Similarities in zooplankton community between River Drawa and its two tributaries (Polish part of River Odra)

Abstract

Zooplankton communities were studied in a river and its tributaries with different hydrological, biological and physico-chemical conditions. Small similarities were noted in the zooplankton community (mostly Rotifera) between a tributary characterised by a regular bed and the river. No influence of a tributary with an irregular bed and variable water flow was noted on the zooplankton of the river it joined. It was concluded that the tributaries had very little influence on the zooplankton community in the river which they joined. The most probable reasons for this were the predatory behaviour of fry, escape of zooplankton into the river vegetation and therefore not carried down by the river current, and reproduction of zooplankton in slack waters, small floodplains and densely vegetated riparian zones of the main river.