USGS scientists conduct fieldwork on coral-rubble keys at Dry Tortugas National Park

The U.S. Geological Survey said a team of agency scientists and National Park Service staff recently conducted fieldwork on the coral-rubble keys protecting Dry Tortugas National Park. The work aimed to improve understanding of how coastal islands change over time and how severe storms affect their growth and erosion.

From October 5 to 10, 2026, the team from the St. Petersburg Coastal and Marine Science Center worked on Bush Key and Long Key. Researchers Anastasios Stathakopoulos, Dan Ciarletta and Lauren Toth collected sediment cores, paleoecological data and Global Positioning System survey measurements.

The islands are composed primarily of coral rubble and other reef-derived carbonate sediments. They provide habitat for nesting seabirds, sea turtles and sharks. Bush Key and Long Key also help shield historic Fort Jefferson on Garden Key, the park's deep-water harbor and other maritime infrastructure from wave action and coastal impacts.

Researchers examined the long-term movement and accumulation of coral-derived sediments that form and sustain the islands. Sediment cores and paleoecological analyses recorded past environmental conditions, while GPS surveys documented current island elevations and shoreline characteristics. The data will help researchers reconstruct changes to the islands over time.

The agency said the project also contributes to research on the connection between offshore coral reefs and island stability. Recent USGS research suggests that some reef-derived material supporting the islands may be thousands of years old. Scientists are working to determine whether the sediment supply is finite and how erosion and sediment transport may affect the future resilience of the islands. The findings will help resource managers plan protection and restoration for ecological habitats, historic resources and coastal infrastructure.