Benthic Habitat Characterization and Habitat Use of Endangered Sea Turtles in Marine Protected Areas of the Greater Everglades

Science Center Objects

USGS assesses how federally endangered sea turtles use the habitat in and around a no-take area in the Dry Tortugas National Park.

USGS research diver over coral reef in the Dry Tortugas
USGS research diver over coral reef in Dry Tortugas National Park

The Science Issue and Relevance: The introduction 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, enforcement of protected area boundaries, as well as whether adequate protection for vulnerable life stages of key species is provided in protected habitats. In Dry Tortugas National Park (DRTO), several MPAs have been established to protect natural and fisheries resources and associated coral reef habitats. We assess use of habitat in and around no-take areas of the Research Natural Area (RNA) by several species of federally endangered sea turtles (i.e., green turtles, Chelonia mydas; hawksbills, Eretmochelys imbricata; and loggerheads, Caretta caretta).

Methodology for Addressing the Issue: We have examined movement of key species across acoustically-monitored RNA boundaries. We quantitatively determine patterns of endangered sea turtle habitat use inside and outside the RNA by instrumenting turtles with both acoustic and satellite tags. We have also integrated USGS Coral Reef Project Scientist Dave Zawada’s high-resolution benthic mapping project to characterize benthic cover in areas where turtles are concentrating or repeatedly visiting. This coverage is a novel use of the Along-Track-Reef-Imaging-System (ATRIS), and a component of sea turtle habitat use studies that has been lacking to date. In 2014, we initiated satellite tagging of nesting loggerhead turtles in Everglades National Park (ENP). Further, by also including a molecular genetic component in our project, we are developing an understanding of the linkages and connections among endangered sea turtles using DRTO, ENP, and potentially other protected areas in the U. S. (i.e., Florida Keys National Marine Sanctuary [FKNMS]) and other countries. Such information is necessary for overall sea turtle population restoration and recovery efforts.

Dry Tortugas Sea Turtle data map
Dry Tortugas sea turtle data map

Future Steps: Since 2008 we have captured and marked 287 individual marine turtles in DRTO (178 green turtles, 100 loggerheads, nine hawksbills) and satellite-tagged over 100 turtles, see http://www.seaturtle.org/tracking/?project_id=402. By analyzing this tracking data, we have been able to delineate core-use areas and migration paths for all three species of turtles tagged. We have also successfully mapped >85 square kilometers of benthic habitat and have obtained 108,075 turtle detections on acoustic receivers throughout DRTO, which allows for fine-scale habitat-use determination. Since 2014 we have captured, marked and satellite-tagged seven loggerhead turtles in ENP. Future efforts and FY2016 fieldwork will include the continuation of satellite tagging and tracking at DRTO and ENP, increasing sample sizes, estimating survival rates, and implementing new tools to understand very fine scale turtle movement patterns, such as accelerometers.

Additional Related Project(s) and Product(s):

Detailed Seafloor Mapping to Enhance Marine-Resource Management (D. Zawada).

Hart KM, White CF, Iverson AR, Whitney N (Submitted) Trading shallow safety for deep sleep: juvenile green turtles risk increased predation for better rest as they grow.