Arca sp. 14

Lunatia sp. 14

Macoma s p, 1 588

M-acoma sp. 3 42
Tage lus divis us 146

Venus sp. 1 28
8/19 /75 (Petersen: 0. 1 m 2; 3 replicates)

Aqrgdalum papyri 3

Anadara transversa 50

Chione sp, 3

Corbula sp. 7

Mulinia lateralis 23

Nucula sp. 7

Tagelus divisus 73

Tellina sp. A 218

Telling sp. B* 116

Unidentified 10

2/17/76 (Petersen: 3 replicates)

Species No. of Individuals/m

Chime sp. 10

Nucula proxima 23

Tellina sp. A 320

Tellina sp. B 33

Un identififed 7

5/10/76 (Petersen grab: 3 replicates)

Barbatia domingensis 99

Chione sp. 10

Lucina nassula 3

Mulinia lateralis 7

Nucula proxima 10

Tagelus divisus 92

Tellina sp. A 158

Tellina sp. B 257

Sphenia 7

Uni den ti fie d 56
12/20/76 (Petersen grab: 0.1 m 2 3 replicates)

arbatia dondngensis 13

Corbula sp. 10

Tellina sp. A. 7

Tellina sp. B 23

Uaidentified 7
2/2/77 (Petersen grab: 0.1 m 2 3 replicates)

Corbula sp. 16

Tellina sp. A 132

Tellina sp. B 50

5/17/77 (Petersen grab: 3 replicates)
Species No. of Individuals 4

Barbatia. domingensis 26

Chione sp. 13

Corbula sp. 7

Lucina nassula 7

Mulinia lateralis 7

Tagelus plebius 13

Telling sp. A 109

Tellina sp. B 10

Uhidentified 10

2
8/23177 (Petersen grab: 0.1 M 3 replicates)

Chicne sp. 7

Corbula sp. 20

M-ulinia lateralis 10

Parvilucina multilineata 3

Nucula Proxima 23

Tagelus plebius 89

Tellina sp. A 28

Tellina sp. C 16

Tellina sp. D 20

Tellina sp. F 3
11/15/77. (Peter;en grab: 0.1 m 3 replicates)

AM&dalum papyrium 3

Anadara trmsversa 3

B arb ati a 10

Corbula sp. 17

11/15/77 (continued)

Species No. of Individuals/m

Lucin- s.p. B 3

Mulinia lateralis 27

Parvilucina multilineata 3

S pheni a 3

Tabelus plebeius 10

Telling sp. A 27

Tellina sp. C 7

Tellina'sp. D 583

Trachycardium muricatum 3

Uaidentified 30
1/31/78 (Petersen: 0.1 m 2 3 replicates)

Anadara trmsversa 20

Barbatia sp. 7

Chione sp. 7

Corbula sp. 3

Mulinia lateralis 30

?xima 13

Telling sp. A 127

Tellina sp. C 110

Tellina sp. D 293

Unidentified 10

2'
5/22/78 (Petersen: 0.1 m ; 3 replicates)

Anadara transversa 63

Barbatia sp. 17

Chione sp. 14

5/22/78 (continued)
Species No. of Individuals/m,

Corbula sp. 13

Muli,,ia lateralis 17

Nucula proxima 10

Sphenia 7

Tagelus plebeius 133

Tellina sp. A 233

Tellina sp. C 183

Tellina sp. D 153

Unidentified 6
7/20/78 (Petersen: 0.1 m 2 3 replicates)

Anadara transversa 10

Corbula sp. 7

Mulinia lateral's 23

Parvilucina multilineata 10

Tagelus plebeius 23

Tellina sp. A 57

Tellina sp. C 27

Tellina sp. D 47

Trachycardium =ricatum 10

Uaidentified 37

12/13/78 (Grab sanple: 0.08 m 3 replicates)

Chione sp. 32

Corbula sp. 16

Mulinia lateralis 4

Nucula prm@ma 12

12/13/78 (continued)

Species No. of Individuals/M.

Parastarte triguetra 16

Parvilucina multilineata 4

Tellina sp. A 136

Telling sp. C 12

Telling sp. D 56

Unidentified 20

1/30/79 (Grab sample: 0.08 M 3 replicates)

=gdalum 2lebeius 8

Anadara transversa 4

Ana malocardia auberiana 4

Chione sp. 56

Corbula sp. 20

Mulinia lateralis 108

Nucula proxima. 44

Parvilucina multilineata 12

Tagelus plebeius 8

Tellina sp. A 92

Tellina sp. C 56

Tellina sp. D 384

Unidentified 24

5/22/79 (Grab sample: 0.08 M 3 replicates)

Anadara transversa 4

BarbDatia sp. 4

Chione sp. 68

Mulinia lateralis 136

5/22/79 (continued)

Species No. of Individuals/m.

