Aquatic Vegetation, Sediments, and Water Quality in the Everglades Agricultural Area Canals.

The canals in the Everglades Agricultural Area contain an abundance of floating aquatic vegetation (FAV) and submerged aquatic vegetation (SAV). These FAV flourish in waters with high phosphorus (P) concentrations and prevent the co-precipitation of P with the limestone bedrock (CaCO3). To test the effects of FAV and SAV and the presence of sediments on water quality in the canals, a lysimeter study was set up and stocked with FAV (water lettuce) and SAV (filamentous algae). There were four treatments with four replicates. Treatment one contained limerock, sediment from the canals, and FAV.  Treatment two contained limerock, sediment, and SAV. Treatment three contained limerock and FAV, while treatment four had limerock and SAV.  After 7 days, the buckets were drained and replaced the water with new, high P canal water. Water samples were taken at 0, 0.25, 1, 3, and 7 days after each weekly water exchange. To test water quality soluble reactive P, total P, total dissolved P, Ca, and total organic carbon were analyzed. Both FAV and SAV in treatments display high P removal rates from the water column over time. The highest TP reduction was observed in treatments containing no sediments, as the sediments can provide an internal source of P. Treatments containing FAV generally showed a great TP reduction in the water column compared to filamentous algae; however, the application of FAV to reduce P concentrations in farm canals may not pose as a viable technique due to the sheer quantity of labile plant biomass.