Local environmental variables outperform spatial and land use pattern in the maintenance and assembly of phytoplankton communities in the wetland cluster

Phytoplankton is a crucial primary producer in wetland ecosystems and is highly sensitive to changes in water quality. It has long been considered one of the most important biological indicators for monitoring water pollution. However, our understanding of the various aspects of phytoplankton communities assembly and the factors driving them remains limited. In this study, we conducted collection and analysis of phytoplankton samples from a temperate wetland cluster encompassing both lake and marsh types under the backdrop of industrial pollution from the petroleum industry. Our aim was to investigate the influence of spatial factors, land use patterns, and local environmental variables on the taxonomic and functional structure of the phytoplankton community, utilizing structural equation modeling (SEM) and variation partitioning. Our results revealed that environmental filtering exerts a greater relative impact on shaping the taxonomic composition of phytoplankton compared to mass effects. Human activities, such as industrial and agricultural production, can lead to landscape modifications that increase water nutrient levels and consequently influence the community composition. Taxonomic beta diversity is determined by both mass effects and environmental filtering. In contrast, functional beta diversity responds more to local environmental gradients, while the land use pattern was not important for facets of beta diversity in the wetland cluster. These results validate the concordance and complementarity between functional and taxonomy-based biome structures, highlighting the significance of integrating multiple ecological drivers. The results of this study contribute to a deeper understanding of wetland community assembly and the processes of biogeography, and are of crucial significance for the biological monitoring and management of freshwater ecosystem environmental pollution.