Nucula Proxima 16

Parvilucina multilineata 4

TaRelus Plebeius 196

Tellina sp. A 60

Tellina sp. C 32

Te'llina sp. D 16

Trachycardium muricatum 4

Unidentified 52
8/21/79 (Grab sample: 0.08 m 2 3 replicates)

Corbula sp. 12

Chione sp. 24

Mulinia lateralis 56

Parvilucina multilineata 4

TaRelus Plebeius 84

Tellina sp. A 24

Tellina sp . C 48

Tellina sp. D 32

Unidentified 24

6/10/80 (Modified Smith-McIntyre dredge; 3 replicates)

Anadara tr-ansve-rsa 80

Chicne sp. 20

Chione cancellata 10

Dipladonta nucleiformis 60

Lu cin a 40

Mulina lateralis 140

6/10/80 (c=tinued)

2
Species No. of Individuals/m

Tagelus divisus 130

Tellina sp. A 50

Tellina sp. C 390

Solen viridis 10

Tellina sp. D 25

Tellina versicolor 340

Unidentifi 90
8/26/80 (Modified Smith-McIntyre dredge: 0.10 M 2 3 replicates)

Anadara transversa 30

Corbula contracta 40

Lucinia pro-zi=a 10

Macoma sp. 10

Mulinia lateralis 40

Phyllodina squamifern 50

Nucula pro-xima 10

Raagia cuneata 10

Thracia sp. 170

Tagelus divisus 120

Tellina versicolor 60

Telling sp. A 10

Tellina sp. B 30

Tellina sp. C 100

Tellina sp. D so

10/28/80 (Modified Smith-McIntyre dredge: 0.10 M 2; 3 replicates)

. Species No. of Individuals/

Chime sp. 30

Cuuingia coarctata 10

Cyclinella tenuis 20

Macoma sp. 10

Mulinia lateralis 1,040

Nucula Proxima 70

Pitar aresta 10

Phyllodina. sqtumiifera 190

Rangia cuneata 10

Telling sp. A 540

Tellina sp. B 1,10

Tellina sp. C 50

Tellina sp. D 70

Tellina sp. F 50

1hracia sp. 200

Unidentified 30

Data for Station .0581 at S.R. 528, north of bridge between lst and 2nd unbuffered

power poles east of IC1,q (11/10/75 thru 1/19/81 (quarterly samples) will be examined

during the latter part of the study period (Mar.-Sept.) when shellfish sampling is

in progress.

3. Grizzle, R.E. 1979. A preliminary investigation of the effects of enrichment

on the macrobenthos in an east-central Florida lagoon. Florida Scient. 42:33-42.

Macroinvetebrate collections were made at 6 stations in lower Sykes

Creek in July 1975 and in February 1976 near the City of Cocoa and I station

each in the Indian (September 1975 and March 1976) and Banana River (January
and July 1975) lagoons, using a 0.1 m@ Peterson grab. Three to 5 grabs were

taken at each station per sampling occasion and pooled for a composite sample.

Each sample was sieved through a 0.42 mm mesh (U.S. Standard No. 40) and the

residue fixed in a 5% formalin solution with rose bengal added. Animals were

sorted in the laboratory and preserved in 80% EtOH. All specimens*were

identified, generally to species, and enumerated. Wet weights were made of

all speciments by group from each sorted sample by blotting the specimens dry
on paper then wei:ghing on a Mettler balance. Molluscs were noi removed fr=

their shells before weighing. Sediment samples were taken from the contents

of one of the replicate samples on one sampling occasion and analyzed for

grain-size distribution (silt-clay particles.< 62 @=; sand particles> 62 Jim;

shell > 1 or 2 mm mesh) and organic content (% volatile).

Sykes Creek stations showed great temporal variability than did the controls

in almost all macrobenthic parameters measured (i.e., species diversity, density,

biomass, and species ratio differences). Sykes Creek stations also had de-

creased species numbers and diversity values and a predominance of opportunistic

species.

Bivalves found:

Anomalocardia auberiana

Parastarte triquetra

Amygdalum papyrium.

