Anthropogenic Barriers Limit Fish Access to Essential Habitats in the Amazon in the Face of Climate Change

Barriers represent one of the greatest threats to river integrity and freshwater fish, as they fragment habitats and impair species dispersal, particularly in a scenario of climate change. In this context, we applied a novel framework that combined predictions of species distribution models with a river connectivity index to identify accessible and climatic-environmental suitable habitats for frugivorous and socioeconomically important fish in the Amazon basin. We also ranked dams based on their potential for river fragmentation and blocking access to climate refuge for fish species that provide essential ecosystem functions and services in the Amazon. Our results revealed that there are still extensive areas that remain both connected and climatic-environmentally suitable along the Amazon-Solimões rivers, acting as core areas for fish dispersal and tracking suitable habitats. However, the planned expansion of hydropower infrastructure combined with climate change can lead to a contraction of areas that will remain simultaneously climatic-environmental suitable and connected. By identifying and ranking the most impactful barriers, our results can provide innovative and applicable information for sustainable energy planning decisions in the Amazon. These results can inform policies and conservation actions aimed at preserving river connectivity, biodiversity, and ecosystem services under rapidly changing conditions.