Biological Report 82 (1 1.64) /00 Cajun Dome Boulevard TR EL-82-4 

.I",, 1986 Lafayette, Louisiana 70506 

Species Profiles: Life Histories and 

Environmental Requirements of Coastal Fishes 

and Invertebrates (Gulf of Mexico) 

AMERICAN OYSTER 

Coastal Ecology Group 

Fish and Wildlife Service Waterways Experiment Station 

U.S. Department of the Interior U.S. Army Corps of Engineers 
Biological Report aZ(11.64) 

TR EL-82-4 

July 1986 

Species Profile: Life Histories and Environmental Requirements 

of Coastal Fishes and Invertebrates (Gulf of Mexico) 

AMERICAN OYSTER 

Jon G. Stanley 

Mai ne Cooperative Fishery Research Unit 

313 Murray Hal 1 

University of Mai ne 

Orono, ME 04469 

and 

Mark A. Sellers 

Program in Oceanography 

University of Maine at Orono 

Ira C. Darling Center 

Walpole, ME 04573 

Project Manager 

Carroll Cordes 

Project Officer 

David Moran 

National Wetlands Research Center 

U.S. Fish and Wildlife Service 

1010 Gause Boulevard 

Sl idel 1 , LA 70458 

Performed for 

Coastal Ecology Group 

Waterways Experiment Station 

U. S. Army Corps of Engineers 

Vicksburg, MS 39180 

and 

National Wetlands Research Center 

Research and Development 

Fish and Wildlife Service 

U. S. Department of the Interior 

Washi ngton, DC 20240 
This series should be referenced as follows: 

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

and environmental requirements of coasts fishes and invertebrates. U. S. Fish 

Wildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL-82-4. 

This profile should be cited as follows: 

Stanley, J.G., and M.A. Sellers. 1986. Species profiles: life histories and 

environmental requirements of coastal fishes and invertebrates (Gul f of 

Mexico)--American oyster. U.S. Fish Wildl. Serv. Biol. Rep. 82(11.64). U.S. 

Army Corps of Engineers, TR EL-82-4. 25 pp. 
PREFACE 

This species profile is one of a series on coastal aquatic organisms, 

principally fish, of sport, commercial, or ecological importance. 'The profiles 

are designed to provide coastal managers, engineers, and biologists with a brief 

comprehensi ve sketch of the biological characteristics and environmental 

requirements of the species and to describe how populations of the species may be 

expected to react to environmental changes caused by coastal development. Each 

profile has sections on taxonomy, 1 ife history, ecological role, environmental 

requi rements , and economic importance, if appl icable. A three-ri ng binder is 

used for this series so that new profiles can be added as they are prepared. 

This project is jointly planned and financed by the U. S. Army Corps of Engineers 

and the U.S. Fish and Wildlife Service. 

Suggestions or questions regarding this report should be directed to one of 

the foll owing addresses. 

Information Transfer Special ist 

National Wetlands Research Center 

U.S. Fish and Wildlife Service 

NASA-Sl i dell Computer Compl ex 

1010 Gause Boulevard 

Slidell, LA 70458 

U.S. Army Engineer Waterways Experiment Station 

Attention: WESER-C 

Post Office Box 631 

Vicksburg, MS 39180 

iii 
Hul tiply 

mil 1 imeters (mn) 

centimeters (on) 

meters (m) 

ki 1 meters ( km) 

CONVERSION TABLE 

Metric to U.S. Customary 

2 

square meters (m ) 10.76 

square ki 1 meters ( km2) 0.3861 

hectares (ha) 2.471 

liters (1) 

cubic neters (m3) 

cubic meters 

To Obtain 

inches 

inches 

feet 

mil es 

square feet 

square !nil es 

acres 

gal 1 ons 

cubic feet 

acre- feet 

mil 1 igrams (mg) 0.00003527 ounces 

grams (g) 0.03527 ounces 

kilograms (k ) 2.205 pounds 

metric tons ft) 2205.0 pounds 

metric tons 1.102 short tons 

ki 1 ocal ories ( kcal ) 3.968 British thennal units 

Cel sius degrees 1.8(Oc) + 32 Fahrenheit degrees 

U.S. Customary to Metric 

inches 25.40 

inches 2.54 

feet (ft) 0.3048 

fathoms 1.829 

miles (mi) 1.609 

nautical miles (mi) 1.852 

square feet (ft2) 

acres 2 

square miles (mi ) 

gallons (gal) 3.785 

cubic feet (ft3) 0.02831 

acre- feet 1233.0 

ounces (02) 28.35 

pounds (lb) 0.4536 

short tons (ton) 0.9072 

British thermal units (Btu) 0.2520 

mil 1 imeters 

centimeters 

ineters 

meters 

kil orneters 

ki 1 oqeters 

square meters 

hectares 

square kilometers 

1 i ters 

cubic meters 

cubic meters 

grains 

ki 1 ograTs 

metric tons 

ki 1 ocal ories 

Fahrenheit degrees 0.5556(OF - 32) Celsius degrees 
CONTENTS 

Page 

PREFACE .................................. ii i 

CONVERSIONTABLE ............................. i v 

ACKNOWLEDGMENTS ............................. vi 

NONMENCLATLlRE/TAXONOMY /RANGE ....................... 1 

MORPHOLOGY/IDENTIFICATION AIDS ...................... 1 

REASONFOR INCLUSION INSERIES ...................... 3 

LIFE HISTORY ............................... 3 

Spawning ................................ 3 

Larvae ................................. 4 

Juveniles ................................ 5 

Adults ................................. 5 

GROWTH CHARACTERISTICS .......................... 6 

COMMERCIAL SHELLFISHERIES ......................... 6 

Popu 1 at i on Dynarni cs ........................... 9 

ECOLOGICALROLE .............................. 10 

ENVIRONMENTAL REQUIREMENTS ........................ 12 

Ternperatu re ............................... 12 

Salinity ................................ 13 

Substrate ................................ 14 

Current ................................. 14 

Oxygen ................................. 14 

Suspended Sol ids and Sedimentation ................... 15 

Other Environmental Requ i rements .................... 15 

LITERATURE CITED 
ACKNOWLEDGMENTS 

We thank Herbert Hidu, Professor of Zoology, University of Maine; 

Mark S. Van Hoose, Biologist 11, Alabama Department of Conservation 

and Natural Resources; Edwin W. Cake, Jr., Head, Oyster Biology 

Section, Gulf Coast Research Laboratory; Mark Chantry, Marine 

Biological Laboratory, Louisiana Department of Wildlife and Fisheries; 

and Dexter S. Haven, Virginia Institute of Marine Science for 

reviewing the manuscript and offering many helpful suggestions. 
Figure 1. American oyster from soft substrate with juvenile attached (Gal tsoff 

1964). 

AMERICAN OYSTER 

I 

Q NOMENCLATURE/TAXONOMY /RANGE 

Scientific name . . . . . Crassostrea 

. . . American 

oyster (Figure 1) 

Other common name . . . Eastern oyster 

Class . . . . . Bivalvia (Pelecypoda) 

Order . . . . . .Mytoloida (Pteroidea) 

Fami ly . . . . . . . . . . . 0s t rei dae 

Geographic range: The American oyster 

lives in estuaries and behind 

barrier islands; it is abundant 

along the gulf coast from Florida to 

Texas (Figure 2). The Gulf of 

Mexico has about 3600 km2 (1400 mi2) 

of habitat sui tab1 e for the American 

oyster (Butler 1954). Its range 

extends to the Yucatan Peninsula of 

Mexico and to Venezuela. Along the 

east coast of North America, it 

occurs from the Gulf of St. 

Lawrence, Canada, to Key Bi scayne, 

Florida. This species was 

introduced with 1 imi ted success to 

Japan, Australia, Great Britain, 

Hawaii, and the west coast of North 

America, but it has not become 

abundant (Ahmed 1975). The American 

oyster is most abundant in the Gulf 

of Mexico, Chesapeake Bay, and Long 

Island Sound. 

MORPHOLOGY/IDENTIFICATION AIDS 

The left valve is almost always 

thicker and heavier than the right, 

and more deeply cupped (Yonge 1960; 

Galtsoff 1964). The oyster is cemented to the substrate on its left 

valve. Hinge teeth are absent, but a 

buttress on the right valve fits into 

a depression on the left. There is no 

gap between the valves when fully 

cl osed . 

Shell shape is variable. On hard 

bottoms, beaks (umbones) usually are 

curved and point toward the posterior, 

whereas in silty environments or on 

reefs, umbones are usually straight. 

Solitary oysters from hard substrates 

are rounded and ornamented with radial 

ridges and foliated processes, whereas 

those from soft substrates or reefs 

are more slender and sparsely ornamented. She1 1 thickness also depends on envi ronment. Oysters on hard 

substrates have thicker and less fragile shells than those on soft substrates. The "index of shape" 

((height + width)/length) varies from 

0.5 to 1.3 in southern populations and 

from 0.6 to 1.2 in northern 

popul ati ons. 

The shell grows along a 

dorsal-ventral axis, but the angle of 

the axis is not permanent and may 

change several times over the lifespan 

of an individual, resulting in a 

zigzag pattern. The growth axis may 

change as much as 90". The shell of 

oysters 3- to 5-years old is usually 

10 to 15 cm long. Although tissue 

mass reaches an upper limit, the shell 

continues to grow over the lifespan of 

an oyster (Stenzel 1971). Throughout 

this review shell height is termed 

1 ength . 

The American oyster is monomyarian (anterior adductor muscle has 

been lost). The interior of the shell 

has a purple-pigmented adductor nuscle 

scar situated slightly posterior and 

ventral. A second muscle scar, of the 

Quenstedt's muscle, is situated 

ventral to and a short distance from 

the hinge. The purple pigmentation on 

the adductor muscle scar distinguishes 

the American oyster from similar 

species. In the mangrove oyster (C. 

rhizo horae) and Pacific oyster (c. * the muscle scar is lightiy 

pigmented and in C. rivularis it is 

u np i gment ed . The shell of the 

mangrove oyster is less plicated than 

that of the American oyster. There 

are no other species of Crassostrea 

sympatric with the American oyster in 

the Mid-Atlantic region. Species of 

Crassostrea are distinguishable from 

species of Ostrea by the promyal 

chamber, which is well developed in 

Crassostrea species, but not i n 

Dstrea. By trapping saltwater, this 

chamber may allow the American oyster 

to tolerate wider fluctuations in 

salinity in estuaries. 

Crassostrea species are oviparous 

(gametes are released into the water), 

whereas Ostrea species incubate fertilized eggs in the mantle cavity. The 

morphology of larval stages is described by Kilgen and Dugas (1984). 