Tagelus plebeius

Brachidontes exustus

4. Heffernan, J.H. , and R.A. Gibson. 1983. A comparison of primary production

rates in Indian River, Florida seagrass systems. Florida Scient. 46:295-306.

Three sites in the Indian River (Jim Island, Link Port, and Vero Beach)

were studied to determine primary production in seagrass meadows. Four to

six 3-hr incubations were made during spring and su r of 1981. . Productivity

estimates were determined using radiocarbon techniques. The following primary

2
productivity rates (mg C/m -h) were recorded (Percent relative standard

deviations are in parenthesis).

Jim Island Link Port Vero Beach

March July March July July

Benthic microalgae 1.66(22.9) 3.30(21.5) 33.8(24.2) 28.9(23.6) 15.0(19.2)

Phytoplankton 0.21(20.6) 2.48(19.0) 1.43(51.5) 2.99(20.0) 7.22(4.9)

Benthic microalgae con=@ibuted significantly to community productivity in

Indian River seagrass beds. During March this fraction accounted for 80-95% of

the primary productivity within the various seagrass beds at Jim Island and

Link Port. During July this group was the largest contributing component in

Vero Beach grass beds. Benthic microalgae had a greater impact on primary

productivity at Link Port and Vero Beach than at Jim Island. Sites farther

from ocean inlets (i.e., Link Port and Vero Beach) typically had reduced light

regimes and current velocities. Sediment microflora proliferate in shallow,

sluggish backwater areas with little water movement, high nutrient concentrations

and poor light regimes, and actually may be adapted to seemingly stressful

conditions. (Round, F.E. 1971. Benthic marine diatoms.. Oceanogr. Mar. Biol.

Rev. 9:83-139; Jones, R.C. 1980. Productivity of algal epiphytes in a Georgia

salt marsh: Effect of inundation frequency and implications for total marsh

productivity. Estuaries 3:315-317). Vero Beach and Link Port more closely

satisfied these conditions than Jim Island which characteristically

exhibited high flushing rates , low nutrient concentrations and high

light penetration.

Phytoplankton had their greatest productivity rates and contribution

to overall co=mmity- production in July at Vero Beach. Phytoplankton
values were also higher at Link Port than Jim Island. Though the fi-@rber

of sampling periods was limited, this agreed with trends of chlorophyll a,

phytoplankton cell abundance and productivity measurements taken during

the Indian River Coastal Zone Study (Gibson, unpubl. data). Weekly

measurements of these parameters from 1976 through 1978 showed values

consistently highest at Vero Beach, lowest at Jim Island and intermediate

at Link Port.

5. Levy, K. D. 1979. The response of the macrobenthos of Turkey Creek,

Florida to salinity and other abiotic factors. M.S. Thesis. Florida

Institute of Technology, Melbourne.

In the vicinity of Turkey Creek, the Indian River has essentially no

flow and little tidal action. Water movement in this area is mostly the

result of wind action (Barile, D.D. 1976. An environmental study of the

M-elbourne-Tillman Drainage District and an evaluation of alternate land

use plans for the city of Palm Bay, Florida. M.S. Thesis. Florida

Institute of Technology, Melbourne. 317 pp.).

Five stations were sampled in late January, April, July, and October,

1978. Only one station was in the Indian River. Three replicate samples

were collected at each station using a coring device operated on the principle

of a posthole digger which obtained an undistrurbed plug of sediment
(15 cm x 15 cm x 10 cm = 2250 cm 3). The total area sampled at each station
was 0.0675m@ (1/15M 2). The contents of each sample were sieved through a
0.5 mm. mesh screen and placed in a solution of approximately 5% MgCl 2 which
served as a relaxant. Samples were fixed with 10% buffered formalin within

8 hours after collection. The formalin was replaced with 70% EtOH after a

minimum of 24 hrs. Animals were then separated from the sieved samples by

examination under a dissecting scope and identified to speices when possible.

Reference for molluscs identification was Abbott (1974). Analysis of the data

included the Canberra metric dissimilarity index and cluster analysis by

flexible sorting. Sixty-one macrofaunal taxa. were obtained from 60 samples

collected during 1978. Nine of the taxa (none of them bivalves) accounted

for over 77% of the 6,513 individuals collected; polychaetes were numerically

dominant, representing 28.4% of the total number of individuals.

