ANIMAL PLANKTON IN THE CHANY TRANSITION AREA

Abstract

The paper explores the research carried out from 1973 till 2010. The Chiniaikhinsky stretch is a transition area from oligohaline area of the Chany to mesohaline one. The stretch animal plankton contains 59 species of systematic groups; they are 28 rotifers, 24 Cladocera and 7 copepods. The stretch animal plankton belongs to fresh water aquaculture and some species belong to brackish water aquaculture. The main part of species is cosmopolitan. The researchers haven’t discovered exotic species and endemic species. Animal plankton development depends on the lake river and the Chulym and Kargat rivers runoff, which flow into the Chany lake. High-water years are characterized by fresh water fauna and dominating Mesocyclops (s. str.) leuckarti Claus, Daphnia longispina O. F. Müller, Chydorus sphaericus (O.F.M.). The authors observed brackish water fauna and dominating Diaphanosoma brachyurum (Lievin), Ceriodaphnia reticulata (Jur.), Arctodiaptomus salinus Daday in the low water years when water salinity exceeded 3 g/l. Abundance of animal plankton in the stretch varied from 623,5 thousand species/м3 to minimum 23,3 thousand species/м3; biomass of animal plankton reached maximum 24,2 g/м3 and minimum 1,2 g/м3. Changes in biomass depend on the level and abundance of dominating species, i. e. on the river runoff. The paper declares that total abundance and biomass were higher in 1973–1997 than in 1998–2010. This is explained by higher level of the river.