三峡水库春季浮游植物群落特征及影响因素

浮游植物群落特征是水域生态系统的一个基础信息,三峡水库作为长江经济带环境保护的重要区域,而关于三峡水库全水域浮游植物群落特征及其影响因素的研究报道仍不多见。为了解三峡水库浮游植物群落特征差异及影响因素等一系列基础信息,于2015年4月对三峡水库进行了大范围的调查,调查范围包括17个长江断面(共51个样点)及22条支流库湾(共122个样点)。结果显示:共采集到浮游植物7门39属61种,以绿藻门、硅藻门、甲藻门为主,其中绿藻门有26种,占据总种数的42.62%;硅藻门有16种,占据总种数的26.23%;甲藻门有7种,占据总种数的11.48%。丰度方面,硅藻门占绝对优势,比例为34.26%,其次是隐藻门(23.72%)、蓝藻门(20.96%)。生物量方面,则是甲藻门占绝对优势,其比例达到了44.18%,随后是隐藻门(29.92%)、硅藻门(14.32%)。丰度和生物量分别变化在2.22×10~4～5.12×10~(7 )cells/L和0.001 8～120.99 mg/L之间,且存在一致的趋势,从三峡大坝往长江上游,丰度值和生物量值逐渐增加。支流库湾浮游植物Shannon-Wiener多样性指数显著高于长江干流(Mann-Whitney U检验,P0.001)。冗余分析(Redundancy Analysis,RDA)表明,在长江干流中,水温(WT)、可溶性硅酸盐(DSi)是影响浮游植物群落结构的主要环境因子(P0.001);在支流库湾中,硝态氮(NO~-_3-N)、水温(WT)是影响浮游植物群落结构的主要环境因子(P=0.002)。该研究的成果有助于全面认识了解三峡水库长江干流和支流库湾春季浮游植物种类组成和影响因子,同时对三峡水库水资源管理和水生态保护具有一定参考价值。

Community Characteristics of the Spring Phytoplankton in the Three Gorges Reservoir and the Influencing Factors

Phytoplankton community characteristics are a basic information of aquatic ecosystems. The Three Gorges Reservoir (TGR) is an important area of environmental protection in the Yangtze River Economic Zone, however the basic information for the phytoplankton community characteristics in the whole reservoir and the influencing factors are rarely reported. To fill this gap, the field survey, including 17 transects (51 sites) in 484km main channels of TGR and 22 tributary bays (122 sites), was carried out in April 2015 to investigate the fundamental information of the water environment and phytoplankton community. A total of 61 species, belonging to 39 genera in 7 phyla were identified. Specifically, for the richness, Chlorophyta (26 species) is the most important component, accounting for 42.62% of the total species number; followed by Bacillariophyta (16 species) for 26.23%, and Pyrrophyta (7 species) for 11.48%. For abundance, Bacillariophyta dominated in all phyla, accounting for 34.26% of the total abundance; followed by Cryptophyta for 23.72%, and Cyanophyta for 20.96%. For biomass, Pyrrophyta is the most important component, accounting for 44.18% of the total biomass; followed by Cryptophyta for 29.92%, and Bacillariophyta for 14.32%. The abundance and biomass of phytoplankton for each site in the Three Gorges Reservoir ranged from 2.22×104-5.12×107 cells/L and 0.001 8-120.99 mg/L, respectively. In addition, we found that i) both the values of abundance and biomass were increasing from the dam of TGR to the upper reache of the Yangtze River ii) the Shannon-Wiener diversity index of phytoplankton in the tributary bay was significantly higher than that in the main channel (Mann-Whitney U test, P < 0.001). Further, redundancy analysis showed that water temperature and dissolve silicate were the main environmental factors affecting the phytoplankton community in the main channel (P < 0.001); while, nitrate and water temperature were the main factors determining phytoplankton community in the tributary bays (P = 0.002). The results of this study give us a comprehensive understanding of the community structure of spring phytoplankton and the influencing factors in the TGR. Meanwhile, it also has some values for ecological protection and water resources management for the TGR.