WALRUS - Walrus Adaptability and Long-term Responses; Using multi-proxy data to project Sustainability

University Of Alaska Fairbanks Campus, Fairbanks AK

Investigators

Abstract

The Pacific walrus (Odobenus rosmarus divergens) is one of many species affected by recent environmental change in the Arctic. Much attention has focused on the loss of sea ice recorded from 2007-2012, the concomitant appearance of thousands of walruses on Alaska's and Russia's beaches, and the unfortunate consequence of large numbers of trampling mortalities. In addition, an unusual number of walruses in poor body condition were reported on Wrangel Island in 2007, many of which subsequently died. While walrus haul-out and mortality events are not historically isolated occurrences, these past haul-outs on Alaska's coasts, associated with reduced sea ice abundance, signify a change to this population. These occurrences are disquieting taken together with a decrease in estimated walrus based on surveys from 2006 versus 1990, (129,000 in 2006 compared to 200,000 in 1990), and current data on reduced fertility. The Pacific walrus is of critical importance to subsistence consumers in Alaska (and other areas of the Arctic). Despite impressive data from in-depth studies of Pacific walruses over the last 40-50 years, it is difficult to implement proposed co-management and conservation plans based on data from such a relatively short time span, much less project the impact of additional changes to the Arctic ecosystem on both walruses and humans subsisting on them. This project aims to integrate several disciplines including archaeology, ethnology, biology, and ecology using diverse sources of data including DNA, stable isotope, steroid, and trace element analysis as well as to ascertain long-term trends of walrus feeding ecology, foraging location, and stock genetics over the last two millenia. This time frame includes large climatic anomalies such as the Medieval Warm and the Little Ice Age, thereby presenting scientists with the possibility of understanding how walruses adapt during times of stress and change. Present-day samples will be obtained from Alaskan subsistence hunters, historic samples will be acquired from museums, and prehistoric samples from archaeological collections. Each type of data will act as a building block to better understand walruses and how they adapt to change in Arctic ecosystems. DNA analysis will provide insights into population bottlenecks and potentially adaptive differentiation between stocks. Stable isotope analysis of bone collagen and growth ring layers of teeth will define overall feeding ecologies of individuals through time. Trace element analysis will reveal foraging locations, potential population structure, and changes of essential and non-essential elements over time. Bone steroid hormones (i.e., stress hormones) can delineate population structure and health over time, and translation of historic taped interviews and use of previously archived studies will reveal traditional knowledge of walrus habitats and feeding habits over the last 100 years.