Under-ice fauna from Svalbard waters

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Abstract
Under-ice fauna (‘sea-ice organisms’) from the Barents Sea between Svalbard and Franz Josef Land and froin Brennevinsfjorden on Nordaustlandet were collected in August 1982 from 40 sampling stations using sampling techniques based on SCUBA-diving. The mean biomass exceeded 1 g per m2 at three stations and mainly consisted of Apherusa glacialis and Gammarus wilkitzkii. Samples from transects (75–110 km long) running into the pack-ice perpendicular to the ice edge between Kongsöya and Franz Josef Land showed that the greatest biomass occurred near the ice edge while the lowest values were recorded 11–13 km from the ice edge. The abundance of calanoid cope pods decreased more rapidly than for Apherusa glacialis and Gammarus wilkitzkii with increasing distance from the ice edge. The composition of the under-ice fauna showed day/night variations in landfast winter-ice near Wilhelmsöya, mainly due to ‘swarms’ of Parathemisto libellula appearing under the ice at night. Such day/night variations were not recorded from the pack-ice where P. libellula was quite rare. Landfast year-ice in Brennevinsfjorden on Nordaustlandet had little under-ice fauna probably due to a thin (5–10 cm) layer of fresh water (‘melting water’) flowing out of the fjord underneath the ice above the more saline water. Low values of under-ice faunal biomass were also recorded from an area near Barentsöya where the pack-ice was melting rapidly.