As they do every May since 1984, the ARCHELON researchers and volunteers started their mission in Zakynthos, Peloponnese and Crete. They will stay there, on the most important nesting beaches, until October, with the aim of documenting the reproductive activity of the Loggerhead sea turtle. In parallel with the preparations for the installation of the Research and Information Stations, the training of the new volunteers also begins. But on their first visit to the nesting beaches on May 11th, three volunteers of the Zakynthos Project were in for a surprise: the first nest of the season had already taken place the night before in Sekania, the Area of Absolute Nature Protection of the National Marine Park of Zakynthos.

"Reviewing time series data from previous years confirmed that for the first time a nest was found so early in May in Laganas Bay", says Aliki Panagopoulou PhD, Research Coordinator at ARCHELON. Meanwhile, on the morning of May 15th, the first Loggerhead nests were recorded both in the Nature Protection Area of Kyparissia Bay and in northern Crete, in Rethymno, these earlier than usual as well.

But why do sea turtles start laying their eggs earlier?

Scientists as early as 2016 predicted that the nesting period would move earlier in the season due to climate change! This is because sea turtles are vulnerable to the effects of climate change both on land and in the sea. Especially as the temperature plays an important role throughout the life cycle of these animals, significantly affecting their reproduction. Starting egg laying earlier in the year may act as an adaptation mechanism for turtles to avoid very high summer temperatures (Patel et al., 2016).

The recent State of Europe's Climate 2023 report published by the European Commission states that during 2023, the average sea surface temperature in all of Europe's seas was the warmest ever recorded. Parts of the Mediterranean and the Atlantic recorded the highest average sea surface temperature values on record there. In the Mediterranean, sea heatwaves were recorded in July and August with sea surface temperatures reaching 5.5o C above average in some areas. The oceans are an important heat store for our planet's climate system, as they cover 2/3 of the earth's surface and have absorbed 90% of the excess heat caused by anthropogenic emissions of greenhouse gases. Changes in ocean temperature can lead to habitat changes and mass die-offs of marine species.

"But even if moving nesting to cooler days provides some relief for turtles, climate change may negatively affect them in other ways. For example, the increase in temperatures prevailing inside the nest during incubation can affect the sex of the hatching turtles. High temperatures lead to the birth of more female than male turtles, which can affect populations and their survival", warns Aliki Panagopoulou.

The study of the effects of climate change and the predictions for the future behavior of loggerhead sea turtles are possible due to the systematic recording of the reproduction of the species in Greece implemented by ARCHELON for the last 40 years. At the same time, the continuation of the protection of the Loggerhead nests and hatchlings on the beaches is of equal importance.

You can also help:

• Become a volunteer with ARCHELON!
• Support our work!
• Learn more about the climate crisis in the report State of the Climate in Europe – 2023