6. Mahoney, R. K. , and R. A. Gibs on. 1983. Phytoplankton ecology of the

Indian River near Vero Beach, Florida. Florida Scient. 46:212-232

Weekly collections made during 1977 in the Indian River near Vero

Beach produced the following total phytoplankton results:

Annual Average Mon th ly Ran ge
.1 total cel:1 numbers 1.4 x 10 10 cells/m 3 2.5 x 10 9-2.5 x 1010 calls /m3
2. cell size 1. 00 x 10 311m3 1.62 x 10 2_ 3.85 x 10 3 VM3
3. biomass 1.82 x 10 12 11m/m3 5.38 x 10 11- 3.30 x 10 12 =/m 3
4. chlorophyll a 10.69 mg/m 3 1.7-15.6 mg/m3

5. phytoplankton dynamics:

Spring: high diatom standing stock (Chaetoceros, Skeletonema,

Nitzschia, Thalassiosira)

Summer: lower standing st ock (decrease in diatoms aad slight

increases in flagellates and dinoflagellates)

Fall: increase in standing stock due to increase in nutrients

from the release of agricultural water into the Indian

River duringhigh rainfall

Most total phytoplankton cell density fluctuations were due to variations

in the diatom cell densities: the flagellate densities ranged over an order of

magnitude during the years' cycle, whereas d:Latom cell densities range over

nearly 3 orders of magnitude.

7. McHugh, J.L., M.W. Summer, P.J. Flagg, D.W. Lipton, and W.J. Behrens. 1982.

Annotated bibliography of the hard clam (Mercenaria mercenaria). NOAA Technical

Report NMFS SSRF-756. National Oceanic and Atmospheric Administration, U.S.

Dept. of Commerce, Rockville, MD.

One citation for the Indian River:
Woodbur@, K.D. 1963. Survival and growth of laboratory-

reared northern clams (Mercenaria mercenaria) and hybrids

(_M_ mercenaria X M. campechiensis) in Florida waters. Proc.

Natl. Shellf. Assn. 52:31-36.

Recorded hard clam production in Florida began in 1880, increased

significantly in 1908 when large clam beds near the Ten Thousand Islands

on the west coast were discovered, peaked in 1932, remained high through

most of WW 11 and then plummeted to a low in 1950. Production has increased

modestly since then. Hurricanes, red tides, fresh water, and mechanical

harvesting have been blamed for disappearance of clam stocks in the Ten

Thousand Islands area, but the cause has not been identified. Dense

concentrations of hard shell clams on the west coast of Florida are found

on firm, sticky mud bottoms with abundance of sea grasses, Thalassia

testudinum or Diplanthera wrightii. Clam growth is not normally interrupted

by winter temps as in northern waters. Clams were carried by air from

Milford, Conn. aid planted in screened boxes. Northern clams were 0.25

to 0.5 in. long and hybrids of male M. campechieusis and female M. mercenaria

were 0.0625 to 0.125 in. long. At Sebastian in Indian River County 50% of

hybrids and 10-15% of northern clams were dead 7 days after planting in

Nov. 1960. By mid-June 1961 max. length of hybrids was 1.25 in., of

northern clams 1.375 in. Salinities were 21 to 29%.

8. Reish, D.J. , and M.L. Hallisey. 1983. A check-list of the benthic

macroinvertab rates of Kennedy Space Center, Florida. Florida Scient.

46 :306-313

A quarterly baseline study of benthic macroinverteb, rates was

conducted from December 1979 to March 1981 in brackish lagoons surrounding

Launch Complex 39A at Kennedy Space Center and from December 1979 to

December 1980 in the Banana River. Three replicate benthic grabs were

taken with an Ecky- Grab (15.24 cm x 15.24 cm x 15.24 cm) at each

station. The samples were fiOld-washed through a 0.5 mm sieve. The

collected material was then placed in 10% buffered formalin for 48 to

72 hrs, transferred to 70% isopropyl alcohol, sorted, and identified.

Bivalves found:

Amygdal papyrium

Anomalocardia auberiana

Brachidontes exustus

Geukensia demissa

Geukensia d.. granosissima

Laevicardium laevigatum

Laevicardium. mortoni

Laevicardium sp.

Lyonsia hyalina floridana

Macoma constricta

'Mulinia lateralis

Ostreidae unid.

Parastarte triguetra

Raagia cuneata

Tagelus divisus

Tagelus plebeius

Tagelus sp.

Tellina aeguistriata

Tellina mera

Tellina paramera

Tellina tampaensis

Te llin aversicolor

Tellina sp.

Bivalvia unid.

9. Th omas J. R. 1974. Benthic species diversity and environmental stability

in the northem Indian River, Florida. M.S. Thesis. Florida Institute of

Technology, Melbourne.

