![]() The rapid return of oysters to pre-flood abundance levels is attributed in part to the ability of oysters in Gulf coast estuaries to spawn multiple times in a single season and in part to their relatively high growth rates. Oyster populations had generally recovered within 1 year’s time-the oysters were younger and smaller but were just as abundant as pre-flood levels. ![]() ![]() Flood events in 2007 caused temporary reductions in salinity and were associated with reductions in oyster abundance, spat settlement, disease levels (weighted prevalence and percent infection), and filtration rates. Filtration rates were calculated as a function of oyster size, temperature, salinity, and total suspended solids. Oysters were also examined quarterly for the presence of Perkinsus marinus. Oysters were sampled monthly in 20 to examine the impacts of changing environmental conditions on oyster populations. As bioindicators, oysters can be deployed for spatial interpolation of nitrogen sources, even in areas lacking extant populations.Ī 2-year period with flood versus drought conditions provided the opportunity to examine the effects of flood disturbance on subtidal eastern oyster Crassostrea virginica biology and population dynamics in a south Texas estuary. This study (1) determined that five individuals represented an optimal sample size (2) verified that δ15N in oysters from two locations converged after shared deployment to a new location reflecting a change in nitrogen sources (3) identified required exposure time and temporal integration (four months for muscle, two to three months for gill and mantle) and (4) demonstrated seasonal δ15N increases in seston (summer) and oysters (winter). To assess nitrogen isotopic fractionation associated with assimilation and baseline variations in oyster mantle, gill, and muscle tissue δ15N, manipulative fieldwork in Chesapeake Bay and corresponding modeling exercises were conducted. Stable nitrogen isotopes (δ15N) in bioindicators are increasingly employed to identify nitrogen sources in many ecosystems and biological characteristics of the eastern oyster (Crassostrea virginica) make it an appropriate species for this purpose. ![]()
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