Meeting Abstract
Harp seals (Pagophilus groenlandicus) live in the extremely cold Arctic and rely on thick insulation to maintain thermal homeostasis. Adult harp seals primarily use blubber for insulation, but newborn harp seals rely on a fur coat as their blubber layer develops. This study examined ontogenetic changes in the thermal properties of harp seal fur during submergence. Thermal conductivity, fur thickness, and thermal resistance were measured in water for pelts of harp seal neonates (1d, n=6), thin whitecoat pups (4d, n=3), fat whitecoat pups (9d, n=4), molting pups (2w, n=4), molted pups (3w, n=5), and adults (n=4) and compared to previous measurements made in air. Using these data, we constructed a mathematical model to estimate whole-body conductive heat loss through both the blubber and the pelt. The model simulated a cylindrical body core placed within a cylindrical layer of blubber, inside a cylindrical layer of pelt (skin and fur). Based on the model output, larger animals lose more heat than smaller animals in air (P<0.0001), but there was not a significant correlation between mass and heat loss in water (P=0.085). When considering heat loss per unit volume, older animals lost significantly less heat than younger animals in both air and water (P<0.0001). In addition, heat loss per unit volume was significantly higher in neonate and thin whitecoat pelts in water than in air (P<0.0014). Overall, fur function is greatly reduced in water for whitecoats, and this renders neonates and thin whitecoats more vulnerable to extreme heat loss when submerged.