Advanced Crassostrea larvae are 

distinguished from the larvae of other 

bi val ves by length-width measurements, 

and an asymmetric umbo. The 

morphology of the dentition on the 

hinge distinguishes the larvae of the 

Ameri can oyster from other bi val ves 

(Lutz et al. 1982). 

REASON FOR INCLUSION IN SERIES 

The American oyster supports an 

important comnerci a1 fishery from the 

Gulf of Mexico to the Gulf of St. Lawrence, and is an important mariculture 

species. More oysters are processed 

than any other single fishery product 

in the United States, and over 10,000 

people work in the oyster industry. 

Oysters are valued as a luxury food 

item and are the keystone species of a 

reef biocoenosis that includes several 

hundred species (Wells 1961). Because 

oysters inhabit estuaries, they are 

particularly vulnerable to urban and 

industrial disturbances (Cake 1983). 

LIFE HISTORY 

Spawni nq 

Gametogenesis and spawning are 

stimulated by changes in water 

temperature (Hopkins et al. 1954; 

Kaufman 1978; Andrews 1979). Spawning 

temperature differs among populations . Based on spawning temperatures, Stauber (1950) recognized three physiological races: one from the Gulf of 

Mexico that spawns when water 

temperatures are near 25 OC, and two 

from the east coast that spawn at 

16 OC and 20 OC. In the Gulf of 

Mexico, the temperature must be 

constantly above 20 OC for spawning, 

and above 25 OC for mass spawnings 

(Schlesselman 1955). In the 
Apalachicola River estuary, Florida, 

the oyster does not spawn until water 

temperature reaches 22.5 OC and mass 

spawning occurs at 26 OC (Ingle 1951). 

The American oyster in the 

northern Gulf of Mexico spawns from 

March through November accordi ng to 

Butler (1954) and from April to 

October according to Hayes and 

Menzel(1981). In Louisiana, spawning 

peaks occur in late May, early June, 

and September (Pollard 1973). In 

Mississippi, most oysters spawn from 

May to October and spawning intensity 

is greatest in June (MacKenzie 1977). 

In Galveston Bay, Texas, spawning 

begins in early April about the time 

water temperatures exceed 20 OC and 

continues at least until the end of 

August (Hopki ns 1931). Spat setting 

indicates that the American oyster 

probably spawns in all months in 

shallow warm bays in Texas (e.g. , Redfish Bay) with the exception of 

July and August (Copeland and Hoese 

1966). Water temperatures exceeding 

35 OC in those months may limit the 

extent of spawning. 

Spawning does not depend directly 

on tidal cycles (Loosanoff and Nomejko 

1951), but sun1 ight may warm the water 

during low tide and stinulate spawning 

(Drinnan and Stal lworthy 1979). 

The timing and intensity of 

spawning is initiated by males that 

release their sperm and a pheromone 

into the water. The females spawn 

when sperm enter their water transport 

system (Andrews 1979), or when pheromone stimulates females to release 

their eggs in a mass spawning (Bahr 

and Lanier 1981). Each female 

produces 23 mil 1 ion to 86 mill ion eggs 

per spawning; the number is proportional to the size of the individual 

(Davis and Chanley 1955). Egg counts 

of 15 million to 115 million were 

cited by Yonge (1960). Females may 

spawn several times in one season 

(Davis and Chanley 1955). The egg 

hatches 6 h after fertilization at 

water temperatures near 24 OC 

(Loosanoff 1965a). 

Larvae 

Oyster larvae are meropl anktonic 

and remain in the water column for 2 

to 3 weeks after hatching (Bahr and 

Lanier 1981). During this period the 

larvae pass through several stages of 

development (Carriker and Palmer 1979; 

Kilgen and Dugas 1984). After the 

blastula (3.2 h), gastrula (4.5 h), 

and trochophore (10 h) stages (Parrish 

1969), the larvae secrete a straighthinge shell and develop a ring of 

locomotory cilia called the velum. 

This strai ght-hinge larva or prodissoconch I is about 75 Dm in diameter. It 

develops into a prodissoconch I1 larva 

(also termed an eyed larva or 

pedi vel iger) , which is characterized 

by a pronounced umbone. This larva is 

a vigorous swimmer, and has a pair of 

pigmented eyes and an elongate foot 

with a large byssal gland (Andrews 

1979). Mean diameter of prodissoconch 

I1 larvae is 0.3 mm. 

Young larvae (prodissoconch I) in 

Little Egg Harbor, New Jersey, stay in 

the water column about 1 m below the 

surface (Carriker 1951). Older larvae 

(prodissoconch I I ) are near the bottom 

of the estuaries during flood tide and 

rise nearer the surface during the ebb 

tide. Andrews (1979) questioned these 

findings because in the laboratory, 

older larvae are stimulated to swim by 

increased salinities and inhibited by 

decreased salinities (Haskin 1964). 

Swimming velocity increased threefold 

when salinity was increased 0.5 ppt/h 

(Hidu and Haskin 1978). Upward swimming is nearly 1 cm/sec (Andrews 

1979). These behavioral traits may 

result in selective tidal transport so 

that larvae position themselves in the 

estuary. Generally, larvae are 

transported toward the head of an 

estuary against a net downstream flow 

(Seliger et al. 1982), presumably 

because they use these behavioral 

responses. Currents carry larvae 

considerable distances: 6.5 km in 

Alligator Harbor, Florida (Marshal 1 

1954), and 10 km in Lou is i ana (Gunter 
1951). Oyster larvae drift westward 

along the coast of the Gulf of Mexico 

(Buroker 1983). 

Ju veni 1 es 

Two to three weeks after 

hatching, oyster larvae commence a 

period of crawling in a circular 

pgtern, presumably seeking a sol id 

surface for attachment (Andrews 1979). 

In Long Island Sound the first set is 

18 days after the first spawning 

(Loosanoff and Nomejko 1951). In 

Galveston Bay, Texas, setting was 

first seen 2 months after spawning 

when the larvae were about 0.2 mm long 

(Hopk i ns 1931). After attachment with 

a droplet of 1 iquid cement exuded from 

a pore in the foot, they lose the 

velum and foot and are called spat 

(spat are newly settled oysters). 

She1 1s are preferred as attachment 

sites. but stones and other firm 

surfaces may be used. Spat that set 

duriug the first 3 days after metamorphosis may grow faster than those setti ng later (Losee 1979). Metamorphosis may be delayed if suitable substrate is not located (Newkirk et al. 

1977). Burke (1983) defined settlement as the behavior of dropping to 

the bottom, in contrast to metamorphosis, which is the irreversible developmental process. 

Several factors influence the 

setting behavior of larvae. Hidu and 

Haskin (1971) be1 ieved that rising 

water temperatures over tidal flats 

during flood tides stimulate setting. 

In the laboratory, rising temperatures 

trigger setting (Lutz et al. 1970). 

Swimming larvae have positive phototaxis, which becomes negative with an 

increase in temperature (Bahr and 

Lanier 1981). Light inhibits setting 

in tanks (Shaw et al. 1970), and 

oysters prefer to set on the undersides of shells (Ritchie and Menzel 

1969). More oysters settle in the 

subtidal zone than elsewhere in 

Delaware Bay (Hidu 1978). In 

shallower water, settlement is 

greatest on artificial substrate held 

away from the bottom because si 1 tat i on 

inhibits setting (Andrews 1979). 

Oyster larvae set in established 

oyster beds and in other habitats with 

firm substrate and suitable salinities. Crisp (1967) postulated that 

larvae are attracted to the proteinaceous surface of the peri ost racum of 

adult she1 1s and observed that larvae 

did not settle on shells that had been 

treated with bleach. Hidu (1969) demonstrated, however, that a water-borne 

factor, perhaps a pheromone, stirmlates larvae to settle on oyster 

shells. Currents also influence setting patterns: settlements in Delaware 

Bay are heaviest where tidal currents 

cut through salt marshes (Keck et al. 

1973). Juveniles 26 to 75 mm in 

height and 7 to 14 months old are 

designated as seed oysters (Chatry et 

al. 1983). 

Adu 1 t 

Because adult oysters are 

sessile, their distribution depends on 

where the larvae set and on subsequent 

survival of the spat. Oysters typically live in clumps called reefs or 

beds, in which they are the dominant 

organism. The mass of shells sometimes a1 ters currents and increases 

deposition of particulates so that the 

local envi ronment is modified. 

Adults are dioecious, but often 

change gender, exhibiting protandrous 

hermaphroditism (Bahr and Lanier 

1981). The gender and the process of 

sex inversion are genetically 

determined by perhaps three loci 

(Haley 1977). Typically the young 

adults are predominantly ma1 es ; 

subsequent sex inversion with age increases the number of females. Sex 

ratios in the James River Estuary, 

Vi r'ginia, change from 90% males at 1 

year of age to 80% females in older 

oysters (Andrews 1979). In Louisiana, 

76% of oysters were males if attached 

to older oysters and 46% were males if 

attached to dead shells (Menzel 1951). 

Oysters may become sexually mature in 
the Gulf of Mexico 4 weeks after 

attachment (Menzel 1951). Those 

oysters that mature during the first 

summer of life, however, do not 

contribute significantly to the year 

class because of the relatively low 

number of eggs that they produce 

(Hayes and Menzel 1981). 

GROWTH CHARACTERISTICS 

American oysters grow fastest 

during their first 3 months of life 

(Bahr 1976). Butler (1954) stated 

that oysters in the gulf region grow 

about 50 mmlyear. In Apalachicola 

Bay, Florida, oysters reach 25 mm in 5 

weeks, and 100 mn in 31 weeks (Ingle 

1950). In a second study, oysters 

were 4 mm at 1 week of age, 8 mm at 2 

weeks of age, and 27 mm at 5 weeks of 

age (Ingle and Dawson 1952). For 

comparison, oysters in Pensacola Bay, 

Florida, rarely exceed 75 mm of growth 

in their first year (Butler 1954). In 

Louisiana, oysters grew at the rate of 

0.26 to 0.30 mm per day during the 

first growing season (Gunter 1951). 

Oysters in Louisiana usually reach 30 

mm in length in 3 months, 55 to 60 mm 

in 1 year, 85 to 95 mm in 2 years, and 

105 to 115 mm in 3 years (Mackin 

1961a). There is variation in growth 

rate in Louisiana: the time to reach 

70 mn was 45 weeks at Grand Pass, 25 

weeks in upper Bastian Bay, and 12 

weeks in lower Bastian Bay (Owen 

1953a). Instantaneous monthly growth 

coefficients ranged from 0.42 to 0.84 

(Gi 11 mor 1982). 

