Project: Establishing baselines for nearshore marine ecosystems by examining sea otter trophic variation over 5,000 years of climatic and anthropogenic change

The PIs will utilize natural stable isotopes of carbon, nitrogen and oxygen to define the trophic position of sea otters and how it has varied from pre-historic (5000BP) to historic (last 300 years) times in the Kodiak and eastern Aleutian regions of Alaska. Stable isotope data from known prey species in each area will be analyzed to construct an isotopic food web to compare with changes in sea otter bone isotope ratios over time. Prehistoric data will come from faunal remains in middens. Oxygen and carbon stable isotope data from archaeological and modern shells and paleo-proxy data from marine sediment cores will be used to evaluate changes in environment that may have affected nearshore ecosystems. These data will be used to evaluate mechanistic explanations for the dramatic recent changes in sea otter trophic position and abundance. One of the extant populations that will be studied is declining, while the other is doing well. Understanding the mechanisms behind these divergent modern trajectories is of fundamental ecological as well as management interest.