Scientists from the United States and Australia found that the temperature increase significantly violated the sex ratio in populations of sea turtles. Researchers compared two animal populations living in the Great Barrier Reef area. In the group living in warmer waters, females were 99.1% of newly born cubs. In the population from the colder region only up to 69% of the females were detected. Such a violation can lead to the extinction of many species of turtles - this, in turn, will affect the life of the whole ecosystem.

In sea turtles, including the green (soup) turtles of Chelonia mydas, the sex of the animal depends on the temperature of the sand in which the eggs were laid. Males appear at a lower temperature, females - at a higher temperature. A rise or fall in temperature by several degrees can not only change the ratio of the sexes in the masonry, but also destroy most of the eggs. At the same time, mortality of cubs of turtles is extremely high. Most of the cubs hatched from eggs do not get to the water: the turtles become prey for predators.

The Great Barrier Reef is inhabited by two large populations of green turtles: the southern and northern. They do not intersect and are genetically separated from each other. Turtles of a certain population feed in the same area and lay eggs on the same stretch of coast where they themselves were born. Scientists analyzed blood samples of 411 green turtles to establish their sex. Belonging to a certain sex was detected by the level of some hormones.

In the southern population, females were between 65% and 69% of animals. In the northern, inhabiting a warmer region, females were 86.8% of adult turtles, 99.8% of "adolescents" and 99.1% of newly hatched cubs. Scientists compared these data with a graph of temperature changes in the Great Barrier Reef area. It turned out that the sex ratio in the northern population has been disrupted for more than 20 years, and this process is associated with an increase in temperatures.

In the future, the lack of male green turtles may become even more acute. Despite the fact that males are able to travel long distances, disrupting the balance of the sexes can reduce the fertility of turtles. This problem is relevant for other species of reptiles, in which sex depends on the temperature of the environment. Scientists have proposed several methods of "protecting" males, including dense tents for beaches where turtles lay eggs.

The study is published in the journal Current Biology.