Ecological health assessment of urban lake based on phytoplankton—A case study of Lake Xihu, Tongling, lower reaches of the Yangtze River

Abstract

为了解铜陵西湖浮游植物群落结构与水生态健康状况，于2016年9月至2017年7月进行6次调查.结果显示：（1）浮游植物共检出6门88种，总密度变化范围为8.20×10⁵~1.60×10⁸ cells/L，均值为2.19×10⁷cells/L，生物量变化范围为1.34~27.76 mg/L，均值为9.45 mg/L，优势种为铜绿微囊藻（Microcystis aeruginosa）、浮游蓝丝藻（Planktothrix sp.）和微囊藻（Microcystis sp.）；（2） RDA分析表明浮游植物生物量主要受水温、悬浮物、总氮、亚硝态氮和总磷影响；（3）浮游植物隶属于22组功能群，基于功能群的Q指数表明，铜陵西湖水质整体处于“中等”状态，7月水生态状况最差，11月最佳；（4）依据候选参数与环境因子的相关性，最终选定生物量、密度和Margalef指数来构建铜陵西湖浮游植物生物完整性指数（P-IBI），其评估结果与Q指数呈显著正相关，但P-IBI评估结果（整体为“较差”状态）更为严格.本研究阐述铜陵西湖浮游植物群落结构特征，并基于浮游植物Q指数和P-IBI评估其生态健康状况，相关研究结果可为其水环境管理及城市湖泊生态健康评估提供一定的科学参考.;In order to establish phytoplankton community structure and assess ecological condition in Lake Xihu (Tongling), 6 times of sampling were conducted from September 2016 to July 2017. A total of 88 phytoplankton species from 6 phyla were identified. The phytoplankton density varied from 8.20×10⁵ cells/L to 1.60×10⁸ cells/L, and the mean was 2.19×10⁷ cells/L. The biomass varied from 1.34 mg/L to 27.76 mg/L, with a mean of 9.45 mg/L. Phytoplankton were mainly dominated by Microcystis aeruginosa, Planktothrix sp. and Microcystis sp.. Phytoplankton biomass was mainly affected by water temperature, suspended solids, total nitrogen, nitrite, and total phosphorus. There were 22 functional groups were identified, and the Q index indicated that the lake was in moderate condition, with the worst and best ecological conditions in July and November, respectively. Three critical indices, i.e., biomass, density, and Margalef, were selected to establish the index of biotic integrity based on phytoplankton (P-IBI) of Lake Xihu, according to the correlations among indices and environmental parameters. Correlation analysis suggested that the P-IBI was significantly and positively correlated with the Q, while the ecological conditions were significantly worse according to the P-IBI (the overall state is low). This study established phytoplankton community structure in Lake Xihu (Tongling), and evaluated its ecological condition based on Q and P-IBI indices, which will provide a certain reference for its water environment management and ecological condition assessment of lake in urban.