The microbial food web in Arctic seawater concentration of dissolved free amino acids and bacterial abundance and activity in the Arctic Ocean and in Resolute Passage

Abstract

In June 1988 the naturally occurring concentration of each of 15 amino acids was less than 20 nM at all depths at a station in the Canadian sector of the Arctic Ocean and at a station in Resolute Passage. In Arctic Ocean water, under the permanent ice pack, bacterial uptake of amino acids and tritiated thymidine was near to below detection, although there were 10 super(4) to 10 super(5) heterotrophic bacteria ml super(-1). In Resolute Passage, uptake of amino acids and thymidine at all depths was low, even at depths where there were visible accumulations of algae which had melted out of the fast ice. Numbers of bacteria were 10 super(5) ml super(-1). In water collected in a small, recently opened lead in land-fast ice, containing substantial clumps of ice algae, amino acid concentrations were micromolar and bacterial uptake rates were high.