Macromolecular compositions of phytoplankton in the Chukchi Sea

Abstract

Macromolecular compositions of phytoplankton in different locations of an ice free Chukchi Sea were analyzed and compared in order to find some ecological indications of algal macromolecular productions and thus evaluate possible changes in physiological condition under ongoing changes in environmental conditions. In the Chukchi Sea, low lipid productions whereas high protein productions were general through the water column, which reflects phytoplankton had a physiologically healthy condition. A small size community of phytoplankton incorporated much more carbon into proteins in nitrate depleted surface water, which suggests that small phytoplankton had less N stress than large phytoplankton since they can easily use assimilated nitrogen. Low incorporation into lipids and relatively high incorporation into proteins at PHL 12 suggestthat phytoplankton had no nitrogen limitation. This is an interesting result since phytoplankton from ACW mass has been thought to be nitrogen limited. The relatively high ammonium is believed to have provided enough nitrogen for phytoplankton demand at PHL 12 where small cells (0.7-5&micro

m) comprised about 50 % of the community.