Note on sea-ice nematodes (Monhysteroidea) from Resolute Passage, Canadian High Arctic

Nematodes from the bottom section of first-year ice sampled every 4 days during April/May 1992 at two adjacent sites of an ice field station in Resolute Passage have been identified as members of the Monhysteroidea: Theristus melnikovi Tchesunov, 1986; Cryonema tenue Tchesunov and Riemann, 1995; and three unknown monhysterids that are similar to Cryonema. The maximum population density of nematodes was 23 810 m−2. None of the ice nematodes has ever been reported from benthic samples and their occurrence in ephemeral sea ice is the subject of hypotheses. Since a drastic change of the community structure was noted to take place within a few days, it is assumed that the majority of ice-nematode species do not represent an autochthonous faunal element in the examined habitat and that the main site for their reproduction is elsewhere. The nematode community found near the undersurface of ephemeral ice is apparently influenced by particular import and export processes that are unknown as yet.