Scientists researching effect of oil spill on endangered turtles

Kemp's ridley sea turtle hatchlings head for the Gulf of Mexico after they were released next to the Padre Island National Seashore, Malaquite Visitor Center, Thursday in Corpus Christi. Kemp's ridley sea turtle hatchlings head for the Gulf of Mexico after they were released next to the Padre Island National Seashore, Malaquite Visitor Center, Thursday in Corpus Christi. Photo: Cody Duty Photo: Cody Duty Image 1 of / 17 Caption Close Scientists researching effect of oil spill on endangered turtles 1 / 17 Back to Gallery

NORTH PADRE ISLAND - Ninety-four tiny members of the world's most endangered sea turtle species struggled across the beach to reach the Gulf of Mexico Thursday as park rangers waved away seagulls looking for a quick meal.

Only a handful of the 3-inch Kemp's ridley turtles will avoid predators and other dangers to become adults. Another threat to the species' long climb back from near extinction over the last three decades, however, may be less obvious than predators.

Scientists in labs at the Padre Island National Seashore and Texas A&M University at Galveston are doing research to determine if the species was harmed by the 2010 BP oil spill caused by an explosion on the Deepwater Horizon platform.

The research is part of a damage assessment being done on other species - including oysters, marine mammals and birds - but no other species is so linked to Texas.

The ridleys' largest nesting grounds are in Mexico, but Texas is their main U.S. nesting ground. Most nests are found on Padre Island, although an increasing number is showing up in the Galveston area. Kemp's ridleys are the only sea turtles whose primary population is found solely in the Gulf of Mexico.

The possible danger from the oil spill is masked by the record number of nests, 205, found so far this year on the Texas Coast. The number surpasses last year's record of 199 nests, said Donna Shaver, chief of the National Parks Service sea turtle science and recovery division. More nests might be found before nesting season ends, usually about July 15.

The Deepwater Horizon oil platform exploded April 20, 2010, just as the nesting season got under way. Oil fouled the area near Louisiana where female turtles normally go to forage for food after nesting.

Shaver said maps showing the movements of turtles tagged with satellite transmitters will be superimposed on maps of the oil spill.

Looking for oil

At North Padre island laboratories, blood samples are being taken along with tissue samples from turtles that died soon after hatching and from eggs that never hatched. These samples are being analyzed for evidence of oil.

At laboratories in Galveston, samples of the carapace, or shell, from live turtles are being examined, said Kimberly Reich, Director of the Trophic Ecology and Sea Turtle Biology Lab at Texas A&M Galveston.

"It's kind of like a tree ring, it gives us history," Reich said about the shell. Scientists can map where the turtle has been and what it's eaten by examining the layers of shell laid down over time, she said.

Scientists in 2010 found scores of dead Kemp's ridley juveniles floating in oil scum in the deep sea among clumps of seaweed. Kemp's ridley turtles spend the first year of their lives floating at sea in islands of sargassum seaweed.

Jim Haas, chief of National Park Service resource protection, said the National Oceanic and Atmospheric Administration is trying to determine how many juvenile turtles died and how the deaths will affect the species.

Assessing information

He said scientists are expected to begin assessing the information from three years of samples in the fall. Until the data are analyzed, the scientists are unwilling to hazard a guess as to whether the oil spill damaged the Kemp's ridley's chances of a comeback.

"We know 500 turtles were found alive and dead" in the oil, said Tom Shearer, wildlife biologist for U.S. Fish and Wildlife Service.

If damage is found, the government agencies will estimate the cost of projects needed to repair the damage and ask BP to pay for it, Haas said.

The movements of sea turtles being tracked with satellite transmitters can be followed at www.seaturtle.org/tracking.

harvey.rice@chron.com