Sanders (1958. Benthic studies in Buzzards Bay I: Animal - sediment

relationships. Limnol. Oceanogr. 3:245-258) and Nichols (1970. Benthic

polychaete assemblages and their relationship to the sediment in Part

Madison, Washington. Mar. Biol. 6:48-57) found the sediment, particularly

the percentage of clay, to be the most significant correlate of faunal

distributions in the benthos. Sanders (1958) and Bloom et al. (1972.

Animal sediment relations and community analysis of a Florida estuary.

Marine Biol. 13:43-56) related an optimum particle size to the distribution

of suspension feeders. Nichols (1970) suggested the importance of the

sorting of particle sizes to the diversity of polychaete asseublages.

Sediment particle size sad sorting coefficients are also probably related

to the stability of the substrate and hence may be indicative of disturbances

to that substrate although such use-as indicators is of doubtful validity.

McNulty et al. (1962. Some relationships between the infauna of the level

bottom and the sediment in South Florida. Bull. Mar. Sci. Gulf Caribb.

12:322-332) suggest that sediments may play a less important role in shallow

waters of Florida. That conclusion is supported in part by Bloom et al. (1972)

in Tampa Bay, Florida.

Nichols (1970) concluded that the lower diversity among marine polychaete

assenblages at the mouth of an estuary than at deeper stations in Puget Sound,

Washington was the result of a shifting substrate and fluctuating salinities

at the estuary mouth. In addition, the work of Rhoades and young (1970. The

influence of deposit feeding organism an sediments stability -and community

trophic structure. J. Mar. Res. 28:150-178) and Levinton (1972.

Stability and trophic structure in deposit-feeding and suspension-feeding

commmities. The Am. Naturalist 106:472-486) suggests that the high

diversity of deposit feeders as opposed to the low diversity of suspension

feeders in benthic commmities is a function of the predictability or

constancy of food supply. Deposit feeders rely on a detritus sink in

which nutrients may be rapidly recycled and which acts as a buffer against

any fluctuations in the "rain" of detritus, from above. Suspension feeders,

on the other hand, are subjected to changes in food availability by currents

and seasonal population changes.

Bottom samples from 15 stations (replicated five times and then pooled)
were taken during June and July, 1973, with a Pcnar grab (0.05m 2 ; depths 2-8 cm)

along a 6.4 nautical mile north-south transect in the Indian River just north

of Titusville. A sluice box was designed to take an aliquot equal to 1/5 the

total area sampled by closing an inner gate subsequent to mixing, which should

randomly distribute the organisms. After removal of the outer gate in the

sluice box, the organisms were captured on a stack of screens; the smallest

mesh size was 0.42 mm. Organisms were fixed in 10% buffered formalin after

relaxation for 10-20 ainutes in 6% MgC1 2* The formalin was replaced after a
minimum of 24 hrs by 70% ethyl alcohol for preservation. Taxonomic ncMen-

clature used for Mollusca followed Abbott (1954. American Seashells. D.V.

Nostrand Co., Princeton, N.J., 541 pp) , Andrews (1971. Seashells of the

Texas Coast. Univ. of Texas Press , Austin. 298 pp) , and Warmke and Abbott

(1962. Caribbean Seashells. Livingston Publ. , Wynnewood, PA. 348 pp) The

mesh size (0.42 mm) of the sieves used, while smaller than that commonly

used for benthic studies (1 mm) was still too coarse to adequately determine

total faunal diversity: 100% retrieval of Nemerteans and Molluscs; 95.5%

for Polychaetes ; 65.2% f or Crus tacea; and 3. 75% for Nematodes (Reish. 1959.

A discussion of the importance of screen size in washing quantitative

marine bottom samples. Ecology 40 :307-309).

The initial effort of the study was directed toward investigating

species diversity with respect to those parameters which may place a

physical stress on the benthic community: salinity, temperature, dissolved

oxygen, nature of substrate, and depth (indirectly by buffering benthos,

against rapid or extreme fluctuation in the environment).

Although physical parameters of the sediment have been shown in

other studies to be a significant determinant of the benthic community,

the physical character of the sediment (i.e., median grain size, sorting

coefficient, and % silt and clay) was shown to be sufficiently homogeneous

so as to have little effect on the diversity and faunal distribution of

the benthos over the length of the transect. No significant correlation

(a = 0.05) was observed in the regression of species richness on salinity

but species richness was significantly correlated with sediment Eh. As the

reducing environment of the sediment increased there is a resultant decrease

in the number of species present. It appears, then, that the absence of

the rooted vegetation to directly supply higher concentrations of dissolved

oxygen in the face of high metabolic activity in the sediments limits the

number of member species that can exist. In addition, seagrasses provide

more stable sediments.

