The Yazoo River Basin of Mississippi includes several rivers and hundreds of fluvial lakes within an area heavily impacted by agriculture. We studied 17 of these lakes distributed over the lower half of the Yazoo River Basin to document fish assemblage and limnological patterns and identify environmental variables that might influence these assemblages with multivariate analyses.

Results/Conclusions

The results showed that hydrological connectivity and forested wetland buffer played a major role controlling the water quality and fish community structure. Lakes with direct connection to the river tended to be deeper, less turbid, produce less phytoplankton biomass, and had greater fish species richness that included more riverine species. Conversely, as connectivity to the river was reduced or lost, lakes became shallow, more turbid, had higher phytoplankton biomass, and a less speciose lacustrine fish community dominated by centrarchid species. In addition, lakes surrounded by forested wetlands had lower pH and dissolved oxygen and more fish taxa that are associated with inundated vegetations. We postulate that after lakes separate from their parent river they function as sinks for sediments introduced during flood events, resulting in loss of depth. As lakes become progressively shallower, area is reduced, and surrounding wetlands are increased. These lake successional processes may have influenced the fish communities and limnological conditions of the lakes. The effects of changes in connectivity and wetland buffers of alluvial lakes need to be included in decisions concerning restoration efforts. Management goals associated with fish assemblages and physicochemical parameters may be attainable by restoring or reducing connectivity to parent rivers and can be influenced by the development of forested wetland areas.