The amount of plastic currently residing in the world’s oceans is so large, it’s almost incomprehensible. Making up part of the estimated 4.8-12.7 million tonnes currently inhabiting our waters is a small form of plastic known as microplastics, which is any plastic less than 5 millimeters in diameter.
Although the understanding that plastic is piling up around the world is widespread, not much scientific literature has been published exploring the scale of microplastic pollution in wild sea turtles, until now.
A new study, published in the journal Global Change Biology, has discovered that all of 102 wild sea turtles that were tested from the Atlantic, Mediterranean, and Pacific Ocean basins were found to have been contaminated with microplastics.
“We report the presence of synthetic particles in every turtle subjected to investigation… which included individuals from all seven species of marine turtle, sampled from three ocean basins.” – Emily M. Duncan, et al.
Microplastics come from a variety of products, including cosmetic exfoliators, cigarette filters, automotive tires, and the breaking down of larger plastics, and they may pose a serious risk to marine life in the future.
According to a meta-analysis from one month prior, microplastics are not expected to cause significant damage to marine life until at least the year 2100. But some scientists are becoming concerned due to their high “abundance and bioavailability,” referring to them as “a pollutant in their own right.”
As described in the study on sea turtles, the prevalence of microplastics in crabs has previously been shown to adversely affect food consumption and energy, while also reducing growth and energy in marine worms. Zooplankton, fish, and dolphins have all also been found to have been contaminated with some form of microplastic pollutant in previous studies.
“It really is a great shame that many or even all of the world’s sea turtles have now ingested microplastics.” – Brenden Godley, study author
Microbeads, another more pervasive form of microplastics, were also found in sea turtles albeit at smaller levels. However, they were banned in the US in 2015 and the UK in 2018 due to their harmful impact on ocean life.
The number of synthetic microparticles found in tested sea turtles numbered over 800, but the most common form was a fiber with primarily blue and black color measuring up to nearly half a centimeter in length. Turtles from the Mediterranean Sea were also found to have higher levels of microplastics than those in the Pacific or Atlantic Oceans.
“Although sample sizes were small for some site‐specific species groups, there was a marked variability of incidence in synthetic particle ingestion among sites, with levels appearing higher in turtles from the Mediterranean.”
Environmental groups like Greenpeace point to this study not as proof of imminent danger to sea turtles, but as evidence that our wasteful use of plastic does in fact affect wildlife and the environment.
“Our society’s addiction to throwaway plastic is fueling a global environmental crisis that must be tackled at source… This important research demonstrates the breadth of our plastics pollution problem.” – Louise Edge, plastics campaigner at Greenpeace
The impact of microplastics on sea turtles is still unknown, but luckily, the levels which are currently being found in marine life are not expected to cause any significant harm – at least until more research is done to discover their full impact on vulnerable marine life.
“Whilst these particles may be ubiquitous, and at higher levels than in marine mammals thus far surveyed, unless they play a role in amplifying exposure to associated contaminants, we suggest they are unlikely to present a significant conservation problem at current levels.”
This study was funded in part by the Karsiyaka Turtle Watch, People’s Trust for Endangered Species, and Sea Life Trust.
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