Growth is influenced by temperature, salinity, intertidal exposure, 

turbidity, and food. Growth is greatest in August and September after 

spawning, when glycogen reserves are 

restored (Loosanoff and Nomejko 1949; 

Price et al. 1975). Growth in the 

gulf region is continuous throughout 

much of the year, though it may be 

interrupted by unusual cold periods or 

by spawning. Growth is slow during 

spawning because most of the energy is 

used for gamete production instead of 

adding body biomass. In Louisiana, 

the glycogen content of oysters 

decl i nes to support gonad maturation 

in April and reaches lowest levels 

during spawning in May, June, and July 

(Hopkins et al. 1954). Butler (1953) 

noted an increase in biomass after 

spawning without an increase in shell 

length. Oysters expend as much as 48% 

of their annual energy budget in 

reproduction (Dame 1976). 

Growth of oysters depends on 

envi ronmental conditions and thei r 

position and density in the oyster 

reef. Fluctuating environments may 

promote better growth. For example, 

oysters in fluctuating salinity within 

normal ranges tend to grow better than 

oysters under a relatively constant 

sal i ni ty (Pierce and Conover 1954). 

Oysters exposed for short periods 

during the tidal cycle grow about the 

same rate as those continuously submerged (Gi llmor 1982). Long exposure 

out of water, however, reduces growth. 

Oysters in reefs exposed about 20% of 

the time may grow about twice as fast 

as those exposed 60% of the time. The 

growth rate of the oyster is directly 

related to phytoplankton density. 

Oysters grow faster in nutrient-rich 

salt ponds than in tidal creeks where 

primary productivity is lower (Manzi 

et al. 1977). Individuals in 

populations of oysters of high density 

grow slower than those at low density 

(Copeland and Hoese 1966). Crowding, 

however, may prevent spawning and thus 

i ndi rectly 1 ead to increased growth 

(Butler 1953). 

A Walford plot predicts that 

oysters in South Carolina would cease 

growing when 140-mn long (Dame 1971); 

however, oysters 200-mm long occur. 

COMMERCIAL SHELLFISHERIES 

The American oyster has traditional ly supported a valuable 

shellfishery along the enti re gulf 

coast . The shellfisheries are 

concentrated in bays and estuaries 

(Figure 2). The landings in the Gulf 

States combined average about 8,000 
metric tons (18 million pounds) 

annually (Table 1). Oyster production 

has been relatively stable; the 

landings since 1950 have varied only 

from 10 million to 27 million pounds. 

The landings of oysters in the Gulf of 

Mexico are about a third of the U.S. 

1 andi ngs . The landings for the 

individuirl States vary by an order of 

magnitude (Table 2). Louisiana has 

the largest she1 lfisheries for 

oysters; annual landings are about 9 

million pounds (4,000 metric tons). 

The west coast of Florida has the 

second largest fishery, about half 

that of Louisiana. Poor year classes 

lead to reduced harvests. Louisiana 

had poor harvests in 1979, 1980, and 

1981; Florida in 1973 through 1976; 

and Texas in 1974, 1975, 1978, 1979 

and 1981. Alabama and Mississippi 

have the same trends as Louisiana. 

Table 1. Oyster landings (thousands of pounds; meat weight) by 

geographic region for the years 1950-1982. (From U.S. Dep. Commer., 

Natl. Mar., Fish. Serv., NOAA, Natl. Fish. Stat. Program. Annual 

summaries of oyster landings .) 

South Gulf of Year New England Mid-Atlantic Chesapeake Atlantic Mexico 
Table 2. Oyster landings (thousands of pounds; meat weight) for the Gulf 

States, 1930-82 (From U.S. Dep. Commer., Nat. Mar. Fish. Serv., NOAA, Natl. 

Fish. Stat. Program. Summation of annual reports. ) 

Years ~lorida~ Alabama Mississippi Louisiana Texas Total 

1930 1,501 

1931 1,406 

1932 1,109 

1934 1,357 

1936 917 

1937 817 

1938 858 

1939 742 

1940 669 

1945 1,496 

1950 873 

1951 681 

1952 542 

1953 564 

1954 668 

1955 6 30 

1956 856 

1957 710 

1958 795 

1959 1,415 

1960 1,931 

196 1 3,255 

1962 4,592 

1963 4,282 

1964 2,793 

1965 3,789 

1966 4,157 

1967 4,578 

1968 5,317 

1969 4,912 

1970 3,573 

1971 3,529 

1972 3,231 

1973 2,409 

1974 2,653 

1975 2,134 

1976 2,602 

1977 4,072 

1978 5,780 

1979 6,048 

1980 6,445 

1981 7,179 

1982 4,833 

a~ulf coast only. 
Oysters are taken by handpicking 

of clumps from reefs (Bahr and Lanier 

1981), hand and patent tonging, and 

dragging and dredging (Korringa 1976). 

In Louisiana, oysters are taken mostly 

with dredges (Pausina 1971). Tonging 

is 1 imited to water 4-m deep or less; 

dredging requires a larger vessel 

(Maghan 1967). In Mississippi coastal 

waters, the method used depends on the 

type of fishery. In the Mississippi 

Sound near Bay St. Louis and Pass 

Christian, oysters are taken by 

dredging or with tongs; in Biloxi Bay 

and Graveline Bayou they are dredged 

for transplantation to grow out sites; 

and near Horn Island they are taken by 

hand for food and recreation (Ogle 

1979). In Alabama, tonging and 

handpicking are the only legal means 

of taking oysters; this is because the 

major reefs are close to shore in 

shallow waters (Mark S. Van Hoose, 

A1 abama Department of Conservation and 

Natural Resources, pers. comm.) . Power equipment has made capture more 

efficient but it also increases the 

potential for depleting the beds. 

The American oyster is the 

dominant species in mariculture in the 

United States. In 1980, the yield of 

oysters in mariculture was 10,753 

metric tons (about 24 million lb) 

valued at $37 million, which was about 

55% of the total U.S. shellfishery 

harvest (19,250 metric tons; 42.4 

mi 11 ion 1 b) . The equi valences between 

different values reported for harvest 

are: 1 bu = 35 1 = 32 kg total weight 

= 7.8 pints of meats = 3.4 kg meat 

weight (Pruder 1975). 

The market quality of the meat 

varies with the season. The yield of 

oyster meat per shell is highest in 

March before reproduction and lowest 

in the summer in Texas (Gunter 1942) 

and Florida (Rockwood and Mazek 1977). 

The reduced yields during spawning 

periods correspond to a reduced 

condition index following spawning 

(Hopkins et al. 1954; Lawrence and 

Scott 1982 ) . 

Even 'wild' oysters are often 

cultivated by altering the substrate. 

Oyster shells (cultch) placed in 

suitable habitat lacking substrate 

promote settlement of the larvae 

(Whi tf i el d and Beaumariage 1977). 

Suitable habitat can be created by 

redepositing buried she1 1 s on the 

surface (May 1976) but only if the 

bottom is relatively hard at the site 

of deposition (Eckmayer 1977). 

Dredging is effective in rehabilitating oyster reefs if the bottom is 

re1 atively hard (Eckmayer 1977). 

Population Dynamics 

A vast majority of the eggs and 

1 arvae produced by Ameri can oysters 

perish before setting. Following 

spawning, oyster larvae are abundant 

plankters, ranging from 2.0 to 5.5 per 

1 iter in Virginia coastal waters 

(Andrews 1979; Seliger et al. 1982). 

In the Mississippi Sound, one half of 

the zooplankters in the summer are 

oyster larvae (Butler 1954). Abundance 

is greatest after high tide (Andrews 

1979). The daily mortality of larvae 

is about 10% (~rinnan and stallworthy 

1979) . 

Newly set spat usually are dense 

on suitable substrates. For exanple, 

in Apalachicola Bay there is an 

average of 2.5 spat set per shell 

(Ingle 1951), or 100 spat/m2 of 

surface area (Menzel et al. 1966). In 

Alabama, there are only 0.06 spat/m2 

in Bayou Cour and 0. 17/m2 in She1 lbank 

Bayou (Eckmayer 1977), where there is 

intensive shrimping, low DO, and 

siltation (Mark S. Van Hoose, pers. 

comm. 1. Ten miles away in Kings 

Bayou, spat density is 1.2 to 10.8/m . In Louisiana, the daily rate of 

setting after peak spawning is as much 

as 90 spat/shell (Hopkins 1955). 

Chatry et al. (1983) observed sets of 

10 to 1,890 oysters/m2 in Louisiana. 

The early mortality of spat has 

not been studied in the gulf region. 

In Massachusetts, the mortality during 
the first mmth ranges from 79% to 99% 

(Krantz and Chamber1 in 1978). Typical 

annual mortality of spat is 60% in 

Louisiana (Mackin 1961a) ; mortality is 

usually 90% to 99% at specific seed 

grounds (Chatry et a1 . 1983). Annual 

mortality of seed oysters is 6% to 11% 

(Owen 1953a). Spat survival is less 

in dense sets than in sparse sets in 

Louisiana (Chatry et al. 1983) and 

Chesapeake Bay (Webster and Shaw 

1968). Mortality tends to be greater 

in small seed oysters than in large 

ones. Production of seed oysters is 

not closely correlated with the number 

of spat (Chatry et al. 1983). 

The mortality of oysters in gulf 

coastal waters varies greatly 

depending upon the rate of freshwater 

inflow and predator abundance. In 

Texas, the mortality of oysters from 

seed to adult (1 year) is 90% (Gunter 

1955). Under optimal conditions, the 

monthly mortality is 2% to 4% in 

Louisiana (Gunter 1953). Mack i n 

(1961a) cited 60% as the annual 

mortality under prevai 1 ing conditions 

of salinity and predators. Based on 

the number of newly dead oysters, Ogle 

(1979) estimated that the monthly 

mortal ity in Mississippi ranged from 

6% to 36%. In Louisiana, newly dead 

oysters made up 5% to 80% of the 

population with an average of 27% 

(Owen et al. 1951). An entire 

population of oysters in some areas 

may be ki 1 1 ed by excessive freshwater 

inflow (and low salinities) from the 

Mississippi and Pearl Rivers (Gunter 

1953; Schlesselman 1955; MacKenzie 

1977), or by high water temperatures 

in isolated bays in Texas (Copeland 

and Hoese 1966). 

