MD-A151 6i4 SPECIES PROFILES- LIFE HISTORIES AND ENVIRONMENTAL 1/1REQUIREMENTS OF COASTA (U) MAINE COOPERATIVE FISHERYRESEARCH UNIT ORONO M A SELLERS ET AL JUL 84 N

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July 1984

DTlC~ELECTE

Species Profiles: Life Histories and MAR 1 3 1985Environmental Requirements of Coastal Fishesjand Invertebrates (North Atlantic) BAMERICAN OYSTER

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FWS/OBS-82/11.23TR EL-82-4July 1984

Species Profiles: Life Histories andEnvironmental Requirements of Coastal Fishes and Invertebrates

(North Atlantic)

AMERICAN OYSTER

by

Mark A. SellersProgram in Oceanography

University of Maine at OronoIra C. Darling CenterWalpole, ME 04573

and

Jon G. StanleyMaine Cooperative Fishery Research Unit

313 Murray HallUniversity of MaineOrono, ME 04469

Project Manager DTICLarry Shanks

Project Officer ELECTENorman Benson

National Coastal Ecosystems Team MAR 0 WU.S. Fish and Wildlife Service

1010 Gause BoulevardSlidell, LA 70458 B

Performed for,oastal Ecology Group

Waterways Experiment StationU.S. Army Corps of Engineers

Vicksburg, MS 39180

and

National Coastal Ecosystems TeamDivision of Biological Services

Research and DevelopmentFish and Wildlife Service

U.S. Department of the InteriorWashington, DC 20240

DIM- UTION STATEMENT A

Appe~dImpublic WosuDistibution Unlimted

This series should be referenced as follows:

U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life histories

and environmental requirements of coasta-T fishes and invertebrates. U.S. FishWildl. Serv. FWS/OBS-82/11. U.S. Army Corps of Engineers, TR EL-82-4.

This profile should be cited as follows:

Sellers, M.A., and J. G. Stanley. 1984. Species profiles: life histories andenvironmental requirements of coastal fishes and invertebrates (North Atlan-tic) -- American oyster. U.S. Fish Wlldl. Sery. FWS/OBS-82/11.23. U.S. AmyCorps of Engineers, TR EL-82-4. 15 pp.

PREFACE

This species profile is one of a series on coastal aquatic organisms,principally fish, of sport, commercial, or ecological importance. The profilesare designed to provide coastal managers, engineers, and biologists with a briefcomprehensive sketch of the biological characteristics and environmental require-ments of the species and to describe how populations of the species may beexpected to react to environmental changes caused by coastal development. Eachprofile has sections on taxonomy, life history, ecological role, environmentalrequirements, and economic importance, if applicable. A three-ring binder isused for this series so that new profiles can be added as they are prepared. Thisproject is jointly planned and financed by the U.S. Army Corps of Engineers andthe U.S. Fish and Wildlife Service.

Suggestions or questions regarding this report should be directed to:

Information Transfer SpecialistNational Coastal Ecosystems TeamU.S. Fish and Wildlife ServiceNASA-Sl1idell1 Computer Compl ex1010 Gause BoulevardSlidell, LA 70458

or

U.S. Army Engineer Waterways Experiment StationAttention: WESERPost Office Box 631Vicksburg, MS5 39180

AicceSSion For

i*ti

(2OT

CONTENTS

Page

PR~EFACE .. .. ....... ...... ....... ....... ...... iiCONVERSION TABLE .. ..... ....... ...... ....... .... vACKNOWLEDGMENTS .. .. ....... ...... ....... ........ vi

NOMENCLATURE/TAXONOMY/RANGE. .. ..... ...... ....... ......MAORPHOLOGY/IDENTIFICATION AIDS .. ..... ...... ....... .... 1REASON FOR INCLUSION 1.1 SERIES . . . ... .. .. .. .. .. .. . .2

LIFE HISTORY. .. ..... .. .. .. .. .. .. .. .. .. .. .. .. 2Spawning. ... ....... ...... ....... ....... ... 2Larvae. .. ....... ....... ...... ....... ..... 3Juveniles . . .... .. .. .. .. .. .. .. .. .. .. .. .. . .3

Adult .. .. ...... ....... ....... ....... ...... 4GROWTH CHARACTERISTICS. .. ....... . . .. .. .. .. .. .. . .4

COMMERCIAL HARVEST .. .... ....... ....... ....... ... 5Population OYndliCS .. .. ....... ....... ...... ..... 5

ECOLOGICAL ROLE. .. .... ....... ...... ....... ..... 8ENVIRONM4ENTAL REQUIREMENTS .. ..... ....... ...... ....... 8

Teiperdture. .. .... ....... ...... ....... ....... 8Salinities .. ..... ....... ...... ....... ....... 9riabi tat. .. .... ........................ 10Other Environmnental Factors......................10

LITERATURE CITED). .... ....... ....... ...... ...... 11

iv

CONVERSI ON FACTORS

Metric to U.S. Customary

Multiply Y To Obtain

millimeters (m) 0.03937 inchescentimeters (cm) 0.3937 inchesmeters (m) 3.281 feetkilometers (kn) 0.6214 miles

square meters (in 2 ) 10.76 square feetsquare kilometers (km ) 0.3861 square mileshectares (ha) 2.471 acres

liters (1) 0. 2642 gallonscubic meters (m) 35.31 cubic feetcubic meters 0.0008110 acre-feet

milligrams (mg) 0.00003527 ouncesgrams (g) 0.03527 ounceskilograms (kg) 2.205 poundsmetric tons (t) 2205.0 poundsmetric tons 1.102 short tonskilocalories (kcal) 3.968 British thermal units

Celsius degrees 1.8(CP) + 32 Fahrenheit degrees

U.S. Customary to Metric

inches 25.40 millimetersinches 2.54 centimetersfeet (ft) 0.3048 metersfathoms 1.829 metersmiles (mi) 1.609 kilometersnautical miles (nmi) 1.852 kilometers

square feet (ft2) 0.0929 square metersacres 0.4047 hectaressquare miles (mi2) 2.590 square kilometers

gallons (gal) 3.785 literscubic feet (ft3) 0.02831 cubic metersacre-feet 1233.0 cubic meters

ounces (oz) 28.35 gramspounds (lb) 0.4536 kilogramsshort tons (ton) 0.9072 metric tonsBritish thermal unit (BTU) 0.2520 kilocalories

Fahrenheit degrees 0.5556(F0 - 32) Celsius degrees

V

ACKNOWLEDGMENTS

We thank Dr. Herbert Hidu, Professor of Zoology, University of Maine, forreviewing the manuscript and offering many helpful suggestions.

vi

vi

Figure 1. American oyster from Wellfleet Harbor, Massachusetts (Galtsoff 1964).

