A Shellfish Study for the Proposed Expansion of Fish Finder Marine 3645 Atlantic Brigantine Boulevard, Brigantine, New Jersey

December 8th & 9th 2011

Survey Conducted For:

Fish Finder Marine Joe & Kim Fumo, Owner(s)

3645 Atlantic Brigantine Boulevard Brigantine, New Jersey 08203

Survey Conducted By:

Richard Stockton College of New Jersey’s

Coastal Research Center 30 Wilson Avenue

Port Republic, NJ. 08241 (609) 652-4245

December 8th & 9th, 2011

A Shellfish Study for the Proposed Expansion of Fish Finder Marine 3645 Atlantic Brigantine Boulevard, Brigantine, Atlantic County, New Jersey

December 8th & 9th, 2011

Introduction A shellfish study was performed on December 8th & 9th 2011 to determine if Fish Finder Marine’s environmental conditions support a viable shellfish population. The shellfish study was designed and implemented using the Shellfish Survey Guidelines published by the New Jersey Department of Environmental Protection (NJDEP) as authorized by Jeffrey C. Lockwood, 1991 National Marine Fisheries Service, Habitat and Protected Resources Division. The proposed expansion of Fish Finder Marine involves extending the existing (western) fixed pier to a distance 260 feet from the existing bulkhead. The pier would extend in the south to north direction and would have 5 finger piers spaced 20 feet apart. The proposed marina is bordered on both sides by existing dock structures. The bay floor slopes from a depth at the bulkhead of -0.5 feet out to a depth of -17.7 feet NGVD 27. The target species are those which fall under the NJAC’s Coastal Zone Management Rules under Shellfish habitat. They include: Hard Clam (Mercenaria mercenaria), Soft Clam (Mya arenaria), Easter Oyster (Crassostrea virginica), Bay Scallops (Argopecten irradians), and Blue Mussels (Mytilus edulis), all of which are shellfish of commercial and biological significance. Methods and Materials The study area was selected by analyzing the area of the proposed marina expansion and evenly distributing the entire study area into uniform sub-sections (chart 1). The range of water depths was from -0.5 to -17.7 feet below the National Geodetic Vertical Datum of 1927 shown in Catalano’s USACOE Permit Plan. Using ESRI ArcGIS 9.3.1 a virtual grid was set up in the same approximate position of the proposed dock system with corresponding known locations totaling 24 points (chart 1). These points within the grid served as the locations for both the juvenile and adult shellfish survey. Using the Leica RTK GPS system 1200, the positions of all the data points for both the juvenile shellfish study and the adult shellfish study were obtained. To conduct the juvenile shellfish study the 24 data point locations stored on the GPS system were used as waypoints to locate each sample site (chart 1, table 3). At each location, a single anchor was set to help stabilize the boat. A Wildco Ponar grab sample; with an area of 0.75 sq. ft., was used to acquire the samples. Replicate grabs were often necessary to obtain a full sample size. Once a full sample was obtained, the material was sifted through a 5mm sieve and inspected for juvenile shellfish. This process was repeated at each individual location. Additional variables such as sediment type, additional bivalve mollusks, as well as aquatic vegetation were also noted at each site. At each location the abundance per square foot (ft2) and size distribution (mean and range) were also reported (tables 1 and 2). To conduct the adult shellfish study, the site locations stored on the GPS were again used to navigate to the pre-established locations (chart 1, table 3). At twelve locations two anchors were set, one at the bow and one at the stern. The anchor lines were let out equally and incrementally in 10’ sections. Each 10’ section was raked using a 16” x 3” toothed bull rake at each location

