崇明岛河道浮游植物群落时空变化及影响因子OA

To investigate the spatiotemporal variations of phytoplankton communities and their influencing factors in the waterways of Chongming Island,this study conducted quarterly surveys on phytoplankton community structure and water quality factors at 24 monitoring sites across the island from 2019 to 2021(data for Summer 2020 was missing due to the COVID-19 pandemic).Using methods such as diversity indices,dominant species identification,and Redundancy Analysis(RDA),the characteristics and driving factors of the community structure were systematically analyzed.The results showed that a total of 236 phytoplankton species,belonging to 7 phyla,were identified,primarily dominated by Bacillariophyta,Chlorophyta,and Euglenophyta.The dominant species comprised 14 species from 3 phyla,with Cyanobacteria accounting for the highest proportion(42.96%),followed by Bacillariophyta and Chlorophyta(each 28.57%).Phytoplankton abundance ranged from 3.49×106 to 2.17×107 cells/L,with the overall community structure showing a successional trend towards a Bacillariophyta-Cyanobacteria-Chlorophyta type.Total biomass ranged from 0.927 to 4.794 mg/L,with the proportion of Bacillariophyta biomass continuously increasing,while that of Cyanobacteria decreased significantly.RDA indicated that salinity(Sal)and pH were the significant water quality factors affecting community structure(P<0.05).The Shannon-Wiener index(H')ranged from 1.50 to 2.61,the Margalef richness index(D)from 1.02 to 2.24,and the Pielou evenness index(J)from 0.44 to 0.79,suggesting the overall water quality was generally mesotrophic,specific regions display distinct signs of eutrophication and pollution.The study demonstrates significant spatiotemporal heterogeneity in the phytoplankton community structure of Chongming Island's waterways,regulated by the combined effects of Sal,pH,and nutrients,indicating a certain risk of eutrophication.This research can provide a scientific basis for water ecological management,eutrophication prevention and control,and biodiversity conservation in Chongming Island.