Scientific publications

Being obligate benthic organisms without dispersal stage in the life cycle marine nematodes are distributed by large areas. We studied occurrence of benthic nematodes in water column in the vicinities of the White Sea biological station of the Lomonosov Moscow state University. Using traps installed on the sandy littoral on different height above the ground surface and different tide levels, we found that the nematodes are less mobile animals within the marine meiobenthos. Nevertheless we found above 40 species in the plankton samples. There are a few locations of their regular occurrence where it is possible to find littoral or sub-littoral nematodes. The rains can be critical for the littoral meiobenthos. We have examined suspension in the water stream during the heavy shower in a low tide and find a lot of meiobenthic organisms. Most abundant were nematodes and harpacticoid copepods, about 12 and 84 ex./l correspondingly. Such density is by order of magnitude greater than the number of real sea plankton at the same season. In the adjacent parts of the sea, the stream formed freshwater lens containing the washed out littoral animals with density about 20 exemplars per liter, including about 1 nematode per liter. This is less than in the stream suspension concentrate, but anyway comparable with the meso-plankton number. The washing out of nematodes and other meiobenthic animals seems to be important dispersal way. In laboratory experiments we found that most of the littoral nematode species lose reversibly their ability to move when salinity reduces below 5–12 ‰, and these unmovable animals can be washed out easily. These washed out animals also can be included in the planktonic food chains.