The sea turtle that refused to be beaten by the storm – via Herp Digest

Science News- Date: October 26, 2017

Source: University of Southern Denmark

Summary: When Eleanor the sea turtle was caught in a tropical storm off the coast of Florida, she coped surprisingly well. In fact, she hardly needed to use any extra energy during the four days the storm raged -- and neither was she injured.

This is Eleanor, Credit Tony Tucker/SDU

As the seas get warmer, Earth suffers the ravages of ever more powerful storms and hurricanes, with massive consequences for both humans and animals. One of the concerns is marine animals, especially endangered species, such as certain whales, manatees, sharks, sea turtles, etc.

A joint Danish/American/Australian team of researchers has discovered that severe weather is not necessarily harmful to individual adult sea turtles. The team was in the process of monitoring sea turtles fitted with GPS transmitters and motion sensors off Sarasota in the USA, when one of the sea turtles was unexpectedly caught in a tropical storm. This provided the team with a unique opportunity to see how a sea turtle would cope with a storm.

"We were delighted to find that she rode out the storm in style without any problem," says Maria Wilson, a biologist at the University of Southern Denmark (SDU).

The study was conducted in 2012 involving colleagues from Mote Marine Laboratory and Aquarium, Sarasota in Florida, Department of Parks and Wildlife, Marine Science Program in Australia and Aarhus University in Denmark. A scientific article has now been published in the Journal of Experimental Biology.

"We know little about how sea turtles manage during hurricanes and tropical storms. Storms could blow sea turtles off course, or surviving a storm could be so exhausting that it drains energy reserves and thus the ability to survive and produce eggs, thereby having a negative impact on the next generation of sea turtles," explains Wilson.

The tagged sea turtle caught in the storm is named Eleanor. She was at sea in the Mexican Gulf in the egg-laying season when she was hit be the storm. Consequently, she had already nested on one of Florida's beaches and had returned to the sea to replenish her energy reserves before coming back to lay more.

Eleanor was caught in tropical storm Debby, which passed through the Mexican Gulf between 23rd and 27th June 2012. Debby caused extensive flooding in Florida, reaching wind speeds of up to 100 kph.

Eleanor was tagged for 16 days, four of which were during the storm. Data from the GPS and animal motion tags showed that she drastically changed behaviour when the storm struck. Before the storm, she rested on the seabed, moving only to go to the surface for air.

When the storm struck, she moved further north than expected. According to the researchers, she was forced by prevailing currents. She also changed her diving patterns, becoming much more active instead of saving energy for the next egg-laying event.

"Even though Eleanor swam for most of the four days the storm raged, she was good at saving energy, ending up actually using no more than she would normally use to produce 12 eggs. Given that sea turtles lay somewhere between 300 and 900 eggs during a nesting season, that's not much. But another fantastic element of Eleanor's story is that, despite the storm pushing her more than 100 km north of 'her' beach, she swam south when it passed and made her nest just 75 metres from her last one -- although with a few days' delay," adds Wilson.

The researchers calculated Eleanor's energy consumption based on motion sensors (3D accelerometers and gyroscopes), which detected when she was swimming. How much energy a swimming sea turtle uses had been determined from earlier experiments in the laboratory, making it possible to estimate how much energy they use sea.

Even though it would seem that sea turtles are sufficiently robust to avoid being at the mercy of storms, such a powerful storm can still be a major threat to them.

"Sea turtles lay their eggs on the beach, and their nests are extremely vulnerable to passing storms. The storm that Eleanor easily survived destroyed almost 90% of nests on the beach where she and several hundred other female turtles had laid their eggs.”

That's why Maria Wilson urges more focus on protecting nests and helping newly hatched turtles and less on adults, when the discussion turns to protecting sea turtles.

Story Source:

Materials provided by University of Southern Denmark. Original written by Birgitte Svennevig. Note: Content may be edited for style and length.

Journal Reference:

            1          Maria Wilson, Anton D. Tucker, Kristian Beedholm, David A. Mann. Changes of loggerhead turtle ( Caretta caretta ) dive behavior associated with tropical storm passage during the inter-nesting period. The Journal of Experimental Biology, 2017; 220 (19): 3432 DOI: 10.1242/jeb.162644

Tropical Storm Debby's pounding waves wiped out turtle nests as well as beaches – via Herp Digest

By Craig Pittman, Times Staff Writer

In Print: Saturday, June 30, 2012

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Tropical Storm Debby did more than just wipe some of Pinellas County's beaches off the map. The storm's pounding waves also destroyed scores of sea turtle nests, potentially ruining what had been a record-breaking nesting season.

"Obviously there's a lot of devastation," said David Yates of the Clearwater Marine Aquarium, which coordinates sea turtle nesting surveys on most of Pinellas' beaches. "We were having the best year in 15 years, and now we've had a substantial washing away."

Sea turtle guardians still are compiling the numbers to chart the losses, but early estimates are that they will be large. Fort De Soto Park supervisor Jim Wilson figures about one-third of the nests there were wiped out.

David Godfrey of the Sea Turtle Conservancy, the world's oldest sea turtle research and conservation group, said that along the gulf coast up to the Panhandle, "so far we're hearing that as many as half or more were lost."

However, state sea turtle biologist Anne Meylan said those estimates may be based on the loss of nest markers, not the nests.

"Losing your stakes isn't the same thing as losing the nests," noted Meylan, who works for the Florida Fish and Wildlife Research Institute in St. Petersburg. As a result, she said, "It's premature to have any estimate of an impact."

She also pointed out that several months still remain in turtle nesting season, so, "We still have time to make up any losses."

From May until September, thousands of female sea turtles — loggerheads and other species — crawl up on Florida beaches, dig a hole and drop in a clutch of eggs, then cover it back up and swim away.

The turtles that lay the eggs are returning to the beaches where they themselves hatched out some 30 years before.

Until this week, volunteers roving along the state's beaches were reporting record high nest numbers, Godfrey said. And the nesting had begun earlier than usual, too, he said.

But then Debby arrived, producing record rainfall and pounding waves that washed away beaches, as well as the nests beneath them.

"Up to that point, we were way ahead of last year," Meylan said.

South of the Tampa Bay area, researchers from Mote Marine Laboratory in Sarasota checking on the 1,367 nests they had marked before the storm between Longboat Key and Venice found markers remained for only 244 nests. That means as many as 82 percent of local nests lost the yellow stakes placed for identification — although it does not necessarily mean the nests are gone.

State biologists have been charting sea turtle nesting for more than 20 years. During that time, the nesting of loggerheads — the most common sea turtle species, but still rare enough to be classified as "threatened" — has been going downhill. The decline has been steepest since a high of 59,918 nests were counted in 1998.

Last year, however, the Florida Fish and Wildlife Conservation Commission documented a record-high nest count for green turtles. Leatherback turtles also had a high number of nests. Loggerhead nesting was close to its five-year average.