The free-living nematodes of middle reaches of the Sylva river and their part in the Meiobenthos

61 taxa of free-living nematodes were founded in middle reaches of the Sylva river, and 6 of them were marked for the Kama basin for the first time. The seasonal dynamics (quantitative values of development) of nematode abundance and biomass depend on life cycles of the dominant species of worms and on abiotic conditions of environment. The part of nematodes in the meiobenthos was sufficiently high. Nematodes had high species diversity, and they occurred in river each month. The nematode abundance accounted 30.5% from the meiobenhos abundance.