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Assessment of the Cumulative Effects of Multiple Stressors on Marine Mammals– Elephant Seals as a Model System
Dr. Daniel Costa | The Regents of the Unversity of California, Santa Cruz
The research project will be a multi-investigator interdisciplinary study using the northern elephant seal as a model system to significantly improve the understanding of the response of marine mammals to exposure from multiple stressors. Our team will integrate physiological and ecological approaches including immunology, stress physiology, toxicology, animal behavior, population biology, and life history theory and will examine cumulative effects of exposure to multiple stressors in elephant seals. This research will focus on specific responses of individual animals, but by incorporating information from our long-term database on elephant seal population demographics, the team will extend this understanding to population-level impacts.
The Population Consequences of Multiple Stressors (PCoMS) framework identified potential approaches to quantifying health-related changes in physiology and behavior associated with different levels of stress exposure. These variables (the ‘health box’ in the PCoMS framework) include energy stores, allostatic load, stress hormones, immune status, organ status, contaminant burden, and parasite load. Concurrent measurements of several or many of these metrics at a variety of life history stages, together with information on individual survival and reproduction, are critical to understanding how stressors potentially interact to influence vital rates. The research project will address these research needs and develop an understanding of interactions between multiple stressors using one of the best studied marine mammal systems, the northern elephant seal. The research team will: 1) Look for mechanistic associations between stressors and health markers in the existing elephant seal dataset. 2) Use a series of carefully designed manipulative experiments to better understand the form and mechanisms of multiple stressor interactions. 3) Implement a PCoMS model using existing and newly acquired elephant seal data. 4) Apply our results to other marine mammal systems by participating in the St Andrews-led interdisciplinary working group and collaborating with the proposed gray whale proposal if funded.
The project research will further develop fundamental knowledge regarding the impact of multiple stressors, knowledge which can then be applied to other marine mammal taxa. These data would be hard, if not impossible to collect from other marine mammal species, especially for threatened, endangered, and at-risk species (TES). Understanding the relationship between multiple stressors and vital rates is directly applicable to other species where such data are difficult to or cannot be collected. The knowledge derived from this research will be integrated into the Office of Naval Research’s Marine Mammal & Biology Program and thereby provide for the development of improved and more cost-effective marine mammal management methods, especially for TES populations responding to multiple stressors.