Green Sea Turtles and Seagrass – A Staple for Over 3000 Years
Sea turtles, also known as marine turtles, are some of the Earth’s oldest animals, with evidence of them roaming the Earth’s oceans for the last 110 million years. Healthy oceans rely on sea turtles because they play an important role in marine ecosystems and influence other species around them. Hawksbill sea turtles, for example that live in coral reefs specialize in eating species of sea sponges which allows less common types of sponges to grow and thus increases the variety of life on the reef.
Sea turtles also provide habitats for many species, like barnacles and small crustaceans, that sea turtles transport during their long migration periods. Green sea turtles play an important role in balancing the ocean’s food chain as their feed on over 200 taxa of vertebrates and invertebrates, which include marine sponges, jellyfish, molluscs and crustaceans. Green sea turtles will also maintain healthy seagrass beds by grazing on them.
Scientists have found that for over 3000 years, generations of green sea turtles have returned to the same Mediterranean seagrass meadows to eat. Researchers from the University of Groningen have been analyzing the bone collagen of sea turtle remains from archaeological sites in the Mediterranean Sea area. By inspecting the bone collagen with a mass spectrometer, they can detect what kind of plants the sea turtles must have eaten. Because carbon doesn’t change when it is digested, they can detect what ratio of carbon is present in the bones and infer the diet from that.
With this information about green sea turtles and seagrass and the use of modern satellite tracking data, the researchers can see the current travelling routes and destinations of sea turtles. Samples taken from the living green sea turtles revealed similar dietary information as those found in the ancient bones. It was found that generations of green sea turtles have been feeding on seagrass meadows along the coasts of Egypt and West Libya.
The Mediterranean Sea is home to 1.2 million hectares of seagrass meadows. Still, unfortunately, as a result of marine heatwaves, which are intensifying due to climate change, ecological degradation and the immediate impacts of coastal development, we are seeing a decrease in the green sea turtles and seagrass meadows. Recent models have shown a high risk of widespread loss of seagrass in the spots where the green sea turtles have been going for millennia. The importance of this study is that because we can trace the data so far back, it allows us to see the human-induced effects on the environment and can allow us to predict the future of green sea turtles.
Project Mania is an ocean conservation NGO working to preserve green sea turtles and seagrass in the Mediterian Sea. The team is working on planting seagrass in these areas and consistently monitoring the variables affecting green sea turtles and seagrass growth to predict which meadows are at risk and which need immediate action. They are also committed to getting the community involved by encouraging them to collect ripped-out seagrass found on the shores of seagrass seeds and donate them to Project Mania to be replanted.
Helping to restore the green sea turtles and seagrass meadows will be important to the species living within them. These meadows also act as a carbon sink which can help mitigate climate change’s effects, such as the heatwaves. Furthermore, protecting the seagrass meadows helps to stop erosion which is important in keeping the sand beaches intact.
The ecosystems are all connected, and if we protect one, it will affect so many others dependent on them. Green sea turtles and seagrass have existed in our waters for millions of years, and we need to work towards protecting them so they can be around for another million more.