AMERICAN OYSTER

NOMENCLATURE/TAXONOMY/RANGE MORPHOLOGY/IDENTIFICATION AIDS

Scientific name ..... .. Crassostrea The left valve is almost alwaysvirginica (Gmelin) thicker and heavier than the right,

Preferred common name . . . American and more deeply cupped (Yonge 1960;oyster (Figure 1) Galtsoff 1964). The oyster is cemented

Other common name . . . Eastern oyster to the substrate on its left valve.Class . . . . . Bivalvia (Pelecypoda) Hinge teeth are absent, but a buttressOrder . . . . . ...... Pteroidea on the right valve fits into a depres-Family ............ . . Ostreidae sion on the left. There is no gap be-Gtween the valves when fully closed.Geographic range : In estuaries,

drowned river mouths, and behind Shell shape is variable. On hardbarrier beaches along the east bottoms, beaks (umbones) usually arecoast of North America, from the curved and point toward the posterior,Gulf of St. Lawrence, Canada, to whereas in silty environments or onKey Biscayne, Florida. In the reefs, umbones are usually straight.Gulf of Mexico to the Yucatan Single oysters from hard substratesPeninsula of Mexico, and in the are rounded and ornamented with radialWest Indies to Venezuela. Intro- ridges and foliated processes, whereasduced to Japan, Australia, Great those from soft substrates or reefsBritain, Hawaii, and the west are more slender and are sparsely or-coast of North America (Ahmed namented. Shell thickness also depends1975). The largest American on environment. Oysters on hard sub-oyster populations are in the strates have thicker and less fragileGulf of Mexico, Chesapeake Bay, shells than those on soft substrate.and Long Island Sound. The index of shape (height + width/!i1

length) varies from 0.5 to 1.3 in on the hinge distinguishes larval C.southern populations and from 0.6 to virginica from other Crassostrea.1.2 in northern populations.

Growth rings are oval with great- REASON FOR INCLUSION IN SERIESest growth along the dorsal-ventralaxis. The principal growth axis is not American oysters support an im-permanent and may change several times portant commercial fishery from theover the lifespan of an individual, Gulf of Mexico to the Gulf of St. Law-resulting in a zigzag pattern. The rence, and are an important maricul-growth axis may change as much as 90°. ture species. More U.S. plants produceOysters 3 to 5 years old are usually oyster products than any other single10 to 15 cm in height. Although tissue fishery product, and over 10,000 peo-mass reaches an upper limit, the shell ple are employed in the oyster indus-continues to grow over the lifespan of try. Oysters are valued as a luxuryan oyster (Stenzel 1971). The largest food item. They are the keystone spe-height reported in the North Atlantic cies of a reef biocoenosis that in-region is 35.5 cm, from the Damaris- cludes several hundred species (Wellscotta River, Maine (Galtsoff 1964). 1961). Because oysters occur in estua-

rine areas, they are vulnerable toThe American oyster is isomyarian disturbance by development projects.

(adductor muscles are equal in size).The interior of the shell has apurple-pigmented adductor muscle scarsituated slightly posterior and yen- LIFE HISTORYtral. A second muscle scar, of thequenstedt muscle, is situated underthe hinge. Chalky deposits may occur Spawningon the inside of the shell. The ad-ductor muscle scar pigmentation dis- Gametogenesis and spawning aretinguishes the American oyster from stimulated by temperature (Hopkins etsimilar species. In C. rhizophorae and al. 1954; Kaufman 1978; Andrews 1979).C. gigas the muscle scar is lightly The temperatures at which spawningpigmented, and in C. conmercialis and occurs differ among populations. Stau-C. rivularis it is unpigmented. Al- ber (1950) recognized three physiolog-though C. -igas has been introduced to ical races, two from the east coastSalt Pond in lue Hill, Maine, Well- and one from the gulf coast, whichfleet Harbor, Massachusetts, and spawn at 16.4'C, 20.0C, and 25.0°C,Mobile Bay, Alabama, the only signif- respectively. Evidence for physiolog-icantly numerous sympatric Crassostrea ical races was given by Loosanoffspecies is C. rhizophorae, which (1969), who found that gametes of 60%occurs along t~e southeastern and gulf of the oysters from Long Island Soundcoasts. The shell of C. rhizophorae is populations ripened at 15°C after 45less plicated than ttiat of _. virgin- days, whereas only 20% of the oystersica. Crassostrea species are distin- from a New Jersey population had ripeulshable from Ustrea species by the gametes after 72 days at the same tem-presence of a promyal chamber, which perature. At 18'C none of the oystersis well developed in C. virginica. from south of New Jersey matured, evenCrassostrea are oviparous, releasing after 3 years. The time required forgametes into the water, whereas Ostrea gonad maturation (D) in Long Islandincubate fertilized eggs in the mantle Sound oysters is inversely proportion-cavity. Advanced Crassostrea larvae al to temperature (T):are distinguished from larvae of otherbivalves by length-width measurements, 0.3554T AWand an asymmetric umbo. The dentition D = 4.8 + 4205 eO-

2

Spawning may depend secondarily on prodissoconch I, which is character-tidal cycle; sunlight warmed water ized by pronounced umbones. Theseduring low tide and stimulated spawn- larvae are vigorous swimmers with aing (Drinnan and Stallworthy 1979). pair of pigmented eyes and an elongate

foot with a large byssal gland (An-Spawning is initiated by one or drews 1979). These larvae are 0.30 mm

more males, which release their sperm in diameter (Galtsoff 1964).and a pheromone into the water. Thefemales spawn when sperm enter the Carriker (1951) found that young-water transport system (Andrews 1979), er larvae stay in the water columnor when pheromone stimulates females about 1.0 m below the surface. Olderto release their eggs in a mass spawn- larvae remain near the bottom in theing (Bahr and Lanier 1981). Females halocline of estuaries during floodproduce 23.2 to 85.8 million eggs per tide and rise nearer the surface dur-spawning, with the number of eggs ing the ebb tide, although Andrewsproportional to the size of the indi- (1979) questioned this finding. Haskinvidual (Davis and Chanley 1955). Fe- (1964) demonstrated that graduallycundities of 15 million to 115 million rising salinities stimulate older lar-were cited by Yonge (1960). Females vae to swim and falling salinitiesmay spawn several times in one season, cause them to sink. Hidu and Haskinand the number of eggs produced is not (1978) observed spiral swimming duringproportional to the spawning interval, constant salinity, and linear swimmingAs spawning interval increases, ob- during gradually increasing salinity;viously the number of eggs per season swimming velocity increased by a fac-decreases (Davis and Chanley 1955). tor of three at salinity nearThe spawning season is longer in warm- 100% seawater. Upward swimming is ater climates: from April to October in nearly 1 cm/sec (Andrews 1979). Thesethe Gulf of Mexico (Hayes and Menzel behavioral traits perhaps result in1981); but from July to August in selective tidal transport and allowMalpeque Bay, Prince Edward Island larvae to avoid being flushed from the(Kennedy and Battle 1963); and only in estuary. Larvie may even be transport-July at Bideford River Estuary, Prince ed up an estuary (Seliger et a;.Edward Island, Canada (Drinnan and 1982).Stallworthy 1979). The egg stage endsat 6 hr after fertilization at 24°C(Loosanoff 1964).

