The significance of man-made lentic waters for the ecology of the Lower River Rhine, especially for the recruitment of potamal fish
Neumann, D.; Staas, S.; Molls, F.; Seidenberg-Busse, C.; Petermeier, A.; Rutschke, J.
Old arms of the Rhine are increasingly silted up or separated from the river due to the deepening of the riverbed. Eutrophic, dredged lakes, connected with the river, offer favourable substitute biotopes for the disappearing lentic waters of the riverside and floodplain; during 1990 the densities of phyto- and zooplankton were much higher in the lakes than in the river itself. The lakes offered shelter, suitable substrates and abundant food for the reproduction of lithophilous and flow-indifferent fish species. The 0+ age-group was recorded and fish behaviour was monitored by echograms during day and night under normal conditions, as well as during strong rises of the river water level.