Phytoplankton functional groups succession and their driving factors in a shallow subtropical lake

Abstract

The succession of phytoplankton functional groups and environmental variables were investigated from January to December 2018 in a shallow subtropical lake, East Taihu Lake, located in the Yangtze Delta of China. Altogether, 125 genera, 21 functional groups, and 7 predominant functional groups, D (Fragilaria acus, Synedra acus, and Nitzschia spp.), P (Fragilaria capucina and Aulacoseira granulate), MP (Oscillatoria spp., Diploneis ovalis, Gomphonema angustatum, Nitzschia palea, and Achnanthes spp.), Y (Cryptomonas ovata, Cryptomonas erosa, Chroomonas acuta, and Ceratium spp.), H2 (Anabaena spp.), M (Microcystis spp.), and W1 (Euglenoids spp.), were identified, and these predominant functional groups exhibited strong seasonal variations. Groups Y and W1 dominated from winter to spring when temperature and light were low. The external pollution load and high levels of nutrients entered the lake in June, allowing group M to become dominant, even ultimately triggering Microcystis blooming. Meanwhile, the abundance of aquatic plants in summer, combined with high levels of transparency and light availability, resulted in Group M being replaced by Group P and then Groups M and H2 rebounding in autumn. The redundancy analysis revealed that water temperature, nutrients, and light availability (Z eu /Z mix ) were the key factors promoting phytoplankton succession. The ecological assessment results demonstrated a good ecological status based on the assemblage index (Q average ¼ 3.0). This work emphasizes the fact that temperature, nutrients, and light were the driving factors for phytoplankton dynamics, and aquatic plants and external pollution were important external factors for the succession of phytoplankton.

Environmental heterogeneity affecting spatial distribution of phytoplankton community structure and functional groups in a large eutrophic lake, Lake Chaohu, China

“…In this study, the dominant functional groups M, H2, MP, and J are all positively correlated with water temperature (WT), and RDA also shows that WT (15%) has the highest interpretation rate of phytoplankton functional groups, indicating that WT is a crucial limiting factor for the dynamics of phytoplankton functional groups in Lake Chaohu. Similar observations have been reported in Lake Santa Lucia, Lake East Taihu, and Lake Okeechobee (Silva et al 2018 ; Nan et al 2020 ; Ma et al 2022 ). In Lake Chaohu, function groups Y and N are dominant in winter, and they are related to low temperature and high turbidity, consistent with the findings of other studies (Xu et al 2011 ; Nan et al 2020 ).…”

“…In this study, the relative biomass of dominant functional group H2 rises in autumn and occupies a higher proportion in Location IV. Furthermore, function group MP is mainly composed of Bacillariophyta species in spring but Cyanophyta species in autumn with increasing water temperature and nutrient concentrations; similarly, research findings have been reported in other aquatic ecosystems such as Lake Luoma, Lake East Taihu, and Daning River (Zhu et al 2013 ; Tian et al 2018 ; Nan et al 2020 ). In this study, the dominant functional groups M, H2, MP, and J are all positively correlated with water temperature (WT), and RDA also shows that WT (15%) has the highest interpretation rate of phytoplankton functional groups, indicating that WT is a crucial limiting factor for the dynamics of phytoplankton functional groups in Lake Chaohu.…”

“…Moreover, in this study, the relative biomass of dominant function group M in Location I is higher than that in the other three locations (Locations II, III, and IV), in which it relates to a large number of nutrients and exogenous organic substances from Shiwuli River, Nanfei River, and Paihe River (Jiang et al 2014 ; Zhong et al 2019 ). In some researches, functional group H2 grows well under low nitrogen, low light, and high phosphorus, and its biomass decreases with rising water levels (Padisák et al 2006 ; Yang et al 2016 ; Nan et al 2020 ). In this study, the relative biomass of dominant functional group H2 rises in autumn and occupies a higher proportion in Location IV.…”

Environmental heterogeneity affecting spatial distribution of phytoplankton community structure and functional groups in a large eutrophic lake, Lake Chaohu, China

“…In this study, Function group MP dominated by Bacillarioplyta species in spring, and it changed to Cyanophyta in autumn with the increase of WT and nutrient concentrations. The same research results were also found in Lake Luoma, Lake East Taihu, and Daning River(Zhu et al, 2013;Tian et al, 2018;Nan et al, 2020). Moreover, the dominant functional groups M, H2, MP and J were all positively correlated with WT in this study, and RDA showed that WT (15%) had the highest interpretation rate of phytoplankton functional groups, indicating that WT was one of the key factors limiting the dynamics of phytoplankton functional groups in Lake Chaohu.…”

“…Moreover, the relative biomass of function group M in Location I was higher than the other three locations (Locations II, III and IV), and a large number of nutrients and exogenous organic substances from Shiwuli River, Nanfei River, and Paihe River were responsible for the water quality of this area(Jiang et al, 2014;Zhong et al, 2019). Usually, functional group H2 grows well under low nitrogen, low light and high phosphorus, and its biomass decreases with rising water levels(Padisák et al, 2006;Nan et al, 2020;Yang et al, 2016). In this study, the relative biomass of H2 rises in autumn and occupies a higher proportion in Location IV.…”