ECOLOGICAL ROLE 

Larvae feed largely on plankton, 

particularly small, naked flagellates 

(chrysophytes) (Gui 1 lard 1957). At 

moderate water temperatures, larval 

growth is best with a diet of naked 

f lagel lates, whereas at temperatures 

above 27 "C naked algae are scarce and 

chlorophytes are more abundant as food 

(Davis and Calabrese 1964). Bacteria 

are not eaten by larvae (Davis 1953). 

Oyster larvae are food for a wide 

variety of filter feeders (Andrews 

1979). 

Adult oysters filter large 

quantities of brackish water. They 

most effectively filter particles in 

the 3- to 4-wn size range (Haven and 

Moral es-A1 amo 1970). Naked f 1 age1 - 

lates are the most important food 

although bacteria are sometimes 

consumed, presumably because they are 

attached to detritus. For each gram 

of dry weight of tissue, an oyster 

held at 21 "C filters 1.5 l/hr, with a 

maximum of 1.9 l/hr (Palmer 1980). At 

temperatures above 25 OC about 8 l/hr 

are f i 1 tered (Langefoss and Maurer 

1975). The volume of water filtered 

per hour is about 1500 times the 

volume of the oyster's body (Loosanoff 

and Nomejko 1946). The filtration 

rate is independent of the available 

food supply, the stage of tide, or the 

time of day. If food is absent, 

however, the valves are closed much of 

the time (Higgins 1980). 

The American oyster is the 

dominant species in the oyster reef 

community. Over 40 macrofaunal species or groups 1 ive in oyster beds 

(Bahr and Lanier 1981), and the total 

number of species in an oyster 

community may exceed 300 (We1 1s 1961). 

On the oyster reef, oysters are 

responsible for as much as 88% of the 

respi ration (Bahr and Lanier 1981). 

Oysters are susceptible to a 

variety of diseases and parasites and 

are preyed upon by several species 

(Galtsoff 1964). The bacterial 

diseases Vi bri o and Pseudomonas 

sometimes kill oysters. The protozoan 

pathogen Perki nsus marinus infects 

oysters from Delaware to Mexico. In 

Texas, the index of stress was in 

direct relation to the level of 

infection (Soni at and Koeni g 1982). 

In Florida, infections of the 
protozoan become lethal only during \ elevated summer water temperatures 

(Quick and Mackin 1971). In Texas. 

the protozoan parasite Cabyrinthomyxa 

marina is thouaht to kill 10% to 50% 

ote adult- oysters (Hofstetter 

1977). Disease epidemics are common 

in the gulf region (Mackin 1961b). In 

Louisiana, all oysters in some locations are infected with the 

gregari ne parasite Nemgop;!j; ostrearum, and in Florida 9 

infected (Owen et al. 1951). The 

parasite, however, did not directly 

cause mortal i ty. 

Predators often limit the 

abundance of oysters. The southern 

oyster dri 11, Thais haemastoma, is 

responsible forhe majority of 

oyster deaths in Louisiana, 

Mississippi, and Alabama. Other 

common predators are the lightning 

whel k (Busycon cont rarium) , the blue 

crab (Callinectes sapidus), and the 

stone crab (Menippe mercenaria) 

(Marshall 1954; Menzel and Nicky 1958; 

Cake 1983). All sizes of oysters are 

killed by oyster drills, which bore 

through the shells with a combination 

of chemical dissolution of the shell 

and drilling (radular rasping). Blue 

crabs prefer small oysters; stone 

crabs will crush any size of oyster 

that they can manipulate, as wi 11 

several species of xanthid mud crabs. 

The southern oyster drill often kills 

without drilling by rasping a minute 

gap between the valves and protruding 

the proboscis into the mantle cavity 

(McGraw and Gunter 1972; Gunter 

1979b). The crown conch (Melongena 

corona) is a predator of oysters along 

Florida's west coast. The southern 

oyster drill has been reported to kill 

50% of the oysters of productive reefs 

and 100% in nonproductive reefs near 

Pass Christian, Mississippi (Chapman 

1959), and 50% to 85% of the oysters 

in Louisiana (Schlesselman 1955). 

Souther? oyster drills have densities 

of 201111 in some oyster reefs (Hopkins 

1955), and a single drill can consume 

up to 4 spatlhr (Butler 1954), or up 

to one adult oyster every 8 days 

(Gunter 1979b). On St. Vincent Bar in 

Apalachicola jay, Florida, there were 

2.8 drillslm , which together with 

stone crabs destroyed 67% of the 

oysters in one month (Menzel et al. 

1957). The dri 11 and the stone crab 

cause serious mortality in Texas 

(Gunter 1955) and Florida (Menzel et 

a1 1966). 

Menzel et a1 . (1966) consider the 

stone crab to be the main enemy of 

oysters in Florida. The density of 

the2 stone crab in Louisiana is 

l/m and each potentially consumes 219 

oysters per year. In laboratory 

experiments, a blue crab ate 19 oyster 

spatlday , but did not consume adults 

unless they were weakened (Menzel and 

Hopkins 1956). The black drum 

(~ogonias cromis) , southern eagle ray 

(My1 i obatis goodei ) , and cownose ray 

(Rh i noptera bonasus ) may destroy an 

oyster reef by eating the spat 

(Schlesselman 1955). 

The oyster crab Pinnotheres lives 

in the mantle cavity and may damage 

the gi 11s of oysters (Schlesselman 

1955). The widespread boring sponge 

Cliona, and the boring clam - i loth ra smithii) weaken the oysand lower market quality 

(Schlesselman 1955). Spat are preyed 

upon by the flatworm Stylochus el 1 ipticus (MacKenzie 1970; Christensen 

1973). The sea anemone (Diadumene 

leucolena) consumes 0.6 to 4.9 oyster 

larvae per minute in the laboratory 

and also feeds on larvae in the 

natural envi ronment (Stei nberg and 

Kennedy 1979). 

Major competitors for space on 

substrate are the slipper shells 

(Crepidula spp.) and the jingle shells 

(Anomia spp.) as well as barnacles and 

other oysters that set on adult shells 

(MacKenzie 1970). The hooked mussel 

(Ischadium recurvum) competes with 

ovsters for soace and food in 

~buisiana (~chlesselman 1955). A 

heavv set of the barnacle Balanus 

imp~ovisus can seriously reduce the 

area of hard surface available to 
oysters (Ingle 1951). According to 

Ingle (1951), slipper shells and the 

hooked mussel are not serious competitors with oysters in Apalachicola 

Bay, Florida. Young oysters may be 

smothered by the excreta of polychaete 

worms of the genus Polydora, or by 

excreta of adult oysters (Stenzel 

1971). Blooms of red tide (Cochlodi nium heterolobatum) at concF 

trations of 500 cells/ml kill oyster 

larvae (Ho and Zubkoff 1979). 

ENVIRONMENTAL REQUIREMENTS 

The American oyster typically 

lives in shallow, well-mixed estuaries, lagoons, and oceanic bays where 

it tolerates widely fluctuating water 

temperatures , salinities, and 

concentrations of suspended sol ids 

(Andrews 1979). Because of tolerance 

to these fluctuations, precise 

envi ronmental requ i rements alone or in 

combination are difficult to define. 

Temperature 

I n 1 aboratory tests, embryos 

develop normal ly at temperatures 

between 20 and 30 "C but abnormalities i n c r e a s e p r o g r e s s i v e l y when 

temperatures decline to 15 "C or rise 

to 35 "C (MacInnes and Calabrese 

1979). On the other hand, Dupuy 

(1975) in his experiments reported 

that embryo abnormalities could be as 

high as 2% at 25 "C and 12% at 30 "C. 

The growth of larvae may be impaired 

by water temperatures of 30 "C and 

higher, and even a brief exposure for 

10 min at water temperatures near 

40 "C retards growth (Hidu et al. 

1974). In other tests, growth was 

fastest and survival highest at water 

temperatures of 27.5 to 32.5 "C (Davis 

and Calabrese 1964). These tests were 

all conducted on oyster stocks from 

the Atlantic coast and exact 

temperature ranges may not apply to 

oyster embryos or larvae from the Gulf 

of Mexico. 

Adults exist within a range of 

water temperatures from -2 "C in New 

England to 36 "C in the Gulf of 

Mexico. During low tide, oysters may 

be exposed to and survive air temperatures below freezing or above 49 "C 

(Galtsoff 1964). Excessively high 

terrperatu res cause mortality; water 

temperatures above 35 "C for the whole 

tidal cycle in Indian River bay, 

Delaware, are known to have killed 

some oysters (Tinsman and Maurer 

1974). The critical thermal maximum 

determined in the laboratory for the 

American oyster is 48 "C (Henderson 

1929). Oysters tolerate freezing of 

their tissues, and revive after thawing (Loosanoff 1965a). Gulf coast 

oysters, however, apparently are not 

as tolerant of freezing (Cake 1983). 

Optimum water temperatures for 

growth, reproduct ion, and survival of 

American oysters range from about 20 

to 30 "C, and the response of oysters 

to temperature changes and extremes 

depend on an interaction of 

environmental conditions. The rate 

that water is pumped through the 

oyster's gill system is determined by 

temperature. A water temperature 

range of 20 to 25 "C results in 

favorable pumping rates for supplying 

needs for oxygen, food, and waste 

disposal (Coll ier 1951). Oysters are 

relatively inactive below 7 "C and 

pumping is greatly reduced. Although 

the threshold for feeding by 

Chesapeake Bay oysters in the 

laboratory is 3 "C (Haven and 

Morales-Alamo 1966), few New England 

oysters feed at temperatures below 

8 "C and growth ceases (Price et al. 

1975). Some growth has been reported 

in Long Island Sound in the winter 

when water is unseasonably warm and 

food is available (Ruddy et al. 1975). 

Growth of Long Island Sound oysters is 

possible between 6 and 32 "C and 

fastest near 26 "C (Galtsoff 1964). 

The exposure of Florida adults to a 

35 "C water temperature accelerated 

gametogenesis and spawning, but the 

exposure prevented subsequent spawning 

in that year (Quick 1971). 
Differences in thermal requirements of oysters from different areas 

have led to the postulation that races 

may be separated on the basis of temperatu re requirements (Ahmed 1975). 

Spawning temperatures for three distinct races were reported by Stauber 

(1950): 16 OC for the northern race 

(New England), 20 OC for the 

mid-Atlantic race, and 25 OC for the 

Gulf of Mexico race. For instance, 

oysters spawn in Galveston Bay, Texas, 

after temperatures exceed 25 OC (Hopkins 1931), and mass spawnings in 

Apalachicola Bay, Florida, do not take 

place until temperatures exceed 26 OC 

(Ingle 1951). Additional evidence for 

the existence of physiological races 

was reported by Menzel (1955), who 

found that ciliary activity continues 

at 0 OC in northern oysters but ceases 

at 6 OC in southern oysters. Andrews 

(1979) be1 ieves there are other races 

as well, but genetic studies do not 

closely support the existence of physiological races. Buroker et al. 

