女山湖围网养殖对水质和大型底栖动物群落结构的影响

为合理利用和保护自然资源,对女山湖围网养殖内外水质的差异和底栖动物的群落特征及生物多样性差异进行监测。2009年3—5月,以黑白瓶法测溶氧(DO),重铬酸盐法测耗氧量(COD),紫外分光光度法测总氮(TN),钼酸铵分光光度法测总磷(TP),PHS-3精密数显酸度计直接测定pH值,重量法测定悬浮性固体和溶解性固体;1/16 Peterson采泥器取样,对底栖动物鉴定、计数,并计算密度和生物量。结果表明,围网内外水质的理化指标存在差异,围网内酸度、COD、TN、TP、有机质高于围网外。检出大型底栖动物18种,网围养殖区底栖动物群落组成与非养殖区差异较大(Jaecard指数为0.46)。围网内大型底栖动物密度、生物量和生物多样性低于围网外。建议通过湖泊围网的合理布局提高湖泊生产力,恢复和维持湖泊生态系统的良性循环。

Effects of enclosure aquaculture on macrozoobenthos community structure and water quality in Nvshan Lake

In this study an attempt was made to investigate the effects of enclosure aquaculture on macrozoobenthos community structure and water quality in Nvshan Lake(117°58′-118°18′E,32°48′-33°02′N).The macrozoobenthos community structure and water quality in Nvshanhu lake were monitored from March to May in 2009.Five samplings were undertaken in four corners and in the middle of the cage.The concentrations of total nitrogen(TN),suspended solids,dissolved oxygen(DO),chemical oxygen demand(COD),hydrogen ion and organic matters were analyzed in and out of the cage.The constitution of Zoobenthic was also studied in the tested regions.The shannon-weinner index(Bi and H′),Pielou’s evenness index(J) and Simpson’s diversity index(D)were used to check the benthos diversity in the cage culture and control region.The results showed that the physical and chemical indicators of water in and out of the enclosure aquaculture zone were different.The values of pH,COD,TN and organic matters in enclosure aquaculture zone were higher than that of outside zone,but the concentrations of suspended solids and DO were lower than that of outside zone.18 species of macrozoobenthos were collected in the research.The community structure of macrozoobenthos in the enclosure aquaculture zone were different from outside zone,where the values of Bi,H′,J and D of the enclosure aquaculture zone were found to be lower than outside zone.All of the macrozoobenthos density,biomass and diversity decreased significantly in the enclosure aquaculture zone.The findings suggested that cage culture brought detrimental effect on the water quality of Nvshan Lake,though it is still in good condition for aquaculture.The rational distribution of enclosure aquaculture zones should be considered to improve the lake productivity and restore the ecosystem virtuous cycle.