渭河流域大型底栖动物多度及其影响因子研究

大型底栖动物多度对于河流生态环境评估具有重要意义,为研究渭河流域大型底栖动物多度及其影响因子以渭河干流陕西段的眉县、咸阳、草滩、临潼、华县等研究点为例,进行了生物采集、野外现场实验和室内实验等.通过对河流水质的分析,结合各研究点大型底栖动物的种类及多度,分析渭河流域环境因子对大型底栖动物多度的影响.结果表明:底栖动物在各研究点不仅个体数目不同,而且在各研究点总个体数中的比例和频度也有差异,造成这些差异的主要原因是各研究点环境因子的异质性.其中,影响底栖生物群落分布的环境因子主要有总氮、总碱度、化学需氧量、六价铬、总溶解固体、流量、水温、渗透系数等.

Macrobenthos abundance and its influencing factors in the Weihe River

Macrobenthos abundance is a major factor to consider when assessing environmental quality of a river.To analyze macrobenthos abundance and its influencing factors,both field and laboratory experiments were done.A total of 6 macrobenthos species were collected,of which,36.66% were chironomids,60.69%were tubificids,0.72% were snalls,0.73% were shrimps,0.50% were caddisflies,0.65% were shellfish,and 0.05% were unidentified species.Macrobenthos were collected,and in situ measurements of stream flow, water temperature and vertical hydraulic conductivity of riverbed sediments were done simultaneously at 5 research sites and 14 sampling sites along the Weihe River in Shaanxi Province.Water quality was determined in the laboratory.The type and abundance of macrobenthos were also analyzed.Data analysis was malnly done by de-trended correspondence analysis (DCA),principal component analysis (PCA),canonical correspondence analysis (CCA),and Student’s t-test.It was found that abundance of chironomids was the highest in Huaxian and Lintong;abundance of snalls and shrimps were the highest in Lintong;abundance of tubificids and caddisflies were the highest in Xianyang and Meixian;and abundance of shellfish was the highest in Caotan.In addition to variation in the number of macrobenthos across different research sites,their proportion and frequency of total individuals also varied,due to differences across research sites.In order to obtaln more objective and reliable data,environmental factors considered in this work included both physical and chemical parameters.Quality of water in Weihe River was not a critical factor affecting macrobenthos abundance,because macrobenthos sensitivity to environmental factors were different.The maln environmental factors influencing macrobenthos distribution are:total nitrogen,alkalinity,chemical oxygen demand,hexavalent chromium,total dissolved solids,stream-flow,temperature and vertical hydraulic conductivity of the riverbed sediments.