Long-Term Effects of Land Use and Cover Change and Dam Rupture on Ichthyofauna in a Neotropical Stream

Abstract

This study evaluates land use and land cover (LULC) changes and their impacts on the fish community of a neotropical stream in the Sorocaba River basin, Brazil, from 2006 to 2023. The watershed experienced landscape changes over time, categorized into four periods: rural interventions, urban interventions, restorative interventions, and post-restorative interventions. The objective was to understand LULC changes and their ecological consequences, focusing on fish assemblages. There were significant differences in land use over time. Forested areas had the most substantial impact on the fish community, explaining 32.7% of the variation, being the only significant LULC variable. LULC changes reflected a considerable impact of human interventions, notably the increase in non-vegetated areas from 2.3% during rural interventions to 46.9% during urban interventions, reflecting environmental degradation caused by urbanization. The fish community was severely affected after the dam collapse in 2013, leaving only one surviving species, Phalloceros harpagos. However, after restoration actions in 2014–2015, some species, such as Astyanax lacustris and Psalidodon fasciatus, returned, and new species, such as Hyphessobrycon bifasciatus and Psalidodon anisitsi, were also recorded. In contrast, species like Coptodon rendalli and Geophagus iporangensis were no longer found. These findings highlight the importance of restoration actions for at least partially recovering aquatic biodiversity in ecosystems impacted by human activities.