Abstract
In southwest Florida, the modified hydrology of the Caloosahatchee River Estuary and watershed has altered freshwater inflow and salinity regimes, causing submerged aquatic vegetation (SAV) loss at regularly monitored sites in the Caloosahatchee River Estuary (CRE). Current management efforts to improve estuary salinity levels for SAV have had little success in restoring SAV coverage, suggesting the need for a more comprehensive management approach that considers multiple stressor impacts on SAV, including both salinity fluctuations and reduced light availability. This study uses data collected from 2020 – 2021 to (1) describe the full distribution and status of CRE SAV for the first time since 1993, linking SAV characteristics with water quality conditions and (2) characterize the distribution, depth limits, percent cover, species composition, and productivity and morphology of SAV as a function of salinity and light availability. Results indicate that the extent of CRE SAV declined between 1993 and 2020. The combined effects of salinity and light availability explain current SAV distribution better than the independent effects of either factor, with the relative influences of light limitation and salinity limitation varying by season and by estuarine zone. These findings emphasize the need for the development and implementation of a more holistic approach to CRE management and restoration that addresses poor optical water quality in concert with salinity needs.
