Climate change means reproduction changes of Sea Turtles in Puerto Vallarta – via Herp Digest

August 21, 2017, Puerto Vallarta News, Mexico

Between June and November, tortoise females reach the beaches of western Mexico to lay their eggs in the warm sand and ensure their reproduction.

About 45 days later, hundreds of youngsters leave their nest to return to the sea, a cycle that specialists consider “normal” in the spawning season.

However, this cycle is increasingly changing, says Vicente Peña, operational manager of the Tortuguera Network, a civil organization that brings together a dozen camps dedicated to the protection of that animal along the banks of Jalisco and Nayarit.

Camp biologists and volunteers have had to extend spawning season activities one or two months longer than usual, as turtles come to the beaches late, guided by an unusual warmth of seawater even in winter.

“Both the sea water and the sand are having a higher temperature that allows this reptile, the sea turtle, to hatch during the winter, something that was not before,” explains Peña during a nighttime egg collection in Puerto Vallarta.

“There is no doubt” that climate change impacts the spawning cycle. “In 20 years, camps have been closed on December 1, now we are working until the last days of January and having pups in March, it is something we do not need to debate, it is a fact”, Emphasizes Peña.

The nest of sand that the female forms to deposit between 100 and 150 eggs requires an average temperature of 29.9 degrees Celsius so that the young can form and survive, says Carlos Flores, one of the biologists who collaborates in two of the camps.

The heat around the nest also affects sex. If higher than average, a larger proportion of females will be born, if smaller, there will be more male offspring.

He says that in recent years the beaches of this region have registered temperatures of between 36 and 38 degrees, and even up to 40. This means that in a few years the species will have difficulty reproducing if there is insufficient protection.

Increasing heat generates a bias in the species, because “the turtles that usually nest in the summer will disappear and will survive those that nest in the fall and winter” when the thermometer does not rise so drastically, adds Peña.

Specialists have adopted natural shading techniques with palm or shade mesh to prevent the intense heat from the sand from damaging the nests they rescue.

Each night during the spawning season biologists and volunteers from the 12 camps in the region conduct rounds to “accompany” the turtles that come to the beach to lay their eggs.

Through their instinct, females choose the safest and most suitable place. With their fins they create a nest where they deposit the eggs. The process takes about 30 or 40 minutes until the turtle covers the gap and ensures that there is no trace that attracts birds and other predators. Then they return to the sea, guided by the light of the moon.

The camp managers collect the eggs and move them to a shady pen and the ideal space conditions for incubation, explains Elizabeth Coronado, a biologist in charge of the nursery in one of the hotels in the port.

Last year in this camp of only 690 meters they rescued 890 nests, which means almost 65,000 turtles released. In others such as Mayto, in the south of Jalisco, up to 2,000 nests have been protected.

Some hotels offer their guests the possibility to help in the camp or the release of the young when they hatch.

“They get involved,” so people go “with an idea of what environmental awareness is,” Coronado says.

For organizations, protecting female turtles and their nests is “very important,” because they have an instinct that helps them identify where they were born, which they will invariably return to adulthood to reproduce.