RESIDUES OF ORGANOCHLORINES IN MALLARDS AND BLUE-WINGED TEAL COLLECTED IN COLOMBIA AND WISCONSIN, 1984-1989

We compared the seasonal concentrations of 12 organochlorine (OC) comp ounds in samples of breast muscle, associated skin, and subcutaneous f at of blue-winged teal (Anas discors) collected in Cienaga Grande de S anta Marta, Colombia (1987-1988), and of mallards (Anas platyrhynchos) and blue-winged teal collected in Wisconsin (1984-1989). Although the se species have similar feeding habits and overlapping breeding distri butions, their winter ranges differ markedly. Most blue-winged teal wi nter in the Neotropics, whereas most mallards remain in the temperate regions of North America. A seasonal comparison of OC exposure in thes e species may help determine the geographic origins of contamination. All examined OCs were found to be below concentrations known to affect reproduction in waterfowl. DDE was most often detected in blue-winged teal and PCBs, in mallards. DDE exposure may have predominantly occur red outside of Wisconsin. The DDE concentration in blue-winged teal sa mples collected in Wisconsin in the spring (GM = 0.406 mu g/g) were gr eater (P < 0.001) than in the fall (GM = 0.033 mu g/g) and greater tha n the concentrations in mallard samples from the spring (GM = 0.058 mu g/g; P(0.001). Cienaga Grande, however, was not a source of DDE conta mination. The DDE concentrations in blue-winged teal samples from Cien aga Grande did not differ between the spring (GM = 0.037 mu g/g) and t he fall (CM = 0.039 mu g/g) and were lower (P < 0.001) than the concen tration in blue-winged teal samples from Wisconsin in the spring. In c ontrast, PCB contamination seemed to have occurred in Wisconsin and af fected mostly mallards. PCBs were not detected in the samples from Col ombia and were detected in only five (8.3%) of the blue-winged teal sa mples from Wisconsin (GM = 0.025 mu g/g), however, those compounds wer e detected in 47% of the mallard samples collected in Wisconsin (GM = 0.272 mu g/g). DDE and PCB concentrations were greater (P = 0.0) in ma llard samples collected from wetlands adjacent to Lake Michigan than i n samples from inland wetlands.