Winter in a Svalbard fiord ecosystem

Abstract

The characteristic phenomena of winter in Hornsund fiord include a winter drop in the yearly biomass maximum to 0.1% for phytoplankton and 10% for zooplankton; a slowing of the growth rate among pelagic dominants such as Pseudocalanus elongatus and Calanus finmarchicus, as well as among the hyperbenthic dominants Onisimus littoralis and Mysis oculata; and heterotrophy or maintenance of metabolism among living phytoplankton cells found in the middle of the polar night in densities of 10-50 cells/L. No winter breeders were observed and 90% of invertebrate species were breeding according to a K strategy. Migration takes place among all seabirds in the area, but c1% of eiders Somateria mollissima, fulmars Fulmarus glacialis and kittiwakes Rissa tridactyla overwinter, feeding in open water. -from Authors