Energy flow through the marine ecosystem of the Lancaster Sound region, Arctic Canada

Abstract

Synthesizes the trophic dynamics of a Canadian arctic marine ecosystem using new data on primary production, zooplankton, the bivalve Mya truncata, and Arctic cod Boreogadus saida, as well as literature values for marine mammals and seabirds. The 98 000km2 region has a high rate of primary production relative to other parts of arctic Canada. About 60 g C.m-2 are fixed annually, of which c90% is contributed by phytoplankton, 10% by ice algae, and 1% by kelp. Phytoplankton production is twofold higher along the south coast of Cornwallis Island than elsewhere in Barrow Strait. Four copeopod species, of which Pseudocalanus acuspes is the most important energetically, graze about 1/3 of the phytoplankton production. Bivalves maintain high bimoass but low energy flow, acting as sedimenting agents. Arctic cod is a major component, with 125 000 tonnes being consumed by marine mammals and 23 000 tonnes by seabirds annually. The ecological efficiency of ringed seal Phoca hispida is near maximum, with 5% of ringed seal ingestion going to bears and humans as seal flesh. The food chain is very long, with bears occupying the fifth trophic level; this is reflected by high biomagnification factors for persistent lipophilic pollutants such as PCBs. -from Authors