JuvenilesLarvae

The larvae at 2 to 3 weeks afterOyster larvae are meroplanktonic, spawning seek a solid surface and com-

remaining in the water column for 2 to mence a period of crawling in a circu-3 weeks following fertilization (Bahr lar area, presumably seeking a placeand Lanier 1981). During this period for attachment (Andrews 1979). Afterthe larvae pass through several stages attachment with a droplet of liquidof development (Carriker and Palmer cement exuded from a pore in the foot,1979). After the blastula (3.2 hr), they lose the velum and foot and aregastrula (4.5 hr), and trochophore (10 now called spat. Shells are preferredhr) stages (Parrish 1969), the larvae as attachment or setting sites, butsecrete a straight-hinge shell and stones and other surfaces may be used.develop a ring of locomotory cilia Spat that set during the first 3 dayscalled the velum. The swimming after metamorphosis may grow fastertrochophore stage is reached in 6-8 hr than those setting later (Losee 1979).(Andrews 1979). This prodissoconch I Metamorphosis may be delayed if suit-or straight-hinge larva is about 75 Pm able substrate is not present (Newkirkin diameter. This stage Is followed by et al. 1977).

3

Several factors influence the Typically the young adults aresetting behavior of larvae. Hidu and predominately males; subsequent sexHaskin (1971) suggested that rising inversion with age increases thetemperature over tidal flats during number of females. Sex ratios in thethe flood tides stimulates setting. In James River Estuary, Virginia, changethe laboratory, rising temperature from 90% males at 1 year of age to 80%triggered setting (Lutz et al. 1970). females in older oysters (AndrewsSwimming larvae have positive photo- 1979).taxis, which becomes negative withincreased temperature (Bahr and Lanier1981). More oysters settled in the GROWTH CHARACTERISTICSsubtidal zone than elsewhere inDelaware Bay (Hidu 1978). Setting was Growth is greatest during thegreater on shells at 2 m depth than on first 3 months, and spat reach 15 mmshells at 1.2 m or 0.3 m (Drinnan and in 9 months (Bahr 1976). In their sec-Stallsworthy 1979). However, Andrews ond year, juveniles that were 11 to 14(1979) observed more setting off the mm on April 3 were 18 to 22 mm on Maybottom, and attributed the opposite 7, 23 to 27 mm on June 5, and 26 to 32results to siltation in shallower mm on July 2 (Carriker et al. 1982).water. Body weight increased from 0.23 g to

4.0 g during this 3-month period.Oyster larvae set in established Monthly shell increment ranged from 1

oyster beds. Crisp (1967) postulated to 3 mm per month in South Carolinathat larvae are attracted to the pro- (Manzi et al. 1977; Manzi and Burrellteinaceous surface of the periostracum 1977); or 20 mm per year in Maineof adult shells and observed that lar- (Price et al. 1975). Instantaneousvae do not settle on shells that had monthly growth coefficients rangedbeen treated with bleach. Hidu (1969) from 0.42 to 0.84 (Gillmor 1982). Thedemonstrated, however, that a water- marketable size of 90 mm is attainedborne factor, perhaps a pheromone, is in 3 to 5 years.involved; larvae settle on oystershells associated with existing oys- Growth is influenced by tempera-ters. Currents also influence setting ture, salinity, intertidal exposure,patterns. Keck et al. (1973) found turbidity, and food. Growth is great-that setting in estuaries is heaviest est in August and September afteron the eroding banks of tidal creeks. spawning, when glycogen reserves are

restored (Loosanoff and Nomejko 1949;Adult Price et al. 1975). Growth ceases dur-

ing winter, except in Florida, whereBecause adults are completely growth was continuous throughout the

sessile, their distribution depends on year (Butler 1952). Growth is slowedwhere the larvae set and on subsequent by spawning because energy is used formortality. Oysters typically occur in gamete production instead of pro-clumps called reefs or beds, in which duction of body biomass. Butler (1953)they are the dominant organism. The noted a weight increase after spawningmass of shells often results in al- without an increase in length.teration of currents and increaseddeposition so that the local environ- Fluctuating environments may pro-ment is modified. mote better growth. Oysters in fluc-

tuating salinity grow better thanAdults are dioecious, but often those under constant conditions

change gender (Bahr and Lanier 1981). (Pierce and Conover 1954). OystersThe gender and the process of sex exposed during the tidal cycle growinversion are genetically determined about the same as those continuouslyby perhaps three loci (Haley 1977). submerged (Gillmor 1982). Long expos-

I

ure, however, reduced growth; those Oysters are harvested in aexposed 20% of the time grow twice as variety of ways, including handpickingfast as those exposed 60% of the time. of clumps from reefs (Bahr and LanierGrowth rate is directly related to 1981), hand and patent tonging, andphytoplankton density, and some of the dragging from sailpowered craft in theobserved effects may be due to changes Chesapeake Bay, and dredging fromin phytoplankton. Manzi et al. (1977) powercraft in Long Island Sound andobserved that oysters grow faster in (Korringa 1976).salt ponds than in tidal creeks, whereprimary productivity is lower. Crowd- The American oyster is also oneing may prevent spawning and thus in- of the predominant species used indirectly may lead to increased growth mariculture, including in the North(Butler 1953). Atlantic region. In 1980 the yield of

cultured oysters was 23,705,000 lbOysters over 200 mm long are not valued at $37,085,000. This repre-

uncommon. A Walford plot of sents 55% of the total harvest ofintertidal oysters predicts that 42,439,000 lb. The equivalences be-oysters would cease growing at 140-mm tween different values reported forlength (Dame 1971). harvest are: 1 bu = 34 1 = 32 kg total

weight = 7.8 pints = 3.4-kg meatweight (Pruder 1975).

The market quality varies withCOMMERCIAL HARVEST the season. The yield of meats is low-

est in the summer months and peaks inThe American oyster had tradi- March (Rockwood and Mazek 1977). This

tionally supported a significant in- corresponds to a reduced-conditiondustry along the entire eastern sea- index following spawning (Hopkins etboard. Today, there are only six com- al. 1954; Lawrence and Scott 1982).mercial areas in the North Atlanticregion (Figure 2). Domestic landingshave decreased from about 100 million Population Dynamicslb during the 1920's to 50 million lbduring the 1960's, and have not recov- The enormous numbers of eggs andered to the original levels (Table 1) larvae produced by American oysters(Matthiessen 1969). Although harvests largely perish before setting. Follow-in the Gulf of Mexico and South Atlan- ing spawning, oyster larvae are commontic have remained stable for the past in the plankton, with numbers reaching30 years, harvests in the mid-Atlantic 5,000 to 10,OOO/kl in Canadian watersand Chesapeake Bay have declined. In (Drinnan and Stallworthy 1979) andLong Island Sound, persistent set 2,000 to 5,500/kl in Virginia (Andrewsfailure has been responsible for de- 1979; Seliger et al. 1982), with aclining stocks. Although oysters spawn peak in abundance after high tideat the summer temperatures of the (Andrews 1979). The daily mortality ofsound (200 to 21*C), setting must larvae is 10% (Drinnan and Stallworthyoccur in warmer estuaries. Because of 1979). Newly set spat had 79% to 99%shoreline development, the amount of mortality in 1 month in Massachusettssetting area has declined (Matthiessen (Krantz and Chamberlin 1978). Spat1969). Heavy mortalities due to the mortality of 50% to 70% in Delawarepredatory starfish Asterias forbesi Bay was reduced to 30% to 40% if spat

