Deep-sea meiobenthos of the central Arctic Ocean: distribution patterns and size-structure under extreme oligotrophic conditions

During the expedition "Arctic Ocean 96" cruise with the Swedish icebreaker ODEN (18.07.-21.09.96), sediments were collected from 20 basin and ridge stations in the abyssal regions of the central Arctic Ocean north of 85°N at water-depth between 864m an 4187m to investigate the question how the extreme scarceness of food in the perennial ice covered deep mediterranean effects the meiobenthic community. Meiofauna densities (including foraminiferans) ranged between 68-247 ind.·10cm-2 and were very low compared to values from temperate, central oceanic regions. Nevertheless, a decrease in abundance with increasing water depth as well as regional differences in abundance and community structure were detectable. Foraminiferans were by far the predominant taxon (58-86%), followed by nematodes (10-27%). Except for harpacticoids all other meiofauna taxa occurred just in low densities and very patchy. Very low meiofaunal abundances and a visible trend towards miniaturisation of organisms may be an outcome of the extremely limited food supply to the benthos under perennial ice-coverage of the central Arctic Ocean.