The effects of the MEGA BORG spill on Gulf of Mexico shrimp

A brown shrimp stock model was developed at the NMFS Galveston Laboratory to assess the effects of the Mega Borg oil spill on the brown shrimp population along the Texas coast. Water and sediment samples from near the Mega Borg spill area were collected and analyzed by the Geochemical and Environmental Research Group at Texas A and M University. Hydrocarbon concentrations found at the sediment collection stations ranged from 1.38 mu g/g to 7.42 mu g/g, while concentrations at the water column sampling sites ranged from 0.69 mu g/1 to 27.39 mu g/l. Evaluation of chromatograms and analytical data suggested that sediments from the area contained primarily biogenic hydrocarbons. Only one station had elevated hydrocarbon levels. However, these values were only three to five times higher than the concentrations measured at the other stations. Evaluation of the water samples from the area showed only very low concentration levels of hydrocarbons were present in the water column. A bioassay study was conducted by the U.S. Environmental Protection Agency, Environmental Research Laboratory in Gulf Breeze, Florida. The main conclusion from the bioassay study was that the concentrations of hydrocarbons measured at the field sites where water samples were taken tended to be three orders of magnitude lower than the hydrocarbon concentrations causing toxic responses (both acute and chronic) in mysid and white shrimp. There were no detected effects to the brown shrimp population along the Texas coast from the Mega Borg oil spill. (DBO)