Seasonal variation of phytoplankton community assembly processes in Tibetan Plateau floodplain

Abstract

Uncovering the mechanisms underlying phytoplankton community assembly remains a major challenge in freshwater ecology. The roles of environmental filtering and spatial processes in shaping phytoplankton metacommunity in Tibetan floodplain ecosystems under various hydrological conditions are still unclear. Here, multivariate statistics and a null model approach were used to compare the spatiotemporal patterns and assembly processes of phytoplankton communities in the river-oxbow lake system of Tibetan Plateau floodplain between non-flood and flood periods. The results showed that phytoplankton communities had significant seasonal and habitat variations, with the seasonal variations being more remarkable. Phytoplankton density, biomass, and alpha diversity were distinctly lower in the flood than non-flood period. The habitat differences (rivers vs. oxbow lakes) in phytoplankton community were less pronounced during the flood than non-flood period, most likely due to the increased hydrological connectivity. There was a significant distance–decay relationship only in lotic phytoplankton communities, and such relationship was stronger in the non-flood than flood period. Variation partitioning and PER-SIMPER analysis showed that the relative role of environmental filtering and spatial processes affecting phytoplankton assemblages varied across hydrological periods, with environmental filtering dominating in the non-flood period and spatial processes in the flood period. These results suggest that the flow regime plays a key role in balancing environmental and spatial factors in shaping phytoplankton communities. This study contributes to a deeper understanding of ecological phenomena in highland floodplains and provides a theoretical basis for floodplain ecosystem maintenance and ecological health management.

PacBio Sequencing Reveals Microbial Community Diversity in Man-made and Natural Habitats

“…The habitats contained a large unique species as follows, outlet (n = 10079), inlet (n = 6960), and surface water (n = 6680). It is important to note that the microbial communities in the surface water of the river can vary due to multiple factors, including natural processes, land use patterns, and seasonal variations [28,29]. However, the distinct differences observed between the inlet and outlet of WWTP and the river water indicate the substantial influence of wastewater treatment processes on the microbial composition [30][31][32].…”

Main predictors of phytoplankton occurrence in lotic ecosystems

“…The dynamics of phytoplankton metacommunities has received increasing attention in Brazilian scientific studies, however, floodplains (Devercelli et al, 2016;Diniz et al, 2023) and lentic environments, such as lakes or reservoirs (e.g., Bortolini et al, 2017Bortolini et al, , 2019Wojciechowski et al, 2017;Rodrigues et al, 2018;Loaiza-Restano et al, 2020), are addressed more frequently. The phytoplankton present in lotic environments is still poorly explored (Huang et al, 2023). In this sense, Medeiros et al ( 2022) evaluated Relative contributions (% explanation) of environment (E), spatial (S), historical metacommunity (HC) and landscape (L) explaining the variation in relative abundance in phytoplankton metacommunities from the seasons winter, spring, summer, autumn, winter and spring, the respectively C1 to C6.…”