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Sea turtles defy a litany of threats

Sea turtle hatchlings
Sea turtle hatchlings usually make their way out of the nest during the night. (Photo: MALCOLM DENEMARK/FLORIDA TODAY)

Despite a hurricane that wiped out countless sea turtle nests or washed back thousands of just-hatched turtles, 27 core index beaches — including Archie Carr National Wildlife Refuge — chalked up some record nesting figures for green sea turtles in 2017.

Four decades ago, biologists thought green sea turtles might go extinct. This year, the threatened reptile dug a record number of nests at the Archie Carr, a key beach for sea turtles that hints at statewide turtle nesting trends.

“No storm season is a total loss for sea turtles, fortunately,” said Michelle Kerr, spokeswoman for the Florida Fish and Wildlife Conservation Commission in St. Petersburg. “Sea turtles lay multiple nests, and there is a high probability that at least a few of those nests will incubate successfully.”

FWC estimates green sea turtles laid a record of about 39,000 nests in the state this year, based on 27 Florida index beaches used to assess nesting trends.

Also based on the index beaches, loggerheads laid about 48,000 nests and leatherbacks about 200, strong numbers but not records, said Beth Mongiovi, a biologist at the commission’s lab in St. Petersburg.

Final statewide nest numbers for the year from the comprehensive Statewide Nesting Beach Survey, which covers 800 miles of Florida coastline, will be available in early 2018.

The Archie Carr refuge spans more than 20 miles between Melbourne Beach and Wabasso Beach in Brevard and Indian River counties.

Sea turtle nesting at Archie Carr is significant, because biologists consider that span of beach among the most important sea turtle nesting spots in North America and indicative of how turtle nesting is going as a whole.

University of Central Florida researchers have gathered nesting figures through Oct. 31 north of the Carr refuge on select beaches in Brevard County, and through Nov. 15 on the Brevard portion of the Carr refuge north of the Sebastian Inlet State Park.

So far, those numbers show:

  • 15,921 loggerhead nests;
  • 18,031 green turtle nests,  15,765 of them in Brevard’s portion of Archie Carr (which tops the record of 12,905 nets along that stretch of beach, set in 2015);
  • 29 leatherback nests.

Some sea turtles got a second lease on life after Irma. Brevard County Zoo took in almost 1,500 just-hatched sea turtles displaced in hurricanes Irma and Jose. The turtles were nursed back to strength at the zoo’s Sea Turtle Healing Center, then transferred to the FWC for release back into the wild.

More than 70 percent of the sea turtle nests lying beneath Treasure Coast beaches when the hurricane hit in mid-September were wiped out by the storm surge, according to Ecological Associates of Jensen Beach.

Despite Irma, sea turtles fared well on the Treasure Coast, too, according to state nesting data.

Indian River County not only set a record for green turtle nests like the rest of the state, said Kendra Cope, the county’s sea turtle coordinator, “we had a record total number of nests for all species of sea turtles.”

The county tallied 8,712 sea turtle nests, surpassing last year’s record of 7,496.

‘Doing pretty well’

Total nest numbers aren’t available for Martin and St. Lucie counties, but “all the species are doing pretty well,” said Grace Dotson, senior scientist at Ecological Associates, which monitors sea turtle nests on sections of shoreline throughout the Treasure Coast.

“The loggerheads are holding their own and green sea turtles are definitely on the uptick,” Dotson said. “Only the leatherbacks, on our beaches anyway, had kind of an off year.”

Sea turtle nesting season runs from early March through October. Nesting periods for each species overlap; but generally, leatherbacks come first followed by loggerheads and then greens.

Luckily, Irma came in mid-September, which is pretty late in the nesting season, Cope said. “By that time all our leatherback nests and about 80 percent of our loggerheads had already hatched.”

The storm took a pretty big toll on greens, though. Only about a quarter of their nests had hatched before the Irma, Cope said. But 111 nests were laid in Indian River County after the storm.

Sea turtles have evolved over the years to deal with hurricanes, Cope said. Each green sea turtle, for example, lays four nests a year.

“They don’t put all their eggs in one basket,” Cope said.

University of Central Florida researchers are studying
University of Central Florida researchers are studying the DNA differences that contribute to a potentially deadly viral disease in sea turtles. (Photo: UCF, under research Permit MTP-186)

Comeback kids

Just 30 years ago, only 464 green sea turtle nests were counted on Florida’s 200 miles of index beaches. That’s about the time “greenies,” loggerheads and leatherbacks, the sea turtles that frequent Florida beaches, were listed as endangered species.

By 2011, the count was up to 10,701; in 2013, it was 25,553 nests; and in 2015, it was about 28,000.

Sea turtles take 20 to 25 years to reach breeding age, Cope said, so the turtles laying eggs now are the products of the protection measures.

Only leatherbacks are still considered “endangered” by the federal Endangered Species Act. Loggerheads and green turtles are listed as “threatened.”

Whether endangered or threatened, sea turtles, their nests and their eggs are protected by federal and state laws.

“Greenies” are the only species of the three that frequent the Indian River Lagoon as well as the ocean. Researchers at the University of Central Florida estimate half the turtles in the lagoon suffer from life-threatening tumors caused by a herpes virus made worse by pollutants in the water.

 

This article has been republished from Florida Today.

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