Atlantic tomcods (a type of cod fish) from the Hudson River have some of the highest levels of toxic pollutants like PCBs (polychlorinated biphenyls), PCDDs (polychlorinated dibenzo-p-dioxins), and PCDFs (polychlorinated dibenzo-p-furans) in their livers among the fishes in nature. The Hudson River has several sources of pollution, including accidental sewage discharges and urban runoff. Perhaps more importantly, the General Electric facilities dumped anywhere between 209,000 and 1,300,000 pounds of PCBs into the river from 1947 to 1976.
Outside of having elevated pollutant accumulation in their bodies, Atlantic tomcods from the Hudson River show a 100-fold reduction in sensitivity to pollutants. That is, they produce less detoxification enzyme, P4501A, when they are exposed to PCBs and PCDDs. Their reduced response to pollutants even carries onto their direct offspring. Thus, this trait is possibly heritable, meaning that some sort of evolutionary change could have occurred in the fish population. Isaac Wirgin at the New York University School of Medicine led an investigation into the mechanism behind this adaptation. His findings appear in a recent issue of Science.
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