Feeding Ecology of Sea Otters in Soft-Bottom Habitats

海獭在所有海洋哺乳动物中是独一无二的，因为随着海獭数量的恢复和范围的扩大，大型觅食锋正在入侵历史上的觅食地。这种种群扩张提供了重要的自然实验，有助于评估水獭如何影响猎物种群、非猎物群落和底栖生物栖息地。尽管之前大多数关于水獭群落角色的研究都来自岩石海岸，但没有人记录下这些令人兴奋的自然实验，而且人们对软沉积物环境中水獭的觅食栖息地几乎一无所知。奥利弗建议建立长期研究，研究海獭如何利用软沉积物猎物群落，这些群落主要由蛤蜊主导。一般的方法是定位活跃的觅食锋和建立永久的水下样带。这些样带将位于被严重开发的旧觅食地，在最近入侵的被严重开发的地点，在相对未开发的将被水獭入侵的觅食地，以及在未开发的地区，不太可能被水獭使用。科迪亚克岛（Kodiak Island）附近的阿福格纳克海峡（Afognak Strait）就存在这样一种进食活动梯度。尽管沿着现有的进食梯度（觅食前沿）进行的定量采样将为海獭种群的变化与猎物群落的变化之间的关系提供相当大的见解，但对永久样带的长期监测更为重要，并将为海獭在构建软沉积物群落中的作用提供最直接的证据。这项工作将与美国鱼类和野生动物管理局在阿拉斯加进行的海獭数量和行为研究密切配合。这是一个本科院校研究奖。

Sea otters are unique among all the marine mammals because large foraging fronts are invading historical feeding grounds as the sea otter populations recover and expand their range. This population expansion provides important natural experiments that help to evaluate how otters affect prey populations, non-prey communities and benthic habitats. Although most previous studies of the community role of otters derive from the rocky shore, none have documented these exciting natural experiments and almost nothing is known about the foraging habitats of otters in soft-sediment environments. Oliver proposes to establish long-term studies of how sea otters utilize soft-sediment prey communities, which are primarily dominated by clams. The general approach is to locate active foraging fronts and to establish permanent underwater transects. These transects will be located in old feeding grounds that are heavily exploited, in recently invaded sites that are heavily exploited, in relatively unexploited feeding grounds that will be invaded by otters, and in unexploited areas that are not likely to be used by otters. One such gradient of feeding activity exists around Afognak Strait, by Kodiak Island. Although the quantitative sampling that will be done along existing feeding gradients (foraging fronts) will provide considerable insight into how changes in sea otter populations relate to changes in prey communities, the long-term monitoring of permanent transects is even more important and will provide the most direct evidence for the sea otter's role in structuring soft-sediment communities. This work is closely coordinated with population and behavior studies of sea otters that will be done by the U.S. Fish and Wildlife Service in Alaska. This is a Research in Undergraduate Institutions Award.