(1979) found that all oysters studied 

were genetical ly identical, except 

those from Nova Scotia and Florida. 

These populations were 82% similar, 

about the level of simi lari ty between 

the American and mangrove oysters, 

which can successfu 1 ly hybridize 

(Menzel 1968). According to Groue and 

Lester (1982), oysters in Laguna 

Madre, Texas, are genetically distinct 

from four other gulf populations. 

Measurement of isozymes in the genetic 

studies, however, may not validate 

these findings. 

Salinity 

Adult oysters in the Gulf of 

Mexico normally occur at salinities 

between 10 and 30 ppt but they 

tolerate a salinity range of 2 to 40 

ppt (Gunter and Geyer 1955); outside 

this range, they die or discontinue 

feeding and reproduction. In the 

Mississippi Sound, salinities among 

productive reefs range from 2 to 22 

ppt (Eleuterius 1977). The optimum 

sal i ni ty range of the American oyster 

in Long Island Sound is 10 to 28 ppt 

(Loosanoff 1965a), but most oysters 

from Long Island Sound survive 3 ppt 

for up to 30 days in the laboratory 

(Loosanoff 1965b). High mortal ity was 

reported during extended exposure of 

oysters to freshwater (t2 ppt 

salinity) during spring floods in 

Mississippi Sound and Louisiana 

marshes (Gunter 1953), in Mobile Bay, 

Alabama (May 1972), and in the Santee 

River, South Carol i na (Burrel 1 1977). 

Many oysters died in the Beaufort 

Inlet, North Carolina, after exposure 

to 5 ppt for about a month (Wells 

1961). Oysters in one Louisiana reef 

died after 14 days at 6 ppt (Anderson 

and Anderson 1975), although most 

oysters in Louisiana coastal waters 

tolerate lower sal i ni ties: Gunter 

(1953) reported that a salinity of 

less than 2 ppt for 14 days killed 

only 12% of a population of oysters. 

Oysters apparently tolerate 

higher salinities in Texas than 

el sewhere. In Laguna Madre, a 

saltwater bay that often has unusually 

high salinities, oysters spawn and 

grow in salinities greater than 40 ppt 

(Breuer 1962). In Redfish Bay and 

Harbor Island, Texas, mass mortality 

occurred at a salinity of 40 ppt but 

the oysters also were exposed to a 

water temperature of 37 OC (Copeland 

and Hoese 1966). 

Salinity requirements or tolerance vary from place to place for 

different life stages and activities. 

In the Gulf of Mexico, best growth and 

reproduction is in oyster reefs with a 

salinity of 12 to 30 ppt, but oyster 

abundance is greatest at 10 to 20 ppt 

(Butler 1954). In Long Island Sound, 

salinities above 7 ppt are required 

for spawning (Loosanoff 1948). 

Unusually high freshwater inflow in 

Mobile Bay, Alabama, inhibits the 

maturation and spawning of oysters 

(May 1972). Excessively low salinity 

inhi bits gonadal maturation in oysters 

in Chesapeake Bay (Butler 1949) and 

Long Island Sound (Loosanoff 1953). 

Reproductive failure may be a direct 
effect of salinity or it might be 

indirectly caused by insufficient 

feeding at low salinity. 

In the laboratory, Atlantic coast 

embryos develop normally at salinities 

of 16 to 30 ppt (MacInnes and Calabrese 1979). Atlantic coast larvae 

tolerate salinities of 3 to 31 ppt 

(Carri ker 1951), but grow fastest and 

survive best at salinities above 12 

ppt (Davis and Calabrese 1964). Larvae in a New Jersey estuary move to 

the ha1 ocl i ne (the boundary between 

low salinity water and deeper high 

salinity water) where salinities are 

above 5 ppt (Carriker 1951). The 

minimum sal i ni ty for good production 

of larvae in Galveston Bay, Texas, is 

about 20 ppt, probably because food is 

more abundant at these salinities 

(Hopkins 1931). In general, spat 

setting is less at lower salinities 

(Menzel et al. 1966). In a 10-year 

study at three sites near Breton 

Sound, Louisiana, optimum salinities 

for spat production were 6 to 8 ppt in 

May and 3 ppt in June and July (Chatry 

et al. 1983). Optimum salinities for 

the growth of spat are 15 to 22 ppt 

(Chanley 1957). 

Heavy freshwater inflow sometimes 

greatly benefits oyster populations 

by ki 11 i ng predators that cannot 

tolerate low salinity water (Owen 

1953b; Marshal 1 1954). For exarnpl e, 

the southern ovster drill and the 

carica) die at 

11DDtWells 1961). ,. - 

and stone crabs succumb at salinities 

below 15 ppt (Menzel et al. 1966). 

Substrate 

The preferred habitats in the 

Gulf of Mexico are shallow bays, mud 

flats, and offshore sandy bars (Butler 

1954; Copeland and Hoese 1966; Menzel 

et al. 1966). Oysters grow equally 

well on rocky bottoms or on mud with a 

consistency that wi 11 hold the oyster 

on the surface, Although most oyster 

reefs are on firm bottoms (Price 

1954), they may also be abundant on 

mud bottoms surrounding the reefs 

(Butler 1954; Menzel et al. 1966). 

Oysters from muddy substrates are more 

slender than those from hard substrates (Gal tsoff 1964). Maximum 

setting is on horizontal surfaces 

(Clime 1976). In Galveston Bay, 

Texas, oysters thrive on bottoms that 

are 17% to 100% sand (Harry 1976). 

The weathering of shells produces grit 

which is thought to clean oyster 

she1 1s of fouling organisms (Gunter 

1979a). 

Currents 

Currents a re particularly 

important to American oyster larvae 

and adults. For maximum feeding, the 

volume of water immediately above an 

oyster bed must be renewed by a 

moderate current 72 times every 24 h 

(Galtsoff 1964). Tidal flows of 156 

to 260 cm/sec or higher are needed for 

optimum growth in Mississippi (Veal et 

al. 1972). Currents are necessary for 

removal of feces and pseudofeces to 

prevent burial of the oyster reef 

(Lund 1957; Stenzel 1971). Currents 

on the sites of oyster bars in 

Beaufort Inlet and the Newport River 

estuary in North Carolina are 11 to 66 

cm/sec (We1 1s 1961). Turbulent 

currents that carry sand and pebbles, 

however, can damage oysters by eroding 

shell surfaces (Galtsoff 1964). A 

velocity of 150 cm/sec was observed to 

cause unattached oysters to tumble 

along the bottom of Long Island Sound 

(MacKenzie 1981). In Delaware Bay, 

oysters are most abundant in areas of 

scour where currents keep the oyster 

beds free of sediments (Keck et a1 . 1973). 

Oxygen 

The hourly oxygen consumption is 

39 ml/kg for a whole animal including 

the shell or 303 ml/kg of wet tissue 

(Hammen 1969). Oxygen consumption 
increases with i ncreasi ng temperature (Figure 3); Q values (the 

factor by which a reaction velocity is 

increased by an increase in 

temperature of 10 "C) range from 1.2 

to 2.3 for gill tissue and 2.7 to 4.2 

for mantle tissue (Bass 1977). Oysters are facultative anaerobes and are 

able to survive daily exposure to low 

oxygen. In 1971, low oxygen killed 

oysters and reduced the setting of 

spat in Mobile Bay, Alabama (May 

1972). Oxygen consumption is zero 

when the valves are closed (Hammen 

1969), but an oxygen debt builds up. 

Figure 3. Oxygen consumption in the 

American oyster as a function of 

salinity and temperature (Shumway 

1982). 

Suspended Solids and Sedimentation 

Extreme conditions, such as those 

associated with large storms, can 

practically destroy an oyster reef. 

The large decrease in oyster meat 

landings in Alabama from 1979 to 1980 

is .a result of Hurricane Frederick 

which struck Alabama in September 

1977. The storm killed oysters by 

covering some reefs with mud and 

washing the substrate off others (Mark 

S. Van Hoose, pers. comm.). Suspended 

solids may clog gills and interfere 

with filter feeding and respiration 

(Cake 1983). Oysters tolerate water 

with suspended sol ids, but the pumping 

rate decreases. In the 1 aboratory, 

pumping is reduced 70% to 85% over the 

range 0 to 1 g/l, depending on the 

nature of the suspended sediment 

(Loosanoff and Tommers 1948). In 

natural envi ronments oysters 

apparently develop and grow better in 

waters with high concentrations of 

suspended solids than in waters with 

low concentrations (Rhoades 1973). 

If covered with sediment, oysters 

die in 1 week at 20 "C and in 2 days 

at 25 OC (Dunnington 1968). The 

mortality of oysters covered with 2 to 

5 cm of sediment near one dredging 

site in Louisiana increased by 48% 

(Rose 1973). In Alabama, however, 

muddy water from dredging generally 

did not harm nearby oyster reefs 

because cu rrents and gravity carried 

the muddy water away from the elevated 

oyster reefs (May 1976). 

Other Environmental Requirements 

Oyster embryos develop normal ly 

within a pH range of 6.75 to 8.75 

(Calabrese and Davis 1966), and 

develop abnormally at a pH above 9.0 

and below 6.5. Larvae tolerate the 

same pH range as embryos but growth is 

fastest at a pH of 8.25 to 8.5. 

Oysters occur at depths of 0.3 m 

above to 12 m below mean low tide 

(Butler 1954). 

LITERATURE CITED 

Ahmed, M. 1975. Speciation in living 

oysters. Adv. Mar. Biol. 13: 

357 -397. 

Anderson, R.D., and J.W. Anderson. 

1975. Effects of salinity 

and selected petroleum hydrocarbons on osmotic and chloride 

requl ation of the Ameri can oyster 

~rassostrea vi rginica. ~hsiol. 

Zoo1 . 48(4) : 420-430. 

Andrews , J .D. 1979. Pel ecypoda: 

Ostreidae. Pages 291-341 ij A.C. 

Giese and J.S. Pearse, eds. 

Reproduction of marine invertebrates. Vol. V. Molluscs: 

pel ecypods and 1 esser classes. 

Academic Press, New York. 

Bahr, L.M., Jr. 1976. Energetic 

aspects of the intertidal oyster 

reef community at Sapelo Island, 

Georgia. Ecology 57(1): 121-131. 

Bahr, L.M., and W.P. Lanier. 1981. The 

ecology of intertidal oyster 

reefs of the South Atlantic 

coast: a community profile. U.S. 

