浮游植物群落对海南小水电建设的响应

为探讨浮游植物群落对海南省小水电建设的响应,分别在海南省主要河流的上游支流已建小水电的蓄水水域与河道、规划(未建)小水电河段采集浮游植物样品进行比较分析.共鉴定出浮游植物种类62个属178种,曲壳藻(Achnanthaceae)、异极藻(Gomphonema)、菱形藻(Nitzschia)、颗粒直链藻(Melosira granulat)、席藻(Phormidium)、颤藻(Oscillatoria)、小球藻(Chlorella vulgaris)、平裂藻(Merismopedia)、舟形藻(Navicula)为主要的优势藻类,浮游植物丰度在5.1-163.6×104个/L之间,浮游植物Shannon-Wiener多样性指数在2.73-4.53之间.研究结果表明,小水电建设对浮游植物的种类组成、优势种、丰度及多样性均有较大的影响.就浮游植物优势种而言,规划小水电河道以蓝藻及部分硅藻为主要优势种,已建小水电河道曲壳藻、异极藻、菱形藻等大型硅藻为主要优势种.在浮游植物组成及生物多样性上,未建小水电河道浮游植物Shannon-Wiener多样性指数略高,且种属分布更加均衡,而已建设水电站均趋向某一类藻占主导优势种.就浮游植物丰度而言,规划小水电河道浮游植物丰度均保持在20-30×104个/L内,已建小水电河段浮游植物保持在5-160×104个/L内且浮游植物丰度差异性较规划小水电大,小水电建设促进了浮游植物丰度的提升,但降低了浮游植物群落结构的稳定性、均衡性.虽然存在水电站阻隔,同一河流水系浮游植物种属来源仍可表现一定的趋同性,梯级水电特别是相邻水电间浮游植物群落组成存在较大的相似性.

Responses of phytoplankton community to the construction of small hydropower stations in Hainan Province

Small hydropower stations (SHS) not only play an important role in electricity generation and water resource regulation in mountain areas, but also at the same time, impose ecological and environmental impacts. To study the responses of phytoplankton community in rivers with construction of SHS, samples of phytoplankton from 7 rivers in Hainan Province where SHS had been or will be built were taken and analyzed. According the results, a total of 178 phytoplankton species belonging to 62 genera were identified, and the dominant species includes Achnanthaceae, Gomphonema, Nitzschia, Melosira granulat, Phormidium, Oscillatoria, Chlorella vulgaris, Merismopedia, and Navicula. Phytoplankton abundance in rivers was from 5.1×10⁴cells/L to 63.6×10⁴cells/L, the diversity index was from 2.73 to 4.53, and Desmids had been found in most SHS. SHS had a great influence on phytoplankton biomass, species composition and dominant species in the rivers. Comparing with thfe rivers with SHS, the rivers without SHS had higher Shannon-Wiener diversity index and the composition of phytoplankton species were more balanced, Cyanobacterias and some Diatoms always dominated the phytoplankton community in the rivers, such as in NDJ-JJ-9 (Cyanophyta 25.7%,Chlorophyta36.9%, Bacillariophyta 36.1%), ZBJ-MMD-11 (Cyanophyta 41.8%, Chlorophyta 33.2%,Bacillariophyta 23.1%), and WLH-SX-13(Cyanophyta 29.1%, Chlorophyta 25.2%, Bacillariophyta 38.8%). In the rivers with SHS, large diatom Achnanthacea,Gomphonema and Nitzschia becoming predominated were common, such as in CHJ-YJ-1 (Bacillariophyta 91.3%), CHJ-YJ-2 (Bacillariophyta 65.9%), and NDJ-GL-6 (Bacillariophyta 56.5%).To phytoplankton abundance, most rivers without SHS were 20-30×10⁴cells/L, while the rivers with SHS were widely different 5-160×10⁴cells/L. The rivers with SHS had higher average abundance and abundance difference index than the ones without SHS. The construction of SHS had changed the hydrodynamic of the rivers, and the changed hydrodynamic might had played an important role in the phytoplankton community. In mountain areas of Hainan province, most rivers were Shallow with less water flow. Stable water environment was suitable for Cyanobacterias and some Diatoms in the river without any SHS. Once SHS had been built, agitation of water body increased and lager Diatoms such as Achnanthaceae Gomphonema and Nitzschia might be dominated. The construction of SHS would also promoted the biomass of the river, but weaken the stability and proportionality of phytoplankton community by increasing fluctuation and agitation. Among cascade SHS, the barrier of the stations, the phytoplankton community could still be some similar especially between adjacent SHS. The correlation coefficient of phytoplankton community between adjacent SHS were all over 0.9 with highly significant correlation(P<0.01).