北江大型底栖无脊椎动物群落结构及水质的生物评价

Benthic macroinvertebrate community structure and bioassessment of water quality of Beijiang River

对北江25个采样点的大型底栖无脊椎动物进行采样调查,并根据大型底栖无脊椎动物的群落结构特征对水质进行生物评价。研究中共采集到大型底栖无脊椎动物46属,分别隶属于15目31科,其中水生昆虫30属,占65.22%;软体动物8属,占17.39%;环节动物6属,占13.04%;甲壳动物2属,占4.35%。出现频率最高的3个种属分别为多足摇蚊属(Polypedilum)、巴蛭属(Barbronia)以及苏氏尾鳃蚓(Branchiurasowerbyi)。应用Shannon-Wiener多样性指数、Margalef多样性指数、Pielou均匀度指数、生物学污染指数BPI(biotic pollution index)、BI(biotic index)、FBI(family biotic index)、Goodnight-Whitley修正指数(GBI)7种生物指数对北江水质进行综合评价。结果表明:与20世纪80年代的评价结果相比,北江的大型底栖无脊椎动物在种类和数量等多方面均发生了较大的变化,生物多样性减少,耐污种所占比例增加,水质理化参数恶化;7种生物指数的评价结果存在一定的差异,部分指数之间存在较高的相关性,FBI指数和BPI指数的准确性和科学性更强,适用于北江水质的生物评价。在25个采样点中,6个采样点水质综合评价等级为较差或极差,16个采样点水质评价等级为一般,3个采样点水质等级为良好,整体水质属于一般的水平。人类活动对河流的水质状况造成了一定的影响。从水质生物学的角度衡量,北江水质整体呈现下降趋势。

Water quality bioassessment was conducted based on the community structure of benthic macroinvertebrates investigated at 25 sampling sites in the Beijiang River.In this study, 46 genera of macroinvertebrates belonging to 31 families and 15 orders were identified, among which aquatic insects （30 genera）, mollusks （eight genera）, annelids （six genera）, and crustaceans （two genera） accounted for 65.22%, 17.39%, 13.04%, and 4.35% of the total, respectively.Polypedilum, Barbronia, and Branchiura sowerbyi were the dominant species among all the benthic macroinvertebrates.The Shannon-Wiener index, Margalef index, Pielou index, biotic pollution index （BPI）, biotic index （BI）, family biotic index （FBI）, and Goodnight-Whitley modified index （GBI） were used to comprehensively evaluate the water quality of the Beijiang River.The results show that the variety and the number of macroinvertebrates during the study period had changed remarkably compared with those in the 1980s.The biodiversity had decreased, the proportion of pollution-tolerant species had increased, and the water quality had deteriorated according to physical and chemical parameters.The evaluation results of the seven biological indices showed a certain difference.Some of the indices had significant correlations between each other.The BPI and FBI indices were more adaptable to the water quality bioassessment of the Beijiang River due to their accuracy and rationality.The water quality was at low or extremely low levels at six sites, at moderate levels at 16 sites, and at high levels at three sites, indicating that the water quality at all the 25 sites was at a moderate level on the whole.Human activities had some influence on the water quality of the river.The overall water quality of the Beijiang River showed a downward trend based on water quality bioassessment.