长江口滴水湖大型底栖动物群落结构及其与环境因子的关系

ON MACROZOOBENTHIC COMMUNITY AND ITS RELATIONSHIP TO ENVIRONMENTAL FACTORS IN DISHUI LAKE

2009年6月—2010年5月,在滴水湖设置8个采样点调查研究了大型底栖动物群落结构特征的时空变化及其与环境因子的关系。在滴水湖共采集到25种大型底栖动物,隶属3门6纲,其中甲壳纲8种(32%)、昆虫纲6种(24%)、寡毛纲和多毛纲各4种(16%)、双壳纲2种(8%)、蛭纲1种(4%)。日本旋卷蜾蠃蜚、微小摇蚊、背蚓虫、黄色羽摇蚊为优势种。底栖动物年均密度和生物量分别为(910.5±107.64)ind./m^2和(8.62±2.01)g/m^2。底栖动物群落结构包括物种组成、现存量和多样性均无显著季节和空间变化。RDA分析结果表明,活性磷酸盐、叶绿素a、CODMn、pH、溶解氧是影响大型底栖动物物种分布的关键环境因子,日本旋卷蜾蠃蜚、日本大螯蜚、红裸须摇蚊和背蚓虫与溶解氧正相关,与营养盐水平和水温负相关,微小摇蚊和黄色羽摇蚊正好相反。Shannon-Wiener多样性指数和BPI生物指数水质生物学评价表明,滴水湖处于中度污染状态。

Macrozoobenthos were monthly sampled at 8 stations of the artificial Dishui Lake near Changjiang(Yangtze) River Estuary, in the suburb of Shanghai, China from June 2009 to May 2010. This round-shaped lake(in diameter 2.6 km, total area 5.56 km^2, water volume 16.2 million m3, max. depth 6.2 m) acts as a tourism area and plays important roles in water regulation and flood control for local water network. In recent years, the lake has been suffered from worsening eutrophication. To provide solution to the issue, spatio-temporal variations in the structural characteristics of macroinvertebrate community and the relationship to environmental factors were studied. A total of 25 macrozoobenthic species were identified belonging to 3 phyla and 4 classes, of which species of Crustacea, Insecta, Oligochaeta, Polychaeta, Bivalvia, and Hirudinea, occupied 8(24% of the total 25 species), 6(24%), 4(16%), 4(16%), 2(8%), and 1(4%), respectively. The macrozoobenthic community was dominated by 4 species: Corphium volutator, Microchironomus sp., Notomastus latericeus, and Chironomus plumosus. The mean density and biomass were(910.5±107.64)ind./m^2 and(8.62±2.01)g/m^2, respectively. No significant spatio-temporal variations in the species composition, standing crop, and diversity were observed. Redundancy analysis indicated that active phosphate, chlorophyll a, permanganate index, pH, and dissolved oxygen were the key environmental factors, which determined the spatio-temporal distribution of macrozoobenthic species composition. Grandidierella japonica, C. volutator, Propsilocerus akamusi, and N. latericeus were negatively correlated with dissolved oxygen and positively with nutrient level and water temperature. The reverse was found for the relationship between Microchironomus sp. and C. plumosus and the three above environmental factors. As indicated by the Shannon-Wiener diversity and biological pollution index(BPI), the Dishui Lake was considered moderately polluted, to which closer monitor is suggested before the situation worsens.