Seagrass Beds and Manatee Foraging Areas in the Ten Thousand Islands: Mapping and Characterizing by Incorporating Manatee GPS Tracking Data and Habitat Information

Science Center Objects

Turbid water conditions make the delineation and characterization of benthic habitats difficult by traditional in situ and remote sensing methods. Consequently, only a small fraction of this valuable resource has been mapped or characterized.

Validated modeling and sampling methodology
Validated modeling and sampling methodology

The Science Issue and Relevance: Turbid water conditions make the delineation and characterization of benthic habitats difficult by traditional in situ and remote sensing methods. Consequently, only a small fraction of this valuable resource has been mapped or characterized. A large population of Florida manatees (Trichechus manatus latirostris) utilizes the resources in and around the TTI area, but because of the lack of adequate seagrass maps, the extent of possible manatee foraging areas and the amount of available forage are not documented. Knowledge of these forage resources for manatees will become more important in the next few decades as power plants that the animals have relied on shut down, and more animals are predicted to migrate south to TTI and the Everglades. In addition, other species, such as fish and sea turtles, rely on these seagrass beds for shelter and forage.

Methodology for Addressing the Issue: Here, we developed and validated modeling and sampling methodology for detecting and characterizing seagrass beds by analyzing GPS telemetry records from radio-tagged manatees. We developed a camera-based quadrat sampler that has proven to be both efficient and sensitive to differences in seagrass abundance and species richness.  Other that the novel telemetry analysis and camera sampler, other sampling strategies are conventional, including spatially stratified sampling, 6” core samples for biomass measures of roots and shoots, and in situ shoot counts. We are analyzing the data is with a custom Bayesian zero-inflated negative binomial with a censored upper tail, and with a custom spatial Bayesian logistic model to predict spatial locations of seagrass.

Future Steps: Our camera-based field sampling proved to be effective for assessing seagrass density and spatial coverage under turbid water conditions, and would be an effective monitoring tool to detect changes in seagrass beds from climate change, sea level rise, or Everglades restoration. We are currently applying the lessons learned, and techniques and methodology developed in this project to other projects and areas. We will be authoring the TTI chapter of the upcoming State of Florida Seagrass Integrated Monitoring and Management (SIMM) publication. We are producing several publications from the TTI seagrass project.

Camera-based quadrat sampler
Camera-based quadrat sampler

Related Project(s):

  • Comprehensive Everglades Restoration, USGS A7R-33
  • Northern Gulf of Mexico Manatee Distribution and Habitat Use, USGS A7R-35
  • Winter aggregations of Florida manatees and their habitat use, USGS A7R-36
  • Puerto Rico: characterization of manatee habitat and use, USGS A7R-37
  • Guantanamo Bay, Cuba: habitat use of Antillean manatees. USGS GGCSSB0000-5
  • Deepwater Horizon NRDAR Assessment: manatees.
Ten Thousand Islands study area
Ten Thousand Islands study area