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How did sea turtles get to the Azores?
Sea turtles in the Azores
Hello! My name is Ana Mafalda Sousa and I’m 25 years old. I’m from Abrantes and I have a master’s degree in Applied Marine Biology from Universidade de Aveiro. Nowadays, I’m working at Universidade dos Açores, studying juvenile sea turtles behaviour around the archipelago.
My interest in sea turtles started during college, when I went to Cape Verde as a volunteer with Turtle Foundation. There I spent two month protecting and monitoring adult sea turtles, their nests and later on, the hatchlings.
How did they got here?
In the Azores the work is a lit bit different. Even though the presence of these creatures is known for a while, with the first records of sea turtles in the Azores made by the Dutch sea captain Van Linschoten, who wrote in his sailing directions in 1595: “…when you pass from 36° to 39 1/3 degrees you will come to see the island of Flores with many turtles floating in the water”, there are still a lot of questions to answer.
For example, where do they come from?
The first scientists to raise this question (Prince Albert I of Monaco, the Dutch scientist Leo Brongersma and the American Archie Carr) noticed that there were no nesting beaches in this Archipelago, so where are the nests where they hatch from?
Later, with the first data collecting and tagging of some individuals, the noticed that there were no hatchlings nor adults in the area, only juveniles with 5 to 55 cm of carapace length.
The sea turtles life cycle can be described starting with the female adults laying their eggs on sandy beaches and after a few months, baby turtles (or hatchlings) hatch and run to the sea. As young (or juvenile) turtles, they swim to foraging ground, where the stay for decades until the reach sexual maturity and return the beach where they were born, starting all over again.
In the 80’s, the tagging records were shared with the Department of Biology of the University of Florida, where Archie Carr worked. Carapace length measurements taken in the Azores complemented the “missing” size classes recorded on the US coasts. On the nesting beaches of Florida (USA) only 5 cm recently hatched turtles, young adults with 50-55 cm of carapace length and larger adults can be seen.
The whereabouts of intermediate-sized turtles (i.e. oceanic juveniles) during this period was regarded as a mystery and was called the “lost year”. Archie Carr published his theory that the turtles from the Azores must be part of the population that reproduces in the southeastern United States.
Most recently, my team of the COSTA project is trying to understand the behaviour of these juvenile sea turtles in the Azores waters with telemetry studies and GPS tags, trying to understand diving behaviour and location to where they “hang” around the archipelago.
Who is around here?
We now know that five out of the seven species of sea turtles occur in the Azores, some more common than the others.
Why should we protect them?
Sea turtles have played vital roles in maintaining the health of the world’s oceans for more than 100 million years. These roles range from maintaining productive coral reef ecosystems to transporting essential nutrients from the oceans to beaches and coastal dunes.
Even though they have been around for so long, they are suffering with anthropogenic factor, such as bycatch, vessel collisions and plastic ingestion. Currently, the amount of plastics entering the oceans is estimated to be between 4-12 million tons annually. The probability of sea turtles interacting with plastics are therefore high, especially in oceanic juveniles. Under the AZORLIT and LIXAZ projects, our team is investigating the ingestion of marine litter in turtles that appear dead in the region. So far, our results show that 83% of the individuals studied had ingested plastics.
By: Ana Mafalda Sousa
Ana Mafalda Sousa
References
Afonso P, Fontes J, Giacomello E, Magalhães MC, Martins HR, Morato T, Neves V, Prieto R, Santos RS, Silva MA, Vandeperre F. 2020 The Azores: A mid-Atlantic hotspot for marine megafauna research and conservation. Frontiers in Marine Science 6:826.
Helen RM, Bjorndal KA, Ferreira RL, Parra H, Pham CK, Rodríguez Y, Santos MR, Vandeperre F, Bolten AB. 2018 Sea turtles: University of Florida – University of the Azores connection 1984 – present. A review. Arquipélago Life and Marine Sciences 35: 85-94.
Pham CK, Rodríguez Y, Dauphin A, Carriço R, Frias J, Vandeperre F, Otero V, Santos MR, Martins HR, Bolten AB, Bjorndal KA. 2017 Plastic ingestion in oceanic-stage loggerhead sea turtles (Caretta caretta) off the North-Atlantic subtropical gyre. Marine Pollution Bulletin 121: 222-229.
Rodríguez, Y., Vandeperre, F., Santos, M. R., Herrera, L., Parra, H., Deshpande, A., … Pham, C. K. (2022). Litter ingestion and entanglement in green turtles: An analysis of two decades of stranding events in the NE Atlantic. Environmental Pollution, 298.
Vandeperre F, Parra H, Pham CK, Machete M, Santos MA, Bjorndal KA, Bolten AB. 2019 Relative abundance of oceanic juvenile loggerhead sea turtles in relation to nest production at source rookeries: implications for recruitment dynamics. Scientific Reports 9:13019.
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