Urban Forest Streams as Refugia for Freshwater Fish in a Century-Old Reforested Landscape

Urban refugia play an increasingly important role in conserving freshwater biodiversity within rapidly developing landscapes, yet empirical evidence from tropical urban streams remains limited, particularly in cities undergoing rapid land-use transformation. This study examines freshwater fish assemblages in three urban streams, including two located within a century-old reforested landscape to evaluate the capacity of urban forest streams to function as biodiversity refugia. A total of 19 species representing 11 families were recorded, with cyprinids dominating the assemblages across sites. Multivariate analyses revealed similarities in species composition between streams within the reforested landscape, while the remaining urban stream supported a distinct fish assemblage. Abundance–biomass comparisons indicated contrasting levels of community stability among streams, suggesting site-specific responses to environmental conditions. Overall, fish assemblage structure varied in relation to microhabitat features and water-quality conditions rather than urban proximity alone. These findings demonstrate that reforested urban streams can act as functional freshwater refugia, offering insights applicable to rapidly urbanizing regions worldwide where legacy forests and restored green spaces are increasingly incorporated into city landscapes.