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until a 30’ transect distance was achieved. At all 24 locations a Wildco Ponar grab sample; with an area of 0.75 sq. ft., was used to acquire samples. Replicate grabs were often necessary to obtain a full sample size. Additional variables such as sediment type, other bivalve mollusks, as well as aquatic vegetation were also noted at each site. At each location, the abundance per ft2 and size distribution (mean and range) was also reported (Tables 1 and 2). Results A total of 20 Hard Clams (Mercenaria mercenaria) were found in the study area. The size frequency distribution of the clams found revealed that multiple year classes were present at the site. This indicates that natural recruitment is taking place in the study area (table 1, chart 2). Juvenile Shellfish As reported above the study area was sampled for juvenile shellfish by utilizing a Wildco Ponar Grab Sample with an area of 0.75 sq. ft. Twenty four sites were established and sampled representing the area of the proposed marina expansion. One juvenile Hard Clam (Mercenaria mercenaria) was found at location S4 resulting in a density 1.333 clams/sq. ft. at that location A total of 18 sq. ft. was sampled producing an overall Hard Clam density of 0.055 clams/sq. ft. across the total surface area. Only one juvenile Hard Clam was collected so the mean size was 1.2 cm with a range of 0 (table 1). Adult Shellfish As reported above the twelve sites were sampled using a 16” x 3” toothed bull rake and all 24 sites were sampled using a Wildco Ponar Grab Sample with an area of 0.75 sq.ft.. A total of 19 adult Hard Clams (Mercenaria mercenaria) were found in the entire area. Each raked site was raked a distance of 30’. Clams were found in 11 of the 24 sites. Locations S5 (1.333 clams/sq. ft.), S11 (4 clams/sq. ft.), and S23 (1.333 clams/sq. ft.), have densities which indicate viable shellfish habitat. However, a total of 497.88 square feet was sampled with an overall density of 0.038 clams/sq. ft. across the entire area. The mean size of the clams collected was 6.37 cm with an overall range of 4.6 from 4.3 to 8.9 cm (table 1). Sedimentology The sedimentology of the area consisted of fine sandy black mud, very fine sandy black mud, fine muddy black/grey sand, fine muddy black sand, medium muddy black/grey sand, and black mud (table 2). Aquatic Vegetation There were 2 major species of aquatic vegetation in the study area, Sea Lettuce (Ulva lactuca), and Agardh’s Red Weed (Agardhiella tenera). At 8 locations Phragmites roots were found, indicating that at one time a marsh existed here. The installation of the bulkhead likely resulted in shoreline retreat as a result of scouring (table 2). Other Shellfish A total of, 3 Rock Crab (Cancer irroratus), 3 Mud Dog Whelk (Nassarius obsoletus), 2 juvenile Blue Crab (Callinectes sapidus), and 1 adult Blue Crab (Callinectes sapidus), were found in the process of locating shellfish (table 1).

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Conclusion The study area at 3645 Atlantic Brigantine Boulevard, Brigantine, Atlantic County, NJ is the location of the proposed expansion of Fish Finder Marine. The area was surveyed by utilizing ArcGIS software, GPS equipment, grab sampling techniques, and a clam rake to help isolate shellfish in accordance with the NJAC’s Coastal Zone Management Rules. It states that “a shellfish habitat area is defined as an area which… has a current shellfish density equal to or greater than 0.20 shellfish per square foot”. Both the juvenile and the adult shellfish study had densities values (averaged across the total surface area) below the cited threshold. Hard Clam (Mercenaria mercenaria) was the only relevant shellfish species found in the study area. There were small areas which did support zones of viable habitat according to the cited density threshold. Location S4 yielded 1.333 juvenile Hard Clams per square foot. Location S5 yielded 1.333 adult Hard Clams per square foot. Location S11 yielded 4 adult Hard Clams per square foot. Location S23 yielded 1.333 Hard Clams per square foot. The juvenile clams (those surveyed with the 5mm sieve screen) produced a value averaged across the total surface area sampled by the ponar grab samples (18.0 ft2) at 0.055 clams per square foot. The adults recovered in the rake and ponar grab sample produced a value averaged across the total surface area of 497.88 square feet yielded 0.038 clams per square foot. These numbers indicate that the clam density within the area delineated for the installation of a marina expansion at Fish Finder Marine does not substantiate a viable Hard Clam habitat.

