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Physiology and Health of Cooperating Arctic Seals (PHOCAS)
April, 24th 2017
There is no region on Earth changing more rapidly in response to climate warming and increasing human impacts than the Arctic. Intense shifts in environmental conditions threaten the overall health and stability of Arctic and sub-Arctic ecosystems, and inevitably, certain species will be disproportionately affected by such changes. Indeed, predicted changes may be too severe and rapid for long-lived, highlyderived taxa such as marine mammals to effectively respond. Current threats to Arctic marine mammals include significant sea-ice habitat losses, changes in the distribution and abundance of prey, climateinduced stressors to body condition and health, and increased anthropogenic disturbance. Unfortunately, we lack sufficient physiological data to make robust and meaningful predictions about the ability of many marine mammal species to respond or adapt to changing conditions. Studies examining species-specific physiological abilities and limitations are urgently needed.
Seals are important high trophic-level predators within Arctic and sub-Arctic ecosystems, and are predicted to be particularly affected by sea ice loss. In addition to using sea ice as a substrate for rest during much of the year, these marine mammals rely on sea ice during a number of critical life-history stages. Bearded seals use pack ice, particularly in regions over shallow areas, as a platform for pupping and molting. Ringed seals maintain breathing holes and excavate subnivean lairs within fast ice over much of the year, hauling out onto exposed sea ice for extended periods only during the spring molt. Spotted seals spend much of the year near edges of pack ice in the Bering and Chukchi Seas. Ultimately, the extent and severity of the consequences stemming from widespread sea ice loss will be dependent on the physiological and behavioral flexibility of each species. Shifts in seasonal sea ice conditions combined with changes in food web-dynamics as a result of climate change may force seals to dive deeper/longer, increase overall foraging effort, and/or travel greater distances to obtain food. Thus, studies describing physiological thresholds, diving capacities, and foraging limitations can improve predictions regarding the vulnerability or resiliency of each species to rapid environmental change.