杭州湾人工潟湖夏季浮游植物群落演替与环境因子的关系

Relationship between summer phytoplankton community succession and environment factors in the artificial lagoon of Hangzhou bay

摘要:

金山城市沙滩是东海杭州湾的一处人工潟湖，是上海首个滨海4A级景区，由于潟湖本身复杂的物理海洋学性质，为了确保金山城市沙滩水质优良，近年来一直在对其进行生态修复。本研究从2016至2018年，连续3年夏季对该潟湖浮游植物群落结构及其变化与环境因子之间的关系进行了调查，结果显示：2016—2018年夏季浮游植物种类不断增多，共发现浮游植物7门109种，其中硅藻门（Bacillariophyta）、蓝藻门（Cyanophyta）和绿藻门（Chlorophyta）种类较多。优势属共发现13个，优势度较大的是微囊藻属（Microcystis）、囊裸藻属（Trachelomonas）、直链藻属（Melosira）和小环藻属（Cyclotella），其中微囊藻属是夏季第一优势属，其他优势属重合度小。2016—2018年浮游植物丰度变化很大，分别为50.78×10⁴~5 957.52×10⁴个/L、5.35×10⁴~25.67×10⁴个/L和474.87×10⁴~1 026.94×10⁴个/L，其中微囊藻丰度最大，分别占97.88%、68.18%和77.23%。调查期间，浮游植物的多样性指数（H'）和均匀度指数（J'）先增大后减小，但总体呈上升趋势，而第一优势属优势度总体下降，说明经过生态修复，水体浮游植物群落发生正向演替，生态风险有减小趋势。RDA分析表明，总氮、总磷、铵盐、亚硝酸盐、无机磷和硅酸盐是影响浮游植物群落的重要环境因子。其中硅酸盐、亚硝酸盐、铵盐和无机磷与该潟湖的浮游植物群落相关性较大。

Abstract:

Jinshan City Beach is an artificial lagoon in Hangzhou Bay of the East China Sea, which is the first coast national AAAA level scenic spot in Shanghai. In order to control the water quality of Jinshan City Beach based on the complex physical oceanographic properties of lagoons, ecological restoration has been carried out in recent years. From 2016 to 2018, the relationship between phytoplankton community succession and environmental factors in this artificial lagoon was investigated for three consecutive summers. The results showed that the number of phytoplankton species increased in summer from 2016 to 2018(109 species of 7 phyla), the species of Bacillariophyta, Cyanophyta and Chlorophyta were dominant. A total of 13 dominant genera were found. The more dominant genera were Microcystis, Trachelomonas, Melosira and Cyclotella. Among them, Microcystis was the most dominant genus in summer, the overlap of other dominant genera was small. From 2016 to 2018, the abundance of phytoplankton varies greatly, ranging from 50.78×10⁴-5 957.52×10⁴ cells/L, 5.35×10⁴-25.67×10⁴ cells/L to 474.87×10⁴-1026.94×10⁴ cells/L respectively, of which Microcystis abundance was the largest, accounting for 97.88%, 68.18%, and 77.23%, respectively. During the survey, the diversity index (H') and evenness index (J') of phytoplankton increased and then decreased, but generally showed an upward trend, while the dominance of the first dominant genus generally decreased, which indicated that after ecological restoration, the phytoplankton community in Jinshan artificial lagoon was in a positive succession, and the ecological risk tended to decrease. RDA result showed that total nitrogen, total phosphorus, ammonium, nitrite, soluble reactive phosphorus and silicate were important environmental factors affecting phytoplankton community. Among them, silicate, nitrite, ammonium and soluble reactive phosphorus are more relevant to the phytoplankton community of the lagoon.