Levels of persistent organic pollutants in eastern north Atlantic humpback whales

Abstract

Blubber lipid concentrations of 14 organochlorine compounds and 10 polychlorinated biphenyls (PCB) were measured by gas chromatography with electron-capture detection in eastern North Atlantic humpback whales Megaptera novaeangliae from Cape Verde (n = 20) and Ireland (n = 4). Concentrations were statistically compared to those from 20 samples collected from the Gulf of Maine in the western North Atlantic. Pollutant burdens were compared using males only, in order to circumvent biases associated with reproductive offloading. Lipid-normalised PCB concentrations were below the estimated threshold toxicity value of 17 000 ng g−1 for blubber in marine mammals. Dichlorodiphenyltrichloroethane (DDT), PCB and chlordane concentrations were an order of magnitude lower than those previously reported for Gulf of Maine humpback whales and higher than those reported from the North Pacific Ocean. Higher concentrations of lower-chlorinated PCB congeners (28, 31 and 52), hexachlorocyclohexanes and hexachlorobenzene in males in eastern North Atlantic sites is consistent with higher latitude feeding grounds. Lower p,p’-DDE (dich loro di phe nyl-dichloroethane):ΣDDT ratios suggest that whales from the eastern North Atlantic harbour more recent inputs of DDT. The ΣDDTs:ΣPCBs ratio was higher for males from Cape Verde (1.69) and Ireland (1.44), indicating proportionately greater sources of agricultural rather than industrial sources of pollutants than for the Gulf of Maine whales (0.75). We demonstrate potential for persistent organochlorine pollutants (POPs) as tracers to determine foraging ground provenance for samples collected on breeding grounds in the North Atlantic. Low concentrations suggest that POPs are unlikely to be a factor in the poor recovery rate of humpback whales in Cape Verde.