04 and the gastropod Urosalpinx cinerea were protected from predators (Tweedin saltwater, and the predatory flat- 1973). Spat survival was less in denseworm Stylochus ellipticus in brackish sets than in sparse sets in Chesapeakewater, have also contributed to de- Bay (Webster and Shaw 1968). Annualclining stocks (Matthiessen 1979). changes in population density in Long

5

I CANADA/i

,. MAINE

i- x. b ,'

NEW " J ,

HAMP-1ISHIRE'

[ I ] 8~heoecsot" Rive U

SPORTLAND

I , Piscatequa River IOyster S tRiverhtRe cNADTLANTC OCEAN

BOSTO 0 so l oo

MASS. eent Say Cmmerci oyster ares

Figure 2. Recent commercia Aerican oyster the N AtlanticRegion. Commercial s now prohibited e a is low in

Pleasant Bay (Ralph Andrews, U.S. Fish and Wildlife Service, Newton Corner,Massachusetts).

6

Table 1. Oyster harvests (thousands of pounds meat weight) bygeographical region for the years 1950-1980 (from various issues ofCurrent Fisheries Statistics, National Oceanic and AtmosphericAdministration).

South Gulf ofYear New Englanda Mid-Atlantic Chesapeake Atlantic Mexico

1950 4727 18170 29954 3033 122921951 1970 17410 29598 3783 115191952 2209 16767 34418 4111 146371953 1038 14462 36946 4019 128361954 745 13377 41587 3811 114431955 619 9848 39227 2260 138811956 506 8466 37064 3656 135131957 405 7981 34234 3069 143071958 276 4296 37530 2651 104081959 387 1392 33322 3516 137211960 500 1154 27111 4119 160981961 453 1921 27500 3984 182401962 294 2362 19939 3850 188381963 452 951 18274 4837 241391964 195 1356 22098 3527 233851965 340 757 21188 4082 191561966 N/Ab N/A 21232 3657 171821967 " " 25798 3160 217471968 o " 22679 2965 267391969 " " 22157 1830 197651970 24668 1626 177141971 25557 1846 202661972 24066 1868 182601973 25400 1656 149141974 " 25021 1841 148781975 22640 1585 192951976 " 20964 1704 215691977 " " 17929 1847 180811978 " " 21531 2138 182121979 " 20428 2441 152891980 " 21906 N/A N/A

a Includes Connecticut and Rhode Island from the Mid-Atlantic Region.

b N/A = Data not available.

Island Sound (MacKenzie 1981) suggest 94% in an estuary (Manzi and Burrellsurvival rates: spat occur at densi- 1977). Survival was 100% in areasties of 200 to 10,000/m2 ; I- to 2-year protected from wave action in Northolds at 300/m 2; and 3- to 4-year-olds Carolina, and 50% per month if exposedat 75/m 2 . Adult survival in South to waves (Ortega 1981).Carolina was 85% in a salt pond and

7

ECOLOGICAL ROLE Delaware Bay in 1957 and in ChesapeakeBay in 1960 (Andrews 1968). Minchinia

Larvae feed on plankton. Guillard costalis caused extensive mortalities(1957) observed that small, naked in the seaside bays of the Delmarvaflagellates (chrysophytes) are the Peninsula in 1960 (Rosenfield 1971).preferred food for larvae. Davis andCalabrese (1964) found that at low Oyster predators include thetemperatures larval growth is best gastropod oyster drills (Urosalpinxwith a diet of naked flagellates: cinerea and Eupleura caudata , thewhereas at temperatures above 27*C wh-Te (Busy con canaliculatum), thenaked algae do not survive and chloro- starfish jAsterias forbesi), and thephytes are a better food source. Lar- crabs (Cancer irroratus, Callinectesvae in turn serve as food for a wide sapidus, and Carcinus maenus)(Galtsoffvariety of filter feeders (Andrews W9ZF1.All oysters are susceptible to1979). predation by oyster drills, which bore

through the shells with a combinationThe adults are important filter of chemical dissolution of the shell

feeders in estuarine ecosystems and and drilling; but only smaller oysters

feed on naked flagellates in the 3- to are susceptible to predation by crabs4-um size range (Haven and Morales- and starfish. Widespread infestation

Alamo 1970). For each gram of dry also occurs from the boring sponge

weight of tissue, an oyster filters Cliona, which lowers quality. Oyster

1.5 l/hr, with a maximum of 1.9 1/hr reefs-may be smothered by excreta of

(Palmer 1980). The filteration rate is worms of the genus Polydora. Juveniles

independent of the algal food concen- are preyed upon by the flatworm Stylo-tration in the seawater. chus ellipticus (MacKenzie 1970).

Oysters are the keystone species Major competitors of the oyster

of a diverse community in the estu- include the slipper limpets (Crepidula

arine ecosystem. Bahr and Lanier sp.) and the jingle shells (nomla

(1981) reported the occurrence of 42 sp.) as well as barnacles and other

macrofaunal species or groups, and oysters that set on adult shells (Mac-

Wells (1961) listed 303 species Kenzle 1970). The mussel (Brachiodon-

associated with the oyster community. tes exustus) may also compete with

Because of their abundance, oysters oysters TUFTega 1981).

are responsible for 87.5% of the res-piration of an oyster reef (Bahr andLanier 1981). ENVIRONMENTAL REQUIREMENTS

Oysters are subjected to a vari- The American oyster typically

ety of diseases and parasites and sup- lives in shallow, well-mixed estu-port several predator populations aries, lagoons, and oceanic bays that(Galtsoff 1964). Bacterial diseases fluctuate widely from hot to cold tem-include Vibrio and Pseudomonas spe- peratures, low to high salinities, andcies. Th-e fungus vermocystidium clear to muddy waters (Andrews 1979).marinum infects oysters in the south- Because they live in such an extremelyern range from Delaware to Mexico. The varied habitat, exact environmentalhaplosporidian protozoan Minchinia requirements alone or in combinationnelsoni is responsible for the disease are difficult to define.MISX (mtlnucleate spheroid unknown),and Minchinia costalis for SSO (sea- Temperatureside organism).F itnchinia nelsoni,found from North Carolina to Massachu- Larvae do not tolerate as wide a

setts (Krantz et al. 1972), caused range of temperatures as adults. Waterextensive oyster mortalities in the temperatures of 300 to 34*C impair

