Chlorophyll a (Chla) and diatom community structure are two indicators of lake water quality. In this study, we investigated the environmental parameters, chlorophyll a, and diatom community of four small urban lakes in Kunming (Beitan, Beihu, Nanhu and Longtan lakes in the campus of Yunnan Normal University) between March 2017 and December 2019. The results showed that the concentrations of total nitrogen (TN), total phosphorus (TP), and Chla in the four lakes showed significant seasonal fluctuation. The Chla concentration in Nanhu Lake, which had the highest nutrient level among the four lakes, was significantly higher than that in the other three lakes and largely affected by TN. In comparison, water temperature significantly contributed to the increases in Chla concentration in the other three lakes. Water temperature and TN were significantly correlated with Chla across the four lakes. Diatom assemblages in Beitan, Nanhu, and Longtan lakes were dominated by planktonic diatoms, and benthic diatoms were dominant in the shallowest lake Beihu, suggesting that water depth significantly affected the proportion of planktonic diatoms and dominant taxa. Water depth, TN, TP, transparency, and water temperature affected the spatio-temporal changes of diatom community structure, with water temperature as the major factor in causing the seasonal variation in diatom community, and TN and TP as the major drivers for community variation among lakes within the same season.
水体叶绿素a浓度(Chla)与硅藻群落特征是指示湖泊水质的常用生物指标。本研究于2017年3月—2019年12月调查了昆明市4个小型湖泊(云南师范大学校园内北潭、北湖、南湖、龙潭)的水体环境指标、Chla浓度和硅藻群落的季节变化。结果显示: 4个湖泊水体总氮(TN)、总磷(TP)和Chla浓度均呈现明显的季节波动。其中,营养水平最高的南湖水体Chla含量显著高于其他3个湖泊,影响南湖Chla变化的主要因子是TN;而在其他3个水体中,水温的增加显著促进了Chla浓度的上升。水温和TN是4个湖泊水体Chla时空变化的主要驱动因子。北潭、南湖和龙潭的硅藻群落以浮游硅藻占优,水深最浅的北湖以底栖硅藻为主,表明水深影响了硅藻群落的浮游物种占比与优势属种。水深、TN、TP、透明度以及水温驱动了硅藻群落的时空变化,其中,水温是影响硅藻群落季节差异的主要因子,而TN和TP是导致同一季节湖泊间硅藻群落差异的主要因子。.
Keywords: chlorophyll a; diatoms; eutrophication; spatio-temporal pattern; urban lake.