Permalink : http://hdl.handle.net/2115/76384

JaLCDOI : 10.14943/bull.fish.69.2.93

KEYWORDS : ingestion rate;grazing impact;Pacific copepods;Arctic Ocean

Increasing numbers of Pacific copepods are being transported from the Bering Sea to the Arctic Ocean, so there is clear potential to affect the structure and composition of the Arctic food web. We investigated the grazing impacts of Arctic and Pacific copepods in the western Arctic Ocean using shipboard experiments during autumn. Ingestion rates for both Arctic and Pacific species were low and linked to low food availability. The ingestion rates varied with species, but were not related to chlorophyll a. The maximum ingestion rates calculated by the Michaelis-Menten equation were higher in the Arctic species (3.6% body carbon day−1) than in the Pacific species (0.10% body carbon day−1). The community grazing impacts were 0-0.57% remove day−1, and the Pacific copepods contributed 0.1-17% for this parameter. Even if Pacific copepods are transported into the Arctic Ocean and ingest the natural protist assemblage, their impact is spatially and seasonally limited, and, at present, Pacific copepods are unlikely to cause a shift in the protist biomass of the western Arctic Ocean during autumn.