![]() Succession of phytoplankton is related to multiple environmental factors such as nutrient concentrations, temperature, and quantity and quality of light in aquatic systems ( Malik and Saros, 2016 Paerl et al., 2016 Thomas et al., 2017). Compositions of species in algal communities are widely used to quantify temporal fluctuations and succession of aquatic ecosystems ( Rodrigues et al., 2015 Wu et al., 2017 Cupertino et al., 2019). Due to their small sizes, short life cycles of individual taxa and rapidly changing community structures, successional changes in phytoplankton communities are useful, rapid, integrative indicators of ecosystem status and trends in aquatic systems ( Camp et al., 2015 Zwart et al., 2015). Phytoplankton, including planktonic algae and cyanobacteria, are primary producers in aquatic ecosystems, which play key roles in providing food for and affecting other organisms, and in turn are regulated by interactions with other organisms ( Hutchins and Boyd, 2016 Kohlbach et al., 2016). ![]() Because the lake is eutrophic and there were already sufficient nutrients available, additional nutrients had little effect on seasonal taxonomic and functional diversity of phytoplankton in Lake Erhai. Most diversity indices of taxonomic and functional groupings were significantly correlated with solar irradiance, but not nutrient concentrations. Instead, the entire phytoplankton community assemblages were important in the pattern. This synchronous temporal pattern was not principally driven by the dominant genera ( Microcystis, Psephonema, and Mougeotia). In order to exclude the influence of dominant species' tolerance to extreme environments, the dominant species were excluded one by one, and the results showed that residual communities still exhibited similar patterns of succession. Significant, positive relationships were observed between taxonomic diversity and functional diversity that were strongly linked through seasons. Alpha diversity and beta diversity, as measured by Shannon-Wiener and Bray-Curtis indices of taxonomic grouping and three functional groupings (FG, MFG, and MBFG) were applied to investigate environmental factors determining diversity. Here, we analyzed absolute and relative proportions of a phytoplankton community during a 3-year period in Lake Erhai, a eutrophic highland lake in China. However, to what extent these taxonomic and functional groupings are congruent at seasonal time-scales and the main environmental factors, which drive succession, have remained less studied. Recently, according to functional groupings, including functional groups (FG), morpho-FG (MFG), and morphology-based FG (MBFG), functional diversity has been used to represent functional aspects of phytoplankton communities. Traditionally, taxonomic diversity based on morphologies has been the measure used for analysis of responses to environmental factors. Populations of phytoplankton can be controlled by bottom-up factors such as nutrients and temperature or top-down such as predation by zooplankton. Information on temporal dynamics of phytoplankton communities and their responses to environmental factors can provide insights into mechanisms driving succession of phytoplankton communities that is useful in programs to manage and or remediate undesirable assemblages. ![]()
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