Numerous green sea turtles living on the Great Barrier Reef in Australia have been dying en masse and falling sick because of the high levels of chemicals people have been releasing into the water, warns the World Wide Fund for Nature (WWF).
Large amounts of toxic effluents from industrial and urban areas near beaches are washed by floods and rainwater into the sea. Once there, these chemicals end up contaminating large swathes of seagrass and coral where the turtles live and feed, the conservationist group says after conducting a five-year study on the health of local green turtles.
“Living as they do in coastal bays, green turtles are directly impacted by human activity,” WWF explains. “What we put down our sinks, the chemicals we use on land and what’s washed off our roads ends up in the ocean, threatening the clean water that turtles need to survive.”
WWF began investigating the health of turtles at the reef, one of the most biodiverse places in the world’s oceans, in 2012 after more than 100 green turtles had been found dead or dying in Upstart Bay, in Queensland. To find out the cause, scientists set about collecting water, sediment and food samples in the area, in addition to blood and shell samples from turtles, in order to test them for a variety of chemicals in them.
They then compared their samples collected near coastal areas with those taken at Howick Island, a relatively untouched marine area several hundred kilometers away. Turtles near the coast in Upstart Bay were found to have significantly higher levels of metals in their systems, including cobalt, antimony and manganese.
In some turtles living near the shore cobalt levels were up to 25 times higher than in turtles further out at sea. Turtles with high concentrations of cobalt in their blood were all found to be in poor health.
“There used to be a theory that the ocean was so huge it would dilute contaminants to such an extent that it remained a relatively healthy environment for marine creatures,” said Associate Professor Caroline Gaus, from the University of Queensland.
“But people should be aware that many of the chemicals we flush down the toilet, apply to our gardens, spray on crops, or use in factories can end up in turtles and we don’t yet know how it is affecting them,” Gaus adds.
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