Generations of green sea turtles have been feeding in the same seagrass beds for approximately three thousand years. This emerged from special research, in which “ancient” bone knowledge is combined with modern satellite data. Research shows the impact that the destruction of certain seagrass beds can have.
Scientists often follow developments during their own careers. They compare the situation at the beginning with the circumstances later. As a result, slow changes in a larger system – such as changes in an animal population – often go unnoticed.
“Even long-term data only goes back a hundred years,” says Willemien de Kock. on the website of the University of Groningen. The historical ecologist took a different approach to his research.
Bones of boxes in the attic
By analyzing sea turtle bones, she was able to determine what the animals ate thousands of years ago. She used bones in boxes in the attic of the Institute of Archeology in Groningen. His supervisor Canan Çakirlar had already excavated these bones, De Kock only had to examine them.
De Kock linked the information she extracted from the bones to modern satellite tracking data from the University of Exeter. This allowed him to see what routes today’s sea turtles take.
Hoe je in een bot het dieet van een dier opspoort
De Kock kon het dieet van de zeeschildpadden uit de botten achterhalen door naar collageen te kijken. Dat is een stofje dat in botten zit. Ze inspecteerde dit met een zogenoemde massaspectrometer. Daarmee kon ze vaststellen welke planten de zeeschildpadden aten. Alles draait daarbij om koolstof.
Zo legt De Kock uit dat de ene plant meer van het lichtere koolstof-12 kan bevatten en een andere juist meer van het zwaardere koolstof-13. “Omdat koolstof niet verandert wanneer het eten verteerd wordt in het lichaam, kunnen we vaststellen welke verhouding van koolstof er in de botten aanwezig is, en daar het dieet uit afleiden.”
In addition, the English researchers had collected small pieces of sea turtle skin. This skin could be examined in the same way as ancient bones.
For example, De Kock discovered that green sea turtles living today are still swimming in the same seagrass beds as their ancestors three thousand years ago.
Their favorite seagrass beds are found along the Egyptian coast and western Libya. This is important information for people who are committed to protecting sea turtles.
Why it is important not only to protect small sea turtles
“We currently devote a lot of energy to protecting the little ones,” says De Kock. For example, volunteers protect the nests of the endangered green sea turtle on the coast of the Mediterranean Sea. “But we don’t protect the place where they spend most of their time: the seagrass beds.”
Baby sea turtles hatch without parents. If they manage to reach the sea, they first float there for a few years and eat everything. It is not until sea turtles are about five years old that they swim to the same area where their parents used to feed.
From then on, the animals only eat seagrass until they die (eventually) at the age of eighty. And so they’ve been eating these sea grasses for thousands of years in one place: along the coast of Egypt and western Libya.
According to De Kock, the research thus shows that it is very important to protect these seagrasses. Like coral, seagrasses are affected by climate change. The research was published Monday in Proceedings of the National Academy of Sciences (PNAS).
“Bacon trailblazer. Certified coffee maven. Zombie lover. Tv specialist. Freelance communicator.”