Molluscan Ecology Program
 
 
 
 

Oyster (Crassostrea virginica) research

 
     
 

Oyster population dynamics

Oyster size-age relationships, survivorship, recruitment, fecundity, and metapopulation dynamics in relation to geographic location and local environmental conditions continue to be examined in a variety of projects being conducted in several Chesapeake Bay tributaries. Many of the extant oyster populations in the James River have been and continue to be the focus of this research.

Carolyn Cox examined seasonal changes in the fecundity of oysters from four oyster reefs in the James River, Virginia as part of her VIMS/SMS M.A. thesis. Adult Crassostrea virginica were examined during the reproductive season of 1986 to determine temporal and spatial variation in fecundity among individual female oysters from four reefs in the James River, Virginia. Sex ratio and oyster abundance were also determined to facilitate estimation of total reproductive output of oyster assemblages. Fecundity was highly variable, both within and among locations. Variation was attributed to differences in oyster size, asynchrony and variation in time since prior spawning, prevalence of parasites (especially Haplosporidium nelsoni (MSX) and Perkinsus marinus) and differing salinity regimes.

Curtis Roegner investigated the survival and growth of newly settled oysters in relation to tidal zonation during the first month of post-settlement life as part of his VIMS/SMS M.A. thesis.

Research sponsors and partners for these projects include:

Related publications include:

Larval oyster biology, growth, and survival

Oyster larvae are planktonic for approximately 21 days before they settle to the bottom and begin life as sessile, benthic invertebrates. The objectives of this research are to describe and quanitfy factors that enhance larval success as well as the ranges of larval physiological tolerances in relation to field and laboratory conditions. These projects have and continue to contribute data that is applied toward management of the Commonwealth's oyster resource.

Shirley Baker examined the effects of low oxygen concentrations on settlement, metamorphosis, and feeding behavior during settlement by oyster larvae as part of her VIMS/SMS doctoral dissertation.

Patrick Baker investigated the settlement behavior of bivalve molluscs using oyster larvae as a model system. His VIMS/SMS dissertation studies were designed to specifically examine a) abundance of late-stage larvae in the plankton, b) the relationship between larval abundance and settlement, and c) mortality immediately following settlement.

Sandra Brooke completed a comparison of natural and laboratory diets for the culture of oyster larvae as well as queen and milk conch, two tropical gastropod species for her VIMS/SMS M.A. thesis project.

Bernadita Campos examined the swimming behavior of three different species of bivalve veligers including oyster larvae in relation to salinity gradients as part of her VIMS/SMS M.A. thesis work.

Laura Castell used the fluorescent dye Nile Red and fluorescence microscopy to quantify lipid content of healthy and stressed individual oyster larvae Crassostrea virginica as part of her VIMS/SMS M.A. thesis project.

David Eggleston described the predator-prey dynamics between the blue crab and juvenile oysters as part of his VIMS/SMS M.A. thesis work.

Kevin McCarthy's VIMS/SMS M.A. thesis examined the vertical distribution of oyster larvae in relation to salinity layers since larval Crassostrea virginica may be retained within estuaries by active depth regulation.

Richard Rheinhardt investigated the development of fouling communities on oyster populations in the James River and evaluated temporal changes in community structure with respect to substrate availability in cultch.

Curtis Roegner investigated the survival and growth of newly settled oysters in relation to tidal zonation during the first month of post-settlement life as part of his VIMS/SMS M.A. thesis.

Research sponsors and partners for these projects include:

Related pubications include:

Oyster settlement and recruitment in relation to reef morphology

Palace Bar Reef, Piankatank River, Virginia was the primary study site for this research. Palace Bar Reef was built in 1993 by the Virginia Marine Resources Commission Shellfish Replenishment Program. This intertidal reef was constructed as a complex of 18 different shell mounds centered along an east-west axis.

This project's objective was to document oyster settlement and recruitment to the clean, planted shells across seasonal and spatial gradients during the first two years post-reef construction.

Ian Bartol examined oyster recruitment patterns in relation to spatial and temporal variables as part of his VIMS/SMS M.A. thesis project.

Research sponsors and partners for this project include:

Related publications include:

Effects of broodstock sanctuaries on restoration success

Shell Bar Reef, Great Wicomico River, Virginia was the primary study site for this research. Shell Bar Reef was built in December 1996 by the Viriginia Marine Resources Commission Oyster Replenishment Program. The reef is an intertidal reef adjacent to natural and artificial shell plants. The reef was made exclusively of oyster shell and live oysters. Shell was dumped from barges to form intertidal and subtidal mounds. Live, disease-resistant broodstock oysters were dredged from Tangier Sound and were placed on the reef. "Broodstock" oysters are large, older oysters who are sexually mature and have high fecundity because of their age and size. It is hoped that these older oysters will stay resistant to diseases like "Dermo" and MSX and will continue to show high fecundity.

This project's objective is to evaluate the use of broodstock sanctuaries in oyster replenishment and restoration efforts. To that end, we are:

  • Monitoring spat settlement, veliger abundance and distribution, disease incidence, and oyster mortality on and adjacent to the reef
  • Describing water circulation patterns within the immediate vicinity of the reef to determine a "sphere of influence" for the reef
  • Quantifying broodstock population fecundity and gonad development
  • Continuing our historic monitoring efforts in the Great Wicomico River to enable the data from our current studies to be placed in proper perspective

Eight intensive sampling stations were conducted in the Great Wicomico River from June through September 1997. All studies were conducted to provide information on seasonal, diurnal, tidal, and spatial scales. Melissa Southworth analyzed the recruitment, fecundity, and physical data as part of her VIMS/SMS M.S. thesis project.

Research sponsors and partners for this project include:

Related publications include:

 
 
 
 
Document last modified 09.08.2010
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