Abstract
The eastern oyster (Crassostrea virginica) and northern quahog (= hard clam, Mercenaria mercenaria) are two species of economic and ecological significance in coastal areas. Both species because they are filter feeders can have profound effects of water quality. Commercial industries for these species, especially within the state of Florida, are relatively large. Crassostrea virginica is also a keystone species in marine ecosystems because oyster reefs provide habitat for numerous marine organisms. The purpose of this experiment is to build upon the already established body of knowledge surrounding effects of Karenia brevis on species of shellfish and to provide an understanding of the kinetics of brevetoxins within shellfish tissue and give an indication of just how long brevetoxins remain in these organisms after a bloom event. Individuals were exposed to Karenia brevis at a concentration of Sx 105 cells-L-1 for eight days. After exposure samples were transferred into clean water for depuration. Individuals were sampled periodically to determine the rate of depuration. Brevetoxin tissue concentrations were determined using an Enzyme Linked Immunosorbent Assay (ELISA). After five days of exposure both species reached brevetoxin tissue concentrations well above safe limits. Clams averaged tissue concentrations of 1,000 ng g1 while the oysters averaged 1,986 ng g-1. After two weeks of depuration both species yielded tissue concentrations that were below safe limits with clams averaging 204.8 ng g-1 and oysters averaging 437.01 ng g-1. Low levels were present in on both species for the duration of the experiment.