First-of-its kind study documents heavy metals, other evidence of poor health
New research is detailing how environmental
In a study that appears in the journal Science of the Total Environment, a multidisciplinary group of researchers set about evaluating turtle health, water quality and other factors in the aftermath of a catastrophic mass death of green turtles in Australia.
“We found evidence of heavy metals – particularly cobalt – in sea turtle populations where we also saw signs of illness,” said lead author Mark Flint, program head of Zoo and Wildlife Conservation Medicine and Ecosystem Health in the College of Veterinary Medicine at The Ohio State University.
“Though we can’t be sure what caused this, there were cyclones and major flooding in this part of Australia two years prior to the start of our study, and that could have drawn out sediment rich in heavy metals that had been lying in rivers and streams benign for the past 50 years,” Flint said.
Green turtles, Chelonia mydas, are an endangered species, and one of the largest sea turtles, weighing in at as much as 400 pounds in adulthood. Green turtles are named for the greenish color of their fat, not their shells, and are found mainly in tropical and subtropical waters, according to the World Wide Fund for Nature-Australia (WWF). The WWF provided funding for this research, and led the Rivers to Reef to Turtles project under which it was conducted.
Large populations live, feed and nest on Australia’s Great Barrier Reef, favoring the bays and protected shores near the coast and around islands.
The Rivers to Reef to Turtles project, which ran from 2014 to 2017, examined health of green turtles at two northern Queensland bays – Cleveland and Upstart – known to be impacted by urban and agricultural human activities and at a third remote “pristine” area, the Howick Group of islands.
Following up on a high number of turtle deaths in 2012 and 2013 that conservationists were
They also counted barnacles on the turtles. Flint’s previous work has shown that high barnacle counts on turtles’ undersides correspond to poor health. The theory behind that? When healthy and feeding normally, a turtle’s
“An unhealthy turtle often has trapped air in its shell and is buoyant, meaning it can’t dive down for food. It’s almost like a balloon,” Flint said. “Also, a turtle that can’t dive sits on the surface of the water where algae and barnacles can grow better.”
In cases where the researchers found dead turtles, they conducted in-depth
The research team found elevated levels of an enzyme called
One in five of the juveniles examined at Cleveland Bay had high barnacle levels (16 or more) and one in 10 of the young turtles at Upstart Bay had excessive barnacle growth. This level of barnacle growth was not seen in any of the turtles at the “pristine” control site.
By the end of the study, the researchers saw some evidence that the population in Cleveland Bay was returning to normal, but the problem still remains
This multidisciplinary approach is the first effort to look with this depth at this population of turtles and the potential links between environmental toxins and their well-being, Flint said.
The researchers suspect that the unhealthy measures seen in the turtles that live in areas affected by urbanization, farming and industry are connected to contaminants in their ecosystem. In particular, the study team found evidence of heavy metals, primarily cobalt, in the turtles’ blood.
Green turtles migrate long distances between feeding grounds and from the beaches on which they hatched. The reptiles are threatened by overharvesting of their eggs, hunting of adults, being caught in fishing gear and loss of nesting beach sites, according to the WWF.
The green turtle is the only “vegetarian” sea turtle, eating mostly
The monitoring of sea turtle health also is important because with their long
This research gives conservationists and marine biologists a baseline understanding of sea turtle health and response to environmental
Other researchers who worked on the study were Ian Bell of the Queensland Department of Environment and Heritage Protection, Anne-Fleur Brand of Utrecht University and the University of Queensland and Christine Madden Hof of the WWF.
CONTACT: Mark Flint, 614-292-6166; Flint.firstname.lastname@example.org
Written by Misti Crane, 614-292-5220; Crane.email@example.com