Connected reservoirs: Modeling aquatic ecosystems along a cascade system in Brazil

Abstract Connected reservoirs along cascade systems have been constructed along large rivers worldwide, establishing a network of aquatic environments that greatly affect matter flux and ecological dynamics. Here, we explore the underlying ecological principles of their unidirectional connectivity, applying a modeling framework that explicitly links reservoir processes along a cascade system. Our study uses an intensively modified large river system with multiple reservoirs in Brazil to showcase the systematic effects of unilaterally connected ecosystems. Given the top priority of nutrient load reduction as a general management strategy, 18 scenarios of reducing nutrient loads were simulated to assess how restoration strategies modify the ecological state downstream. According to the model simulations, the exact spatial implementation of nutrient load reductions along a reservoir chain highly influenced the ecosystem status and functioning systematically. This finding points to new opportunities in river basin management and restoration strategies.