Water depth appears to be strongly correlated with species richness and

eveness but in opposite directions. In the deeper water where grasses are

absent and temperature and dissolved oxygen are lower, the amount of dissolved

oxygen available for respiration serves to decrease the number of species and

increase the evenness.

Rhoades and Young (1970) suggested a close relationship between deposit

feeders and suspension feeders. The reworking of sediments by the burrowing

activities of deposit feeders results in an unstable sediment surface layer

that is easily resuspended by weak wave and current action. This unstable

sediment layer may preclude the presence of large numbers of suspension feeders

through the reduction of stable attachment sites, clogging of gills or other

respiratory s turctures , and burying of newly settled larvae. Trophic exclusion

was found in the study at the biologically accommodated stations (i.e., not

limited by physical parameters) where increasing percentages of suspension

feeders were correlated with decreasing percentages of deposit feeders. For

physically controlled stations (i.e., low dissolved oxygen and redox) , trophic

exclusion was not found.

Molluscs found:

1. Pelecypoda

a. Gemma sp. 4 individuals along 15-station transect

b. Tagelus, divisus 1 11 it it it

C. Lyonsia hyalina 27

d. (hione cancellata 6

e. Brachidontes exustus 241

f. Apygdalum papyria 3

g. Nucula proxima '3

h. Mulinia lateralis 174

i. Tellina sp. 10

J. Laevicardium sp. 7

k. Anomalocaldia cuneimeris 3

10. Virnstein, R.W. , P.S. YAkkelsen, K.D. Cairns and M.A. Capone. 1983. Seagrass

beds versus sand bottoms: The trophic importance of their associated benthic

invertebrates. Florida Scient. 46:363-381.

Samples were taken from caged and adjacent natural uncaged sand and

seagrass with a post-hole type sampler which removed a sediment core 15 x 15 x

15 cm, along with any overlying seagrass and animals, which are retained by 0.5-mm

mesh sieve covering the top. A sample consisted of 4 replicate cores from each

habitat -2 from each cage - to account for variation between cages. Samples-

we're sieved on a 0.5-mm. mesh sieve, relaxed in 0.3% propylene phenoxytol in

seawater (McKay and Hartz band 1970), fixed for 24 hrs in 10% formalin in seawater

with the vital stain rose bengal added (Mas on and Yevich 1967), then transferred

to 70% ethanol for storage. Samples were sorted under a dissecting microscope,

and retained animals were -identified to lowest possible taxon. To test for

significant differences in mean abundance between pairs of samples, t-tests

were used.

Not only are densities of macrofauna much greater in seagrass than in sand,

but those animals which are more abundant in seagrass (the epifauna especially)

are also more heavily preyed on, and thus are trophically more important than

the infauna of seagrass. The epifaunal macrobenthos of seagrass meadows form an

important trophic pathway to higher predators via the decapods. Although absolute

predation intensities remain unknown, the primary pathway of transfer to higher

trophic levels differs between the 2 habitats - though the epifaunra in seagrass

meadows, and through the infauna in bare sand bottoms.

2
Bivalves found in 1.26 m sanpled seagrass and bare sand substrate:

1, Parastarte triquetra 145 individuals

2. Chione cancellata 53 individuals

3. Amygdalum papyrium 32

4. Mercenaria mercenaria 38

5. Mysella sp. 25

6. Crassostrea virginica 11

7. Anadara transversa 7

8. Lyonsia, floridana 8

9. Mulinia lateralis 9

10. Tellina ta=aensis 10

11. Tagelus plebeius 5

12. Tellina mera 5

13. Musculus lateralis 4

14. Abra aegualis 6

15. Macoma tenta 3

16. Sphenia antillensis 5

17. Lucina pectinata 2

18. Anomalocardia auberiana 2

19. Anomala simplex I

20. Corbicula ccntracta 1

21. Nucula crenulata 1

22. Macoma brevifrons 1

23. Tellina versicolor 1

24, TellIna sp, 1

25. Tagelus_ divisus 1

26. unid. Bivalvia 4

Weiderhold, C.N. 1976. Annual cycles of macrofaunal benthic invertebrates

in the northern Indian River, Florida. M.S. Thesis. Florida Institute of

Technology.

