新疆额尔齐斯河大型底栖动物的群落结构及水质生物学评价

The community structure of macrozoobenthos and biological assessment of water quality in the Irtysh River of Xinjiang

新疆额尔齐斯河是中国唯一流入北冰洋的河流,整个流域有着极为丰富的底栖动物资源。2012年7月、8月、10月与2013年5月分别对额尔齐斯河干流、5条主要支流以及附属水库的大型底栖动物群落结构特征进行了调查。结果表明:共采集大型底栖动物117种,其中水生昆虫106种(90.6%),软体动物6种(5.1%),寡毛类3种(2.6%),其他大型底栖动物2种(1.7%);优势种主要为似动蜉(Cinygmula sp.)、四节蜉(Baetis sp.)、直突摇蚊(Orthocladius sp.)、蜉蝣科(Ephemeridae sp.)、多足摇蚊(Polypedilum sp.)、摇蚊(Apedilum sp.)、霍甫水丝蚓(Limnodrilus hoffmeisteri)、短脉纹石娥(Cheumatopsyche sp.)、小蜉(Ephemerella sp.)、寡角摇蚊(Diamesa sp.);大型底栖动物的密度(P=0.558)与生物量(P=0.464)季节性差异不显著,年平均密度与生物量分别为519.05 ind·m-2、3.30g·m-2,大型底栖动物密度存在明显的空间差异,整体上上游(604.53 ind·m-2)高于下游(447.82 ind·m-2);大型底栖动物年平均Margalef指数、Shannon指数、Simpson指数、Pielou指数分别为1.12、0.53、0.65、0.52;聚类分析显示,多样性指数较低的185团北湾、布尔津河口、盐池、小635采样点聚为一类,其余各点聚为一类;利用科级生物指数(FBI)、Beck指数、Chandler生物记分制(CS)以及BMWP指数评价额尔齐斯河各段水质,整体上水质属轻度污染;Spearman相关性分析显示,水生昆虫的分布与水体透明度呈显著正相关,而寡毛类的分布与盐度、电导率和矿化度呈显著正相关,与电阻呈显著负相关,软体动物的分布与环境因子的关系不显著。

Irtysh River in Xinjiang Uygur Autonomous Region is the only river in China that disgorges into Arctic Ocean and tremendously abundant in natural resources of zoobenthos throughout the drainage basin. In the present study, we conducted an investigation on the community structure of macrozoobenthos in Irtysh River in July, August and October 2012 and May 2013, which focused on the mainstream, five main tributaries and one affiliated reservoir. We identified 117 macrozoobenthos species, of which 106 species were aquatic insects （90.6%） , 6 species were Mollusea （5.1%） , 3 species were Oligochaetas （2.6%） and 2 species belonged to other macroinvertebretes （ 1.7% ）. The dominant species were composed primarily of Cinygmula sp. , Baetis sp. , Orthocladius sp Ephemeridae sp. , Polypedilum sp. , Apedilum sp. , Limnodrilus hoffmeisteri, Cheumatopsyche sp. , Ephemerella sp. , and Diamesa sp. The density （P=0. 558 ） and bio- mass （P = 0. 464 ） of macrozoobenthos showed no significant seasonal difference. The average density and biomass of macrozoobenthos were 519.05 ind · m-2 and 3.30 g ·m-2, respectively. The density showed a significant spatial difference, with a higher mean value in the upstream （604.53 ind · m-2 ） than in the downstream （447.82 ind · m-2）. Annual mean values of Margalef, Shannon, Simpson and Pielou＇ s indices were 1.12, 0.53, 0.65 and 0.52, respectively. Clustering analysis was applied for assessing the diversity status of macrozoobenthos at different sampling sites of Irtysh River. The results showed that the community structure of macrozoobenthos was divided into two types： （i） one group had low diversity index at sampling sites 1,6, 8 and 9 ; （ii） the other group exhibited relatively high diversity at other sampling sites. Based on the biological indices （ FBI index, Beck Index, BMWP index and Chandler score system （CS） ） of macrozoobenthos, water quality in Irtysh River was assessed. The results indicated that the water quality in Irtysh River was characterized as slight pollution. Spearman correction analysis showed that the distribution of aquatic insects was correlated positively with water transparency. Oligochaeta was correlated positively with salinity, conductivity and total dissolved solid （TDS）, and had a negative relation with resistance. There was no significant relationship between the distribution of Mollusca and environmental factors.