Ein Fließgewässer im urbanen Umfeld. Analyse des ökologischen Zustandes des unteren Belmer Baches (Osnabrück, Niedersachsen) anhand des Makrozoobenthos

The organic pollution of the lower Belmer Bach can be attributed to its agriculturally intensively used drainage area. Already before entering the urbanized region, the macrozoobenthos is poor in species due to saprobic pollution and the structural poverty of the waterbed and the banks.When comparing the species numbers of a reference sampling plot located before the urban region and a sampling plot situated within this region, hardly any differences could be ascertained. The longitudinal isolation and the rise in temperature of i 1 °C in the urban brook section negatively influence its fauna; this, however, is compensated by the varied riparian vegetation and the greater structural diversity of the waterbed due to hydraulic engineering. A rise in temperature of i 5 °C and a continuous inflow of suspendedmatter from a sewageworks reduce the macrozoobenthos to few dominant taxa.