Variation of phytoplankton communities and their driving factors along a disturbed temperate river-to-sea ecosystem

• Published in: Ecological indicators Vol. 118; p. 106776
• Main Authors: Zhang, Shasha, Xu, Hangzhou, Zhang, Yanfang, Li, Yizhen, Wei, Jielin, Pei, Haiyan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2020
• Subjects: algae; anthropogenic activities; Anthropogenic effects; aquatic ecosystems; biodiversity; China; community structure; Cyclotella meneghiniana; Environmental variables; Fragilaria; humans; nitrogen; organic matter; phosphorus; Phytoplankton; River ecosystem; rivers; watersheds; wetlands; China; River ecosystem; Phytoplankton; Anthropogenic effects; Environmental variables
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2020.106776

[Display omitted] •Cyclotella meneghiniana predominates over Cyclotella gamma along the river.•Variation of river’s algal diversity accords with intermediate disturbance hypothesis.•DO and organics positively affect algae in source and anthropic area, respectively.•Human disturbance more clearly affects abundant taxa rather than rare taxa. Phytoplankton, as an important primary producer in rivers, greatly affects an aquatic ecosystem’s function and biodiversity. However, the effect of human activities on phytoplankton community composition remains largely unstudied in rivers. Herein a typical temperate river, Xiaoqing River in the north of China, was the target to investigate the phytoplankton distribution and regime along stretches subject to different human disturbances. Other than in the wetland located in a tributary of the river, which had Cyanophyta as the dominant phylum, Bacillariophyta overwhelmingly predominated across the sampling sites. Notably, the main genus was Fragilaria in the source region of the river, while Cyclotella dominated along the trunk of the river, and the main species shifted from Cyclotella gamma Sovereign to Cyclotella meneghiniana Kützing when the river entered the sea. Phytoplankton community structures in the source region were affected to some extent by DO and pH, and in the human activity areas were mainly influenced by nitrogen, phosphorus, and CODMn. Human interference led to a decrease in diatom density by increasing the concentration of nutrients and organic matter. Furthermore, algal diversity was higher and density was lower in the disturbed areas than in the catchment areas, in accordance with the intermediate disturbance hypothesis. It was also found that human activities more obviously affected the abundant than rare phytoplankton communities.