浮游植物群落对不同沉水植物生境的响应

Responses of phytoplankton to different submerged plant habitats

结合沉水植物的生长状况及其对水质的改善效果,从浮游植物的密度、生物量、群落结构以及生物多样性的角度探讨了浮游植物群落对不同沉水植物生境的响应过程。结果显示:4种沉水植物对水体中TN、NO_3^--N有明显的去除效果,去除效率依次为常绿苦草>普通苦草>马来眼子菜>黑藻;伴随着沉水植物生长引起的生境差异和水质条件的变化,浮游植物优势种类由单一隐藻门转变为隐藻门、硅藻门、绿藻门及蓝藻门的种类同时占优势;从浮游植物的生物量、生物多样性指数和均匀度指数来看,不同供试沉水植物之间有较大差异,均以其中水质改善效果相对较差的黑藻处理为最大,全年平均值分别为1.485 mg/L、2.2和0.62,表明黑藻生境对浮游植物生长的抑制作用较小,有利于浮游植物形成稳定复杂的群落结构;浮游植物生物量与营养盐水平显著正相关,Shannon-Wiener多样性指数及Pielou均匀度指数与氮磷比显著负相关。

Combining with the growing conditions of submerged macrophytes and their improve- ments of water quality, this paper explored the effect of submerged macrophytes reconstruction on phytoplankton community in term of the density, biomass, community structure, and bio-diversity of phytoplankton. The results showed that four submerged macrophytes all have significant removal effi- ciency on TN,NO3- -N with the order Vallisneria longipedunculata （G）〉 Vallisneria spiralis（P）〉Potamgeton malaianus （M）〉Hydrilla verticillata （H）. The dominants of phytoplankton were turned after the reconstruction of submerged macrophytes, from Cryptophyta alone to Cryptophyta associated with Bacillariophyceae, Chlorophyta, Cyanophyta. Biomass, bio-diversity and uniformity index of phyto- plankton were also different under four submerged macrophytes habitat,with the highest annual mean in Hydrilla verticillata （H）pits, which were 1. 485 mg/L, 2.2 and 0.62 respectively. These indicated that Hydrilla verticillata （H）habitat was benefit for phytoplankton to form a complex and stable com- munity structure even it was inefficient in nutrients removal. The biomass of phytoplankton was signif- icantly positive correlation with the nutrients in water, and bio-diversity and uniformity index were negatively correlated with phosphorus.