Sea turtles follow 3000-year-old routine, new study reveals

One of the turtles previously admitted to the Sea Turtle Hospital at uShaka Sea and later released on the KZN North Coast. Picture: Don Hunter/Supplied

One of the turtles previously admitted to the Sea Turtle Hospital at uShaka Sea and later released on the KZN North Coast. Picture: Don Hunter/Supplied

Published Aug 3, 2023


Green sea turtles in the Mediterranean Sea have been shown to maintain remarkably consistent foraging habits over the past 3000 years, according to a groundbreaking study.

The research sheds light on ecologically critical and unprotected coasts in North Africa, highlighting the significance of deep historical data in guiding present-day conservation efforts.

The study, published in the Proceedings of the National Academy of Sciences, was conducted by a team of researchers led by Willemien de Kock, a post-doctoral researcher at the Groningen Institute of Archaeology.

They collaborated with the North Cyprus Society for the Protection of Turtles to gather sea turtle bones from three Bronze and Iron Age sites dating back 2700 to 4700 years. The ancient dump sites were filled with discarded bones and shells from past turtle meals.

By analysing the chemical make-up of the bones and comparing them with modern seagrass meadows chemical signatures, the researchers were able to establish a direct connection between ancient and present-day turtle behaviour.

The results revealed that the turtles of the Iron Age fed in the same meadows as their modern counterparts, indicating an incredible continuity in their foraging routines.

Green sea turtles (Chelonia mydas) are known for their affinity for routine. They return to the same spot where they hatched to lay their eggs and frequently revisit specific seagrass meadows, sometimes occupying areas as small as 50 square metres, to feed on their preferred food - seagrass.

Alberto Taurozzi, a co-author of the study and a paleo-biologist at the University of Copenhagen, emphasised that most conservation efforts focus on protecting where sea turtles breed, neglecting their crucial foraging grounds.

He pointed out that turtles breed only once every few years, while they spend the majority of their lives in these often-overlooked meadows along the North African coast.

The findings not only highlight the long-standing traditions of sea turtles but also underscore their mutual dependence with seagrass meadows. As sea turtles graze on the seagrass, the plants maintain their lushness, and the meadows need the turtles to thrive.

Unfortunately, these vital foraging grounds currently lack governmental protection. The North African coast, where these meadows are situated, faces conflicts that restrict research with plans for oil developments in the area on the horizon.

Moreover, the impacts of climate change, such as more frequent and intense heat waves, threaten the future of these meadows. Without adequate protection from these stressors, the green sea turtles may have to seek new foraging areas.

The study’s lead author, Willemien de Kock, stressed the importance of interdisciplinary research for conservation efforts.

She believes that “this combination of ancient chemistry and modern satellite techniques can be applied to understand other marine animals, such as fish and whales, and help in telling their stories more clearly to the world.”

Cyler Conrad, a cultural resources environmental scientist at the Pacific Northwest National Laboratory, described the study as "really thrilling" and pointed out that few studies have successfully traced such ancient connections between animals and their environment.

The research’s implications extend beyond sea turtles, as this innovative approach to studying past animal behaviour has the potential to revolutionise conservation efforts for various marine species.

Protecting these ancient traditions and habitats can serve as a critical buffer against climate change and preserve the delicate balance of marine ecosystems.