Oyster Reef Habitats
     

Oyster reefs, often referred to as oyster bars, are common submerged habitats in the southern United States. Oyster reefs in Florida are found in nearshore areas and estuaries of both coasts, but grow especially vigorously near estuarine river mouths where waters are brackish and less than 10 meters deep. For example, the Apalachicola River in northern Florida is a particularly productive area for oysters, and supplies over 90% of the state’s annual oyster catch. Within the Indian River Lagoon, oyster reefs may be found in the vicinity of spoil islands and impounded areas. In addition to being commercially valuable, oyster reefs serve a number of important ecological roles in coastal systems: providing important habitat for a large number of species; improving water quality; stabilizing bottom areas, and influencing water circulation patterns within estuaries.

Oyster reefs are built primarily by the eastern oyster, Crassostrea virginica, through successive reproduction and settlement of larvae onto existing reef structure. Oysters in Florida spawn from late spring through the fall. The planktonic larvae that develop require a hard substratum to settle upon in order to complete development to the juvenile stage, and prefer to settle on the shells of other oysters. Thus, over time, continued settlement and subsequent growth of generations of oysters may form massive reef structures consisting of staggering numbers of individuals. Luntz (1960), estimated that 5,895 oysters, the equivalent of 45 bushels, occurred within a single square yard of oyster reef.

As successive generations of oysters settle and grow, reefs become highly complex, with many structural irregularities and infoldings that provide a wealth of microhabitats for many different species of animals. Wells (1961) listed 303 different species utilizing oyster reef as habitat in North Carolina. Common Indian River Lagoon species associated with oyster reefs include bivalves such as the hard clam (Mercenaria mercenaria) and bay scallop (Argopecten irradians concentricus); space competitors such as the scorched mussel (Brachidontes exustus), ribbed mussel (Geukensia demissa), the jingle shell (Anomia simplex), and barnacles of the Balanus genus; gastropod mollusks such as the conchs (Melongena spp. and Strombas spp.) and rocksnails (Thais spp.); numerous sponge species; flatworms; polychaete worms; amphipods; isopods; shrimp; and fishes such as blennies, gobies, spadefish, snappers, drum, and seatrout, among others.

Beyond providing smaller organisms with habitat, oyster reefs also provide food to a wide variety of secondary consumers. Many species of fish prey upon oyster reef associates; while others such as the black drum (Pogonias cromis) and cow-nosed ray (Rhinoptera bonasus) prey upon oysters themselves. Other species that utilize oyster reefs for foraging and feeding include the xanthid crabs, also known as mud crabs; swimming crabs of the genus Callinectes; mollusks such as the thick lipped oyster drill (Eupleura caudata), the sharp-rib drill (E. sulcidentata), the Atlantic oyster drill (Urosalpinx cinerea), the Tampa drill (U. tampaensis), the knobbed whelk (Busycon carica), the lighthire whelk (B. contrarium), and the pear whelk (B. spiratum pyruloides); flatworms such as oyster leeches (Stylochus spp.); boring sponges (Cliona spp.); and annelid worms (Polydora spp.).

Oyster reefs also contribute to improved water quality in areas where they occur. Oysters are filter feeders which strain microalgae, suspended particulate organic matter, and possibly dissolved organic matter from the water column over their gills in order to feed. Under optimal temperature and salinity conditions, a single oyster may filter as much as 15 liters of water per hour, up to 1500 times its body volume. Spread over an entire reef, for an entire day, the potential for oysters to improve water clarity is immense. Additionally, since oysters are sessile, and bioaccumulate some potential toxins and pollutants found in the water column, they have been used to assess the environmental health of some areas.

Over-harvesting, as well as persistent diseases such as MSX and Dermo have taken a devastating toll on many oyster populations along the east and Gulf coasts. In recent years, oyster reef restoration has been a concern for resource managers all along the East Coast of the United States, but especially in areas where oyster harvesting has historically been commercially important. In the late 1800s, for example, annual oyster harvests in the southeastern United States routinely topped 10 million pounds per year, and peaked in 1908 when the harvest was nearly 20 million pounds. However, annual harvests since that time have declined steadily. Today, annual harvests for oysters in the southeast averages approximately 3 million pounds per year. In many areas, efforts are underway to revitalize depleted oyster reefs and encourage growth of new reefs. For example, the Florida Department of Agriculture has stockpiled calico scallop shells from processors and placed these on depleted oyster reefs from the spring through the fall spawning periods, when larvae are most abundant in the water column. Oyster larvae, having a preference for settling on shell material, then attach themselves onto the newly placed shells and metamorphose to the juvenile stage. These young oysters, under optimal conditions, will grow to marketable size in as little as 18 – 24 months.

[A more detailed look at some emerging human-induced threats facing the oyster reefs of the IRL is available here.]

