Study On The Ecology Of Macrobenthos In Xiquanyan Reservoir

The ecological study of macrobenthos was conducted on thirteen typical sampling stations in Xiquanyan reservoir, in May, Aug. and Oct.2010, of which9sampling stations was established in the reservoir district and4sampling stations in the upper rivers of the reservoir. The macrobenthos were investigated by quantitative study. The macrobenthos abundance、 biomass、secondary production and biodiversity were analyzed through multivariate statistic analysis. The macrobenthos community was analyzed according to Cluster and MDS. The ABC method (abundance biomass comparison) was used to detect pollution-induced disturbance in macrobenthos communities. The water environmental quality was evaluated by diversity index and biological index. The CCA was used to detect the correlation between macrobenthos and environmental factors. The purpose of this paper was to provide a guideline of management and the ecology repair as well as a foundation for the future study in Xiquanyan reservoir.Total of70species were identified, among which, the species of aquatic insects were56, accounting for80.00percent; followed by oligochaeta,7species, accounting for10.00percent;2leeches species, accounting for2.86percent;5molluscs species, accounting for7.14percent.There were found7dominant species,such as Limnodrilus hoffmeisteri、Chironomus sinicus、Hydropsyche nakaharai、Branchiura sowerbyi、Tanypus chinensis and one species of Arctocorisa sp..The abundance、biomass and secondary production in spring、summer、autumn was6624ind./m2、111.54g/m2、1.451×108gAFDW,6672ind./m2、82.502g/m2、7.283×107gAFDW,18560ind./m2、92.894g/m2、1.720×108gAFDW; The total fish potential production was63.71t. According to the functional feeding groups abundance:GC>FC>SH>SC>PR.The results show that biodiversity were lower in the reservoir area than in the upper rivers of the reservoir area; Comprehensive the two areas, the richest biodiversity was in atumn that follow by summer, the biodiversity in spring was the poorest. The macrobenthos community was unstatble in the reservoir area, it was disturbed to a moderate disagree in spring、summer and autumn. For the upper rivers of the reservoir area, it was the same as the reservoir area in summer,but the macrobenthos community was statble in autumn.All sampling stations of the Xiquanyan Reservoir were divided into the reservoir area and the upper rivers of the reservoir area. The reservoir area was divided into two or three areas, but it was changed by the main line,which was roughly to the rivers’warehousing mouth place, the reservoir center and the dam outlet. The comparability is close within groups and the great change between groups. The results of Canonical Correspondence Analysis respected that, the environmental factors on the macrobenthos community effect was changed from season to season. WD、 NO3-N and chla were the main factors on the community of macrobenthos in spring; In summer, WD、NO3-N、chla、CODMn and TN were the main factors; In autumn, WD、chla、 DO、NH3-N、CODMn、BOD5and TP were play the leading roles.On the whole, the reservoir area was polluted to a moderate disgree, the upper rivers of the reservoir area was polluted slightly.