Abstract: An investigation of macrozoobenthos was conducted in the main stream of middle reaches of Luanhe River, an important river in North China in October 2007. The macrozoobenthos in the stream was richer in species. A total of 37 species were collected, 5 species of which were dominant species. The mean biomass was 54 g·m-2, and the mean density was 1128 ind·m-2. Only one species of Ephemeroptera was found in all sampling sites, suggesting that the water quality of the stream was good. The abundance, biomass, and biodiversity index of the macrozoobenthos in lower reaches were lower than those in upper reaches. Macrozoobenthos distribution had a close relation to habitat condition. Lower reaches were intensively disturbed by human activities, whose habitat condition was worse in quality, being not beneficial to the survival and reproduction of macrozoobenthos.

Key words: Recirculated landfill leachate, Antioxidant system, Membrane lipid peroxidation, Cynodon dactylon, Irrigation