Fish Wildl. Serv., Biol. Serv. 

Program, FWS/OBS-81/15. 105 pp. 

Bass, E .L. 1977. Influences of temperature and sal inity on oxygen consum~tion of tissues in the American' oyster (Crassostrea virginica). Comp. Biochem. Physiol. 

583: 125-130. 

Burke, R.D. 1983. The induction of 

metamorphosis of marine invertebrate larvae: stimulus and response. Can. J. Zool. 61(8): 

1701-1719. 

Buroker, N.E. 1983. Population 

aenetics of the American ovster. 

trassostrea virginica aloig thi 

Atlantic coast and Gulf of 

Mexico. Mar. Biol. (Berl.) 

Bu roker, N .E., W .K. Hershberger, and 

K.K. Chew. 1979. Population genetics of the family Ostreidae 2. 

Intraspecif ic studies of the genera Crassostrea and ~accostrea. 

Mar. Biol . (Berl .) 54: 171-184. 

Burrell, V.G., Jr. 1977. Mortalities 

of oysters and hard clam associated with heavy runoff in the 

Santee River system, South Carolina, in the spring of 1975. 

Proc. Natl . She1 1 fish. Assoc. 

67: 35-43. 

But 1 er, P .A. 1949. Gametogenesis i n 

the oyster under conditions of 

depressed salinity. Biol. Bull. 

(Woods Hole) 96(3): 263-269. 

Butler, P.A. 1953. Shell growth versus 

meat yield in the oyster C. virginica. Proc. Natl. ~halfish. 

Assoc. 44: 157-162. 

Breuer, J.P. 1962. An ecological Butler, P.A. 1954. Summary of our 

survey of the lower Laguna Madre knowledge of the oyster in the 

of Texas, 1953-1959. Pub1 . Inst. Gulf of Mexico. U.S. Fish Wildl. 

Mar. Sci . Uni v. Tex. 8: 153-183. Serv. Fish. Bull. 55(89):479-489. 
Cake, E.W., Jr. 1983. Habitat 

suitability models: Gulf of 

Mexico American oysters. U.S. 

Fish Wi ldl . Serv. 

FWS/OBS-82/10.57. 37 pp. 

Calabrese, A., and H.C. Davis. 1966. 

The DH tolerance of embryos and 

1 arvae of Mercenaria mercenaria 

and Crassost rea vi r g i n i ca . Biol. Bull. (Woods Hole) 

Carriker, M.R. 1951. Ecological observations on the distribution of 

oyster larvae in New Jersey estuaries. Ecol . Monogr. 21 (1 ): 19-38. 

Carriker, M.R., and R.E. Palmer. 1979. 

Ultrastructural morphogenesis of 

prodi ssoconch and early dissoconch valves of the ovster (Cras- ., *- 

sostrea vi rginica) . Proc. Natl . Shel lf ish. Assoc. 69:103-128. 

Chanley, P.E. 1957. Survival of some 

juvenile bivalves in water of low 

salinity. Proc. Natl. Shellfish. 

Assoc. 48:52-65. 

Chapman, C.R. 1959. Oyster drill 

' Thais haemastoma predation in 

Mississi~~i Sound. Proc. Natl . Shel lf ish: Assoc. 49:87-97. 

Chatry, M., R.J. Dugas, and K.A. 

Easley. 1983. Optimum salinity 

regime for oyster production on 

Louisiana's State seed grounds. 

Contrib. Mar. Sci. 26:81-94. 

interpretations. Proc. Natl . Shellfish. Assoc. 42:13-38. 

Copeland, B.J., and H.D. Hoese. 1966. 

Growth and mortality of the Ameri can oyster ~rassostrea vi rgi nica 

in high salinity shallow bays in 

central Texas. - Pub1 . Inst.- Mar. 

Sci . Univ. Texas. 11: 149-158. 

Crisp, D.J. 1967. Chemical factors 

inducing settlement in Crassostrea virginica (Gmel in). J. Anim. 

Ecol . 36(2): 329-335. 

Dame, R.F., Jr. 1971. The ecological 

energies of growth, respi ration 

and assimilation in the intertidal American oyster Crassostrea 

vi rgi ni ca (Gmeli n) . Ph .D. Thesis. 

University of South Carolina, 

~olumbia.~81 pp. 

Dame, R.F. 1976. Energy flow in an 

intertidal oyster population. 

Estuarine Coastal Mar. Sci. 4(3): 

243-253. 

Davis, H.C. 1953. On food and feeding 

of larvae of the American oyster, 

C. vir inica. Biol. Bull. (Woods 

no1 eh: 334-350. 

Davis, H.C., and A. Calabrese. 1964. 

Combi ned effects of temperature 

and salinity on development of 

eggs and growth of larvae of M. 

mercenaria and C. virginica. U.7. 

Fish Wildl. Serv. Fish. Bull. 

63(3) : 643-655. 

Christensen, D.J. 1973. Prey prefer- Davis, H.C., and P.E. Chanley. 1955. 

ence of Stylochus elli ticus in Spawning and egg production of 

Chesapeake BT *atl.oysters and clams. Biol. Bull. 

She1 lf ish. Assoc. 63: 35-58. (Woods Hole) 110:117-128. 

Clime, R.D. 1976. Setting orientation Drinnan, R.E., and W.B. Stallworthy. 

in the oysters Ostrea edulis L. 1979. Oyster larval populations 

and Crassostrea virginica Gmelin. and assessment of spatfall, 

~aster'ss. University of Bideford River, P. E. I., 1963 

Maine at Orono. 94 pp. and 1964. Can. Fish. Mar. Serv. 

Tech. Rep. (797): 1-13. 

Collier, A. 1951. A study of the response of oysters to temperature Dunnington, E .A., Jr. 1968. survival 

and some long-range ecological time of oysters after burial at 
various temperatures. Proc. Natl . Shellfish. Assoc. 58:lOl-103. 

Dupuy, J.L. 1975. Some physical and 

nutritional factors which affect 

the growth and setting of the 

larvae of the oyster, Crassostrea 

vir inica in the 1aboratory.Pages 

&in F.J. Yernber, ed. 

Physiologlyal ecol ogy of 

estuarine organisms. University 

of South Carolina Press, 

Columbia. 

Eckmayer, W.J. 1977. Oyster reef 

cultivation for cultch material. 

Ala. Mar. Resour. Bull .12:23-30. 

Eleuterius, C.K. 1977. Location of 

the Mississippi Sound oyster 

reefs as related to salinity of 

bottom waters during 1973-1975. 

Gulf Res. Rep. 6(1):17-23. 

Galtsoff, P.S. 1964. The American 

oyster Crassostrea vi rginica 

(Gmelin). U.S. Fish Wildl. Serv. 

>. Gillmor. R.B. 1982. Assessment of 

intertidal growth and capacity 

adaptations in suspension-feeding 

bivalves. Mar. Biol. (Berl.) 

68(3): 277-286. 

Groue, K.J., and L.J. Lester. 1982. 

A morphological and genetic 

analysis of geographic variation 

among oysters in the Gulf of 

Mexico. Veliger 24(4): 331-335. 

Guillard, R.R. 1957. Some factors in 

the use of nannoplankton cultures 

as food for larval and juvenile 

bivalves. Proc. Natl. Shellfish. 

Assoc. 48: 134-142. 

Gunter, G. 1942. Seasonal condition 

of Texas oysters. Trans. Tex. 

Acad. Sci . 25:89-93. 

Gunter, G. 1951. The West lndian tree 

oyster on the Louisiana coast, 

and notes on growth of the three 

gulf coast oysters. Science 

113(2940):516-517. 

Gunter, G. 1953. The relationship of 

the Bonnet Carre spillway to 

oyster beds in Mississippi Sound 

and the Louisiana marsh, with a 

report on the 1950 opening. Publ. 

Inst. Mar. Sci. Univ. Texas. 

3(1): 17-71. 

Gunter, G. 1955. Mortality of oysters 

and abundance of certain associates as related to salinity. 

Ecology 36 (4) : 601-605. 

Gunter, G. 1979a. The grit principle 

and the morphology of oyster 

reefs. Proc. Natl. Shellfish. 

Assoc. 69: 1-5. 

Gunter, G. 1979b. Studies of the 

southern oyster borer, Thais 

haemastoma. Gulf Res. Rep. 6:249- 

260. 

Gunter, G., and R.A. Geyer. 1955. 

Studies of fouling organisms in 

the northwestern Gulf of Mexico. 

Publ. Inst. Mar. Sci. Univ. Tex. 

4(1): 39-67. 

Haley, L.E. 1977. Sex determination in 

the American oyster. J. Hered. 

68(2): 114-116. 

Hammen, C.S. 1969. Metabolism of the 

oyster Crassostrea virginica. Am. 

Zoo1 . 9(2): 309-318. 

Harry, H.W. 1976. Correlation of 

benthic mol lusca with substrate 

composition in 1 ower Gal veston 

Bay, Texas. Veliger 19(2):135- 

153. 

Haskin, H.H. 1964. The distribution of 

oyster larvae. Proc. of a symposium on experimental marine ecology. Univ. R.I. Grad. School 

Oceanogr. Occas. Pap. 2: 76-80. 

Haven, D.S., and R. Morales-Alamo. 

1966. Aspects of bi odeposi tion 

by oysters and other invertebrate 

f i 1 ter feeders. Limn01 . Oceanogr. 

11(4):487-498. 
Haven, D.S., and R. Morales-Alamo. 

1970. Filtration of particles 

from susoension bv the American 

oyster '~rassostrea 

Biol. Bull. (Woods 

Hayes, P.F., and R.W. Menzel. 1981. 

The reproductive cycle of early 

setting Crassostrea vi rgini ca 

(Gmel in) in the northern Gulf of 

Mexico, and its inplications for 

population recruitment. Biol. 

Bull. (Woods Hole) 160:80-88. 

Henderson, J .T. 1929. Lethal temperatures of Lame1 1 i branchiata. Can. 

Biol . 4(25): 397-411. 

Hidu, H. 1969. Gregarious setting in 

the American oyster Crassostrea 

vi r i nica Gmel i n. Chesapeake Sci . h92. 

Hidu, H. 1978. Setting of estuarine 

i nvertebrates in Delaware Bay, 

New Jersey, related to intertidal-subtidal gradients. Int. 

Rev. Gesamten Hydrobiol . 63:637- 

662. 

Hidu, H., and H.H. Haskin. 1971. 

Setting of the American oyster 

related to environmental factors 

and larval behavior. Proc. Natl. 

Shellfish. Assoc. 61:35-50. 

