Collaborative Research: Modeling organismal responses to changing ecological regimes via investigation of stress, growth and reproduction in the longest-lived mammal

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This project uses new techniques to analyze historical museum specimens of whale baleen (long vertical strips of keratin that grow slowly from a whale's upper jaw) to investigate how environmental change affects long-lived animals. Environmental change can have dramatic effects on wildlife, but these effects often unfold slowly across many years, challenging scientists' ability to gather data across sufficient stretches of time. It has recently been discovered that baleen contains hormones that are deposited as the baleen grows, such that one piece of baleen contains a detailed record of individual whales’ reproductive history, stress and general health across decades. Baleen also contains carbon and nitrogen signatures that enable reconstruction of the whale's diet as well as its migration history. This project will use these new techniques to analyze museum baleen collected from the 1800s to the 1980s from bowhead whales (Balaena mysticetus), which can live 200 years, to investigate long-term, multi-year impacts of environmental change on stress, growth and reproduction in a long-lived mammal. Statistical modeling will put results into a broader context, illuminating how whales, and by extension other long-lived mammals, respond to environmental change over time. The project will engage ~40 undergraduates in Smithsonian-based research, train a postdoc and PhD student, result in numerous public talks at participating museums, involve Native Alaskan communities whose ancestors originally collected the specimens, and distribute results at scientific conferences and in peer-reviewed publications, thus contributing to broader societal impacts.Environmental change causes physiological impacts that can last years in long-lived species, yet there is a dearth of methods for quantifying such impacts and their population effects across the necessary decadal timescales. This project employs recently developed analytic techniques for whale baleen to address this data gap, testing the hypothesis that sudden changes in marine conditions cause subsequent multi-year impacts on stress, growth and reproduction of individuals, and that this information can be used to model population-level responses to current and predicted environmental change. The project utilizes archived museum specimens of baleen from bowhead whales (Balaena mysticetus), selected due to their slow-growing baleen, exceptionally long lifespan (200 years), large range, and well-documented environmental shifts in their North Pacific winter and Arctic Ocean summer habitats. Fifty-six specimens of baleen collected from 1859-1989 will be sampled at 2-cm intervals for stable isotopes and 4-cm intervals for adrenal, thyroid and reproductive hormones, enabling reconstruction of individual histories across decades with approximately monthly resolution. Specific objectives include: (1) Determine lifetime endocrine history of juveniles before and after a well-documented 1977 North Pacific ecological regime shift, using a panel of four hormones to assess stress physiology; (2) Assess potential impacts of such stress on juvenile growth rate; (3) Expand a long-term dataset on historic patterns of stress and reproduction in adults in eras characterized by varying anthropogenic and environmental impacts; (4) Use the resulting data to model linkages between ecological change, individual physiology, and potential population impacts, using the Population Consequences of Disturbance framework.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.