Change font size:

Research

Seagrass SAV

Under a contract with SFWMD, SCCF has been monitoring submerged vascular plants from upriver near Beautiful Island to San Carlos Bay since 2004. This monitoring project was designed to detect changes in seagrass health and coverage as a response to water quality changes. The data shows a dramatic response to long periods of high volume river discharges of dark water. The data is also being used to calibrate and validate simulation models of each seagrass species. Models are being developed to predict seagrass response to changes in salinity, light, and temperature.

Clam Bayou

Despite repeated attempts to re-introduce tidal flooding to this mangrove-lined lagoon, Clam Bayou remained isolated from tidal flow resulting in severely degraded mangrove wetlands. All reproductively productive mangroves were now standing dead snags. The purpose of this research was to characterize mangrove, fish, and seagrass communities in Clam Bayou in addition to a reference embayment to provide benchmarks for measuring restoration success. A box culvert provided a permanent tidal connection and a restoration solution for Clam Bayou in 2006. Now that the communities are well-characterized, predictions about the pace and direction of recovery can be inferred.

Related Publications: Final report to City of Sanibel, Restoration and Creation Conference Proceedings 2006, Journal of Coastal Research (in press), co-authored with James Evans, City of Sanibel

Mangrove Restoration at Shell Point

A large mangrove die-off area within the protected coastline managed by Estero Bay Aquatic Buffer Preserve was targeted as a demonstration of new restoration techniques. Within the die-off area, black mangrove seedlings were thriving in circular patches of saltwort (Batis maritima). To test the prediction that saltwort surved as a nurse species to black mangrove seedlings, survivorship of black mangroves was determined in saltwort patches and outside. No surviving black mangroves were left after two months, while half of those planted in saltwort survived.

Related Publications: Final report to SFWMD, Hydrobiologia 2005, co-authored with Megan Tinsley, Audubon of Florida

Blue Crab Populations in the Caloosahatchee

Blue crab landings data were compiled and analyzed to develop management targets related to the freshwater inflow to the Caloosahatchee estuary. Landings, effort and catch-per-unit effort of the blue crab landings were analyzed relative to environmental conditions within and around the Caloosahatchee River/Estuary. Major findings of this study are a correlation between the Secchi disk measurement and the catch per unit effort (CPUE) of crabs caught in the Caloosahatchee River. When Secchi disk readings were high (water was clearer), the CPUE was higher. Other water quality parameters, including flow rate did not correlate with landings.

Related Publications: Final report to SFWMD.

Ecological and Geographical Extent of Lake Okeechobee Releases to the Caloosahatchee Estuary

Above-average hurricane activity and rainfall forced multiple releases of large volumes of freshwater into the Caloosahatchee Estuary in 2005 and 2006. The purpose of this research was to characterize the optical properties of water from the lake and basin sources and determine whether releases were responsible for light limitation in seagrass populations. Seagrass growth rate near the mouth of the Caloosahatchee River was significantly lower than other stations in the lower estuary. Lake releases were typified by high total suspended solids (TSS) and high colored dissolved organic matter (CDOM). Basin freshwater releases were high in CDOM. Mass spectrometry of dissolved organic matter (DOM) indicated that UV and bacterial degradation was occurring as DOM from freshwater sources significantly differed from DOM in the estuary.

Related Publications: Final report to SFWMD, Milbrandt, in prep, Estuaries and Coasts.

Macroalgae and seagrass monitoring during spring and summer of 2006.

As a consequence of large watershed influxes of nutrients and turbid water following several hurricanes, seagrass coverage was reduced and algal biomass was high.

Macroalgal biomass, Karenia spp. cell density, and seagrass characteristics and growth rate in the water surrounding Sanibel were recorded in the spring and summer of 2006. Average macroalgal biomass in July in water surrounding Sanibel was high (M = 215 g d wt m-2) compared to other estuaries such as Biscayne Bay, and indicative of eutrophic conditions. At sites near the river, turtle grass percent cover was more than 70% lower than it was in 2005. Turtle grass abundance and growth were higher at sites farther from the river mouth, though epiphytic algal coverage was often high at all sites. Light attenuation underneath dense algal mats averaged less than 7% of surface irradiance, which is below the level required by seagrasses for growth.

Identification of Microbes Critical to the Enhancement of Seagrass Restoration

A greenhouse experiment was designed to repeat an experiment in the field. Seagrasses were transplanted with autoclaved sediments and 10 mM sodium sulfide to determine whether rhizome associated bacteria were moderating toxic effects from sulfide intrusion. The highest growth rates were recorded in untransplanted seagrasses, followed by seagrasses transplanted in native soils and the lowest growth was observed in seagrasses transplanted with autoclaved sediments. Subsequent analysis of DNA from the rhizome bacterial community was largely inconclusive.

Relevant Publications: Milbrandt, in press, Botanica marina. Final report to Charlotte Harbor National Estuary Program .

Vallisneria americana Temperature Curves

Seagrasses and brackish submersed vegetation like tapegrass are valuable components of the estuarine ecosystem. The experiment measures growth and photosynthetic rate of tapegrass at two salinities and two light levels at six different temperatures in order to determine the relationship between environmental parameters and photosynthesis and thus plant growth. The temperature ranges tested cover the range of normal river temperatures (14 to 34o C). The results of these measurements will provide information to calibrate a model of tapegrass that can be used to predict response of tapegrass to discharges of fresh water.

Repair and Maintenance of Seagrass Meadows in Charlotte Harbor

Propeller scarring of seagrass beds is a widespread problem in Charlotte Harbor. Shallow water and inexperienced boaters cause thousands of scars every year. New techniques for restoration of these propeller scars were monitored to determine feasibility of prop scar restoration in Southwest Florida. Injections of prop scars and bringing scars back to grade were monitored relative to targets and unmanipulated scars. While no significant differences were observed, there were greater growth rates in injected scars over the one year monitoring period. Differences among treatments was thought to be masked by heavy macroalgal biomass at the study site. Additional monitoring of the study site, plus additional restoration of propeller scars is planned.

Relevant Publications: Final report to West Coast Inland Navigation District.