Plastic and, in particular, microplastics now represent one of the main threats to marine animals, which die from ingesting or becoming entangled in waste. Plastic is present throughout the marine food chain and poses a serious risk to more than 800 species, among them sea turtles. The problem is severe and, according to a new study, affects all seven existing turtle species.

No turtle is safe

Researchers from the University of Exeter and the Plymouth Marine Laboratory analysed one hundred and two sea turtles from the Atlantic and Pacific oceans and the Mediterranean Sea, finding microplastics in the intestines of every single animal. The study examined all seven turtle species, each of which is at risk of extinction: the leatherback turtle (Dermochelys coriacea), the green turtle (Chelonia mydas), the loggerhead turtle (Caretta caretta), the hawksbill turtle (Eretmochelys imbricata), Kemp's ridley turtle (Lepidochelys kempii), the olive ridley turtle (Lepidochelys olivacea) and the flatback turtle (Natator depressus), confirming that the scourge of plastic afflicts every one of them.

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The Mediterranean takes last place

The study, entitled Microplastic ingestion ubiquitous in marine turtles and published in the journal Global change biology, highlighted the presence, on average, of 150 plastic fragments less than half a centimetre long in each animal (the researchers analysed only a portion of each animal's intestine, however, so the total number of particles is estimated to be approximately 20 times higher). Although the sample sizes used were small, making an accurate comparison between the areas studied impossible, it emerged that turtles swimming in the Mediterranean Sea contain the most plastic — in one individual, 500 fragments were found.

The impact of microplastics on turtles

While the ingestion of large quantities of plastic is immediately, or near-immediately, lethal for sea turtles, the effect of microplastics on these animals is not yet known. "Thanks to their small size they can pass through the intestine without causing a blockage, as often happens with larger plastic fragments," explained the study's lead author, Emily Duncan of the Center for ecology and conservation at the University of Exeter. "However, microplastics can contaminate animals with bacteria or viruses, or they can affect the turtle at a cellular or subcellular level. This requires further investigation."

A shared responsibility

"Over the years we have found microplastics in almost every species of marine animal we have studied," said Penelope Lindeque, co-author of the report, "from tiny zooplankton to dolphins, and now it is the turn of turtles. This study provides further evidence that we all need to help reduce the amount of plastic waste released into the seas and keep the oceans clean, healthy and productive for future generations." Consumers play an essential role in curbing the plastic problem, but it falls to institutions to drastically curtail the production of single-use plastic, for the health of all species that depend on seas and oceans, including our own.