Restoration of Submerged Aquatic Vegetation on Lake Apopka

Lake Apopka has suffered from decades of nutrient and pollutant loading primarily due to agricultural runoff. Historically, the lake supported healthy populations of submerged aquatic vegetation (SAV), but after degradation, the lake has become mostly barren. Restoration of SAV is critical for resident species, such as largemouth bass, that rely on SAV for food, habitat, and healthy water quality. This project was funded by the St. John’s River Water Management District to identify or develop effective strategies for restoring SAV in Lake Apopka. FWRI researchers consulted with University of Florida (UF) faculty and staff as well as the Aquaculture facility at Duke Energy to advise on seed bank germination, eelgrass (Vallisneria sp.) life history, and experimental design. The Freshwater Plants Research teams’ formal contribution was a three-year seed bank emergence study, which entailed monthly visits to Lake Apopka to collect sediment cores that were transported to a greenhouse at Eckerd College and evaluated for germination of SAV. Additionally, researchers collected environmental data such as depth and Secchi readings and water quality measurements such as dissolved oxygen, temperature, conductivity, and pH in the study area. Grow-out experiments in the greenhouse showed higher germination rates for sediment cores taken within eelgrass patches compared to sediment cores taken outside eelgrass patches, in addition to seasonal fluctuations in germination rates. Additionally, researchers used side-scan sonar (SSS) to monitor stability and expansion of eelgrass patches in Lake Apopka. Results were provided to UF along with feedback on status and results of other studies that they conducted for this project.