Environmental variability shapes ecological uniqueness and phytoplankton contributions in urban lakes

Abstract Urban lakes provide critical ecosystem services, yet they are under increasing threat from anthropogenic pressures, such as pollution and habitat degradation. This study evaluates the effects of environmental variability on phytoplankton beta diversity in urban lakes, using local contributions to betadiversity (LCBD) and species contributions (SCBD) as key metrics. Phytoplankton were sampled from 14 urban lakes in Goiânia, Goiás, Brazil, during both rainy and dry periods from 2022 to 2024. The LCBD and SCBD metrics were related to local and temporal environmental conditions, trophic state, species richness, and phytoplankton density. The results showed that lower species richness is associated with higher LCBD. This indicates that LCBD decreases as lake richness increases. Cyanobacteria, for example, made significant contributions to beta diversity (higher SCBD). Additionally, SCBD was positively correlated with phytoplankton density, highlighting the importance of species identity in shaping community structure. These findings underscore the importance of LCBD and SCBD in guiding conservation and management efforts and in prioritizing the protection and restoration of biodiversity in urban lake networks.