By: Tom Harvey, Texas Parks and Wildlife Department
Impact on World’s Most Endangered Sea Turtle Studied on Land, at Sea, in Labs
The Deepwater Horizon Natural Resource Damage Assessment (NRDA) Trustees this week offered a glimpse into the world of scientists working to assess injuries caused by the April 2010 Deepwater Horizon Oil Spill on the world’s most endangered sea turtle, the Kemp’s ridley. Assessment work includes field and laboratory tests to determine oil-related turtle exposure and satellite tracking via transmitters attached to turtles that come ashore to nest and lay eggs.
The assessment is taking place during the current 2012 Kemp’s ridley nesting season at Padre Island National Seashore (near Corpus Christi, Texas). This area makes for an ideal study site because more Kemp’s ridley nests have been found here than at any other single location in the United States.
The primary nesting site of the Kemp’s Ridley is near Rancho Nuevo, Mexico, with significant additional nesting in Texas. The full feeding and migratory range of the sea turtle includes most of the Gulf of Mexico. That range includes the site of the Deepwater Horizon (MC 252) mobile drilling rig and the waters and coastal areas polluted by crude oil and dispersants released after the 2010 rig explosion.
Assessing sea turtle injury is one component of the broader Deepwater Horizon Natural Resource Damage Assessment, the most comprehensive NRDA ever undertaken for the largest oil spill in U.S. history. NRDA is a scientific and legal process designed to determine ecological and other injuries caused by the discharge of oil or releases of other hazardous substances. The goal of NRDA is determining the type and amount of restoration needed to compensate the public for harm to natural resources that occur as a result of an oil spill. For more information, see www.gulfspillrestoration.noaa.gov.
International efforts to protect the Kemp’s ridley began 34 years ago with efforts to increase nesting by establishing a secondary nesting site at Padre Island. A key goal is to provide a safeguard for the species should nesting success at the beaches in Mexico decrease.
Satellite tracking of the Kemp’s ridleys began in 1997. Movements were tracked to help predict where and when the turtles might nest again, and assist field staff and volunteers in detecting and protecting nests. Turtles were also tracked to identify habitats used in the Gulf of Mexico. This historical monitoring revealed that after the nesting season, most of the tracked turtles left south Texas and traveled northward, parallel to the coast, with their last identified location in the northern or eastern Gulf of Mexico. Since the Deepwater Horizon Oil Spill, similar NRDA-sponsored studies are providing data being used to determine Kemp’s ridley exposure to and injury resulting from MC 252 oil and dispersants.
Along with satellite tracking, NRDA scientists are also collecting blood and tissue samples from adult turtles and fail-to-hatch turtle eggs for chemical and toxicological analysis. These analyses include testing for the presence of both polycyclic aromatic hydrocarbons (PAHs), organic compounds present in crude oil, and for the “fingerprint” of MC252 oil from the Deepwater Horizon spill.
The Kemp’s ridley assessment work at Padre Island National Seashore is led by Donna Shaver, Ph.D., in coordination with a team of other state, federal and university scientists. Shaver is the chief of sea turtle science and recovery at the National Seashore, where she has worked on Kemp’s ridley recovery for more than 20 years.
To follow the movements of sea turtles being tracked with satellite transmitters, visit http://www.seaturtle.org/tracking, then selecting the link “Padre Island National Seashore Kemp’s Ridley Tracking Program-2012.” These web pages include maps and data showing the movements of 10 turtles tagged with satellite transmitters.