8

growth, and even a brief exposure for oysters but ceased at 6*C in southern10 min at 40°C retards growth in oysters. Andrews (1979) believes thereCheasepeake Bay (Hidu et al. 1974). are other races as well. Genetic stud-The temperatures cited for fastest ies did not closely support the exist-growth and highest survival, 27.50 to ence of physiological races. Buroker32.5*C, in Long Island Sound (Davis et al. (1979) found that all oystersand Calabrese 1964), seem a bit high. studied were identical, except oysters

from Nova Scotia and Florida. TheseAdults tolerate a water tempera- populations were 82% similar, about

ture range from -1.70C in New England the level of similarity between C.to 360C in the Gulf of Mexico. Oysters virginica and C. rhizophorae, whichmay be exposed at low tide to temper- can successfully hybridize (Bahr andatures below freezing or above 49*C Lanier 1981). Oysters in Laguna Madre,(Galtsoff 1964). High temperatures Texas, however, are genetically dis-increase the mortality rate; tempera- tinct from four other gulf populationstures above 35*C for the whole tidal (Groue and Lester 1982). Measurementcycle caused death of some oysters of isozymes in the genetic studies,(Tinsman and Maurer 1974). The criti- however, may not indicate these races.

cal thermal maxima for the Americanoyster is 48.5*C (Henderson 1929). SalinitiesOysters tolerate freezing of theirtissues, and revive after thawing Salinities above 7.5 ppt are re-(Loosanoff 1965a). quired for spawning (Loosanoff 1948).

Larvae tolerate salinities of 3.1 toOptimum temperatures for adult 30.6 ppt (Carriker 1951), but grow

American oysters are 200 to 30*C. Op- fastest and survive best at salinitiestimum temperatures for pumping were above 12.5 ppt (Davis and Calabrese200 to 25°C (Collier 1951). Growth 1964). Most larvae in a New Jerseyceased below about 8°C (Price et al. estuary were in the halocline at1975). Oysters at 20 to 7°C remained salinities above 5 ppt (Carrikerinactive. Exposure to warm tempera- 1951). Optimum salinities for thetures out of season stimulated growth growth of spat were 15 to 22 pptif food was available (Ruddy et al. (Chanley 1957).1975). Growth is possible between 60and 32°C with the optimum at 250 to Adult oysters tolerate a salinity26°C (Galtsoff 1964). Exposure to 35°C range of 5 to 30 ppt, outside of whichwater accelerated gametogenesis and they discontinue feeding and reproduc-spawning, but subsequent spawning was ing. The optimum salinity range is 10prevented (Quick 1971). to 28 ppt (Loosanoff 1965a). Loosanoff

(1965b) found that many oysters sur-Differences in thermal require- vive 3 ppt for 30 days. Large mortal-

ments of oysters from different areas ities, however, have been associatedhave led to the postulation of differ- with prolonged spring floods in theent races, each with different temper- James River, Virginia (Andrews et al.ature requirements (Ahmed 1975). 1959); in Mobile Bay, Alabama (MaySpawning temperatures for three dis- 1972); and in the Santee River, Southtinct races were reported by Stauber Carolina (Burrell 1977). Salinities(1950) to be 16.4°C for the northern during these freshets were below 2race (New England), 20.0°C for the ppt. Oysters in Louisiana died aftermid-Atlantic race, and 25.00C for the 14 days at 6 ppt (Anderson andGulf of Mexico race. Additional evi- Anderson 1975).dence for the existence of physiolog-ical races was reported by Menzel Low salinity inhibits gonadal(1955), who found that ciliary activ- maturation in oysters in Chesapeake

soity continued at O°C in northern Bay (Butler 1949) and Long Island

Loi

Sound (Loosanoff 1953). Reproductive elevation, 2.0/m 2 at 0.5 m, 0.41m 2 at/faSlure may be a direct effect of sa- 1 m, and none at 0.5 m. alilnty or might be caused by inade-quate feeding at low salinity. Lowered Other Environmental Factorsusalinity may benefit oyster popula-tions by k blling predators. Oyster Hourly oxygen consumption is 39drills and starfish cannot toleratH ml/kg for a whole animal or 303 ml/kgbrackish water (Loosanoff 1965a). of wet tissue (Hammen 1969). Oxygen

consumption increases with increasingHabitat temperature- Q values (the factor by

which a reactiAR velocity is increasedOysters can grow equally well on by a rise in temperature of 10C) re-

rocky bottoms or on mud capable of ported by Bass (1977) range from 1.2supporting their weight. Soft muddy to 2.3 for gill and 2.7 to 4.2 forsubstrates may be improved by adding mantle tissue. There is a strong in-clam or oyster shells. Oysters from teraction between temperature andmuddy substrates are more slender than salinity; oxygen consumption increasesthose from hard substrates (Galtsoff much more at high temperatures if the1964). Hidu (1978) found that oysters salnty is ,ower m(Figure 3). Oystersprefer to set on the bottom rather are facultative anaerobes and are ablethan on panels suspended in the water to survive daily exposure. They canacolumn, and are generally found sub- also survive anaerobically for 3 days

tidally in Delaware Bay. The preferred following spawning (Galtsoff 1964).habitats in shallow estuarne waters Oxygen consumption is zero with the

include flats and offshore bars (Hidu valves closed (Hammen 1969).1968) and oyster reefs (Bahr and Lan- Oier 1981). Maximum setting occurs on Oysters are able to toleratehorizontal surfaces (Clime 1976). turbid water, but pumping rate de-creases with increasing turbidity.

Currents are important to Ameri- Pumping rate can be reduced 70%-85%can oysters. The volume of water in- over the range 0 to 1 r/e , dependingmediately above an oyster bed must be one the range 0 the suspended sedi-renewed 72 times every 24 hr for maxt- ment (Loosanoff and Tommers 1948). Inmum feeding; therefore, oysters re- natural environments, however, oystersquire a moderate current (Galtsoff grow better in the more turbid zones1964). Tidal flows of 156 to 260 gn oyster beds than in less turbidcm/sec or higher are needed for opti- areas (Rhoades 1973).mum growth (Veal et al. 1972). Turbu-lent currents, however, can damageshells from transported sand and peb-bles (Galtsoff 1964). Although ad -bl act of 19s. alheoug a

attached oysters to tumble along the 402 ConsumI.bottom (MacKenzie 1981). They arefound in greatest abundance in areas mi/hr/gof scour where current keeps the beds . .2

free of sediment (Keck et al. 1973).Currents are also necessary forremoval of silt and feces. .

Distribution is strongly corre-

lated with mean low tide (MLT) ppielevation in Great Bay, New Hampshire Figure 3. Oxygen consumption in Ameri-,(Hardwtck-Witman and Matthlesson can oyster as a function of salinity1983). There were 5.6/M 2 at 0 m MLT and temperature (Shunuay 1982).

10

LITERATURE CITED

Ahmed, M. 1975. Speciation in living of Biological Services, Washing-oysters. Adv. Mar. Biol. 13: ton, D.C. FWS/OBS-81/15.357-397.

