Space-use strategy is an important determinant of PCB concentrations in female polar bears in the Barents Sea

Space-use was examined in 54 female polar bears (Ursus maritimus) from Svalbard and the Barents Sea that were collared with satellite transmitters to provide information on their spatial positions and annual home range sizes. Plasma samples from the same animals were analyzed for concentrations of six relevant PCB congeners (PCB-99, -153, -156, -180, -194, and -118). Factors related to space-use strategy (such as home range size; annual, spring, and winter longitudinal position; and spring and summer latitudinal position) were important determinants of PCB concentrations in plasma. In addition, reproductive status of the polar bears and plasma lipid content affected PCB concentrations. Among the tested variables, annual home range size was the variable that affected sigmaPCB5 (sum of PCB-99, -153, -156, -180, and -194) to the largest degree (r2 = 0.22). We propose that the positive effect of home range size on sigmaPCB5 in female polar bears is related to the higher energetic costs required to occupy large home range sizes as compared to small home range sizes. Polar bears with large home range sizes would need to consume more prey than bears with small home range sizes, and increased feeding without a change in elimination of persistent compounds can explain their higher sigmaPCB5 concentrations. Polar bears with large home range sizes were also more pelagic, inhabiting areas further east, closer to the ice-edge zone than animals with small home range sizes. Thus, prey choice associated with a pelagic space-use strategy may also explain the higher sigmaPCB5 in polar bears with large home range sizes.