Ecological Insight into Flooding from Historic Flow Events in the Mississippi River

The Mississippi River basin is the largest river floodplain ecosystem in North America. This basin currently supports the most diverse freshwater ichthyofauna in North America. Historically, the river replenished nutrients and sediments on the floodplain, while the floodplain filtered solids and provided nursery habitat for aquatic organisms, such as fish. Floods in the Mississippi River offer a unique opportunity to evaluate the response of fish assemblages to lateral floodplain connectivity. Positive ecological response to historic flows in large river systems is often over shadowed because of societal priorities of measuring economic hardship. We examined biological data collected by the Long Term Resource Monitoring Program and the Open Rivers and Wetlands Field station to investigate potential ecological responses during historic flow events.  Response to flooding was evident during flow events for all years but was most pronounced during historic flows.  Indications of reproductive success were noted in many species and may be synchronous for some species.  Other species benefited from exploiting floodplain food resources and likely experienced increased growth which lead to greater reproductive success during the next reproductive season.  Improved fish growth may be substantiated by the capture of record sized individuals in the sport fishery during subsequent years.