Hidu, H., and H.H. Haskin. 1978. 

Swimming speeds of oyster larvae 

Crassostrea virginica in different salinities and temperatures. 

Estuaries l(4): 252-255. 

Hidu, H., W.H. Roosenburg, K.G. Drobeck, A.J. McErlean, and J.A. Mihursky . 1974. Thermal tolerance 

of oyster larvae Crassostrea figinica (Gmelin), as related to 

power plant operation. Proc. 

Natl. Shel lfish. Assoc. 64:102- 

110. 

Higgins, P.J. 1980. Effects of food 

availability on the valve movements and feeding behavior of 

juveni le Crassostrea vi rgini ca 

(Gmelin). I. Valve movements and 

periodic activity. J. EXP. Mar. 

Biol . Ecol . 45: 229-244. 

Ho, M.-S, and P.L. Zubkoff. 1979. The 

effects of a Cochlodinium 

heterol abatum bloom on the 

survival and calcium uptake by 

larvae of the American oyster, 

Crassostrea vi rginica. - pages 

409-413 - in D.L. Taylor and H.H. 

Sel iger, eds. ~oxfc dinof lagel - 

late blooms. Elsevier, New York. 

Hofstetter, R.P. 1977. Trends in population levels of the American 

oyster Crassostrea vi rgi nica 

Gmelin on public reefs in 

Gal ves ton Bay, Texas. Tech. 

Series-24, PWD-Bull-3000-29. 101 

PP 

Hopkins, A.E. 1931. Factors influencing the spawning and setting of 

oysters in Galveston Bay, Tex. 

Bull. U.S. Bur. Fish. 47(3):57- 

83. 

Hopkins, S.H. 1955. Oyster setting on 

the gulf coast. Proc. Natl. 

Shel l fish. Assoc. 45: 52-55. 

Hopkins, S.H., J.G. Mackin, and R.W. 

Menzel. 1954. The annual cycle of 

reproduction, growth, and fattening in Louisiana oysters. Proc. 

Nat 1. Shel lfish . Assoc. 44:39-50. 

Ingle, R.M. 1950. Summer growth of 

the American oyster in Florida 

waters. Science 112(2908): 338- 

339. 

Ingle, R.M. 1951. Spawning and setting of oysters in re1 ati on to 

seasonal envi ronmental changes. 

Bull. Mar. Sci. Gulf Caribb. 

l(2): 111-135. 

Ingle, R.M., and C.E. Dawson, Jr. 

1952. Growth of the American 

oyster Crassostrea vir inica 

(Gmelin) in Florida watek 

Mar. Sci. Gulf Caribb. 2:393-404. 
@ Kaufman, Z.S. 1978. Dependence of the 

time of gamete 'maturation and 

spawning on the environmental 

temperatu re in Vi rai ni a ovster 

Keck, R., D. Maurer, and L. Watling. 

1973. Tidal stream development 

and its effect on the distribution of the American oyster. 

Hydrobiol ogia 42(4) : 369-379. 

Kilgen, R.H., and R.J. Dugas. 1984. 

The ecology of oyster reefs of 

the northern Gulf of Mexico: A 

cormunity profile. U.S. Fish 

Wildl. Serv. Biol. Rep. (in 

prep 

Korringa, P. 1976. Farming the cupped 

oysters of the genus Crassostrea: 

A multidisciplinary treatise. 

Elsevier, Amsterdam. 238 pp. 

Krantz, G.E., and J.F. Chamber1 in. 

1978. Blue crab predation of 

cultchless oyster spat. Proc. 

Natl . Shellfish. Assoc. 68: 38-41. 

Langefoss, C.M., and D. Maurer. 1975. 

Energy partitioning in the American oyster, Crassostrea v i r g i ni ca (Gmel in). Proc. Natl . She1 1- 

Lawrence, D.R., and G.I. Scott. 1982. 

The determination and use of 

condition index of oysters. 

Estuaries 5(1):23-27. 

Loosanoff, V.L. 1948. Gonadal develooment and soawnina of ovsters 

(c. vir inicaj in lo; salinities. 

A~at*1:705. (Abstr.) 

Loosanoff, V.L. 1953. Behavior of 

oysters in water of low salinities. Proc. Natl. Shellfish. 

Assoc. 43: 135-151. 

Loosanoff, V.L. 1965a. The American or 

eastern oyster. U.S. Fish Wildl. 

Serv. Circ. 205. 36 pp. 

Loosanoff , V .L. 1965b. Gonad development and discharge of spawn in 

oysters of Long Island Sound. 

Biol. Bull. (Woods Hole) 129(3): 

546-561. 

Loosanoff , V.L., and C .A. Nomejko. 

1946. Feeding of oysters in 

relation to tidal stages and to 

periods of liqht and darkness. 

Biol. ~~11.- (Woods Hole) 

90 (3) : 244-264. 

Loosanoff, V.L., and C.A. Nomejko. 

1949. Growth of oysters, 0. 

vi rginica, during different 

months. Biol. Bull. (Woods Hole) 

97(1):82-94. 

Loosanoff, V.L., and C .A. Nomejko. 

1951. Spawning and setting of 

the ~merican oyster, 0. vi rginica 

in relation to lunar ohase. 

Ecology 32(1) : 223-234. 

Loosanoff, V.L., and F.D. Tommers. 

1948. Effect of suspended silt 

and other substances on rate of 

feeding of oysters. Science 107: 

69-70. 

Losee, E. 1979. Relationship between 

larval and spat growth rates in 

the oyster ~rassostrea vir inica. 

Aquaculture 16(2): 123-1 re- 6 

Lund, E.J. 1957. Self-silting, survival of the oyster as a closed 

system, and reducing tendencies 

of the environment of the oyster. 

Publ. Inst. Mar. Sci. Univ. Tex. 

4(2): 313-319. 

Lutz, R.A., H. Hidu, and K.G. Drobeck. 

1970. Acute temperature increase 

as a stimulus to settinq in the 

American oyster ~rassostkea eginica. Proc. Natl. Shellfish. 

Assoc. 60:68-71. 

Lutz, R., J. Goodsell, M. Castagna, S. 

Chapman, C. Newell, H. Hidu, R. 

Mann, D. Jablonski, V. Kennedy, 

S. Siddall, R. Goldberg, H. 
Beattie, C. Falmagne, A. Chestnut 

and A. Partridge. 1982. Preliminary observations on the usefulness of hinge structures for 

identification of bivalve larvae. 

J. Shellfish Res. 2(1): 65-70. 

MacInnes, J.R., and A. Calabrese.1979. 

Combined effects of salinity, 

temperature, and copper on 

embryos and early larvae of the 

~merjcan oyster, C rassost rea 

vi rgi nica. Arch. Envi ron. Contam. 

Toxi col . 8: 553-562. 

MacKenzie, C.L., Jr. 1970. Causes of 

oyster spat mortality, conditions 

of oyster setting beds, and 

recommendations for oys t'er bed 

management. Proc. Natl. Shellfish. Assoc. 60: 59-67. 

MacKenzie, C.L., Jr. 1977. Development of an aquacultural program 

for rehabi 1 i tation of damaged 

oyster reefs in Mississippi. U.S. 

~kl. Mar. Fish. Serv. ~ar. Fish 

Rev. 39 (8): 1-3. 

MacKenzie, C.L., Jr. 1981. Biotic potential and envi ronmental resistance in the American oyster Crassostrea virginica in Long Island 

Sound. Aquaculture 22 (3) : 229-268. 

Mackin, J.G. 1961a. A method of 

estimation of mortality rates in 

oysters. Proc. Natl. Shellfish. 

Assoc. 50: 41-52. 

Mackin, 3.6. 1961b. Mortalities of 

oyster. Proc. Natl. Shellfish. 

Assoc. 50:21-40. 

Maghan, B.W. 1967. The Mississippi 

oyster industry. U.S. Fish 

Wildl. Serv. Fish. Leafl. 607. 

12 PP. 

Manzi, J.J., V.G. Burrell, and W.Z. 

Carlson. 1977. A comparison of 

growth and survival of subtidal 

Crassostrea vi rginica (Gmel in) in 

South Carolina salt marsh impoundments. Aquaculture 12: 293- 

310. 

Marshal 1. N. 1954. Factors contro

1 ing the distribution of oyster

in a neutral estuary. Ecolog

35 (30): 322-327. 

May, E.B. 1972. The effect of flood

water on oysters in Mobile Bay

Proc. Natl . She1 lfish. Assoc

62: 67-71. 

May, E.B. 1976. Shell dredging i

Alabama. Pages 378-385 A.H. 

Bouma, ed. Shell dredging and it

influence on gulf coast environ

ments. Gulf Publ. Co., Houston

Texas. 

McGraw, K.A., and G. Gunter. 1972

Observations on killing of th

Virginia oyster by the gu

oyster borer, ~hai; haemastoma

with evidence of a paralyt

secretion. Proc. Natl. ~hellfjs

Assoc. 62:95-97. 

Menzel, R.W. 1951. Early sexua

development and growth of th

American oyster in Louisian

waters. Science 113(2947):719

721. 

Menzel, R.W. 1955. Some phases of th

biology of Ostrea equestris and 

comparison with Crassostrea c

h inica (Gmelin). Publ. Inst. Marniv. Tex. 4:69-153. 

Menzel , R .W. 1968. Cytotaxonomy o

species of clams (Mercenaria) an

oysters (Crassost rea) . Sylrp 

Mollusca Mar. Biol. Assoc. Indi

1: 53-58. 

Menzel, R.W., and S.H. Hopkins. 1956

Crabs as predators of oysters i

Louisiana. Proc. Natl. Shellfish

Assoc. 46:177-184. 

Menzel , R.W., and F.E. Nicky. 1958

Studies of the distribution an

feeding habits of some oyste

predators in A1 li gator Harbor

Florida. Bull. Mar. Sci. Gu

Cari bb. 8(2): 125-145. 

2 2 
Menzel, R.W., N.C. Hulings, and R.R. 

Hathaway. 1957. Causes of 

depletion of oysters in St. 

Vincent Bay, Apalachicola Bay, 

Florida. Proc. Natl . Shel lfish. 

Assoc. 48: 66-71. 

Menzel, R.W., N.C. Hulings, and R.R. 

Hathaway. 1966. Oyster abundance 

in Apalachicola Bay, Florida, in 

relati on to biotic associations 

influenced by salinity and other 

factors. Gulf Res. Rep. 2(2):73- 

96. 

Newkirk, G.F., L.E. Haley, D.L. Waugh, 

and R. Doyle. 1977. Genetics of 

larvae and spat growth rate in 

the oyster Crassostrea vir inica. 

