Urbanization and stream identity shape beta diversity and its components: evidence from stream-dwelling macroinvertebrate assemblages

Abstract Urbanization contributes to an overall decline in the diversity of freshwater macroinvertebrate assemblages, while beta diversity in stream communities is primarily driven by local environmental conditions. Our study explored how anthropogenic stream modification influences taxonomic beta diversity and its components richness difference (D) and replacement (R) in low-order stream macroinvertebrate assemblages and how environmental variables shape these patterns. The two components (D and R) together with the Jaccard similarity (S) were used to generate the ternary diagrams (SDR simplexes) to evaluate the effects of urban land-use change and stream identity. We found that effect of urbanization on compositional heterogeneity varies across streams due to their unique characteristics. Furthermore, our results indicated that stream size drove community differences among natural and degree of urbanization between urban stream sections. The varying responses of streams beta diversity to anthropogenic modifications highlight the need for site-specific management in conservation strategies. To our knowledge, this is the first study to examine how local environmental parameters influence compositional heterogeneity among samples (beta diversity, replacement and richness difference component) in natural and urban sections of low-order streams, focusing on the entire macroinvertebrate assemblages.