Physiological and behavioral responses of northern elephant seals (Mirounga angustirostris) to global change among three northern California rookeries

Abstract

The California coast provides a unique study system for investigating the effects of warming and habitat quality on the thermoregulatory capacity of the northern elephant seal (NES). In California, island rookeries such as the offshore site at the Farallon Islands National Wildlife Refuge are experiencing habitat loss and reduced suitable haul-out surfaces due to erosion from storm events. Extreme weather events are increasing in frequency and severity with global change. Semi-aquatic animals face a unique thermal challenge. They possess adaptations to conserve heat when immersed in cold water during deep dives but must compensate for such heat-conserving properties of their physiology when transitioning to heat exposure on land. Therefore, these animals must precisely thermoregulate with physiological and behavioral adjustments across a broad thermal range. We investigated how environmental variables affect seal thermoregulation at three northern California rookeries, the southeast Farallon Island (SEFI), Point Reyes National Seashore (PORE) and Año Nuevo State Park (ANSP). Infrared thermography was used to determine seal skin surface temperature and weather data was collected at each site. We found that average surface temperature increases with solar radiation, maximum surface temperature decreases with increasing wind speed, and thermal window area percentage decreases with relative humidity and increases with ambient temperature. Climatic variation may present physiological and behavioral challenges for marine mammals that experience significant life-history stages on land. Such ongoing findings will be fundamental in predicting climate change vulnerabilities and will be critical in mitigating the impacts of anthropogenic warming and promoting resilience in these populations. Carol Baird Graduate Student Award for Field Research; The Neubacher Fund for Marine Science at Point Reyes National Seashore. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.