Meeting Abstract

P2.38  Tuesday, Jan. 5  Fatty acid and stable isotope analyses explain variability in ecosystem productivity and consumption patterns of top predators DOUGLAS, Hector/D*; SPRINGER, Alan/M; BUDGE, Suzanne; AUCOIN, Lacey; University of Alaska Fairbanks, Kuskokwim; University of Alaska Fairbanks, IMS; Dalhousie University; Dalhousie University hddouglas@yahoo.com

The utility of seabirds as environmental indicators depends upon the sensitivity and resolution of the scientific tools employed as well as the ecology of the animals. Planktivorous auklets occupy a trophic niche close to the base of the marine food web and may serve as sensitive indicators of climate-induced change. We discuss how the combined application of stable isotope and fatty acid (FA) analyses with this guild can help explain variability in ecosystem productivity and consumption patterns of top predators. We tested for differences in diets among crested and least auklets (Aethia cristatella, A. pusilla ) in the Bering Sea at several levels (interdecadal, geographic, seasonal). Interdecadal differences in stable isotope composition (C, N) at Little Diomede I. in the northern Bering Sea exhibited a pattern similar to the trend observed in bowhead whale baleen. Auklet FA profiles exhibited seasonal and geographic patterns that contrast dependence upon local versus advected production. As we predicted, there were interspecific differences in FA profiles that could readily be discriminated at all levels of comparison. Contrary to predictions and assumptions in the literature, adult auklet diets differed significantly from chicks. The results of this preliminary study illustrate the power of these techniques to discriminate patterns from the fine scale to the global in populations of these top predators and the marine food web. Hence, these tools have utility for studying climate induced change in the northern oceans.