Earlier this year, three team members from the JCU Turtle Health Research group went to Heron Island on the search for some new turtle tenants for the Caraplace. Knowing that disease is playing a key role in population decline, and having learnt just last year that the green sea turtles are born without a developed immune system, we are now even more driven to continue filling in our knowledge gaps on these iconic creatures; and these hatchlings are very important for helping us to do just that. This project is part of a larger conservation effort to help green sea turtles (Chelonia mydas), which are a globally endangered species.
Over three days on the island, the team members witnessed many majestic turtles hauling themselves up the beach, searching for the perfect spot and then digging tirelessly to lay their eggs. The first digging stage is called body pitting (pictured below) and the second is where the female digs a smaller, deep chamber in which to lay her eggs. They also saw the emergence of several nests that had been laid previously, and from which the new turtle hatchlings appeared in a burst of energy as they started out their lives with a mad dash to the ocean, leaving only their fin prints and empty shells behind. It was a beautiful sight.
However, in nature nothing stays that serene for long. Although turtles are biologically wired to hatch at night when the temperature has cooled and there are fewer predators around, occasionally a nest will hatch during the daytime if it is located under a shady tree. This leaves the newborn hatchlings open to predation, and the new recruits gathered this year came from one such nest, which hatched in the afternoon. With a flock of seagulls circling overhead, numerous black tip reef sharks thrashing around at the water’s edge, and the resident sea eagle hunting along the beach, this batch of hatchlings really had no chance of making it past the reef flat.
Of more than 100 hatchlings in the clutch, only 36 were collected by the team once they had fully hatched and were on their run to the sea, so the predators had their fill as well. The survival rate of turtles at this stage in their life is very low, and almost nothing is known about them until they return to inshore areas as new recruits at around the age of 15 years. Our new residents are now well settled in at the Caraplace and are growing nicely , providing us with new insights into their early development on a daily basis.
You can follow the progress of our hatchlings though our social media pages (top right).
Written by Rebecca Diggins
Edited by Associate Profesor Ellen Ariel