Mar. Biol. (Berl .) 41(1 ?- :4952. 

Ogle, J. 1979. A study of four oyster 

reefs in Mississippi. Gulf Res. 

Rep. 6: 261-265. 

Owen, H.M. 1953a. Growth and mortal - 

ity of oysters in Louisiana. 

Bull. Mar. Sci. Gulf Caribb. 

31 (1):44-54. 

Owen, H.M. 1953b. The relationship of 

high temperature and low rainfall 

to oyster production in Louisiana. Bull. Mar. Sci. Gulf Caribb. 

3(1): 34-43. 

Owen, H.M., L.L. Walters, and L.A. 

B regan. 1951. Et i 01 ogi cal 

studies on oyster mortalitv. I. 

Nemato sis ktrearum prytLirch, 

hrozoa: Porospordae) . J. 

Mar. Res. 10:82-90. 

Palmer, R.E. 1980. Behavioral and 

rhythmic aspects of filtration in 

the bay scall op, Argopecten 

i rradians concentri cus, and the 

oyster, Crassostrea vi r inica. J. 

Exp. Mar. Biol. Ecol&281. 

Parrish, F.K. 1969. Early molluscan 

development. Proceedings of the 

conference on she1 lf ish culture. 

Regional Marine Resources Council, Hauppauge, N.Y. 

Pausina, B.V. 1971. Louisiana oyster 

culture. Proc. 1st Annu. Meet. 

World Maricult. Soc. 1: 29-34. 

Pierce, M.E., and J.T. Conover. 1954. 

A study of the growth of oysters 

u nder different ecol ogi cal conditions in Great Pond. Biol. 

Bull . (Woods Hol e) 107: 318. 

(Abstr.) 

Pol lard, J .F. 1973. Experiments to 

reestablish historical oyster 

seed grounds and to control the 

southern oyster dri 11. La. 

Wildl. Fish. Comm. Tech. Bull. 6. 

82 PP 

Price, W.A. 1954. Oyster reefs of the 

Gulf of Mexico. U.S. Fish Wildl. 

Serv. Fish. Bull. 55(89): 491. 

Price, A.H., C.T. Hess, and C.W. 

Smith. 1975. Observations of 

Crassostrea virginica cultured in 

the heated effluent and discharged radionuclides of a 

nuclear power reactor. Proc. 

Natl . Shel lfish. Assoc. 66:54-68. 

Pruder, G.D. 1975. Engineering aspects 

of bivalve molluscan mariculture: 

cu 1 tu re sys tem conf i gu rat i ons . College of Marine Studies, 

University of Delaware, Newark. 

13 PP. 

Quick, J.A., Jr. 1971. Pathological 

and parasitological effects of 

elevated temperatures on the oysnary investigation: the e'ffect of 

elevated temperature on the American oyster ~rassostrea virginica 

(Gmelin). Fla. Dep. Nat. Resour. 

Prof. pap. Ser. 15. 190 pp. 

Quick, J.A., Jr., and J.G. Mackin. 

1971. Oyster parasitism by 

Labyri nthomyxa marina i n Florida. 

Fla. Dep. Nat. Resour. Mar. Res. 

Lab. Prof. Pap. Ser. 13:l-55. 
Rhoades, D.C. 1973. The influence of 

deposit-feeding benthos on water 

turbidity and nutrient recycl ing. 

Am. J. Sci. 273: 1-22. 

Ritchie, T.P., and R.W. Menzel. 1969. 

Influence of light on larval 

settlement of American oysters. 

Proc. Natl . Shellfish. Assoc. 

59: 116-120. 

Rockwood, C.E., and W.F. Mazek. 1977. 

Seasonal variations in oyster 

meat yields in Apalachicola Bay, 

Florida. Bull. Mar. Sci. 27(2): 

346-347. 

Rose, C.D. 1973. Mortality of marketsized oysters C rassostrea 

vir inica in the vicinity of a 6%- re g~ ng operation. Chesapeake 

Ruddy, G.M., S.Y. Feng, and G.S. 

Campbell. 1975. The effect of 

prolonged exposure to elevated 

temperatures on the biochemical 

constituents , gonadal development, and shell deposition of the 

American oyster, Crassostrea 

vi rgi ni ca. Comp. Bi ochem. 

Physiol. 51B(2): 157-164. 

Schlesselman, G.W. 1955. The gulf 

coast oyster industry of the 

United States. Geograph. Rev. 

45(4): 531-541. 

Seliger, H.H., J.A. Boggs, R.B. 

Rivkin, W.H. Biggley, and K.R.H. 

Aspden. 1982. The transport of 

oyster larvae in an estuary. Mar. 

Biol . (Berl .) 71(1): 57-72. 

Shaw, R., D.C. Arnold, and W.P. Stallworthy. 1970. Effects of light 

on spat settlement of the Ameri - 

can oyster, Crassostrea virgini- 

- ca. J. Fish. Res. Board Can. 

27(4): 743-748. 

Shumway, S.E. 1982. Oxygen consumption 

in oysters: an overview. Mar. 

Biol. Lett. 3:l-23. 

Soniat, T.M., and M.L. Koenig. 1982. 

The effect of ~arasi tsm by 

Perkinsus marinus on the free 

amino acid composition of 

Crassostrea vi rginica mantle 

tissue. J. Shellfish Res. 2(1): 

Stauber, L.A. 1950. The problem of 

physiological species with special reference to oysters and 

oyster drills. Ecology 31:109- 

118. 

Steinberg, P.D., and V.S. Kennedy. 

1979. Predation upon Crassostrea 

virginica (Gmelin) larvae by two 

invertebrate species common to 

Chesapeake Bay oyster bars. 

Vel i ger 22: 78-84. 

Stenzel, H.B. 1971. Oysters. Pages 

N953-N1224 in K.C. Moore, ed. 

Treatise on invertebrate paleontology. Part N, Vol. 3. Mollusca 

6. Geol. Soc. Am., Boulder, 

Colo. and University of Kansas, 

Lawrence. 

Tinsman, J .C., and D.L. Maurer. 1974. 

Effects of a thermal effluent on 

the American oyster. Pages 223- 

236 in J.W. Gibbons and R.R. 

ShariE, eds . Thermal ecology. 

Proc. Symp. held at Augusta, Ga. 

May 3-5, 1973. Natl. Tech. Inf. 

Serv. Springfield, Va., ISBN 

0-87079-014-X. 

Veal, C .D., W.H. Brown, and W.J. 

Demoran. 1972. Developments in 

off-bottom oyster culture in 

Mississippi. Am. Soc. Agric. Eng. 

Pap. 72-575. 20 pp. 

Webster, J.R., and W.N. Shaw. 1968. 

Setting and first season survival 

of the American oyster Crassostrea virginica near Oxford, 

Maryland, 1961-62. U. S. Fish 

Wildl. Serv. Spec. Sci. Rep. Fish 

No. 567. 6 pp. 
a Wells, H.W. 1961. The fauna of oyster management in Apal achi cola Bay 

beds, with special reference to past-present-future. Fla. Mar. 

the salinitv factor. Ecol. Res. Pub1 . 26: 130-140. 

Monogr. 31: 239-266. 

Yonge, C.M. 1960. Oysters. Willmer 

Whitfield, W.K., Jr., and D.S. Beau- Brothers and Haran, Ltd., 

mariage. 1977. She1 lfish Birkenhead, England. 209 pp. 
10171 .I01 -- --- ------ - 1. Racop~**l I ALC@%I~O~ No _

REPORT DOCUMENTATION 1. REPORT NO. 2. 

PAGE Biological Report 82(11.64)* 

4. TbIIa and Subtatla L n*oon DS~. Species Profiles: Life Hi stories and Environmental 

Requirements of Coastal Fishes and Invertebrates (Gulf of July 1986 

6. Mexico) -- American Oyster 

7. Autho.(%l a. hdomng Orsrn,zat,on nap

Jon G. Stanlev and Mark A. Sellers 

9. radonn~ns Oaan~ralaon Mama and Addraaa 

Maine Cooperative Fish and Wildlife Research Unit 

313 .Murray Hal 1 

ni versi ty a ne 

Orono, Maine 04469 

12 Soon%orlns Orsanlzation Mama and Addmsa 

National Wet1 ands Research Center U.S. Army Corps of Engineers 

Fish and Wildlife Service Waterways Experiment Station 

U.S. Dep. of the Interior P.O. Box 631 

Washington, DC 20240 Vicksburg, MS 39180 

I 

IS. 8uppIamantary Ndaa 

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

16 Abrrna (Umlt: tOQ words) 

Species profiles are 1 i terature summaries of the taxonomy, morphology, 1 ife 

history, and environmental requirements of coastal aquatic species. They are 

designed to assist in environmental impact assessment. The American oyster, 

Crassostrea virginica, is an important commercial species. Spawning occurs 

repeatedly during warmer months with millions of eggs released. Embryos and 

larvae are carried by currents throughout the estuaries and oceanic bays where 

they occur. The surviving larvae cement themselves to a solid object, where they 

remain for the remainder of life. Unable to move, they must tolerate changes in 

the environment that range from -2 to 36 OC (air temperature), 2 to 40 ppt 

salinity, and clear or muddy water. The density and occurrence of adults is 

limited by predators, chiefly oyster drills, whelks, fish, and crabs. 

17. Oocurrwnt Analy~s 0. Dawnotan 

Estuaries Fisheries Oxygen consumption 

Oysters Sal i ni ty Life cycles 

Growth Temperature 

Feeding Habits Suspended sediments 

I b. tdanllfian/Opan.lndad Tarrna 

American oyster Spawning 

~rassostrea vi rgi nica 

Salinity requirements 

Temperature requi rements 

L COSATI fl*ldlCmup 

--------. ---- 1L Av4,labllity Slatamant 19. Security CIS~~ (The~ Rewnl 21. No. Of pas.~ 

Unclassified 

.--- 

I Unl imi ted Release XI. SocurlW Class (Thns PSI~I I Unclassified 
TAKE 1 PRIDE 

212 Amerzcd 

DEPARTMENT OF THE INTERIOR 

U.S. FISH AND WILDLIFE SERVICE 

As the Nation's principal conservation agency. the Department of the Interior has responsibility for most of 0ur.nationally owned public lands and natural resources. This includes 

fostering the wisest use of our land and water resources, protecting our fish and wildlife, 

preserving theenvironmental and cultural values of our national parks and historical places, 

and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in 

the best interests of all our people. The Department also has a major responsibility for 

American Indian reservation communities and for people who live in island territories under 

U.S. administration.