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Water Quality Characteristics for Fish Finder Marine,

Brigantine, NJ.

Site of the Proposed Marina Expansion

Temperature, Salinity, Dissolved Oxygen, Depth, pH, Specific Conductivity, and Turbidity Data for Shellfish Habitat

Introduction: The Richard Stockton Coastal Research Center (CRC) completed a juvenile and adult hard clam study for the proposed development of Fish Finder Marine, Brigantine, NJ in December 2011. Twenty four sites were survey for juvenile and adult hard clams. In this study, one juvenile clams was observed and 19 adult clams were obtained within 497.88 square feet of space raked in the project area. A water quality assessment was also included in the proposal based on the follow variables: temperature, salinity, dissolved oxygen, depth, pH, specific conductivity, and turbidity for the water just above the sediment surface. Water Quality at the Site: The CRC complied the data on December 8th & 9th 2011 with a study of the water quality parameters for the 24 sites subjected to clam raking or grab sampling using a YSI water quality probe to obtain the results listed in table 7, below. The table lists the site location using the same designations used in the clam study. The dissolved oxygen values are shown as both a percentage of the maximum level in seawater and as milligrams per liter of water. The depth of measurement at the mid-tidal elevation stage the work was done is also listed. The specific conductivity is given as well although the salinity is the most common expression of the salt content of the water. Conclusions: The average temperature of 10.92 degrees Celsius is normal for the time of year within the bay environment of Atlantic County. The salinity is also within normal ranges for mid-tide conditions behind the barrier island, however, the average value of 28.0 ppt failed to fall within the optimal range for the Hard Clam of 26.5 to 27.5 ppt. The dissolved oxygen levels are excellent with average values of 9.66 mg/L, and 105.80% respectively. The pH value of 7.91 is within the normal range for all stages of Hard Clam development. None of the remaining water quality parameters including depth, specific conductivity (44.32 mS/cm), and turbidity (9.30 NTU), would dictate that shellfish could not live in the waters of the proposed development of Fish Finder Marine (see appendix at end).

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0

1

2

3

4

5

6

7

8

0-25 25-38 38 51 51-63 63-76 76-102

Frequency

Data Bin Ranges (mm)

Chart 2: Length Frequency for Hard Clams Collected During Site Inspection at Fish Finder Marine, Brigantine, NJ. December 8th & 9th

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Transect Juvenile Clams (live) Adult Clams (live) Clams Per Site Other Shellfish Observations Transect Length Grab Sample Area Juvenile Hard Clam Density Adult Hard Clam Density Mean Range

