Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 15, 1999
Publication Date: N/A
Technical Abstract: Recently, oyster (Crassostrea virginica) populations have declined significantly in the Chesapeake Bay due to disease, overfishing, and environmental stress. Since little is known about levels of agricultural chemicals within oyster tissue and of the direct or indirect effects of these residues on the survival of oysters, a method was developed to screen nsample extracts for over 60 pesticides. This method involves solvent extraction followed by clean-up on multiple solid phase extraction (SPE) cartridges and analysis by GC-MS. During 1997, oyster tissues, water, and sediment samples were collected from two Chesapeake Bay tributaries. While herbicides were dominant in water samples, the insecticides endosulfan, endosulfan sulfate, and chlorpyrifos were frequently detected in oyster tissues. In 1998, investigations focused on oyster and water tissues collected from several sites in the Choptank River and UMD Horn Point Oyster Hatchery facility, as well as 100 mussel and oyster samples from NOAA's Mussel Watch Program. The 1998 results again showed the herbicides dominating water samples, while the insecticides dominated the oyster tissue samples. In both water and oyster extracts, pesticide levels were greater at the up-stream sites than in the hatchery. Although, it appears that current pesticide levels pose no direct toxicological effects on adult oyster communities, it is possible that these chemicals could impact early developmental stages by altering the composition of the algal food supply in the river or by hindering larval metamorphosis. The information gathered by this two year study will be instrumental in developing future studies to model natural conditions and determine the effects of pesticides on oyster larvae growth and survival rates.