by Dr. Ryan P. Moyer
Coastal Acidification Studies in Tampa Bay
The coastal wetlands research group at FWRI has recently begun pilot field studies to understand the potential buffering effects that seagrass meadows may have on acidified coastal waters. The project was initiated in May 2014, when the coastal wetlands team joined a team of collaborators from the U.S. Geological Survey, ESA Associates, and the Tampa Bay Estuary Program to conduct diurnal sampling at two locations in Tampa Bay. This work uses cutting-edge autonomous seafloor sensors with discrete measurements of water column chemistry to understand the hydrodynamics and biogeochemistry of seagrass habitats in Old Tampa Bay offshore of Rocky Point, and in Lower Tampa Bay offshore of Fort DeSoto. Parameters measured over a continuous 30-hour period include dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), pH, dissolved oxygen, temperature, salinity, current speed and direction, and total nitrogen and phosphorus.
Coastal waters experience much higher diurnal geochemical variability than open ocean waters due to the high rates of photosynthesis and respiration that occur in coastal estuaries such as Tampa Bay. As the concentration of atmospheric carbon dioxide (CO2) increases, some excess CO2 is transferred to surface waters, thereby lowering pH and resulting in a phenomenon known as ocean acidification. Since coastal waters have higher rates of respiration (produces CO2) and photosynthesis (consumes CO2), they may serve as a natural buffer area for organisms to adapt to acidified waters. Further, seagrass acreage in Tampa Bay has been slowly recovering since the 1980s and is now the highest it has been since the 1950s. This increase in seagrass means more photosynthesis, and less CO2 in Tampa Bay waters – a trend that is opposite of the expected acidification trend (lower pH) that has been observed in most other coastal and open ocean areas. Thus, Tampa Bay may provide insights towards utilizing strategic habitat restoration to minimize the impacts of ocean acidification in coastal waters. The coastal wetlands research group at FWRI, along with our partners, is trying to understand this unique geochemical occurrence in Tampa Bay, and hope to develop a Bay-wide coastal acidification monitoring program for Tampa Bay in collaboration with the Environmental Planning Commission of Hillsborough County.
Vegetation Monitoring at Clam Bayou
The FWRI coastal wetlands research team also continues to monitor water quality and vegetation in mangrove and salt marsh habitats of Clam Bayou in Gulfport, FL. This work compares commonly used monitoring techniques in tidal coastal wetlands in support of the Coastal Habitats Integrated mapping and Monitoring Program (CHIMMP). The project was initiated in July 2014, when water quality monitoring activities began as part of a consortium with researchers from the University of South Florida College of Marine Science, the U.S. Geological Survey, and YSI Inc. Then in December 2014, permanent vegetation monitoring plots were established to compare several different field-based monitoring techniques. Water quality monitoring activities have continued monthly, and vegetation monitoring has been conducted every four months. Three salt marsh transects and three mangrove plots are visited quarterly. The following parameters are measured: sediment accretion, soil moisture, soil pH, porewater salinity, tidal creek salinity, temperature, dissolved oxygen, and pH, vegetation density, canopy height, canopy density, vegetative species identification, and mangrove diameter. To date, the monitoring efforts have documented a major shift towards mangrove vegetation in salt marsh habitats at Clam Bayou. Information gained from this study will help make recommendations for the development of future coastal wetland monitoring programs statewide. Coastal wetlands are particularly vulnerable to natural and anthropogenic impacts on local hydrology and water quality, which in turn determine the suitability of the habitat for numerous fish and bird species. The wetlands found at Clam Bayou are especially vulnerable due to their proximity to urbanization and altered hydrology.