Incorporating river morphodynamics in the characterization of key ecological system units for conservation in the western Amazon

This study presents a novel methodology for developing a conservation Blueprint in the western Amazon, focusing on the Marañón, Napo, and Ucayali basins. Our approach highlights the critical role of fluvial integrity in shaping ecological functions and biodiversity through floodplain reshaping, habitat interconnecting across forests, and the transport and distribution of sediments, nutrients, and minerals throughout the region. We introduced two ecological attributes, the Modern Morphodynamics Index (MOR) and the Suspended Sediment Index (SSI), which together provide an improved representation of the temporal dynamics and connectivity that rivers impart to the landscape, as well as their influence on biotic dynamics. Our methodology integrates quantification and classification of biotic (five taxa) and abiotic variables across spatially nested hierarchies to assess ecological conditions and human-induced pressure. The resulting Ecological System (ES) units prioritizes areas with high ecological condition scores (i.e., high integrity) and low anthropogenic impact, enabling the development of more targeted conservation strategies. Our findings underscore (1) the value of incorporating MOR and SSI, which identify regions characterized by high dynamism and substantial sediment and nutrient loads as major drivers of biotic patterns; and (2) the urgent need for expanded species diversity surveys to better understand spatiotemporal distribution patterns across these complex river systems. Overall, this comprehensive framework offers a robust foundation for informing conservation planning and infrastructure development, supporting the long-term sustainable management of these critical Amazonian ecosystems.