太湖浮游植物群落结构及其与水质指标间的关系

Structure of Phytoplankton Community and Relationship between Phytoplankton Community and Water Quality in Taihu Lake

为了探讨太湖浮游植物群落结构时空分布特征、以及太湖浮游植物群落指标与水质指标间的关系,于2013年1月─2013年12月对太湖7个点位浮游植物群落结构和水质指标(水温、透明度、p H、溶解氧、电导率、总氮、总磷、氨氮、高锰酸盐指数、化学需氧量、氟化物、生化需氧量、硝酸盐氮、亚硝酸盐氮、溶解性磷酸盐和叶绿素a)进行月度调查,研究其浮游植物群落结构和湖泊水质的时空分布;并利用Pearson相关性分析浮游植物密度、浮游植物多样性与水质指标间的关系;找出影响太湖浮游植物群落结构的主要水质指标。结果表明:太湖7个点位共获得124种浮游植物物种,其中蓝藻门(Cyanophyta)30种、绿藻门(Bacillariophyta)47种、硅藻门(Chlorophyta)34种、隐藻门(Cryptophyta)3种、裸藻门(Euglenophyta)6种和甲藻门(Dinoflagellate)4种;其中蓝藻门的微囊藻属(Microcystis spp.)为绝对优势种群,优势度为80.8%;太湖浮游植物总密度与蓝藻门密度呈极显著正相关(r=1.000,P<0.000 1);绿藻门和硅藻门占浮游植物总密度百分比分别和蓝藻门占浮游植物总密度百分比呈极显著负相关(r=-0.497,P<0.000 1;r=-0.814,P<0.000 1)。太湖7个点位水质首要污染物为总氮,其次是总磷和化学需氧量;西太湖污染物浓度最高。从空间上看,太湖浮游植物总密度最高值出现在贡湖湾(远离其入湖口处),且贡湖湾浮游植物群落多样性相对低于太湖其他点位,同时贡湖湾微囊藻属密度百分比达90.1%,远高于太湖其他点位;从时间上看,太湖浮游植物总密度最高值出现在12月份、其次是6月份;通过浮游植物群落指标与水质指标相关性分析,水温、透明度、总氮、化学需氧量、叶绿素a是影响太湖浮游植物群落结构的主要水质指标。控制太湖入湖口水质污染物浓度排放和修复水生态环境是太湖蓝藻治理的有效方法,同时加强太湖入冬藻类监测以预防冬季太湖蓝藻爆发。

To research the structure of phytoplankton community and relationship between phytoplankton community and water quality in Taihu Lake, phytoplankton community structure and water quality indicators （temperature, transparency, pH value, dissolved oxygen, conductivity, total nitrogen, total phosphorus, ammonia, high manganese on permanganate index, chemical oxygen demand, fluoride, biological oxygen demand, nitrate, nitrite, phosphate solubility and chlorophyll a） were monthly investigated at seven sites in Taihu Lake between January and December of 2013 in our study. Meanwhile, Pearson’s correlations between phytoplankton communities and environmental variables were used to find the factors that influenced the distribution of phytoplankton community. The results found that there were 124 species of phytoplankton, including 30 taxa Cyanophyta, 47 kinds of Bacillariophyta, 34 species Chlorophyta, 3 Cryptophyta, 6 Euglenophyta, 4 Dinoflagellate; as an absolute dominant species, dominance of Microcystis spp. was 80.8 %. From space, phytoplankton density in Gonghu was highest among the seven sites. Diversity of phytoplankton community was lower than other sites. Meanwhile, density percentage of Microcystis spp. in Gonghu was 90.1%, far higher than other sites. From the time point of view, December was when the density of phytoplankton community in Taihu Lake was highest, followed by June. The principal pollutant was total nitrogen, secondly total phosphorus, thirdly chemical oxygen demand. Concentration of pollutants in West Taihu was highest in our study. Through correlation analysis of phytoplankton community and water quality, it showed that water temperature, transparency, total nitrogen, chemical oxygen demand and chlorophyll a were main factors that influenced phytoplankton community structure in Taihu Lake. Controlling water pollutant emissions and restoring ecological function should be an effective method to manage cyanobacteria bloom in Taihu Lake. Meanwhile, enhancing times of algae monitoring in winter will be to prevent outbreak of algae in Taihu Lake.