A square sample grid 75m on a side was set up in water 1.0-1.5m deep

in the Indian River near Kennedy Space Center. At the center and four

corners of this grid, benthic core samples were taken with a 15.25 cm
dian-ter (0.76m2 ) corer. Core samples were obtained by divers using

snorkels. The core sample was washed through a Imm sieve and the retained
material was relaxed in a 6% MgC12 solution for 10 to 20 min. The sample
was then placed in a 10% buffered formalin solution for a minimum of 24 hrs,

after which it was transferred to 70% ethyl alcohol for preservation until

sorted. Monthly analysis of the 5 sample sites over a year's cycle.

Taxonomic nomenclature followed Abbott (1954) and Andrews (1971; Seashells

of the Texas Coast. University of Texas press, Austin, Texas, 298 pp).

Molluscs found:

1. Pelecypoda

a. Pellina sp. 2-6mm; 2-10 individuals/care; density of bivalve

coincided with sea grass density.

b. Laevicardium mortoni 4-10mm; 2-4 individuals/core; density of bivalve

coincided with sea grass density.

c. Cylichna auberi 2-6mm; 0-10 individuals/ core; density of bivalves

coincidedwith sea grass density.

d. -Brachidcntes exustus 2-12mm; 3-10 individuals/core; no pattern

established with grass bed density.

2. Gastropoda

a. Marginella, apicina. 1-8mm; 5 indivuals/core; animal density did

not coincide with sea grass density.

Most of the animals whose cycles coincided exactly with the grass bed

density cycle were primarily suspension feeders. Suspension feeder cycles

also tended to correlate strongly with plankton cycles by a lag of one

month (Clark.,ZB.- 1975. Fourth Quarterly and Annual Report on the Indian

River Ecological Study. Submitted to the Orlando Utilities Co., 56 pp),

indicating that plankton may be an important alternate food source to these
forms.*

Because of the fine particle size, the sampling area supported a greater

density of deposit feeders than suspension feeders. The inverse relationship

between deposit feeders and suspension feeders supported Rhoads and Young

(1970.The influence of deposit feeding organisms on sediment stability and

community trophic structure. J. Mar. Res. 128:150-178) hypothesis of trophic

group exclusion or an amensalistic affect in which deposit feeders limit or

eliminate groups of suspension feeders by reworking t
he bottom sediments

producing a fluid fecal-rich surface which is easily suspended by low velocity

tidal currents. This instability tends to: 1) clog the filtering structure

of suspension feeding organisms; 2) bury newly settled larvae or discourage

the settling of suspension feeding larvae; and 3) prevent sessile epifauna.

from attaching to an unstable mud bottom.

12. Young, D.K. , and M.W. Young. 1977. Community structure of the macrobenthos

associated with seagrass of the Indian River Estuary, Florida, pp. 359-381.

In: B.C. Coull (ed) , Ecology of warine Benthos. Uaiversity of South Carolina

Press , Columbia.

Effects of predation on community structure of macrobenthos associated with

stands of Halodule wrightii in the Indian River estuary in east central

Florida were studied using cages. At the site characterized by a physically

unstable and unpredictable environment, the increases of several species within

the cage were in accord with predator-prey theory. At the other extreme, where

the environment was more physically stable and predictable, increases in diversity

of caged macrofauna. was inconsistent with current hypotheses of biological

interactions affecting community structure.

Bivalues found:

Brachidontes exustus

Anygdalum papyrium

Parastarte triquetra.

Tellina tammaensis

Chione, cancellata

Lyonsia hyalina, floridona

Lucina pectinata,

Tagelus 2lebeius

AnouLalocardia anberiana.

Macoma, constricta.

Macoma sp. A

Parvilucina. multilineata

Laevicardium sp. A

Corbicula cmtracta

Tellina versilcolor

Codakia orbicularis

Pteria colytrbus

Anomia simplex

Mulinla lateralis

Tellina paramera

Crassostrea virginica

The following literature was also searched, but the contents were found not to be

pertinent to the major emphasis of our proposed research:

Barnett, D. 1977. Factors influencing the distribution of gastropods living

in a soft substrate intertidal area. M.S. Thesis. Florida *Institute of

Technology, Melbourne.

Theroux, R.B., and R.L. Wigley. 1983. Distribution and abundance of East Coast

bivalve mollusks based on specimens in the National Marine Fisheries Service

Woods Role Collection. NOAA Technical Report NMFS SSRF-768. National Oceanic

and Atmospheric Administration, U.S. Dept. of Commerce, Rockville, MD.

