156米蓄水后三峡水库支流童庄河河口段浮游植物群落的时空动态

2007年3月至12月按季节对童庄河河口段浮游植物进行调查,共采集到浮游植物133种,隶属于6门62属.不同季节的种类为34～88种,拟多甲藻为春夏季、隐藻为秋冬季主要优势种类,现存量的主要组成具有明显的季节变化,多样性指数从高至低依次为夏季、冬季、秋季和春季.上、中、下游断面之间,种类主要门类组成顺序不变.夏季上游断面密度和生物量、冬季上游断面生物量显著高于中游、下游断面.多样性指数自上游断面至下游断面,秋季依次小幅下降、冬季呈依次升高趋势.0～15 m现存量分布,春、冬季下降,夏、秋季为上升-下降分布.0 m或1 m最高、15 m最低.与156 m蓄水前同期相比,蓄水后种类增加了1.88倍,种类的主要门类组成没变.春季优势种类由3种减少到1种,秋季新出现了1种优势种类.现存量主要组成变得更单一,多样性指数下降了32.32%～85.52%.现存量的垂直分布基本不变.

Spatial and Temporal Dynamic of Phytoplankton Community in Tributaty Tongzhuang River Estuary after 156m Impoundment of the Three Georges Reservoir

Phytoplankton in the estuary of Tongzhuang River were investigated from March to December in 2007, One hundred and thirty three species were determined, belonging to 62 genera of six phylum, respectively. Species number varied among 34 to 38 in different seasons with Peridiniopsis spp. dominant in spring and summer and Cryptomonas spp. in autumn and winter. The composition of standing biomass changed significantly with seasons. Phytoplankton diversity index decreased from summer to spring of next year. Yet the composition of species in phylum level was not changed as compared among upstream, midstream and downstream sections. The density and biomass in summer and the biomass in winter were much higher in upstream section than in midstream and downstream sections, respectively. Phytoplankton diversity index decreased slightly in autumn and increased in winter from up- stream to downstream. From 0 to 15 meters depth, the standing biomass decreased in spring and winter but changed from up to down in summer and autumn. The standing biomass reached the maximum in the 0 or 1 meters depth and the minimum in the15 meters depth. The species number increased by 1.88 folds after 156 meters impoundment but the composition of main species did not change. The number of dominant species reduced from three to one species in spring but a new dominant species appeared in autumn. Phytoplankton diversity index decreased by 32.32%-85.52% and the vertical distribution of standing biomass did almostly not changed.