Sea turtles have nothing to celebrate today

World Turtle Day, celebrated on May 23, is the perfect opportunity to learn more about the friendly reptiles with a shell on their backs. There are nearly 360 species of turtles on Earth, of which as many as half have endangered status. Meanwhile, sea turtles still remember the days of the dinosaurs and have played an important role in coastal ecosystems for 110 million years. Can they be saved from extinction?

Seven species

The vast majority of turtles in the world are fond of terrestrial environments. Only seven species have chosen to live in water, although none of them have gills and all need air to breathe. These include:

• Bay turtle (Lepidochelys kempii) – critically endangered, in 2019. There were only 22,000 living in the world. individuals;
• Olive ridley turtle (Lepidochelys olivacea) – an endangered species, for the time being still found from the west coast of North America to Southeast Asia;
• Natator tortoise (Natator depressus) – living only in the coastal waters of Australia;
• The edible turtle (Chelonia mydas) – an endangered species, as you can easily guess from the name;
• Caretta caretta (Caretta caretta) – the only one of the sea turtles that breeds around the Mediterranean Sea, unfortunately, with an ever-decreasing population;
• The chinstrap tortoise (Eretmochelys imbricata) – a critically endangered species with only five populations left in the world;
• Leatherback turtle (Dermochelys coriacea) – the largest of the sea turtles, growing more than 2 meters in length and unfortunately facing extinction.

So the balance sheet is not optimistic. Sea turtles are gradually disappearing from the face of the Earth, and the culprit, of course, is man. In the last two hundred years, we have managed to decimate a population that has existed in the world more than 300 times longer than we have.

What threatens sea turtles?

Turtle stew was a prized specialty in the Western Pacific and among the island peoples of the Indian Ocean for hundreds of years. Not even the fact that sea turtle meat is sometimes toxic to humans, and poisoning can lead to death, prevented this. Prior to the species protection bans, humans also killed turtles for their shells, skin and even oil.

Currently, the biggest threat to sea turtles is fishing. Gill nets, longlines and trawls are lethal traps, and the predatory depletion of local shoals limits the turtles’ food sources. To make matters worse, the crusted reptiles are finding it increasingly difficult to find a nesting site, which is always done on land. Beaches besieged by tourists, harbors and marinas with constant boat and ship traffic, and concrete boulevards put female turtles in a tricky situation.

Sea turtles also suffer from the tons of plastic that land in the seas and oceans every year, leading to suffocation and poisoning. Petroleum-based contaminants penetrate organisms and weaken the immune system – marine researchers are increasingly encountering cases of a cancerous disease known as fibropapillmatosis and causing tumor-like growths on reptiles’ bodies.

Sea turtles and climate change

As animals that depend on the marine ecosystem, turtles are also severely affected by a warming climate. Increasing the frequency and severity of violent storms threatens the reproduction process. The encroaching water on the beaches destroys nests and limits the space for building new ones.

However, the rise in global temperature has another rather surprising effect on sea turtles. It has to do with the fact that in some reptile species the sex of the offspring is determined only after fertilization and egg-laying and is a direct result of the temperature level during incubation. If it exceeds 31°C, the young will be female, while if it is lower than 27.7°C, males will hatch. The temperature oscillating in the mentioned range is the most favorable, as it means that baby turtles will be a mix of both sexes.

Study published by Australian researchers in 2023, indicates that a century-long rise in temperature in some regions of the world of 1.15-1.68°C has caused dramatic changes in litter structure. In 17 of the 64 sites studied, females accounted for more than 90 percent of the offspring. Experts fear that there may eventually be a shortage of males to fertilize.

World Turtle Day provides an opportunity to publicize the problems facing marine ecosystems as a result of human economic activity. Organizations such as WWF are actively involved in saving turtles, promoting sustainable fishing and protecting nesting beaches. Time will tell how many of the remaining seven sea turtle species will be saved from extinction later this century.