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Turtles manage to avoid predators, but plastic a much bigger threat


Baby turtles are being “trapped” in oceans off Queensland and around Australia where they are feasting on smorgasbords of plastic waste, putting their lives at risk.

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New research has identified for the first time that small juvenile turtles are eating plastic at alarming rates, with the turtles in waters of Queensland among the worst affected.

The study, published today in the scientific journal Frontiers in Marine Science, found around 83 per cent of green turtles and 86 per cent of loggerhead turtles off the coast of Queensland were found to have ingested plastics.

James Cook University Professor Mark Hamann said one turtle in the Pacific Ocean off Queensland had 144 pieces of plastic inside it, while one found in the Indian Ocean had ingested 343 pieces of plastic.

It is a shock finding that raises concerns that juvenile turtles are being “trapped” in habitats with high amounts of plastic debris. This ecological trap means that while the turtles have adapted after hatching to live in parts of the ocean where predators are scarce, these areas also now contain large amounts of plastic pollution.

Hamann said the findings were concerning for the impact of plastic on turtle populations.

“It’s really important because we think this is the most vulnerable age class of turtles, these young turtles that can eat lots of little pieces of plastic,” he said.

“We have to try and understand the magnitude of the issue. Are we likely to lose entire young cohorts to plastic or are we just seeing the unlucky individuals?”

The study, by the James Cook University team in Townsville along with a unit from the UK’s Exeter University, found plastic inside young turtles along the Pacific and Indian Ocean coasts of Australia.

The researchers examined the contents of the stomach and other organs of turtles stranded or caught off Queensland as well as the Indian Ocean off Western Australia.

Hamann said the proportion of turtles that had ingested plastic was much higher in the Pacific Ocean off Queensland than in the Indian Ocean.

From the specimens collected from the Pacific Ocean, green turtles were most likely to have eaten plastics, with 83 per cent of turtles found with plastic in their system.

More than 80 per cent of loggerhead turtles and flatback turtles also had plastic in their system.

Of turtles examined from the Indian Ocean, the flatback turtles were the worst impacted with 28 per cent of the turtles examined having ingested plastic, he said.

Lead author Dr Emily Duncan of the University of Exeter said the plastics in the two oceans that were eaten by the turtles were also different. Plastic found in turtles from the Pacific Ocean were hard fragments, most likely from products dumped by humans, while those in the Indian ocean were mostly fibres from fishing ropes or nets.

The findings add to disturbing statistics on the number of adult turtles worldwide that have choked on plastic bags, ingested plastics or inhaled straws preventing them from breathing.

When marine animals eat plastic it can block their digestive system, causing a long, slow death from starvation. Sharp pieces of plastic can also pierce the gut wall, causing infection or death. As little one piece of plastic can kill an animal.

“Plastics now make up 80 per cent of all marine debris and can be found everywhere, from surface waters to deep-sea sediments,” Hamann said.

“Plastic ingestion and entanglement, which can cause suffocation, has now been documented for every species of marine turtle.

“We don’t know whether eating one piece or 100 pieces is necessarily any worse for the animal. The problem is that they’re finding it and eating it,” he said.

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