The loggerhead turtle is increasingly common on the Spanish coasts. It is a bad sign about the Mediterranean

The Mediterranean is being invaded. The ‘fried egg’ jellyfish or the imposing lionfish They are two undesirable new tenants, but there is one animal that is much less annoying, It is not invasive and yet it is a problem that it is colonizing the western Mediterranean. This is the loggerhead sea turtle.

And it is another adaptive response to climate change.

The loggerhead turtle. Its scientific name is Caretta caretta and is one of only two species of sea turtle (the other is the Chelonia mydasor green turtle) that reproduces in the Mediterranean beaches. If you look at the map, its distribution is worldwide. They enjoy warm waters with a wide range of surface temperatures (a range between 13 and 28 degrees Celsius), but things change during the spawning season.

Nesting females prefer temperatures between 27 and 28 degrees, making Mediterranean beaches an ideal area to lay eggs. The traditional spawning grounds in the Mediterranean were the eastern area, especially the Greek beaches, but something is happening: an increase in temperatures is creating a double imbalance.

A determining factor. It is curious, but temperature controls both the willingness of turtles to nest in an area and, and this is almost the most important, the sixth of their hatchlings. The sexual determination of chelonians depends on the incubation temperature in the eggs buried in the sand. With this strict fan of 27-28 degrees, a balanced population between males and females is achieved.

With higher temperatures, there is a imbalance towards the predominant birth of females. This is a problem for the turtle population itself, since an imbalance of this type would put the species at risk. And even more curious is that mature females have instinctively found a biological refuge on the coasts of the western Mediterranean, where the beaches are somewhat colder (for the moment). The objective is to ensure greater sexual diversity.

Increase in nesting. HE esteem that, in the Mediterranean basin, there are about 8,000 eggs per year. The traditional places are Greece, Türkiye, Libya, Tunisia and Cyprus, but little by little we are seeing that change in the balance. In 2001 found a first nest on a beach in Almería, in Vera, and since then loggerhead turtle nests have been recorded in other parts of the geography of the western Mediterranean.

The turtles They are spawning in Spainbut also in Italy, Malta and Tunisia. In addition to the Almeria coast, the areas in which the turtles are creating nests are Catalonia, the Balearic Islands, Valencia, Murcia and they have been observed in Fuengirola and Marbella.

Conservation and awareness. There are organizations that, increasingly, point out that nesting has been increasing in recent years, and regardless of what it means at a climatic level, it is another problem due to the human factor. In countries “accustomed” to this, where nests are protected, the population knows not to interfere with them.

In others where turtles are beginning to nest, it is possible that we, maliciously or unintentionally, interfere with the reproductive cycles of a species that is considered under threat. That is why it is also they throw citizen awareness campaigns to inform about them and how to proceed if someone finds a nest that is not already being monitored. For example, performing events in schools on biology and conservation of the species.

It is also perform awareness work with fishermen as a target audience, since fishing activities are one of the main causes of death. Likewise, when a clutch is detected, there is the possibility of protecting the nest in situ (where the turtles have to hatch correctly and take the infernal path to the sea) or take the eggs to controlled breeding centerswhere they mature and are subsequently released.

Turtle nursery in Fuerteventura

Poison beyond the heat. But there is another problem apart from climate change and human action: the pollutants that are poisoning the turtles. In recent years there has been studied the liver of at least a dozen loggerhead turtles, finding traces of PCB, PCDF and PCDD.

These are chemicals, pesticides that alter the immune and hormonal systems of turtles. It is something that comes from the hand of the esurface runoff carrying chemical waste from agriculture and industry to the rivers that subsequently flow into the sea.

And torture, unfortunately, is becoming a thermometer of the state of our waters, both in terms of temperature and the presence of chemicals that are already altering the fauna.

Images | H. Zell, Dionysisa303

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