Seasonal dynamics of macroinvertebrates associated with submersed macrophytes in a lowland river downstream of a dam reservoir

Abstract

Two species of Potamogeton (pectinatus and lucens) with contrasting leave morphology, appeared in the Warta River as the consequence of water management - low volume discharges through the dam reservoir in summer. A similar sequence of invertebrate taxa as colonizers was observed over two cycles, Hydra sp. being initially the dominant. In spite of a similar pattern of colonization of two macrophyte species, P. pectinatus and P. lucens, the density of invertebrates was higher on the first one; this may be an effect of larger surface of the leaves of the first species. Chironomidae dominated, especially scrapers (Cricotopus as epiphyton consumers) and, in decreasing order, predators (P. arcuatus) and filtering collectors (Tanytarsus sp.).