不同降雨强度对亚热带水源水库浮游植物群落结构的影响及其驱动因子

Effects of different rainfall intensities on the phytoplankton community structure of subtropical source water reservoirs and its driving factors

为了解降雨事件对亚热带水库浮游植物群落结构的影响,于2022年5月和6月分别在两次不同强度降雨期间进行浮游植物采集调查。结合浮游植物门分类和功能群分类方法,运用非度量多维尺度分析(NMDS)探究两次降雨以及降雨前后浮游植物群落的差异性,并采用冗余分析(RDA)和方差分析(VPA)探明浮游植物群落结构演替的驱动因子。结果表明:共检出浮游植物8门69属125种,功能群划分为11种,其中S1、SN、MP和N为主要功能群。降雨Ⅰ和降雨Ⅱ前后浮游植物群落结构均发生了变化:降雨Ⅰ期间由蓝藻向硅藻演替,且雨期硅藻占优;降雨Ⅱ期间由蓝藻向硅藻和绿藻轻微演替,但蓝藻始终处于绝对优势地位。雨期功能群SN和S1丰度百分比减小,而MP或N丰度百分比增大,与蓝藻向硅藻或绿藻演替的变化特征一致。冗余分析和方差分析表明,混合层深度(Z_(mix))、水温和营养盐共同驱动了浮游植物群落的演替,且门分类比功能群分类能更好地解释浮游植物群落变化。本文可为降雨条件下浮游植物的响应机制研究提供参考。

Phytoplankton surveys were carried out in May and June 2022 around two different intensities of rainfall events to better understand how rainfall affect the phytoplankton community structure in subtropical reservoirs.In combination of taxonomic and functional group classification methods,the variability of phytoplankton communities before and after the two rainfall events were examined in this study using non-metric multidimensional scaling(NMDS),and the driving factors behind the structural succession of phytoplankton communities were investigated using redundancy analysis(RDA)and variance partitioning analysis(VPA).The results showed that 125 species of phytoplankton were detected in 8 phyla and 69 genera,and the functional groups were divided into 11 species,among which S1,SN,MP,and N were the main functional groups.The phytoplankton community structure changed before and after Rainfall Ⅰ and Rainfall Ⅱ.The phytoplankton community evolved from Cyanobacteria to Bacillariophyta in Rainfall Ⅰ,and Bacillariophyta were dominant during the rainy period;whereas Cyanobacteria were always completely dominant in Rainfall Ⅱ,during which the phytoplankton community evolved slightly from Cyanobacteria to Bacillariophyta and Chlorophyta.In line with the succession of Cyanobacteria to Bacillariophyta or Chlorophyta,the relative abundance of functional groups SN and S1 decreased while that of MP or N increased during the rainy period.Redundancy analysis and Variance partitioning analysis showed that mixing depth(Z_(mix)),water temperature,and nutrients jointly drove the succession of phytoplankton communities and the taxonomic group classification could better explain the changes of phytoplankton communities than the functional group classification.This paper can served as a reference for the investigation of phytoplankton response mechanisms in the presence of precipitation.