Composition and distribution of the pelagic and sympagic algal assemblages in the Laptev Sea during autumnal freeze-up

The phytoplankton and ice algal assemblages in the Siberian Laptev Sea during the autumnal freeze-up period of 1995 are described. The spatial distribution of algal taxa (diatoms, dinoflagellates, chrysophytes, chlorophytes) in the newly formed ice and waters at the surface and at 5 m depth differed considerably between regions. This was also true for algal biomass measured by in situ fluorescence, chlorophyll (Chl) a and taxon-specific carbon content. Highest in situ fluorescence and Chl a concentrations (ranging from 0.1 to 3.2 μg l–1) occurred in surface waters with maxima in Buor Khaya Bay east of Lena Delta. The algal standing stock on the shelf consisted mainly of diatoms, dinoflagellates, chrysophytes and chlorophytes with a total abundance (excluding unidentified flagellates