BIOLOGIYA MORYA, 2014, Vol. 40, No. 4, pp. 268-278

Metazoan meiobenthos and nematode taxocenosis in the Nyegga pockmark field (Norwegian Sea)

© 2014 D. A. Portnova¹, V. O. Mokievskiy¹, H. Haflidason², C. Todt³

¹Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow 117997;
²University of Bergen, Department of Earth Science, Marine Geology and Geophysics, Bergen 7800;
³University of Bergen, University Museum of Bergen, Bergen 7800

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Based on visual observations in the Nyegga methane seep area, we identified the arbitrary boundaries and types of microbiotopes: siboglinid fields, bacterial mats, and background sediment. The metazoan meiobenthos was represented by 14 major taxa; nematodes were dominant at seven out of the eight stations. The taxonomic diversity of meiobenthos in siboglinid fields was higher than that of background sediment. The average abundance of organisms in siboglinid fields was 1.3 times higher than that in background sediment. The values of abundance of nematodes and meiobenthos as a whole varied among bacterial mats. The modal size fraction of meiobenthos and nematodes occurred in samples obtained on sieves with a 63-125 μm mesh size regardless of the microbiotope. A total of 88 species of nematodes belonging to 26 families and 63 genera were identified. The species diversity decreased in the direction from background sediment to siboglinid fields and further to bacterial mats.

Key words: meiobenthos, marine free-living nematodes, methane seeps, Nyegga.