Although this report is aa excellent source on the geographical distribution,

bathymetric occurrence, and occurrence according to sedimient type for over 108,000

speciments of bivalve mollusks (5 subclasses, 8 orders, 46 families, 99 genera, and

164 species) collected over a period of 21 yrs., the geographic area covered is too

broad to be of use for a specific area such as the Indian River Estuary.

Godcharles , M.F. , and W. C. Jaap. 1973. Exploratory clam survey of Florida near

shore and estuarine waters with commercial hydraulic dredging rXear. Professional

Papers Series Number Twenty-one. Florida Dept. of Natural Resources, St.

Petersburg, FL.

This survey addressed the distribution and abundance of'coTrywarcial clams

(Mercenaria mercenaria, Mercenaria campechiensis Macrocallis ta nimbos a, Rangia

cuneata) , using hydraulic and escalator dredges at 846 stations along the west and

southeast coasts of Florida, during 1970 and 1971. Only coastal nearshore waters

were sampled in the Ft. Pierce area; no stations were located in the Indian River.

The following people were interviewed for their knowledge of prior bivalves/

phytoplankton studies on the Indian River estuary:

Dr. Llewlyn Erhardt - Reported no studies on bivalves conducted at UCF.
Profess or
Biology Department
University of Central Florida

Mr. Carlton Hall - No studies an shellfish sponsored by NASA..
Marine Ecologist
Bionetics
Kennedy Space Center

Dr. S. Mahadevan - Prepared an annotated bibliography of published
Research Scientist
Mote Marine Lab and unpublished benthic com=ity studies conducted

in Florida's coastal and estuarine waters; only

3 F.I.T. theses were cited for the Indian River.

Dr. Norman Blakes - Applied to Gulf and South Atlantic Fisheries
Professor
and Development Foundation for a research grant entitled:
Dr. Bruce J. Barber
Research Associate "Stock Assessment, Growth and Reproduction and
Dept. of Marine Science
University of South Florida Transplant Survival of Hard Clams (Mercenaria

in the Indian River, Florida." This study, if

funded, would complement the research objectives of

the Florida Institute of Technology/Harbor Branch

Institutestudy. The stock assessment portion of

their study is miniscule compared to our proposed

population survey, but the growth, reproduction, and
transplant survival aspects' of their study will aid

in interpreting our data for management implications.

APPENDIX B

NUMBERS ACCORDING TO SIZE CLASS (mm SHELL LENGTH) OF MERCENARIA

MERCENARIA AND MULINIA LATERhLIS COLLECTED ALONG TRANSECTS A, B, C AND

D IN THE GRANT, MELBOURNE, AND MERRITT ISLAND AREAS OF THE INDIAN RIVER

LAGOON.

SHELL LENGTH (mm)

viercenaria mercenaria

G F-AUN T @JELBOURNE MERRITT ISLAND
A B c D A B c D A B c D

2.8-9.9 3.8 3.1 2.9 1.3 1 0.2 0.1 0.3 0.3

10 .0-19.9 5.1 5.3 3.7 2.1 O.L. 0.3 0.5 - - - -

20.0-29.9 - 0.3 0.6 0.7 - 0.1 - - 0.2 0.1

30.0-39.9 0.2 0.1 - 0.7 - 0.2 0.1 - 0.1 - -

40.0-49.9 0.2 0.4 0.6 0.6 0.6 0.1 - - 0.1 0.2 0.1

50.0-59.9 0.7 0.4 0.3 0.4 0.2 0.2 0.2 0.4 0.3 0.2 0.1 -

60,0-69,9 0*4 0*2 0*6 0,4 0,4 0*1 - 0*4 0*3 0*1 0*3 -

70.0-79.9 0.2 0.4 0.1 0.1 0.2 0.3 0.1 0.1 0.1 - - -

80.0-89.9 - 0.1 0.1 - 0.1 0.2 - 0.1 0.1 0.1 0.1 -

90.0-99.9 - - 0.1 0.1 0.1 0.1 - 0.1 - - - 0.1

100.0-109.9 - - - - - - -

110.0-119.9 - 0.1 - - - - - - - - Oil -

Mulinia lateralis

2.80-9.99 45 34 43 67 509 818 684 416 328 1007 924 904

10.0-20.0 9 10 6 6 1 8 19 29 0.3 0.2 0.1 2

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