ИСТИНА

Nematode collection of 987 specimens gathered in six hydrothermal sites along MidAtlantic Ridge from 38ºN to 22ºN was examined. Altogether 17 species were isolated, the most numerous are Prochaetosoma sp., Paracanthonchus sp., Oncholaimus sp., Desmodora sp., Thalassomonhystera vandoverae Zekely, 2006, Innocuonema sp., Halomonhystera sp., Prochromadorella sp., Microlaimus sp., Leptolaimus sp. arranged in decreasing order. Hydrothermal vent sites present quite peculiar biotopes with nematode communities strongly distinguished from those of surrounding oligotrophic abyssal plains. Endemism of the nematofauna of the deep-sea hydrothermal vent biotopes is comparatively low and does not exceed the species level. In the generic composition and average body size, nematode communities of the hydrothermal vents are more similar to those of shallow water sediments than to communities of the surrounding abyssal bottom. Species richness of the deep-sea hydrothermal nematodofauna is low, especially in comparison with that of surrounding abyssal oligotrophic plains. The project is supported by grant RFBR 09-04-01212-а.