Thermocline stratification favors phytoplankton spatial overlap and species diversity in a subtropical deep reservoir

Li Wang; Jiarui Liu; Zhen Bao; Xufa Ma; Hong Shen; Ping Xie; Jun Chen

doi:10.1016/j.scitotenv.2023.169712

Thermocline stratification favors phytoplankton spatial overlap and species diversity in a subtropical deep reservoir

Sci Total Environ. 2024 Feb 25:913:169712. doi: 10.1016/j.scitotenv.2023.169712. Epub 2023 Dec 30.

Authors

Li Wang¹, Jiarui Liu², Zhen Bao³, Xufa Ma⁴, Hong Shen², Ping Xie², Jun Chen⁵

Affiliations

¹ Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
² Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
³ Hangzhou Ecological Environment Monitoring Center of Zhejiang, Hangzhou 31000, China.
⁴ College of Fisheries, Huazhong Agricultural University, Wuhan 430070, China.
⁵ Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: chenjun@ihb.ac.cn.

PMID: 38160822
DOI: 10.1016/j.scitotenv.2023.169712

Abstract

Spatial segregation of species along opposing resource gradients is a major research topic in ecology as it enables the coexistence and maintenance of high diversity. Thermocline stratification causes heterogeneous resource distribution, however, the effect of thermocline stratification on phytoplankton dynamic in-depth profiles is still unclear. To understand the underlying mechanism behind the effects of thermocline stratification on phytoplankton species diversity in stratified lakes, the monthly changes in thermocline parameters, deep chlorophyll maxima (DCM) parameters, spatial overlap (SO) among major phytoplankton taxonomic groups, and phytoplankton species diversity were evaluated in Lake Qiandaohu in the Zhejiang Province of China from April 2017 to December 2018. Thermocline depth (TD) was significantly negatively related to thermocline strength (TS). The monthly air temperature was the main driver behind the thermocline and the seasonal thermal-stratification cycle was divided into two stratification stages. Significant linear relationships were observed between the DCM parameters (depth, concentration, and thickness) and TD during the strong stratification period. TD was significantly positively related to phytoplankton species diversity and the SO between Cryptophyta and Chlorophyta as well as between Cryptophyta and Bacillariophyta during weak stratification periods. Significant positive correlations were observed between SO and Shannon diversity during both periods. Structural equation modeling (SEM) showed that air temperature significantly decreased TD and increased species diversity by increasing SO during the strong stratification period. Strong stratification under warming favored the formation of shallower and thinner DCMs, leading to phytoplankton coexistence and maintenance of high species diversity through a preclusion of dominance. This study characterized the temporal dynamics of phytoplankton dynamic in-depth profiles in response to strong stratification from warming.

Keywords: Deep chlorophyll maxima; Spatial overlap; Species diversity; Thermocline depth; Vertical distribution of phytoplankton.

MeSH terms

China
Chlorophyll
Diatoms*
Ecology
Lakes / chemistry
Phytoplankton*
Seasons

Substances

Chlorophyll