The green turtles that swim through the pristine waters and stunning coral of the Great Barrier Reef have human medicines and industrial chemicals coursing through their veins. As part of an ongoing conservation project called Rivers to Reef to Turtles, the team aim to assess how humans are impacting the reef and its inhabitants, such as green turtles.
By analyzing the blood of the reptiles, the researchers have identified many chemicals of worry. These include ones that form human medicine, others that originate from agriculture, and some derived from the cosmetic industry.
“What you put down your sink, spray on your farms, or release from industries ends up in the marine environment and in turtles in the Great Barrier Reef,” explains team member Dr Amy Heffernan in a statement. “Turtles could be used as a biomonitoring tool to reveal which chemicals are entering Great Barrier Reef waters and how they are impacting wildlife.”
Turtles are well placed to see how human activity is impacting marine life. As creatures that frequent shallow coastal areas, which are frequently regions preferred by people, they often come into contact with the chemicals and pollutants washed into rivers and oceans.
This can accumulate to such levels in their tissue that it can then be detected through tests.
“Rivers to Reef to Turtles has revealed to people that the chemicals humans manufacture wind up in the sea and are absorbed by marine life,” says WWF-Australia spokesperson Christine Hof. This can occur in a number of ways. A major problem is agricultural runoff, in which the pesticides, herbicides, and insecticides sprayed onto fields are flushed into rivers and coastal waters when it floods or rains.
In fact, one of the chemicals identified in the turtles' blood was ethiofencarb sulfone, a breakdown product of an insecticide. But these pollutants can harm the reptiles in other indirect ways too, including algal blooms through eutrophication and the die-off of seagrass, a major component in the diet of turtles.
The team also detected chemicals that may be a bit more of a surprise. They found traces of allopurinol, for example, which is more frequently reserved for the treatment of gout or kidney stones, as well as milrinone, a form of heart medicine. These have probably entered the environment via the bathrooms of households, flushed down toilets and sinks.
The project aims to build a better picture of how we are polluting the Great Barrier Reef, the impact it is having on the wildlife, and how best to mitigate it.