Bioaccumulation of polychlorinated biphenyls and organochlorine pesticides in young-of-the-year bluefish (Pomatomus saltatrix) in the vicinity of a Superfund Site in New Bedford Harbor, Massachusetts, and in the adjacent waters

Abstract

Spatial gradients of polychlorinated biphenyls (PCBs) and organochlorine pesticides were examined in the young-of-the-year (YOY) bluefish (Pomatomus saltatrix) in the vicinity of a PCB Superfund Site in New Bedford Harbor, Massachusetts, and in the adjacent waters. PCB concentrations in bluefish varied between different locations, and also among fish from a given location. A generally decreasing gradient in PCB concentrations was evident as the bluefish were collected away from the Superfund Site. The average sum of PCB concentrations were highest for bluefish collected in the Upper Harbor between Interstate-195 Bridge and Coggeshall Street Bridge (Upper Harbor), followed by bluefish in Lower Harbor from north of Popes Island Bridge (Lower Harbor), and bluefish from Outer Harbor south of Hurricane Barrier (Outer Harbor). The levels of PCBs in bluefish from Clarks Cove and PCBs in bluefish from Buzzards Bay were similar and lowest among all bluefish specimens analyzed in the present study. Pesticide concentrations were about one order of magnitude or lower than the PCB concentrations, and the gradient of pesticide concentrations generally followed the gradient of PCB concentrations. Some of the commonly detected pesticides in the order of decreasing concentrations included DDTs and metabolites, heptachlor epoxide, endosulfan sulfate, and α-chlordane. Distribution of PCBs and organochlorine pesticides were examined in the tissues of YOY bluefish from Clarks Cove. PCBs and lipids in the brain samples of YOY bluefish were generally numerically greater than PCBs in the liver samples, but these differences were not statistically significant. PCBs and lipids in hypaxial muscle samples were numerically greater than PCBs in epaxial muscle samples, although these two groups of tissues were not statistically different. Despite the higher susceptibility of lighter PCB homologs to geophysical and biogeochemical weathering processes, the relative dominance of lighter homologs in the Upper Harbor and Lower Harbor samples suggested ongoing or recent sources of these lighter PCBs, particularly Aroclor 1242 and Aroclor 1016 in this area. The presence of heavier homologs in the Upper Harbor and Lower Harbor bluefish samples could be attributed to Aroclor 1252 and Aroclor 1254 that were being used in relatively smaller quantities in the manufacture of electrical components in addition to Aroclor 1242 and Aroclor 1016. The concentration of heavier PCB homologs appears to increase in YOY bluefish the further away from the PCB Superfund Site in the Acushnet Estuary the samples were collected. Principal component analyses of PCB 153 normalized concentrations of the individual PCB congeners resulted in two general groupings; a relatively tight group comprised of YOY bluefish from Upper Harbor, Lower Harbor, and Outer Harbor, and a rather loose and more dispersed group comprised of Buzzards Bay bluefish and the tissue samples of bluefish from Clarks Cove. Principal component analyses of major pesticides suggested close groupings of bluefish from Clarks Cove and bluefish from Buzzards Bay. Pesticides in bluefish from Upper Harbor, Lower Harbor, and Outer Harbor formed a loose group, with some bluefish from these locations populating close to Clarks Cove and Buzzards Bay bluefish. Although PCBs have been implicated in various behavioral and health effects in the experimental and field studies, the deleterious effects of chronic exposure to high concentrations of PCBs and the potential for recruitment of New Bedford Harbor YOY bluefish population to the adult stock remains obscure. Adaptive or evolutionary resistance to contaminants have been documented in resident species in some highly contaminated estuaries, however similar responses have not been investigated in the migratory species like bluefish. The results of the present study provide a reference baseline for YOY bluefish for "before-and-after" comparative studies and other toxicological studies for the New Bedford Harbor Superfund Site that is currently being remediated.