S1 - 1 Hard Clam: 8.4 cm 1 - Rocks 30' 0.75' - 0.024 8.4 0

S2 - 1 Hard Clam: 5.5 cm 1 -1 Adult Hard Clam

Shell30' 0.75' - 0.024 5.5 0

S3 -2 Hard Clam: 7.2 cm, 7.4

cm2 -

2 Adult Hard Clam Shells, Rocks

30' 0.75' - 0.05 7.3 0.2

S4 1 Hard Clam: 1.2 cm - 1 - - - 0.75' 1.333 - 1.2 0

S5 - 1 Hard Clam: 4.8 cm 1 -Razor Clam Shell, Gravel in substrate

- 0.75' - 1.333 4.8 0

S6 - - 0 1 Blue Crab

(Callinectes sapidus ): 4.2 cm

Blue Mussel Shells, Hard Clam Shells

- 0.75' - - - -

S7 - 1 Hard Clam: 7.1 cm 1 -1 Adult Hard Clam

Shell, 1 Adult Razor Clam Shell

30' 0.75' - 0.024 7.1 0

S8 -3 Hard Clam: 4.6 cm, 4.3

cm, 5.1 cm3

2 Rock Crabs (Cancer irroratus ): 3.7 cm, 4.1

cm

Rocks, Hard Clam shells, Tube worm

casings, Oyster shells 30' 0.75' - 0.073 4.6 0.8

5.7 -5 Hard Clam: 5.7 cm, 6.3 cm, 8.3 cm, 8.0 cm, 5.7

cm5 - - 30' 0.75' - 0.123 6.8 2.6

S10 - - 01 Mud Dog Whelk

(Nassarius obsoletus)Blue Mussel Shells, Jingle Clam Shells

- 0.75' - - - -

S11 - 3 Hard Clam: 7.4 cm, 4.4 cm, 5.8 cm

31 Rock Crab (Cancer

irroratus): 3.5 cm Tube worm casings - 0.75' - 4 5.86 3

S12 - - 0

1 Juvenile Blue Crab (Callinectes sapidus): 2.6 cm, 2 Mud Dog Whelk (Nassarius obsoletus)

Significant amount of Tube worm casings,

- 0.75' - - - -

S13 - - 0 - - 30' 0.75' - - - -

S14 - - 0 -Tube worm, Juvenile

Hard Clam Shells30' 0.75' - - - -

S15 - 1 Hard Clam: 6.2 cm 1 -Blue mussel Shells, tube worm casings,

rocks

30' 0.75' - 0.024 6.2 0

S16 - - 0 -1 Tube Worm, Tube

Worm Casings, Snail shells

- 0.75' - - - -

S17 - - 0 -24 Tube Worms,

Crushed Blue Mussel Shells

- 0.75' - - - -

S18 - - 0 -Crushed Blue Mussel Shells, Snail Shells, Tube Worm Casings

- 0.75' - - - -

S19 - - 0 - - 30' 0.75' - - - -

S20 - - 0 - - 30' 0.75' - - - -

S21 - - 0 - 36 Blue mussel shells 30' 0.75' - - - -

S22 - - 01 Blue Crab (Callinectes

sapidus): 2.9 cm

24 juvenile clam shells, Hard Clam

Shells, Blue Mussel Shells

- 0.75' - - - -

S23 - 1 Hard Clam: 8.9 cm 1 -Crushed Blue Mussel

Shells, 12 Juvenile Hard Clam Shells

- 0.75' - 1.333 8.9 0

S24 - - 0 -Clam Shells, Crushed Blue Mussel Shells, 1

Tape Worm- 0.75' - - - -

Table 1: Sample Sites Used to Determine the Density of Adult and Juvenile Hard Clams

Adult Shellfish Study: 497.88 sq. ft. sampled, 19 adult Hard Clams = 0.038 clams/sq. ft.; Juvenile Shellfish Study: 18 sq. ft. sampled, 1 Juvenile Hard Clams = 0.055 clams/ sq. ft.

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Site # Species & viability of aquatic vegetation SedimentS1 Agardh's Red Weed (Agardhiella tenera), and Minimal amounts of Sea

Lettuce (Ulva lactua) Fine Muddy Sand, Black/Grey

S2 Minimal amounts of Sea Lettuce (Ulva lactua ), and Agardh's Red Weed (Agardhiella tenera ) Fine Muddy Sand, Black

S3 Agardh's Red Weed (Agardhiella tenera) , and Sea Lettuce (Ulva lactua) Medium Muddy Sand, Black/Grey

S4 Phragmities Roots Fine Sandy Mud, Black

S5 Phragmities Roots Fine Sandy Mud, Black

S6 Phragmities Roots Fine Sandy Mud, Black

S7 Ahardh's Red Weed (Agardhiella tenera) , and Phragmities Roots Medium Muddy Sand, Black/Grey

S8 Phragmities Roots Very Fine Sandy Mud, Black

S9 Sea Lettuce (Ulva lactua) , and Phragmities Roots Very Fine Sandy Mud, BlackS10 Phragmities Roots Very Fine Sandy Mud, BlackS11 Sea Lettuce (Ulva lactua) Very Fine Sandy Mud, BlackS12 no vegitation found Very Fine Sandy Mud, BlackS13 no vegitation found Mud, Black

