淡水排放对杭州湾湿地浮游动物群落分布的影响

INFLUENCE OF FRESHWATER DISCHARGE ON ZOOPLANKT COMMUNITY DISTRIBUTION IN THE MUDFLAT WETLANDS OF THE HANGZHOU BAY

于2010年4月至2011年1月对杭州湾南岸滩涂湿地5个断面(S1-S3为排水区,S4-S5为非排水区)的高潮位和中潮位分别进行浮游动物群落结构的周年调查,共发现浮游动物38种(轮虫15种,枝角类4种,桡足类19种)。排水区浮游动物年平均密度88.89 ind./L,生物量0.41 mg/L,非排水区平均密度仅4.21 ind./L,生物量0.10 mg/L。排水区轮虫和桡足类的第一优势种分别为萼花臂尾轮虫(Brachionus calyciflorus)和汤匙华哲水蚤(Sinocalanus dorrii),而非排水区第一优势种为中华哲水蚤(Calanus sinicus)。S2-S3断面中潮位的水体营养盐浓度、浮游动物密度和生物量均明显大于高潮位。淡水排放、潮沟径流和潮汐决定了滩涂湿地群落的时空格局,后两者还解释了排水区中、高潮位间群落结构组成的差异。

In order to understand the spatiotemporal distribution of zooplankton species composition, abundance and biodiversity in the mudflat wetlands of Hangzhou Bay, 40 samples were conducted at middle to high tide levels in five sampling stations （S1-S3 for discharge area, and S4-S5 for non-discharge area） in April （spring）, July （summer）, October （autumn）, 2010 and January （winter）, 2011. A total of 38 species of zooplankton （15 Rotifera, 4 Cladocera, 19 Copepoda） were found. The annual average density （88.89 ind./L） and biomass （0.41 mg/L） of zooplankton in the discharge area were much higher than those, i.e., 4.21 ind./L and 0.10 mg/L, respectively, in the non-discharge area. The dominant species of rotifers and copepods in the discharge area were Brachionus calyciflorus and Sinocalanus dorrii, respectively, and Calanus sinicus dominated copepods in the non-discharge area. Water nutrient concentrations, community density, and biomass of the zooplankton at middle tide level in stations S2-S3 were much higher than those at high tide level. The zooplankton community in the mudflat wetlands, the effects of the freshwater discharge, tidal creek spread, and tidal conditions determined the temporal pattern of the main zooplankton species, and the tidal creek spread and tidal conditions explained differences in composition and structure between the middle and the high tide level.