Loggerheads and Greens are the most common sea turtles in the Mediterranean. Some are visitors from the Atlantic, but the turtles that hatch along Mediterranean shores are from distinct subpopulations. While most nesting occurs in the eastern basin, both visiting and native subpopulations travel and forage throughout the Mediterranean.
Loggerheads are the most frequently found sea turtle in the Mediterranean, with around 7,000 nests each year. They consume a variety of species; sponges, crustaceans and sea urchins are among their favorites. Most loggerheads nest on the beaches of Greece, Turkey and Cyprus.
Green sea turtles follow a similar pattern to loggerheads, nesting in much smaller numbers (around 2,000 nests per year), primarily in Turkey, Cyprus and Syria. While juvenile greens are more omnivorous, adults are mainly vegetarian, feeding on sea grasses and algae.
The green sea turtles found in the Mediterranean are endangered as are the Atlantic loggerhead subpopulations that visit. The Mediterranean loggerhead subpopulation is listed as least concern, but this listing is entirely dependent on continuing conservation practices in the region.
Dangers sea turtles face at sea
Sea turtles find a rich bounty of food and nesting locations in the Mediterranean, but they also face challenges, including bycatch risk, plastic pollution, human interference on nesting beaches, and climate change.
There are likely over 44,000 incidental sea turtle deaths due to bycatch each year in the Mediterranean. Longlines, bottom trawlers, set nets and demersal longlines all contribute to these numbers. Fishing practices have begun to change in the Mediterranean and many fisheries now use bycatch reduction devices such as fisheyes, extended funnels and jones-davis devices. Organizations such as Doga Dernegi, WWF Turkey and the Mediterranean Association to Save the Sea Turtle are working to reduce bycatch.
Plastics are another risk for sea turtles and their danger is compounded for these top-level consumers. Loggerheads can mistake plastic bags for jellyfish and also consume fish and other animals that have previously eaten plastics. Green sea turtle adults may eat plastic that resembles their vegetarian diet. In one study 100% of green sea turtles were found to have ingested macroplastics, and another showed that 100% of all sea turtle species had ingested microplastics.
Plastics don’t only pose a danger as a mistaken food item; sea turtles can become entangled in plastic debris and small plastic pieces in beach sand may even impact nesting success. Plastics may increase the temperature of nests to nonviable levels and may change the sex ratio of hatchlings, threatening the success of future generations. Male sea turtles are only born at cooler temperatures and research shows numbers are already highly skewed toward female hatchlings. With the climate pushing temperatures upward, plastic in the sand might further exacerbate these stresses on nesting sea turtles.
Sea turtles may be making their accommodations for warming temperatures; evidence shows that nesting may be moving westward. While numbers are still small, there has been an increase in nesting on beaches in the northwest region of the Mediterranean.
Despite the difficulties sea turtles face, recent studies show that worldwide sea turtle populations are increasing, likely due in large part to human influence. Sea turtles benefit greatly from nesting surveys and protection as well as local education outreach. Many locations in the Mediterranean already have extensive sea turtle programs, and efforts are being made to coordinate conservation and research efforts across the 21 countries of the Mediterranean.
How can we help?
Individuals can make a difference every day by reducing plastic use and carefully disposing of plastic waste, on land and water. And beachgoers can take a few precautions which will greatly benefit sea turtle hatchlings. Turning off lights at night can make a big difference for emerging hatchlings which head for the brightest light—naturally over the sea, but with artificial lights, they can sometimes become confused. Other helpful precautions at the beach include removing beach gear and toys at the end of a visit and filling in holes where hatchlings (or their mothers) might become trapped and of course, not disturbing nesting mothers or their hatchlings.
With a little help from their human neighbors, the ancient and majestic sea turtle will continue for generations to come in the Mediterranean.
Written by Rachel Edicott