SCIENTISTS want every major bay and estuary along the Great Barrier Reef tested for contaminants to identify ‘hotspots’, after alarming levels of chemicals were found in “stressed” green turtles in the northern Great Barrier Reef.
Rehabilitation programs should then be directed to the catchments of pollution ‘hotspots’ to reduce contaminants.
They’re among the key recommendations in the final report of the Rivers to Reef to Turtles project, led by WWF-Australia and supported by major partner Banrock Station Wines Environmental Trust.
The final report also calls for checks on a wider range of contaminants in Reef waters and for turtles to be routinely tested to understand how chemicals are impacting wildlife.
The Rivers to Reef to Turtles project has provided, for the first time, evidence that poor water quality harms green turtles and has shown these iconic Reef animals are strong indicators of ocean health.
Over the past four years, the project has generated world headlines with revelations green turtles had heart and gout medication, pesticides, industrial chemicals, and staggering levels of cobalt in their blood.
The ground-breaking study was prompted by the mass stranding of green turtles in June 2012, when more than 100 green turtles washed up dead or dying in Upstart Bay, south of Townsville.
Scientists tested sediment, water, green turtles and the forage they eat in two coastal locations – Upstart Bay and Cleveland Bay – and compared the results to tests on the same samples from the remote Howick group of islands.
There were elevated levels of metals such as cobalt, antimony and manganese in the coastal turtles’ food (seagrass and algae) and in their blood, with many showing signs of stress, including liver dysfunction and neurological inflammation.
Upstart Bay turtles had cobalt levels up to 25 times higher than remote populations, levels greater than those recorded previously for any vertebrate species and within the range expected to cause acute toxicity in other species.
“We believe the metals found in turtles washed off the land from both natural and human related sources. The ratio of cobalt found in turtles’ blood and shell is consistent with the theory that there was acute cobalt exposure at Upstart Bay in 2012,” said Christine Madden Hof, WWF-Australia Marine Species Project Manager.
The testing also showed there were thousands of chemicals in turtles that couldn’t be identified.
Scientists believe chronic stress may be the cause of eye lesions found in 23% of green turtles in Upstart Bay and 10% of green turtles in Cleveland Bay. The lesions are possibly impacting the turtles’ ability to feed and reproduce.
There was no blueprint for what the project team set out to do. The scientists had to come up with new methodologies, tools and approaches to test the links between water quality and green turtle health.
They devised new ways to screen for chemicals in water, sediment, seagrass and in the blood and shell of turtles.
In an Australian first, researchers grew skin cells of green turtles in a lab to test the impact of chemicals without harming a turtle.
The photo below left shows green turtle skin cells grown in a lab, while on the right, cells have been exposed to different doses of chemicals with a fatal dose indicated by a blue colour.
The project team says greater investment is needed so their new techniques can be further developed to improve Reef monitoring.
“Existing Reef monitoring programs do not test for many of the contaminants found by our project. That’s why we’re calling for checks on a wider range of chemicals, including metals,” said Ms Madden Hof.
“If we found all these contaminants in just two coastal locations what’s happening in the Reef’s other major bays and estuaries?
“What effects are chemicals having on other wildlife in these waterways?
“We have shown turtles are good indicators of Reef health because they absorb chemicals in their environment.
“Using methods developed for this project could provide a cost effective, early warning sign of poor water quality and chemical contamination,” she said.
Rivers to Reef to Turtles is a multi-collaborative project led by WWF-Australia and supported by major partner Banrock Station Wines Environmental Trust. Collaborative partners included TropWATER (James Cook University), QAEHS/Entox and Vet-MARTI (The University of Queensland), the Queensland Government, Griffith University, a number of Indigenous ranger groups and others.