Variation of ostracod communities in a lowland river channel as exemplified by the lower course of the Oder (N‐W Poland)

Abstract

The study has investigated the variation in the ostracod communities of the lower course of the Oder River in relation to different substrates in two habitat types: river bed and littoral. Mineral sediment prevailed in the littoral, whereas organic sediment prevailed in the river bed. Physocypria kraepelini and Darwinula stevensoni were typical taxa of the river bed, while juvenile Candoninae, Cypria ophtalmica, and Cypridopsis vidua were typical of the littoral. Eutrophic waters of the lower course of the river provided favorable conditions for the development of ostracods, confirmed by high population density: 1200 ind. m−2 for the littoral and 39 100 ind. m−2 for the river bed. Insufficient amount of organic matter, turbulences, and water level fluctuations in the littoral resulted in the population density there being 30 times lower than in the river bed. In the littoral the number of Ostracoda taxa was higher than in the river bed. The species composition of the Ostracoda in the littoral and river bed was analogous to the littoral and profundal zone of lakes.