Endangered sea turtles are nesting in record numbers across the U.S. Southeast this summer, surveys reveal, with new nests up "dramatically" from past years. U.S. officials credit the comeback to 30 years of federal protection, since many of this year's nests come from turtles born on the same beaches in the 1970s. Nonetheless, the agency warns this rebound could still be sunk by ongoing threats like ocean pollution and sea-level rise.

"Green turtle nest numbers are through the roof," says Bill Miller, manager of Florida's Hobe Sound National Wildlife Refuge, where a recent count of 1,147 green sea turtles more than doubled the 2011 record of 543. At nearby Archie Carr National Wildlife Refuge, the endangered species had built 10,420 nests as of Aug. 21, a 73 percent increase from the previous record of 6,023. Green sea turtle nesting season lasts until November.

Loggerhead sea turtles, another endangered species, are also on the upswing. A mid-August count at South Carolina's Cape Romain National Wildlife Refuge found 1,878 nests, which is 200 more than last year and the most since loggerheads first received federal protection in 1978. This summer has seen an above-average number of loggerhead nests in Georgia, Florida and both Carolinas, the U.S. Fish and Wildlife Service reports.

Green and loggerhead turtles need decades to reach maturity, but even after long ocean journeys, they still return to lay eggs in the area where they hatched. That's why this year's nesting boom is so rewarding, FWS officials say. "It takes 30 to 35 years for these turtles to reach maturity," Cape Romain NWR manager Sarah Dawsey tells Reuters. "We're just now seeing those turtles who were first protected in 1978 coming back to nest."

The U.S. government protects endangered sea turtles in several ways. Coastal wildlife refuges provide key nesting habitat, for example, since they're largely free of sea walls, beach lights and other types of development that can deter or disorient turtles. Refuge workers also cage eggs against predators like raccoons and opossums, and relocate nests at risk of washing away. And since the Endangered Species Act forbids killing or disturbing endangered turtles, they're also relatively safe from human hunters.

Sea turtles still face plenty of manmade threats, though. Artificial lights on land lure hatchlings away from the sea, while motorized boats can fatally wound them and commercial fishing nets can tangle them up as "bycatch." And as a recent study reported, some sea turtles now eat twice as much plastic debris as they did 25 years ago, a dangerously indigestible diet that's especially popular among younger turtles. On top of that, nesting habitats are increasingly at risk from polluted runoff and sea-level rise.

"If we don't do something about ocean debris, loss of habitat to erosion and sea-level rise, and the pollution of lagoons and estuaries from runoff, nesting gains will be outweighed by environmental degradations," Miller says.

Related sea turtle stories on MNN:

The opinions expressed by MNN Bloggers and those providing comments are theirs alone, and do not reflect the opinions of MNN.com. While we have reviewed their content to make sure it complies with our Terms and Conditions, MNN is not responsible for the accuracy of any of their information.