Careta Careta and the shock of the climate crisis

“As in May every year since 1984, researchers and volunteers of “Archeleon” started their missions in Zakynthos, Peloponnese and Crete this year. In the evening of May 10, members of the Zakynthos program set up their tents and set off for their first visit to the spawning beaches the next morning. When they arrived at Sekania, Zakynthos National Marine Park’s Special Nature Reserve, they were in for a surprise, as the first nest of the season had already been established.

THE Rania SpyropoulouA biologist-oceanographer and board member of the environmental organization Archelon, speaking with “K”, describes how what was initially good news led to thoughts and concerns about the future of Caretta sea turtles (Caretta caretta).

As Ms Spyropoulou explained, Karetta traditionally arrives on her “favourite” Greek beaches after May 22 to start spawning, usually on the 25th. “There is always a slight change, but the ten days we celebrate this year are not the obvious wide gap of before» Ms. Spyropoulou notes, adding that a review of time series data from previous years confirmed nesting in Laganas Bay in early May for the first time.

“The problem is widespread and it is happening for the first time. We are in contact with the relevant organizations of the neighboring countries to see what is happening in the entire Mediterranean Sea.

Other beaches frequented by sea turtles gave a similar picture. On the morning of May 15, the first Caretta nests were also recorded in the Kiparissia Bay Nature Reserve, while in Rethymno, north of Crete, nests were established earlier than usual. “The problem is widespread and it is happening for the first time. We are in contact with the relevant organizations of our neighboring countries to see what is happening in the entire Mediterranean Sea”, says Mrs. Spyropoulou.

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According to the association’s research team, scientific predictions about the earlier spawning season in spring are confirmed. climate crisis.

In 2016, an international study involving Greek scientists used data from all regions monitored by Archelon and applied them to climate models. According to this study, we expect a change in the onset of spawning in the Mediterranean Sea. In fact, according to the study, if the climate crisis continues at the same rate, by 2100 ovulation could start even 50 days earlier.

Starting to lay eggs earlier in the year works as an adaptation mechanism for turtles to avoid very high summer temperatures.

Sea turtles are vulnerable to the effects of climate change both on land and in the sea. Temperature, in particular, plays an important role throughout the life cycle of specific animals, significantly influencing their reproduction. Starting to lay eggs earlier in the year works as an adaptation mechanism for turtles to avoid very high summer temperatures.

Average sea surface temperatures across all European seas for the whole year were the warmest ever recorded, according to the latest State of the Climate in Europe 2023 report published by the European Commission. Parts of the Mediterranean Sea and Atlantic Ocean recorded the highest mean sea surface temperature values ​​there on record.

Sea heatwaves were recorded in the Mediterranean last July and August, with sea surface temperatures reaching an average of 5.5 degrees Celsius in some areas.

As Ms. Spyropoulou points out, “oceans are an important heat sink for our planet’s climate system, as they cover 2/3 of the Earth’s surface and absorb 90% of the above-ground heat generated by man-made greenhouse gas emissions. . Changes in ocean temperatures will lead to changes in habitats and marine species. can lead to mass destruction”.

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One of the already obvious changes is the increase in female karettas and the corresponding decrease in males.

“When it is very hot inside the nest and the temperature exceeds a certain threshold, most of the baby turtles become female. In other words, the heat in the nest “pushes” the sex to the female, while the cool environment, on the contrary, favors the males.”

Ms. Spyropoulou explains why this happened. “Sea turtles are reptiles. In eggs, the sex of embryos is not determined by DNA, but by the temperature of the environment in which the egg is incubated. Thus, when it is very hot inside the nest and the temperature exceeds a certain threshold, most of the baby turtles emerge as females. In other words, the heat in the nest “pushes” sex to the female, while the cool environment favors the males. This is a problem in the long run, given the rising temperatures, as the species will begin to have difficulty mating. That’s why it’s so valuable to protect the more shaded beaches, such as the one on the island of Marathonisi in Zakynthos, where the male turtles are born. Temperatures are rising at all the other beaches that Caretta visited.”

Rising temperatures on land and sea are not the only threats facing sea turtles in the context of the climate crisis. Ms. Spyropoulou explains to “K” that after the pandemic The protective measures that must be taken by businessmen operating on the beaches chosen by carettas to give birth have been significantly weakened..

“Before the pandemic, we were businessmen, hoteliers, etc. we achieved a satisfactory level of synergy with Unfortunately, after the pandemic, we almost started from scratch. The “invasion” of tourism has set us back – those who should help us in our work do not always listen to us. Beach umbrellas are back…in their prime. At some beaches, umbrellas must be collected at night. While we used to achieve 60-80% compliance with this measure, we are now down to 30% in some cases.”

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