The effect of seasonality on fish composition in Amazonian streams: An analysis in areas with local-scale deforestation

de Oliveira J.C.; Röpke C.; Amadio S.A.; Alves-Oliveira J.R.; Mendes D.M.M.; Hercos A.P. · Biota Neotropica (2026) · DOI: 10.1590/1676-0611-bn-2025-1801

Resumen

Amazonian streams are among the most biodiverse freshwater ecosystems, playing a fundamental role in maintaining trophic networks and essential ecological processes. The structure of fish assemblages in these systems is influenced by a combination of environmental and historical factors, including biogeographic and phylogenetic processes. Riparian vegetation and seasonality act as important determinants of species composition in these streams. The objective of this study was to investigate how riparian vegetation integrity and seasonal variation influence the structure and distribution of fish assemblages in Amazonian streams. To this end, samples were collected during different hydrological periods, representing the dry, rainy, and transitional seasons. The methods used to evaluate fish assemblages considered environmental variables associated with habitat integrity, stream hydrology, and surrounding landscape characteristics. The results revealed that seasonality plays a central role in structuring fish communities, with significant changes in species composition between hydrological periods. Environmental integrity also contributed to patterns of assemblage variation, though to a lesser extent than seasonal changes.