Click a highlighted link to read more about individual species:

Species Name:

Common name:

Comments:

Invertebrates:

   

Amygdalum papyrium

Atlantic papermussel

 

Anadara transversa

transverse ark

 

Anomia simplex

jingle shell

 

Argopecten irradians concentricus

bay scallop

 

Astyris lunata

lunar dovesnail

 

Balanus spp.

barnacles

 

Bittiolum varium

grass cerith

 

Boonea impressa

impressed odostome

 

Boonea seminuda

half-smooth odostome

 

Brachidontes exustus

scorched mussel

 

Busycon carica

knobbed whelk

 

Busycon contrarium

lightning whelk

 

Busycon spiratum pyruloides

none

 

Busycon spp.

whelks

 

Caecum pulchellum

beautiful caecum

 

Callinectes ornatus

ornate blue crab

 

Callinectes sapidus

blue crab

 

Callinectes similis

lesser blue crab

 

Cerithiopsis greenii

none

 

Cliona spp.

boring sponges

 

Costoanachis avara

greedy dovesnail

 

Crassostrea virginica

eastern oyster

 

Crepidula aculeata

spiny slippersnail

 

Crepidula convexa

convex slippersnail

 

Crepidula plana

eastern white slippersnail

 

Diodora cayenensis

cayenne keyhole limpet

 

Dyspanopeus_sayii

Say’s mud crab

 

Dyspanopeus spp.

mud crabs

 

Epitomapta roseola

none  

Eupleura caudata

thick lipped oyster drill

 

Eupleura sulcidentata

sharp-rib drill

 

Eurypanopeus depressus

depressed mud crab

 

Eurypanopeus spp.

mud crabs

 

Geukensia demissa

ribbed mussel

 

Hemipholis elongata

none

 

Hexapanopeus angustifrons

narrow mud crab

 

Hexapanopeus spp.

mud crabs

 

Ischadium recurvum

hooked mussel

 

Isognomon alatus

flat tree oyster

 

Lithophaga bisulcata

mahogany datemussel

 

Luidia clathrata

gray sea star

 

Luidia senegalenis

nine-armed sea star

 

Melongena corona

crown conch

 

Melongena sprucecreekensis

none

 

Menippe mercenaria

stone crab

 

Mercenaria mercenaria

hard clam

 

Mulinia lateralis

dwarf surfclam

 

Musculus lateralis

lateral mussel

 

Mytilopsis leucophaeata

dark falsemussel

 

Nereis spp.

clamworms

 

Ophiactis savignyi

savigny’s brittlestar

 

Ophiothrix angulata

angular brittlestar

 

Oreaster reticulatus

cushion star

 

Ostreola equestris

crested oyster

 

Panopeus herbstii

common mud crab

 

Panopeus lacustris

knotfingered mud crab

 

Panopeus spp.

mud crabs

 

Parastarte triquetra

brown gemclam

 

Pinnotheres maculatus

mussel peacrab

 

Pinnotheres ostreum

oyster peacrab

 

Polydora ligni

Polydora mudworm

 

Polydora spp.

blisterworms

 

Pyrgocythara plicosa

plicate mangelia

 

Rupellaria typica

Atlantic rupellar

 

Seila adamsi

none

 

Siphonaria pectinata

striped false limpet

 

Sphenia antillensis

Antillean sphenia

 

Spurilla neapolitana

neopolitan spurilla

 

Strombas gigas

queen conch

 

Stylochus spp.

oyster leech

 

Thais spp.

rocksnails

 

Triphora nigrocincta

black-line triphora

 

Truncatella pulchella

beautiful trucatella

 

Urosalpinx cinerea

Atlantic oyster drill

 

Urosalpinx tampaensis

Tampa drill

 

Vitrinella floridana

Florida vitrinella

 

Vertebrates:

Abudefduf saxatilis

sergeant major

 

Chaetodipterus faber

spadefish

 

Cynoscion nebulosus

spotted seatrout

 

Cynoscion nothus

silver seatrout

 

Eucinostomus argentus

spotfin mojarra

 

Eucinostomus gula

silver jenny

 

Eucinostomus havana

bigeye mojarra

 

Eucinostomus jonesii

slender mojarra

 

Eucinostomus lefroyi

mottled mojarra

 

Eucinostomus melanopterus

flagfin mojarra

 

Lutjanus analis

mutton snapper

 

Lutjanus apodus

schoolmaster

 

Lutjanus cyanopterus

cubera snapper

 

Lutjanus griseus

gray (mangrove) snapper

 

Lutjanus jocu

dog snapper

 

Lutjanus mahogani

mahogany snapper

 

Lutjanus synagris

lane snapper

 

Mugil cephalus

striped mullet

 

Mugil curema

white mullet

 

Mugil curvidens

none

 

Mugil gaimardianus

redeye mullet

 

Mugil gyrans

fantail mullet

 

Mugil liza

liza

 

Opsanus tao

oyster toadfish

 

Pogonias cromis

black drum

 

Rhinoptera bonasus

cownosed ray

 


Further Reading:  

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 and Wildlife Service, Blot.
     Program, Washington D.C. FWS/OBS 81/15. 105 pp.

Burrell, V.G. 1986. Species Profiles: Life Histories and Environmental Requirements
     of Coastal
Fishes and Invertebrates (South Atlantic): American Oyster. U.S. Fish
     and Wildlife Service.  Biological Report 82(11.57). U.S. Army Corps of
     Engineers. TR EL-82-4. 17 pp.

Kumari, Siva, and C. Solis. 1995. The State of the Bay: a Characterization of the
     Galveston Bay Ecosystem. Rice university, Houston, TX. Accessed on-line at:
     www.rice.edu/armadillo/Galveston/Chap3/oyster.html.

Livingston, Robert J. 1990. Inshore Marine Habitats. In: Ecosystems of Florida,  
     Ronald L. Myers and John J. Ewel, Eds. University of Central Florida Press,
     Orlando, FL. Pp. 549-573.

Lunz, G.R., Jr. 1960. Intertidal Oysters. Wards Natl. Sci. Bull. 34(1): 3-7

Wells, H.W. 1961. The Fauna of Oyster Beds with Special Reference to the Salinity
     Factor. Ecological Monographs 31(3): 239-266.

 

Report by:  K. Hill, Smithsonian Marine Station
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Page last updated: June 23,  2002