Abstract:

Investigations of macrozoobenthos in the Jinggu River were carried out both in high flow period (July 2011) and low flow period (April 2012) for researching the impacts of small hydropower plants(SHPs) on macrozoobenthos.Cobble substrate samples were collected with a surber net (0.09 m2); reservoir sediment samples were collected with a weighted Petersen grab (1/16 m2) and cleaned with a 250 μm sieve. Large animals were manually sorted in a white porcelain dish and small ones were sorted under a dissecting microscope. Specimens were all preserved in 10% formalin.Altogether 61 species belonging to 54 genera, 34 families were recorded,among which, there were 7 species of Oligochaetes, 7 species of Molluscans, 44 species of aquatic insects and 3 other species.The measured density of macrozoobenthos was 1135.3ind./m2, and biomass was 7.93 g/m2during high flow period; 1231.6 ind./m2 in density and 6.92 g/m2 in biomass during low flow period. Taxon number of low flow period was much higher compared to high flow period, density also higher in low flow period, while biomass was lower in low flow period.The dominant species in these two seasons were Corbicula fluminea, Hydropsyche sp. and Polypedilum sp..On the basis of individuals, the composition of the functional feeding groups in the Jinggu River was classified as about 50 percent collectors and 50 percentothers.We did hierarchical agglomerative clustering with macrozoobenthic data of the Xiaoheijiang River and the Jinggu River, the analyzed results showed SHPs have caused some impacts on macrozoobenthic resources.Due to the constructions of SHPs, habitat in the Jinggu River can be classified into three types, i.e. reservoir section, waterreducing section and mixing section.Obviously, taxon number of reservoir section was much less compared to waterreducing section and mixing section, and standing crop was highest in mixing section, lower in waterreducing section, and lowest in reservoir section.Results showed that SHPs had the greatest impact on reservoir section, less impact on waterreducing section, and minimal impact on mixing section.Biodiversity and standing crop were higher in the Jinggu River than the main stem of the Lancangjiang River. The reasons of the status of macrozoobenthos were discussed, and we thought the basic reason was SHPs blocked the river longitudinal continuity. Meanwhile, two types of habitat restoration measures were discussed.Ecological flow was the most effective way to restore rivers hydrological regimes, and artificial step pool system was one of the most effective ways to restore physical habitat