Bass, E.L. 1977. Influences of temper-Anderson, R.D., and J.W. Anderson. ature and salinity on oxygen con-

1975. Effects of salinity and sumption of tissues in the Amer-selected petroleum hydrocarbons ican oyster (Crassostrea virgin-on osmotic and chloride regula- ica). Comp. Blochem. Physiol.tion of the American oyster Cras- 3SWE125-130.sostrea vtirqnica. Physiol. ZoTT48(4):420-430. Buroker, N.E., W.K. Hershberger, and

K.K. Chew. 1979. Population ge-Andrews, J.D. 1968. Oyster mortality etics of the family Ostreidae 2.

studies in Virginia: VII. Review Intraspecific studies of the gen-of epizootiology and origin of era Crassostrea and Saccostrea.Minchinia nelsoni. Proc. Natl. Mar. Biol. (Berlin) 54 17-14.T-Shellfish. Assoc. 58:23-36.

Burrell, V.G., Jr. 1977. MortalitiesAndrews, J.D. 1979. Pelecypoda: of oysters and hard clams associ-

Ostreidae. Pages 291-341 in A.C. ated with heavy runoff in theGiese and J.S. Pearse, eds. Santee River system, South Caro-Reproduction of marine inverte- lina, in the spring of 1975.brates. Vol. V. Molluscs: Pelecy- Proc. Natl. Shellfish. Assoc.pods and lesser classes. Academic 67:35-43.Press, New York.

Butler, P.A. 1949. Gametogenesis inAndrews, J.D., D. Haven, and D.B. the oyster under conditions of

Quayle. 1959. Freshwater kill of depressed salinity. Biol. Bull.oysters (Crassostrea vtrginica) (Woods Hole) 96(3):263-269.in James River, Virginia, 158.Proc. Natl. Shellfish. Assoc. 49: Butler, P.A. 1952. Seasonal growth of29-49. oysters (C. vtrginica) in Flori-

da. Proc.-Ratl. Shellfish. Assoc.Bahr, L.M., Jr. 1976. Energetic 43:188-191.

aspects of the intertidal oysterreef community at Sapelo Island, Butler, P.A. 1953. Shell growth versusGeorgia. Ecology 57(1):121-131. meat yield in the oyster C. vir-

inmica. Proc. Natl. SheTifsh.h-

Bahr, L.M., and W.P. Lanier. 1981. The Xssoc. 44: 157-162.ecology of intertidal oysterreefs of the South Atlantic Cake, E.W. 1983. Habitat suitabilitycoast: a community profile. U.S. index models: Gulf of MexicoFish and Wildlfie Service, Office American oyster. U.S. Dept. Int.

11

Fish Wildl. Serv. FWS/OBS-82/10. and salinity on development of57. 37 pp. eggs and growth of larvae of M.

mercenarla and C. virginlca. U. .

Carriker, M.R. 1951. Ecological obser- Tli1FsW-iTdl. Serv_. ish. Bull.vations on the distribution of 63(3):643-655.oyster larvae in New Jersey estu-aries. Ecol. Monogr. 21(1):19-38. Davis, H.C., and P.E. Chanley. 1955.

Spawning and egg production ofCarriker, M.R., and R.E. Palmer. 1979. oysters and clams. Biol. Bull.

Ultrastructural morphogenesis of (Woods Hole) 110:117-128.prodissoconch and early disso-conch valves of the oyster (Cras- Drinnan, R.E., and W.B. Stallworthy.sostrea virgtnica). Proc. Nat1. 1979. Oyster larval populationsShellfish. Assoc. 69:103-128. and assessment of spatfall,

Bideford River, P. E. I., 1963Carriker, M.R., C.P. Swann, and J.W. and 1964. Can. Fish. Mar. Serv.

Ewart. 1982. An exploratory study Tech. Rep. (797):1-13.with the proton microprobe of theontogenetic distribution of 16 Galtsoff, P.S. 1964. The Americanelements in the shell of living oyster Crassostrea virginicaoysters (Crassostrea virginica). (Gmelln). U.S. Fish Wlldl. Serv.Mar. Bio'. (Berl.) 69:235-246. Fish. Bull. 64:1-480.

Chanley, P.E. 1957. Survival of some Gillmor, R.B. 1982. Assessment ofjuvenile bivalves in water of low intertidal growth and capacitysalinity. Proc. Natl. Shellfish. adaptations in suspension-feedingAssoc. 48:52-65. bivalves. Mar. Biol. (Berl.)

Clime, R.D. 1976. Setting orientation 68(3):277-286.

in the oysters Ostrea edulls L.and Crassostrea v-- En-Win. Groue, K.J., and L.J. Lester. 1982.Master's Iesis. university of A morphological and geneticMaine at Orono. 94 pp. analysis of geographic variation

among oysters in the Gulf ofCollier, A. 1951. A study of the re- Mexico. Veliger 24(4):331-335.

sponse of oysters to temperatureand some long-range ecological Gutllard, R.R. 1957. Some factors inintepretatlons. Proc. Natl. the use of nannoplankton cultures

Shellfish. Assoc. 42:13-38. as food for larval and juvenilebivalves. Proc. Natl. Shellfish.

Crisp, D.J. 1967. Chemical factors Assoc. 48:134-142.

inducing settlement in Crassos-trea virginica (Gmelin). J.ATnmi. Haley, L.E. 1977. Sex determination inolT. 36(2):32-335. the American oyster. J. Hered.

68(2):114-116.Dame, R.F., Jr. 1971. The ecological

energies of growth, respiration Hammen, C.S. 1969. Metabolism of theand assimilation in the inter- oyster Crassostrea virginica. Am.tidal American oyster Crassostrea Zool. 9gT2Ju93TE.virgtnica (Gmelln). Ph.D.TeisTUniversity of South Carolina, Hardwlck-Witman, M.N., and G.C. Mat-Columbia. 81 pp. thlessen. 1983. Intertidal macro-

algae and invertebrates; seasonalDavis, H.C., and A. Calabrese. 1964. and spatial abundance patterns

Combined effects of temperature along an estuarine gradient.

12

Estuarine Coastal Shelf Sc. ent salinities and temperatures.16(2):113-129. Estuaries 1(4):252-255.

Haskin, H.H. 1964. The distribution of Hidu, H., W.H. Roosenburg, K.G. Dro-oyster larvae. Proc. of a sympo- beck, A.J. McErlean, and J.A. Mi-sium on experimental marine ecol- hursky. 1974. Thermal toleranceogy. Occas. Pap. 2, Grad. School of oyster larvae Crassostrea vir-Oceanogr. Univ. R.I.:76-80. 2intca Gmelin, as related to pow-

r plant operation. Proc. Natl.Haven, 0.S., and R. Morales-Alamo. Shellfish. Assoc. 64:102-110.1970. Filtration of particlesfrom suspension by the American Hopkins, S.H., J.G. Mackin, and R.W.oyster Crassostrea virginica. Menzel. 1954. The annual cycle ofBiol. Bull. (Woods iole) 139(2): reproduction, growth, and fatten-248-264. ing in Louisiana oysters. Proc.

