The monitoring of sea turtles is a long and slow process that may well keep them alive
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In the middle of a hot night in July on the beach of the island of Wassaw, near Savannah, in Georgia, the volunteer Gabi Steinbach plunged his shoulder into the shoulder in the sand to reach a rubber turtle nest which hatched five days before. She took out the remaining egg shells, and her volunteer colleague Sheri Pittman sorted and counted by the light of the moon and a front lamp tinged with a red. Certain fragments are too small to count, but Pittman uses the biggest parts to determine how many newborns came out of this nest.
“Any egg shell that exceeds 50% counts as an egg egg,” said Kristen Zemaitis, who led a team of volunteers with the Caretta research project. The team also investigated unregistered eggs for signs of development. “Then we will classify this at different stages to see the development percentage in each egg.”
All this information tells the story of this nest, one that the Caretta team has been following for about two months since an adult turtle has crawled on the beach, dug a hole with its fins and laid these eggs. As far as possible, these volunteer teams also catalog the nesting mother, taking action and recording her tag number if she has one.
It is an effort of all night and summer.
Data on Wassaw Island is part of a vast mosaic of information collected by volunteers along all the coasts of 100 miles of Georgia, as well as the Côtes de la Florida, the Carolines and the Virginia. By patrolling the beaches during the night or at dawn, they inventory thousands of sea turtles nests each year. Volunteers amass data on nesting locations, the number of newborns, nest success rates, mother’s details, and more.
The data collection effort began in the 1960s on only a few Georgia barriers. This led to successful attempts in the late 1980s and early 1990s to protect adults from sea turtles from shrimp nets and nests against human interference.
All of this work has enabled scientists to better understand the population of sea turtles over time, to follow their long decline and the extraordinary resurgence of protected newborns in the 80s and 90s and finally returned to the nest in the last decade. It also helps researchers, armed with new technologies, to monitor how turtles react to new threats posed by the increase in seas and temperatures. But it is a long and slow work – and a large part of today’s research will probably not bear fruit for decades.
Like many turtles, the sex of the rubber sea turtles depends on the incubation temperature of their nests – a warmer incubation produces women. Thus, as climate change progresses, there could be many more women than men. It is difficult to predict exactly how problematic it will be for sea turtles, said Zemaitis.
The reproduction of sea turtles is a set of figures: turtles lay a lot of eggs in many nests to increase the chances that some of their babies survive many threats stacked against them. The turtles mate in the ocean, then the females were six to eight nests in one season, about two weeks apart. Scientists know DNA tests that women often mate with several men, but they can also store sperm so that they do not have to find a male with which to mate each time they put a nest.
This means that having fewer men than women cannot necessarily prevent women from nesting – but it could harm the genetic diversity of turtles.
“An ecologist of the population would tell you, you only need a few men to populate, you know, as many women as possible, essentially,” said Zemaitis. “With fewer and fewer men, this reduces the genetic pool over the years. We do not know what effect it will have. “
To help follow the impacts, the Caretta research project teams have used thermometers inside the sea turtle nests since about 2000.
Their work is also part of a wider effort to follow the DNA of the sea turtle. The researcher at the University of Georgia, Brian Shamblin, has directed this effort since 2008, and his project now collects DNA samples to turtle nests all along the northern coast of Florida on the border of Caroline in North Virginia. They know much more about women because researchers can take samples from mothers while laying their eggs and each nest, but Shamblin and his team are now working to get more genetic information on male sea turtles so that they can better follow the changing population.
Sea turtles take around 30 years to reach sexual maturity. The newborns who are crawling towards the ocean today will not be back before the 2050s. Although researchers cannot draw conclusions from their current data, they will be critical decades from now on.
“It is important to collect data now and we can look back [in] 30 years old and say, well, this is the temperature they incubated, that’s probably why we see this number of men, “said Zemaitis.
The same difficulty – having to move over the time of turtles – haunts research on the other major threat that climate change poses for sea turtles. The rising seas erud the beaches on which the turtles nest and could possibly make certain historical nesting beaches unusable for turtles.
“If we worry about climate change, we are worried about elevation of sea level,” said Shamblin. “How many room for maneuver do we have here so that these women choose new beaches to colonize?”
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This is a major objective of his work on the DNA of turtles. Although the Wassaw team patrols the night and can identify the turtles when they pose their nests, a large part of the data collection elsewhere occurs in the morning after the disappearance of mothers. Shamblin uses DNA samples taken from each nest to match them with the turtles that put them.
Conventional wisdom has long argued that turtles come back to the beach where they hatched to put their own nests, but the reality is often less precise. Shamblin and his team use the DNA match to follow how flexible turtles are on where they nest.
Until now, the answer has been mixed. Certain individual turtles stop on several beaches through different states in a single season, while others stick resolutely with the same stretch of sand. Some of the strongest Fidelity sites – which means that the same turtles constantly nest in the same place – is on two islands with Roman National Wildlife Refuge, near Charleston, in South Carolina. This is a concern, said Shamblin.
“About 25% of all rubber turtle nests in the north of Florida are on these two islands,” he said. “It is therefore a very high density nesting area. These are also two of the most erosioned islands in the state of South Carolina. ”
But there is also hope, because some turtles try several beaches, especially the youngest who nest for the first time. This means that the population could gradually move away from the disappearance beaches while the sea level continues to increase. In Georgia, many beaches are less developed than in neighboring states, and they naturally share sand between them, so it could become a destination for sea turtles as other beaches disappear – provided that turtles are flexible.
But, once again, scientists will not be certain for decades, which makes the conservation of sea turtles different from other challenges, said Mark Dodd, who heads the sea turtle conservation program for the Georgia Department of Natural Resources and studied the turtles of Georgia for decades.
“We are used to working on a problem and solving it in two or three years, to feel good about your skin and to move on to the following thing,” he said. “With sea turtles, it is a long -term commitment. It is the one who, you know, it will probably not be completely done during my entire career.”
Even without the uncertainties of climate change, newborn sea turtles face long chances to survive. After a long night to dig up several successful nests, the volunteers on Wassaw found a nest where no new-new was made-perhaps trapped by strong precipitation compacting the sand, just one of the many natural dangers they face.
But in another nest, they found a trap – a tiny living sea turtle that did not go out with his niche comrades. While in the morning began to go out on the ocean, Zemaitis put it on the sand.
“We are just going to give him a little space to stretch his legs, stretch his fins, warm up for the big trek towards the ocean,” she said.
The newborn, just an inch and a half, used its teenage fins to drag a little through the beach towards the water. The first waves were overwhelmed on the newborn while they broke over his head. But finally, to applaud the volunteers and researchers who look, the turtle took swimming. If it survives predators and other dangers in the open ocean, this sea turtle could be back in 30 years to reproduce – even if it finds a coastline radically modified by climate change.
