Influence of tributary water chemistry on hydrodynamics and fish biogeography about the confluence of Negro and Solimões rivers, Brazil

As part of a project to investigate the hydrodynamic, sediment transport and mixing processes about the large confluences of the Amazon Basin, two field studies were conducted under high and low flow conditions about the confluence of the Negro and Solimões Rivers. To date, little is understood about how differences in tributary water physico-chemistry (e.g. temperature, pH, conductivity) are related to local hydrodynamic and mixing processes about confluences, especially large confluences and further how these differences could influence fish biogeography about such confluences. Presented herein are some key findings from the field study conducted about this confluence under high flow conditions as well as a conceptual model that helps to explain how tributary water characteristic differences influence local confluence hydrodynamic and mixing processes. These findings are then used to briefly discuss how local confluence dynamics may influence fish biogeography with the Amazon Basin.