A brief look at the free-living Nematoda of the oxic/anoxic interface with a new genus record (Trefusia) for the Black Sea

In order to provide the first comparative source of nematofaunal data at the oxic/anoxic interface off the Sinop Peninsula, the southern Black Sea, a survey of meiofauna and nematode fauna was conducted in August 2011 aboard the exploration vessel (E/V) Nautilus with ROV during the Black Sea Expedition NA012. Higher meiofaunal taxa and nematode composition were investigated. Free-living marine nematodes were the most abundant group at each site. A total of 84 species were found, belonging to 23 families. The suboxic zone was dominated by the nematode Trefusia aff. longicauda (42%). This is the first record of the genus Trefusia De Man, 1893 for the Black Sea. Although many factors are likely to influence the changes in the meiofaunal abundance and the composition of nematode assemblages, we suggest that oxygen reduction indeed affected the meiofaunal abundance and the nematode composition, however, a particular preference of several taxa for extreme conditions may be suggested.