Copepod-based food webs: auklets and oceanography in the Bering Sea

Abstract

distribution of copepod biornass in the Bering Sea apparently governs the numbers and distribution of nesting least auklets Aethia pusilla, which feed principally on copepods during the breeding season. Least auklets prey on 3 species of large calanoids, 2 characteristic of the outer shelf domain and 1 of the middle shelf domain of the Bering Sea, in proportions determined by their availability. Copepod production in the outer shelf domain is high and relatively tightly coupled to upper trophic levels; thus, competition for copepod biomass may limit the number of auklets in the southeastern Bering Sea. A well developed advectlve regime across the northern shelf, originating along the continental slope, apparently supplies copepods to the Bering Strait region. Advective replenishment of copepods and absence of significant competition might explain why auklet populations there are much larger than on the southeastern shelf. Recent demographic changes in populations of auklets and piscivorous seabirds suggest posslble multispecies Interactions among members of copepod-based food webs in the Bering Sea.