Meeting Abstract
Ice-dependent Arctic seals, including bearded (Erignathus barbatus), ringed (Pusa hispida), and spotted (Phoca largha) seals, are uniquely affected by sea ice loss. These species use sea ice as a substrate for various critical functions, including rest, giving birth, nursing, predator avoidance, and foraging. They also rely on sea ice during the annual molt, when they shed several layers of epidermis and fur and grow a new coat. To facilitate this process, seals haul out for extended periods, increase blood flow to the skin, and maintain elevated skin temperatures. Molting is assumed to have a significant metabolic cost, which would increase if appropriate haul-out substrate were unavailable; however, molting costs have only been quantified for a few species. Working with trained seals, we tracked changes in coat condition and seasonal energetic demands to identify key periods when the loss of sea ice may have the greatest impact. We documented the timing, progression, and duration of the visible molt for bearded (n=2), ringed (n=3), and spotted (n=4) seals. In addition, we used open-flow respirometry to track fine-scale changes in the resting metabolic rate (RMR) of six seals for a minimum of one year. We observed clear patterns in seasonal costs that related to the distinct molting strategies of each species. For species that molted over a short interval (spotted: 36±4.6 days, ringed: 29±2.5 days), RMR increased on average 26-47% across the molting period. In contrast, molting over a longer interval (bearded: 107±14.8 days) appeared to limit the cost of molting as indicated by a stable annual RMR. This study highlights the relationship between molting strategy and seasonal energetic requirements and provides quantitative data that can be used to assess species-specific vulnerabilities to changing conditions.
