Burrowing aquatic invertebrates increase phosphorus uptake by aquatic sediments in drainage ditches

Agricultural contributes to eutrophication of coastal and estuarine environments through movement of nutrients such as phosphorus to adjacent bodies of water. Drainage ditches represent a location where the transport of nutrient can be targeted. Current research on phosphorus retention within ditch sediments has focused on physical and biogeochemical processes as they relate to hydrology, water and sediment chemistry, and soil microbes, but have largely ignored influences of aquatic macrofauna. Bioturbation by burrowing aquatic invertebrates can alter rates of biogeochemical cycles and alter rates of flux for dissolved species across the sediment-water interface. Sediment and water mesocosms were used to test the effects of the aquatic larvae of the midge Chironomus on the exchange of phosphorus between sediment and water. Results from these experiments show that burrowing midge larvae increase rates of phosphorus uptake by aquatic sediments under some environmental conditions, and increase rates of release of phosphorus to the overlying water under other conditions.