L. Forró szerk.: Miscellanea Zoologica Hungarica 10. 1995 (Budapest, 1995)

Tittizer, T., Leuchs, H.; Banning, M.: The consequences of river impoundments for the macrozoobenthos - demonstrated at the example of the River Danube in Germany

< 0.2 m/s 0.2-0.29 m/s 0,3.0.39 m/s > 0,39 m/s average velocitv of flow Fig. 10. Average population densities of chironomid larvae (subfamily Chironominae) in dependence on velocity of flow (examination 1989; rkm 2354-2376) Fig. 11. Average population densities of chironomid larvae (subfamily Chironominae) in dependence on water depth (examination 1989; rkm 2354-2376) Thienemann 1954) pointed out. The enormous widening of the cross section during the regulation of River Danube has created vast areas with that relatively shallow water depths (cf. Fig. 2). In 1989 in the Geisling impoundment not only chironomid larvae were found in sometimes unusually high densities. For instance, the phytoplankton-feeding sphere shell Sphaerium corneum reached abundances with maximum densities of 120,000 individuals per square metre, while the crustacean Corophium cuivispinum was observed in some areas in densities up to 350,000 individuals per square metre. The enormous populations of this detritus feeding