How much plastic does it take to kill a sea turtle? According to new research, it does not need much.
A study published in the journal nature On Thursday, it was found that sea turtles have a 50 percent higher mortality rate after taking 14 plastic pieces.
This means researchers would expect that 50 percent of sea turtles who have eaten this amount of plastic will die. The scientists also found that if a turtle had at least 226 pieces of plastic in her gut, she would surely die.
Scientists have made an effort to investigate the exact impact of marine pollution on marine life after discovering that plastic affects 700 different marine species, according to New Study chief investigator Britta Denise Hardesty.
To calculate the effects, a team of scientists led by Hardesty studied data from approximately 300 turtle necropsies in Australia whose deaths were recorded in three different categories: non-plastic, unknown cause, plastic-related.
With these distinctions, researchers were able to compare the unknown and plastic-related deaths with the plastic-related deaths to determine what a normal amount of plastic taken up by turtles is.
Within the population they tested, the amount of debris found in the entrails of turtles ranged from a single piece to 329 pieces.
Not all scientists, however, agree with the conclusions of the study.
"I am more optimistic than the authors," said biologist Jennifer Lynch, who is not affiliated with the study, in an e-mail.
A study she carried out in 2017 found that turtles are not affected by small amounts of plastic waste or even after taking 200 to 300 pieces of plastic.
"All studies have a certain bias, my study was biased towards healthy turtles who were actively foraging when they drowned on a longline hook," said Lynch, who wants to write a refutation of the study with other researchers.
"[The present] The study focuses on stranded turtles that died for a variety of causes, often for unknown reasons. "
Nevertheless, the new study contributes to a growing body of scientific literature on plastic and tortoise mortality.
Another important finding in the study was related to the age of the turtles caused by the debris.
Researchers also found a significantly greater amount of plastic in young turtles compared to adults. For them, this signaled that adult plastics mistakenly took less than younger sea turtles.
Brendan Godley, a conservator unaffiliated with the study, said in an email that this research points to the likelihood that plastic is a major threat to recent life stages that was suspected but unknown.
"This is particularly worrisome because plastic parts and baby turtles are likely to come together in similar areas," he explained.
But that does not mean turtles are on their way to extinction. Sea turtle populations actually respond well to conservation efforts.
It just signals that sea turtles are in danger if marine pollution worsens, Godley said.
While the exact amount of plastic that causes death could be hotly debated, scientists were aware that plastic poses a threat to sea turtle populations for a while. In fact, sea turtles were among the first animals recorded to take plastic.
And with the rising plastic deposits in the ocean, the threat posed by debris to marine life has expanded far beyond the sea turtles and will continue to grow if no solution is found.