S14 Sea Lettuce (Ulva lactua), and Minimal amounts of Agardh's Red Weed (Agardhiella tenera) Very Fine Sand Mud, Black

S15 Sea Lettuce (Ulva lactua) Very Fine Sand Mud, BlackS16 no vegitation found Very Fine Sandy Mud, BlackS17 no vegitation found Very Fine Sandy Mud, BlackS18 Phragmities Roots Very Fine Sandy Mud, BlackS19 Minimal amounts of Sea Lettuce (Ulva lactua ) Very Fine Sand Mud, BlackS20 no vegitation found Very Fine Sand Mud, BlackS21 no vegitation found Mud, BlackS22 no vegitation found Very Fine Sandy Mud, BlackS23 no vegitation found Very Fine Sandy Mud, BlackS24 no vegitation found Fine Sandy Mud, Black

Table 2: Aquatic Vegetation & Sediment Type

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Transect Easting NorthingS1 522756.72 204668.65S2 522731.79 204667.87S3 522706.71 204667.10S4 522756.20 204683.68S5 522731.22 204682.92S6 522706.17 204682.07S7 522755.80 204698.64S8 522730.74 204697.95S9 522705.79 204697.06

S10 522755.25 204713.77S11 522730.26 204712.78S12 522705.27 204712.09S13 522754.72 204728.62S14 522729.79 204727.72S15 522704.86 204727.05S16 522754.30 204743.53S17 522729.30 204742.92S18 522704.30 204742.04S19 522753.88 204758.60S20 522728.83 204757.86S21 522703.78 204757.03S22 522753.36 204773.60S23 522728.38 204772.81S24 522703.36 204772.10

December 8th & 9th Survey PointsTable 3: Fish Finder Marine Shellfish Study

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SiteTemperature

(Celsius)Salinity

(ppt)Dissolved Oxygen

(as a %)Dissolved Oxygen

(mg/L)Depth (feet) pH

Specific Conductivity

(mS/cm) Turbidity (NTU)S1 10.89 27.41 111.1 10.07 0.638 7.90 44.21 9.30S2 11.34 27.55 112.6 10.17 1.490 7.90 44.51 8.90S3 11.23 27.64 121.5 10.80 1.150 7.86 44.48 8.76S4 11.24 27.54 102.9 9.45 0.951 7.93 44.05 9.60S5 11.40 27.55 102.8 9.40 1.468 7.92 44.49 9.55S6 11.36 27.53 101.0 9.17 1.167 7.93 44.12 9.90S7 10.80 28.81 103.8 9.32 2.760 7.94 44.74 8.60S8 10.89 28.77 111.0 10.14 2.993 7.92 44.66 9.20S9 10.79 28.74 114.6 10.40 3.842 7.75 44.62 9.00

S10 10.83 28.57 116.0 10.20 3.813 7.93 44.45 9.80S11 10.77 28.43 97.5 9.08 3.150 7.93 44.31 8.80S12 10.69 28.71 109.8 9.95 4.569 7.88 44.60 10.10S13 10.81 28.46 107.3 9.74 2.701 7.95 44.25 8.20S14 10.76 28.49 104.7 9.51 5.844 7.95 44.33 9.20S15 10.64 28.42 105.1 9.63 3.841 7.94 44.27 8.50S16 10.61 28.28 102.6 9.45 6.261 7.93 44.00 9.10S17 10.56 28.17 102.3 9.42 6.449 7.95 43.89 9.70S18 10.54 28.1 101.5 9.4 2.874 7.94 43.76 10.50S19 11.08 27.41 90.7 8.90 7.801 7.92 44.18 9.10S20 11.07 27.45 102.8 9.41 6.070 7.92 44.78 8.80S21 11.19 27.45 106.4 9.56 2.680 7.92 44.09 9.30S22 10.84 27.49 99.9 9.25 14.800 7.91 44.65 10.10S23 10.93 27.48 109.7 9.97 15.230 7.90 44.23 9.80S24 10.85 27.52 101.7 9.39 8.760 7.91 44.10 9.50

Avg 10.92 28.00 105.80 9.66 4.64 7.91 44.32 9.30

Table 4: Fish Finder Marine Shellfish Study Water Quality Data

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References

1. J. C. Lockwood, “Shellfish Survey Guidelines”, National Marine Fisheries Service, Habitat and Protected Resources Division, Highlands, N.J., 1991.