Natl. Shellfish. Assoc. 44:39-50.Hayes, P.F., and R.W. Menzel. 1981.

The reproductive cycle of early Kaufman, Z.S. 1978. Dependence of thesetting Crassostrea virginica time of gamete maturation and(Gmelin) in the northern Gulf of spawning on the environmentalMexico, and its implications for temperature in Virginia oysterpopulation recruitment. Biol. Crassostrea virginica. Hydrobiol.Bull. (Woods Hole) 160:80-88. J-1T434.7-30.

Henderson, J.T. 1929. Lethal tempera- Keck, R., D. Maurer, and L. Watling.tures of Lamellibranchiata. Con- 1973. Tidal stream developmenttrib. Can. Biol 4(25:397-411. and its effect on the distribu-

t3 tton of the American oyster.

Hidu, H. 1968. Inshore settlement of Hydrobiologia 42(4):369-379.Crassostrea vtrinica in Delawarebay. Proc. Natl. Shellfish. Kennedy, A.V., and H.I. Battle. 1963.Assoc. 58:4. (Abstr.) Cyclic changes in the gonad of

the American oyster CrassostreaHidu, H. 1969. Gregarious setting in virginica. Can. J. Zool. 42(2):

the American oyster Crassostrea 305-321.yr11 Gmelin. Chesapeake Sct.1012JT8592. Korringa, P. 1976. Farming the cupped

oysters of the genus Crassostrea:Hidu, H. 1978. Setting of estuarine A multidisciplinary treatise.

invertebrates in Delaware Bay, Elsevier, Amsterdam. 238 pp.New Jersey, related to inter-tidal-subtidal gradients. Int. Krantz, G.E., and J.F. Chamberlin.Rev. Gesamten Hydrobiol. 63:637- 1978. Blue crab predation of662. cultchless oyster spat. Proc.

Natl. Shellfish. Assoc. 68:38-41.Hidu, H., and H.H. Haskin. 1971.

Setting of the American oyster Krantz, G.E., L.R. Buchanan, C.A.related to environmental factors Farley, and H.A. Carr. 1972.and larval behavior. Proc. Natl. Minchinia nelsoni in oysters fromShellfish. Assoc. 61:35-50. Massachusetts waters. Proc. Natl.

Shellfish. Assoc. 62:83-85.Hidu, H., and H.H. Haskin. 1978.

Swimming speeds of oyster larvae Lawrence, D.R., and G.I. Scott. 1982.Crassostrea virginica in differ- The determination and use of

13

condition index of oysters. MacKenzie, C.L., Jr. 1970. Causes ofEstuaries 5(1):23-27. oyster spat mortality, conditions

of oyster setting beds, andLoosanoff, V.L. 1948. Gonadal devel- recommendations for oyster bed

opment and spawning of oysters management. Proc. Natl. Shell-(C. virginica) in low salinities. fish. Assoc. 60:59-67.Anat. Rec. 101:705. (Abstr.)

MacKenzie, C.L., Jr. 1981. Biotic po-Loosanoff, V.L. 1953. Behavior of tential and environmental resist-

oysters in water of low salin- ance in the American oyster Cras-ities. Proc. Natl. Shellfish. sostrea virginica in Long IslandAssoc. 43:135-151. Sound. Aquaculture 22(3):229-268.

Loosanoff, V.L. 1965a. The American or Manzi, J.J., and V.G. Burrell, Jr.eastern oyster. U.S. Fish Wildi. 1977. A comparison of growth andServ. Circ. 205. 36 pp. survival of subtidal Crassostrea

virginica in South Carolina saltLoosanoff, V.L. 1965b. Gonad develop- marsh impoundments. Proc. Natl.

ment and discharqe of spawn in Shellfish. Assoc. 67:120-121.oysters of Long Island Sound.Biol. Bull. (Woods Hole) 129(3):546-561. Manzi, J.J., V.G. Burrell, and W.Z.

Carlson. 1977. A comparison ofgrowth and survival of subtidal

Loosanoff, V.L. 1969. Maturation of Crassostrea virginica (Gmelin) ingonads of oysters, Crassostrea South Carolina salt marsh im-virginica, of iffirent poundments. Aquaculture 12:293- A

geographical areas subjected to 310.relatively low temperatures.

Veliger 11(3):153-163. Matthiessen, G.C. 1969. A review ofoyster culture and the oysterindustry in North America. Woods

Loosanoff, V.L., and C.A. Nomejko. Hole Oceanogr. Inst. Contrib. No.1949. Growth of oysters, C. 2528. 52 pp.virginica, during differentmonths. Biol. Bull. (Woods Hole) May, E.B. 1972. The effect of flood-97(1):82-94. water on oysters in Mobile Bay.

Loosanoff, V.L., and F.D. Tommers. Proc. Natl. Shellfish. Assoc.1948. Effect of suspended silt 62:67-71.

and other substances on rate of Menzel, R.W. 1955. Some phases of thefeeding of oysters. Science 107: biology of Ostrea equestris and a69-70. comparison with Crassostrea vir-

gLnica (Gmelin). Publ. Inst. Mar.Losee, E. 1979. Relationship between S-ci.Univ. Tex. 4:69-153.

larval and spat growth rates inthe oyster Crassostrea virginica. Newkirk, G.F., L.E. Haley, D.L. Waugh,AquacultureT2):J1Z. and R. Doyle. 1977. Genetics of

larvae and spat growth rate inLutz, R.A., H. Hidu, and K.G. Drobeck. the oyster Crassostrea y.ica.

1970. Acute temperature increase Mar. Biol. (Berl.) 41(1J4952-.as a stimulus to setting in theAmerican oyster Crassostrea vir- Ortega, S. 1981. Environmental stress,ginica. Proc. Natl. Shellfi-sh. competition and dominance ofAss7 60:68-71. Crassostrea virginica near Beau-

14

fort, North Carolina USA. Mar. Rockwood, C.E., and W.F. Mazek. 1977.Biol. (Berl.) 62(1):47-56. Seasonal variations in oyster

meat yields in Apalachicola Bay,Palmer, R.E. 1980. Behavioral and Florida. Bull. Mar. Sci. 27(2):

rhythmic aspects of filtration in 346-347.the bay scallop, Argopectenirradians concentricus, and the Rosenfield, A. 1971. Oyster diseasesoyster, Crassostrea virginica. J. of North America and some methodsExp. Mar. Biol. Ecol. 45273-295. for their control. Pages 67-78

in K.S. Price and D. Maurer, eds.Parrish, F.K. 1969. Early molluscan AFtificial propagation of com-

development. Proceedings of the mercially valuable shellfish.conference on shellfish culture. University of Delaware, Newark.Regional Marine Resources Coun-cil, Hauppange, N.Y. Ruddy, G.M., S.Y. Feng, and G.S.

Campbell. 1975. The effect ofPierce, M.E., and J.T. Conover. 1954. prolonged exposure to elevated

A study of the growth of oysters temperatures on the biochemicalunder different ecological con- constituents, gonadal develop-ditions in Great Pond. Biol. ment, and shell deposition of theBull. (Woods Hole) 107:318. American oyster, Crassostrea(Abstr.). virginica. Comp. Biochem.

