Polychlorinated biphenyls and toxaphene in preferred prey fish of coastal southeastern U.S. bottlenose dolphins (Tursiops truncatus).

Legacy organochlorine (OC) contaminants continue to pose a potential risk to ecological and human health in coastal aquatic ecosystems of the southeastern United States. Polychlorinated biphenyls (PCBs) and toxaphene (TOX) were analyzed by gas chromatography with electron capture detection and negative chemical ionization mass spectrometry in 77 composites of four inshore fish species commonly preyed upon by bottlenose dolphins (Tursiops truncatus) from estuaries near Savannah, Georgia (SAV), Brunswick, Georgia (BRN), and Jacksonville, Florida (JAX), USA. Whereas seasonal and species-specific differences were minimal, differences among mean total PCB concentrations (sigmaPCBs) by estuary (42.0 +/- 48.3, 1.59 +/- 1.24, and 0.281 +/- 0.075 microg/g lipid for BRN, JAX, and SAV, respectively) were highly significant. This estuary-specific trend also held true for mean total toxaphene concentrations (sigmaTOX): 49 +/- 100 (BRN), 1.2 +/- 0.52 (JAX), and 0.40 +/- 0.19 microg/g lipid (SAV). Congener profiles of PCBs also were found to be significantly different among estuaries, with BRN and (to a lesser extent) JAX samples enriched with highly chlorinated homologs associated with Aroclor 1268, a legacy OC linked to a historical point source in Brunswick. The observed spatial heterogeneity in OC concentrations and PCB congener profiles suggests that contaminated fish from Brunswick pose the greatest risk to ecological and human health via biomagnification and seafood consumption; highly chlorinated PCBs (and possibly toxaphene) are transported in a southerly, alongshore direction; and the uniqueness of Aroclor 1268 underscores its utility as a signature proxy in future regional ecotoxicological studies.