2. N.J.A.C., “Coastal Zone Management Rules”, 7:7E-3.2, 19-22, (2009).

3. R. J. Catalano. PE., “Fish Finder Marine USACOE Permit Application Plan”, (2011).

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APPENDIX OF LITERATURE FOUND DISCUSSING HARD CLAM HABITAT PARAMETERS

The References Below Cover Specific Parameters for Mercenaria mercenaria clams Hill, K. (2004). Smithsonian Marine Station at Fort Pierce. Retrieved January

13, 2012, from http://www.sms.si.edu/irlspec/mercen_mercen.htm Abundance: “In the IRL as in other areas within its range, Mercenaria mercenaria is most abundant in shell-containing soft bottoms. They are also found (in decreasing order of abundance) on sand flats, sand/mud flats and on muddy bottoms (Wells 1957; Pratt 1953). A study by Peterson et al., (1984) also showed that densities of 0 - 2 year old hard clams in eelgrass (Zostera marina) beds of North Carolina was more than 5 times the average density of clams in nearby sand flats (9 per square meter in eelgrass, vs. 1.6 per square meter in nearby sand flats. Further, hard clams from Zostera beds appeared to be somewhat larger, on average, than those from sand flats. Hydrodynamic baffling by seagrasses may be at least partially responsible for the observed result (Peterson et al., 1984). Reduction in currents near the benthos enhances the deposition of fine sediments and suspended materials between blades of seagrass, especially near patch edges. Hydrodynamic baffling therefore provides a rich food source for juvenile clams.” Mann, R., Harding, J. M., Southworth, M. J., Wesson, J. A. (2005). Northern

Quahog (hard clam) Mercenaria mercenaria abundance and habitat use in Chesepeake Bay. Journal of Shellfisheries Research, 24(2), 509-516.

“Clam densities decreased significantly across the four types of substrate with the highest densities observed in shell substrate followed by sand, mud and anoxic muds in order of decreasing occupation (Kruskal Wallis, H = 1,414.27, DF = 3, P < 0.01; Fig. 3). Less than 1% of all clams collected were from anoxic mud substrates whereas shell, sand, and mud substrates contained 11%, 68% and 21% of clams, respectively. Although shell and sand substrates contained the highest observed densities of hard clams, these substrate types were only present in 38% of patent tong samples collected from potential clam habitats.” Mulholland, R. (1984). Habitat Suitability Index Models: Hard Clam. Florida

Cooperative Fish and Wildlife Research Unit. FWS/OBS-82/10.77 SPECIFIC HABITAT REQUIREMENTS: Embryo, Larva, Juvenile

pH. “Calabrese (1972) observed that the successful recruitment of mercenaria requires that the pH of estuarine waters not fall below 7.0; he found no significant decrease in the number of clam embryos developing normally within the pH range of 7.0-8.75, but that number was greatly reduced at pH 9.0. Survival of clam larvae was normal at pH 6.25-8.75, but the range for normal

