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Habitat use of threatened and endangered sea turtles in the Greater Everglades

low lying sea turtle nest
Project Investigator: Kristen Hart

Project Personnel: Michael Cherkiss

Project Start Date: 2009 End Date: 2017



This project addresses the specific resource management information need regarding endangered species use of Park resources, and condition and location of those resources (i.e., seagrass, sponge, and hardbottom habitats, as well as nesting beaches).

Institution of marine protected areas (MPAs) in which human use is highly regulated has become a priority management tool for at-risk coral reef habitats. The effectiveness of MPAs may be heavily dependent upon reserve factors such as size, placement or location, and enforcement of protected area boundaries, as well as whether adequate protection for vulnerable life stages of key species is provided in protected habitats. In the Dry Tortugas National Park (DRTO), several MPAs have been established to protect natural and fisheries resources and associated coral reef habitats. This project proposes exploratory research to conduct a coupled habitat + species sampling project within and around the new Research Natural Area (RNA) of DRTO. Specifically, we will assess use of habitat in and around no-take areas of the RNA by several species of federally endangered sea turtles (i.e., greens (Chelonia mydas), hawksbills (Eretmochelys imbricata), and loggerheads (Caretta caretta). Green turtles are almost exclusively herbivorous, consuming seagrasses and algae, Hawksbills eat sponges, and thus are found associated with coral reefs and sponge cover, and Loggerheads feed on benthic invertebrates such as lobsters and crabs, as well as on fishery discards. Thus, these species are directly linked to key habitats of interest in DRTO and the surrounding waters. All three species are particularly suitable for immediate monitoring because they also nest on sandy upland areas of the Tortugas islands.

Specific objectives of the project are as follows:

  • Quantitatively determine patterns of turtle habitat use inside and outside the RNA by instrumenting turtles with satellite tags and analyzing acoustic data previously collected on our own acoustic receivers (N=7) and those of our partners (N=72). With acoustically-logged data that has been collected, we are assessing the proportion of time each turtle spends inside the RNA, and with satellite-derived data, we are assessing the proportion of time each turtle spends outside the RNA or in areas not adjacent to acoustic receivers. Such information will be important for Park managers to assess appropriateness of current RNA boundaries for these high-profile endangered species.
  • Include a molecular genetic component in our project to develop an understanding of the linkages and connections among endangered sea turtles using DRTO and potentially other protected areas in the U. S. (i.e., Everglades National Park (ENP), Florida Keys National Marine Sanctuary (FKNMS)) and other countries. Such information is necessary for overall sea turtle population restoration and recovery efforts.
  • Include a diet component in our project to assess direct use of park resources by sea turtles. Specifically, we are using gastric lavages and isotope sampling to assess diet of all three species of sea turtles.
  • Estimate growth rates for juvenile green turtles that are resident within DRTO.

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Script last updated: 23 October 2018 @ 12:03 PM by THF. Record creator: KP. Record last updated by: KP.