短期酸化对新安江流域屯溪段水体浮游植物群落结构及多样性的影响

Short-term Impact of Acidification on the Community Structure and Diversity of Aquatic Phytoplankton in Xin'anjiang River Basin( Tunxi Section

为了探讨酸雨引起的水体酸化对新安江流域屯溪段浮游植物群落结构、丰度以及多样性的影响,对该流域3个采样站点以及流域附近一小型人工湖泊内浮游植物（同源性不同）进行调查并模拟酸胁迫（p H值4.50、5.65）处理。经酸化处理24 h后,各采样站点浮游植物与未经模拟酸雨处理的对照组相比种类及丰度呈降低趋势;较低p H值下（4.50）金藻门、黄藻门种类消失,优势种类硅藻门和绿藻门浮游植物受到的影响较大,种属数降低范围为0%～75%和27.3%～79.2%,蓝藻门受影响较小,裸藻门、甲藻门种属数未受影响;整体上各站点辛普森多样性指数、香农-维纳指数经酸化处理后均呈降低趋势。水体酸化对浮游植物种类与丰度的抑制效应在高NH3-N和总磷水平下较小。研究结果表明,不同门类浮游植物对酸胁迫的敏感性有较大差异,群落组成不同的水体,短期酸化处理都会显著改变浮游植物群落结构、降低浮游植物丰度以及多样性。作为长期受酸雨胁迫较为严重的地区,酸雨引起的水体酸化将可能成为影响新安江流域浮游植物群落结构的重要因子。

In order to learn the potential effects of acid rain induced acidification on the community structure,abundance and diversity of freshwater phytoplankton,we simulated acid treatment at p H 4. 50 and 5. 65 and tested how acid shock affected the distributions of phytoplankton communities in Xin ＇anjiang River Basin（ Tunxi Section）. Three sampling sites of Xin＇anjiang River Basin（ Tunxi Section） and a small artificial lake near the water-shed were selected. Our results indicated that both species amount and the total number of phytoplankton were all reduced with deceased p H compared with the control treatment after 24 hours. The rare species of Chrysophyta and Xanthophyta were disappeared,and the number of dominant species of Bacillariophyta and Chlorophyta were decreased by acid shock in a range of 0%-75% and 27.3%-79.2%,respectively. However,Cyanophyta and the rare species of Euglenophyta and P yrroptata were less or not significantly affected by acid shock. Basically,both Simpson＇s diversity index and Shannon-Wiener index were decreased in consequence of water acidification / lowered in p H. The inhibition effects of acid shock on species richness and abundance were mitigated under waters with high NH3-N and total phosphorous concentrations. Based on the present results,we can get a conclusion that phytoplankton in different phylum showed different sensitivity to acid shock,and the community structure,the abundance and diversity of phytoplankton in waters with different species composition were all affected by the simulated acid treatments. As an area that frequently encounter with the stress of acid deposition,enhanced acid inputs are expected to be the key environmental factor in regulating the phytoplankton composition and biomass in Xin＇anjiang River Basin.