A recent study found microplastics in the intestines of humans around the globe, and new research has now done the same for sea turtles.
Researchers at the UK’s University of Exeter and the Plymouth Marine Laboratory, a research organization also in the UK, led a team that studied 102 sea turtles in the Atlantic and Pacific oceans as well as the Mediterranean Sea.
According to a paper published in the journal Global Change Biology earlier this month detailing their findings, synthetic particles less than 5 millimeters in length, including microplastics, were found in every single turtle studied.
More than 800 synthetic particles were found in the 102 turtles included in the study, with the most common being fibers that are shed by things like clothing, car tires, cigarette filters, ropes, and fishing nets as they break down after finding their way into the sea. Because the researchers only examined a part of each animal’s gut, they estimate that the total number of particles in each animal is actually about 20 times higher than what they found.
Scientists don’t know how sea turtles come to ingest microplastics and synthetic fibers, but likely sources include polluted seawater or contaminated prey and plants that the turtles eat. The study’s lead author, Emily Duncan of the University of Exeter’s Centre for Ecology and Conservation, said that we also don’t yet know what effects these synthetic particles might have on the sea turtles, and called for further research to fill these gaps in our knowledge.
“[The particles’] small size means they can pass through the gut without causing a blockage, as is frequently reported with larger plastic fragments,” Duncan said in a statement. “However, future work should focus on whether microplastics may be affecting aquatic organisms more subtly. For example, they may possibly carry contaminants, bacteria or viruses, or they may affect the turtle at a cellular or subcellular level. This requires further investigation.”
The main threats to the world’s seven sea turtle species are all manmade. According to the WWF, these threats include being hunted for their eggs, meat, skin, and shells; destruction of the coastal habitats they rely on to nest and breed their young; and capture in fishing gear, which causes them to drown.
Climate change also poses a severe threat to sea turtles, as it can increase sand temperatures, which influences the gender of sea turtle hatchlings. Additional research published this month by University of Exeter scientists found that up to 93 percent of green turtle hatchlings could be female by 2100, as climate change is driving the “feminization” of the species.
Green turtles are listed as Endangered on the IUCN Red List, while Kemp’s Ridley sea turtles and Hawksbill turtles are both listed as Critically Endangered. Leatherbacks, Olive Ridleys, and Loggerheads are all listed as Vulnerable. (There is not enough data on the seventh sea turtle species, the Flatback, to assess its conservation status.)
“It really is a great shame that many or even all of the world’s sea turtles have now ingested microplastics,” University of Exeter Professor Brendan Godley, a co-author of the study on synthetic particles in sea turtles and the study on how climate change is impacting nesting green turtles, said in a statement. “At the moment, this is not the main threat to this species group but it is a clear sign that we need to act to better govern global waste.”
Turtles in the Mediterranean were found to have the most synthetic particles in their intestines, which is consistent with current estimates that the Mediterranean has higher rates of contamination than the Atlantic or Pacific. The study’s sample size and methodology did not allow for the researchers to produce a detailed geographical analysis of the rates at which different sea turtle populations are ingesting synthetic particles, however.
“While this study has been successful, it does not feel like a success to have found microplastic in the gut of every single turtle we have investigated,” study co-author Dr. Penelope Lindeque of the Plymouth Marine Laboratory said in a statement. “From our work over the years we have found microplastic in nearly all the species of marine animals we have looked at; from tiny zooplankton at the base of the marine food web to fish larvae, dolphins and now turtles.”
“This is more proof that we urgently need to reduce plastic production worldwide,” Graham Forbes, head of Greenpeace’s Global Plastic Project, said in a statement. Greenpeace Research Laboratories contributed to the study.
“From whales that have washed ashore with their stomachs filled with plastic to microplastics found in over 100 turtles from three oceans, marine life is suffering because companies are addicted to single-use plastics and not doing enough to tackle the problem. How many more studies like this do we need for corporations to take strong action to curb the production of throwaway plastic, which is predicted to quadruple by 2050? This global environmental crisis must be tackled at the source for the sake of marine life, the world’s oceans, our health, and our communities.”
• Duncan, E. M., Broderick, A. C., Fuller, W. J., Galloway, T. S., Godfrey, M. H., Hamann, M., … & Santillo, D. (2018). Microplastic ingestion ubiquitous in marine turtles. Global Change Biology. doi:10.1111/gcb.14519
• Patricio, A. R., Varela, M. R., Barbosa, C., Broderick, A. C., Catry, P., Hawkes, L. A., Regalla, A., & Godley, B. J. (2018). Climate change resilience of a globally important sea turtle nesting population. Global Change Biology. doi:10.1111/gcb.14520
This article was written by Mike Gaworecki and first published by Mongabay.com on 21 Dec 2018.