Category Archives: Research Spotlight

Habitat Research:
Coastal Wetlands

by Dr. Ryan P. Moyer

 

Coastal Acidification Studies in Tampa Bay

Women kneeling in field
FWRI coastal wetlands technician Christina Powell conducting coastal acidification sampling of Tampa Bay waters in Old Tampa Bay. Researchers collected samples every three hours over a 30-hour period to measure dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), pH, dissolved oxygen, temperature, salinity, and total nitrogen and phosphorus.

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

Woman on boat
FWC intern Alexandra Wilcox (left) and coastal wetlands technician Kara Radabaugh (right) measure salt marsh soil pH at Clam Bayou in Gulfport, FL, while coastal eetlands technician Amanda Chappel (center) records the data.

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.

 

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Scanning the Ocean Floor for Fish Habitat

by Eric Weather

Maximizing the Efficiency of Reef Fish Surveys Through IncorporaThe Gulf of Mexico benthic habitat can be summarized as a mosaic of sand with limestone rock outcroppings (reefs).  These reefs facilitate the settlement and growth of a wide variety of benthic organisms including corals, sponges and crustaceans.  They also support a diverse fish community from tiny blennies and gobies to commercially and recreationally important groupers and snappers.  The Fisheries-Independent Monitoring (FIM) program in cooperation with the National Marine Fisheries Service (NMFS) conducts annual fisheries monitoring on these reef habitats to provide data for single species and ecosystem-based management initiatives.  In 2009, the FIM program implemented the use of side-scan sonar to identify and classify the benthic habitats in the eastern Gulf of Mexico between 10 m and 110 m deep.  These sonars are towed behind a survey vessel and are equipped with two side-facing transducers that generate and receive sound signals.  When a signal is generated it propagates through the water column and reflects off the seafloor and then back to the transducer.  The intensity at which the return signal is received is interpreted into an image that is deciphered by a trained survey technician.  The configuration of the transducers on the sonar allows the sound signal to ensonify a very wide swath of the seafloor (up to 300 m) at one time.  As the survey vessel moves through the water, a streaming image of the seafloor is generated, as depicted in the video.  When rocky outcrops are identified by a survey technician they are given a habitat category based on their structure and complexity and become the basis for the NMFS/FIM reef-fish survey.  Additionally, these data are used by regional geologists, cartographers and other biologists to help answer a wide variety of research related questions regarding the benthic habitats of the eastern Gulf of Mexico.