Physiol. 51B(2):157-164.Price, A.H., C.T. Hess, and C.W.

Smith. 1975. Observations of Seliger, H.H., J.A. Boggs, R.B.Crassostrea virginica cultured in Rivkin, W.H. Biggley, and K.R.H.the heated eTfflent and dis- Aspden. 1982. The transport of

oyster larvae in an estuary. Mar.charged radionuclides of a Biol. (Berl.) 71(1):57-72.nuclear power reactor. Proc.Natl. Shellfish. Assoc. 66:54-68. Shumway, S.E. 1982. Oxygen consumption

in oysters: an overview. Mar.Pruder, G.D. 1975. Engineering aspects Biol. Let. 3:1-23.

of bivalve molluscan mariculture:culture system configurations. Stauber, L.A. 1950. The problem ofCollege of Marine Studies, physiological species with spe-University of Delaware, Newark. cial reference to oysters and

oyster drills. Ecology 31:109-Quick, J.A., Jr. 1971. Pathological 118.

and parasitological effects ofelevated temperatures on the oys- Stenzel, H.B. 1971. Oysters. Pagester Crassostrea virginica with N953-N1224 in R.C. Moore, ed.emphasis on the pathogen Lab rin Treatise on-Tnvertebrate paleon-thomyxa marina. Pages 10 in tology. Part N, Vol. 3. MolluscaJ.A."Quic_,J., ed. A prelim- 6. Geological Society of America,nary investigation: the effect of Inc., and University of Kansas.elevated temperature on the Amer- Boulder, Colo.ican oyster Crassostrea virginica(Gmelin). Fla. Dep. Nit. Resour. Tinsman, J.C., and D.L. Maurer. 1974.Prof. Pap. Effects of a thermal effluent on

the American oyster. Pages 223-Rhoades, D.C. 1973. The influence of 236 in J.W. Gibbons and R.R.

deposit-feeding benthos on water ShariT7, eds. Thermal ecology.turbidity and nutrient recycling. Proc. Symp. held at Augusta, Ga.Am. J. Sci. 273:1-22. May 3-5, 1973. Natl. Tech. Inf.

15

Serv. Springfield, Va., ISBN Webster, J.R., and W.N. Shaw. 1968.0-87079-014-X. Setting and first season survival

of the American oyster Crassos-trea virginlca near Oxfor-d,ary-

Tweed, S.M. 1973. Settlement and sur- ln, 16-62 U.S. Fish Wildl.vival of Crassostrea virginica on Serv. Spec. Sci. Rep. Fish. No.Delaware Bay seed oyster beds. 567. 6 pp.Proc. Natl. Shellfish. Assoc.64:8-9. Wells, H.W. 1961. The fauna of oyster

beds, with special reference tothe salinity factor. Ecol.

Veal, C.D., W.H. Brown, and W.J. Monogr. 31:239-266.Demoran. 1972. Developments inoff-bottom oyster culture in Yonge, C.M. 1960. Oysters. WillmerMississippi. Am. Soc. Agric. Eng. Brothers and Haran, Ltd.,Pap. 72-575. 20 pp. Birtenhead, London. 209 pp.

16

50272-101

REPORT DOCUMENTATION .._REPORT NO. 2. 3. Recipient's Accession No.

.- ,---PAGE FWS/OBS-82/11.23* ___ ___

4. Title and Subtitle 5. Report Date

Species Profiles: Life Histories and Environmental July 1984Requirements of Coastal Fishes and Invertebrates (North --Atlantic) -- American Oys.ter

7. Author(s) B. PeformingOganizationRept. No

Mark A. Sellers and Jon G. Stanley __ .. Prmo zao R No

9. Performing Organization Name and Address Unit

Program in Oceanography Maine Cooperative Fishery Research

University of Maine at Unit 11. Contract(C) or Grant(G) No.

Orono 313 Murray Hall (C)Ira C. Darling Center University of MaineWalpole, ME 04573 Orono, ME 04469 (G)

12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered

National Coastal Ecosystems Team U.S. Army Corps of EngineersFish and Wildlife Service Waterways Experiment StationU.S. Dept. of the Interior P.O. Box 631 14.

Washington, DC 20240 Vicksburg, MS 3918015. Supplementary Notes

*U.S. Army Corps of Engineers report No. TR EL-82-4

16. Abstract (Limit: 200 words)

Species profiles are literature summaries of the taxonomy, morphology, range, lifehistory, and environmental requirements of coastal aquatic species. They are designedto assist in environmental impact assessment. The American oyster, Crassostreavirginica, is an important commercial and mariculture species. Spawning occursrepeatedly during warmer months with millions of eggs released. Embryos and larvaeare carried by currents throughout the estuaries and oceanic bays where they occur.The few surviving larvae cement themselves to a solid object, where they remain for theremainder of life. Unable to move, they must tolerate changes in the environment thatrange from -1.7o to 4goC, 5 to 30 ppt salinity, and clear or muddy water.-,-

17. Document Analysis a. Descriptors

EstuariesOystersGrowthFeeding

b. Identfers/Oven-Ended Tems

American oysterCrassostrea virginicaSalinity requirementsTemperature requirements

jI. , ~r ~enen ISRMM LIToN STATEMN' A 9 s' c ~ . 71

U Unclassified 16

L I Dstributic Unlimite4 UnclassifiedAn ANSIl-Z39 18)- OPT-ON&L FORM -7

7

.°I

i61 i fl

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L±iwaian Islands

" Headquarters. Division of Biological I - - . 4\Services. Washington. DC .

X Eastern Energy and Land Use Team er.oc nLeelown. WV

* Nat onal Coastal Ecosystems Team- Virgin Islands

S~idell, LA

* Western Energy and Land Use TeamFt Colins CO

* Locations of Regional Offices

REGION I REGION 2 REGION 3Regional Director Regional Director Regional Director

U.S. Fish and Wildlife Service U.S. Fish and Wildlife Service U.S. Fish and Wildlife ServiceLloyd Five Hundred Building, Suite 1692 P.O. Box 1306 Federal Building, Fort Snelling500 N.E. Multnornah Street Albuquerque, New Mexico 87103 Twin Cities, Minnesota 55111Portland, Oregon 97232

REGION 4 REGION 5 REGION 6Regional Director Regional Director Regional DirectorU.S. Fish and Wildlife Service U.S. Fish and Wildlife Service U.S. Fish and Wildlife ServiceRichard B. Russell Building One Gateway Center P.O. Box 2548675 Spring Street, S.W. Newton Corner, Massachusetts 02158 Denver Federal CenterAtlanta, Georgia 30303 Denver, Colorado 80225

REGION 7Regional DirectorU.S. Fish and Wildlife Service1011 E. Tudor RoadAnchorage, Alaska 99503

Mm sin '"Mm"

*-Mpw-w-ww-