Proceedings of the 2020 Mississippi Water Resources Conference

Year: 2020 Authors: Bacon P., Taylor J.M., Testa III S., Rigby J.R.

Voluntary flooding of post-harvest agriculture fields is a management practice that can be utilized to help mitigate permanent loss of wetlands and decrease losses of fertile soil associated with heavy winter rainfall. These inundated fields may promote positive community responses that increase habitat suitability for wetland species such as migratory waterbirds and shorebirds. For many migratory shorebird species, aquatic macroinvertebrates are a primary diet component vital to meeting the energetic requirements necessary for daily activity, as well as seasonal migrations. In order to utilize crop systems as temporary seasonal conservation management units, aquatic macroinvertebrate community structure and trophic stability must be established quickly. The focus of this study was to evaluate and quantify macroinvertebrate community structure and secondary production in post-harvest voluntary flooded agriculture fields. Three post-harvest corn fields, located in the Mississippi Delta were selected, were inundated with surface water from a tailwater recovery storage reservoir. Macroinvertebrate diversity and richness along with secondary production of dominant taxa were investigated over a five month period. Macroinvertebrates were quantitatively collected weekly to bi-monthly. Samples were brought back to the laboratory for processing and identification to determine species richness and diversity. Secondary production estimates were calculated for the dominant taxa, nonbiting midge larvae (Diptera: Chironomidae), using the size-frequency method. Macroinvertebrate diversity, density, and overall production of dominant taxa greatly increased after two weeks, then stabilized over the remaining inundation period. The overall observed trends functionally represent the increased habitat value of controlled flooded post-harvest agriculture fields and demonstrate this management practice may provide a strong energetic contribution or "payoff" critical to wetland species at higher trophic levels.