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growth was 6.75-8.50. Although clam larvae can survive at pH 6.25, a pH of 7.0 is required for normal development of the embryo. Levels of pH below 7.0 limit recruitment of the species (Calabrese 1972).” Dissolved oxygen. “Morrison (1971) found that growth of shelled veligers of M. mercenaria was normal when dissolved oxygen concentration was 4.2 mg/l or greater. Growth essentially ceased at concentrations of 2.4 mg/l and less. Larvae survived extended exposures (14 days) to 1 mg/l dissolved oxygen but grew little. Prolonged exposure to levels of less than 4.0 mg/l lengthened the clam's planktonic stage and decreased its probability of survival. Embryos developed normally at oxygen levels as low as 0.5 mg/l; however, 100% mortality occurred at 0.2 mg/l. Fluctuations in dissolved oxygen do not affect adult hard clams as much as do fluctuations in temperature and salinity (Stanley and DeWitt 1983). The burrowing ability of M. mercenaria was neither severely nor permanently impaired by exposure to reduced oxygen levels (less than 1mgl1 seawater) for up to 3 weeks (Savage 1976). Pratt and Campbell (1956) found no correlation between growth rates and various concentrations of dissolved oxygen. All life stages tolerate nearly anoxic conditions for long periods, though they may cease growing (Stanley and DeWitt 1983).” Salinity. “Salinity appears to be most critical for M. mercenaria during the egg and larval stages (Stanley and DeWitt 1983). At Long Island Sound, New York, eggs developed into straight-hinged veligers only within the relatively narrow salinity range of 20.0 to 32.5 parts per thousand (ppt ), The optimum for development of clam eggs was about 26.5 to 27.5 ppt (Davis 1958). Growth of larvae, once they attained the straight-hinged stage, was comparatively good at salinities as low as 20 ppt (Davis 1958), but Chanley (1958) found that growth of juvenile M. mercenaria was retarded at salinities of 22.5 ppt or lower. Castagna and Chanley (1973) found that metamorphosis of M. mercenaria from veliger to seed clam (byssal plantigrade stage) was inhibited below 17.5 to 20 ppt.” Temperature. “Davis and Ca1abrese (1964) noted that 1aboratory-rea red straight-hinged veligers of M. mercenaria were capable of ingestion, but not digestion, at 10°C (50°F),- and consequently did not grow. Growth was positively related to temperature at 18.0° to 30.0°C (64° to 86°F). Growth of straighthinged veligers of M. mercenaria was little affected by temperature differences within the range of 20° to 30°C (68° to 86°F). Although the optimum temperature for growth of M. mercenaria larvae was not well defined, growth was optimum at the following temperature/salinity combinations: 30°C (86°F)/22.5 ppt and higher, 27.5°C (81.5°F)/17.5 and 20.0 ppt, and 25°C (77°F)/15.0 ppt.” Substrate. “The nature of the bottom substrate seems to be the main factor responsible for settling of larvae and for the qualitative composition of bottom communities (Thorson 1955). Keck et ale (1974) reported from laboratory studies that significantly higher (P ~ 0.05) numbers of M. mercenaria larvae set in sand than in mud; they suggested that the addition of organic material to the sediment may be responsible for reduced setting because of increased bacteria levels, reduced dissolved oxygen, and increased production of hydrogen sulfide. Carriker (1959) recommended that the substrate be firm and free of excessive organic mud for larval clam culture; muddy bottoms can be surfaced with shells, sand, or gravel. Adult Clams were most abundant in predominantly fine sediments, but in these sediments their abundance was generally

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a function of the coarseness of the minor constituents. Clams do not grow well in silty substrates. Pratt and Campbell (1956) found an inverse relationship between growth of M. mercenaria and the fineness of the sediment (expressed as percentage of silt and clay). The inferior growth was attributed to frequent gi1l clearing, which expended energy and interfered with feeding. Johnson (1977) also reported slower growth of M. mercenaria in finer sediment due to increased expulsion of pseudofeces.” Suspended solids. “Davis (1960) noted that both the larvae and egg stage are affected by suspended solids. “Eggs did not develop correctly at silt concentrations of 3.0 or 4.0 g/L, and straight-hinged veligers was normal at silt concentrations of 0.75g/L, retarded at 1.0 to 2.0g/L, and negligible at 3.0 and 4.0g/L”. ”

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