Plastic Halloween toys were found among hundreds of plastic items collected from dead sea turtles in the Mediterranean, according to a study published in the scientific journal Marine Pollution Bulletin.
The team from the University of Exeter and the North Cyprus Society for the Protection of Turtles (SPOT) examined 135 loggerhead turtles either killed as bycatch (accidentally caught in fishing nets) or washed up off the coast of Northern Cyprus. Almost half of them contained macroplastics (classed as pieces larger than 5 mm), including bottle tops and Halloween toys. The authors believe loggerheads can be used as a bioindicator species to help understand the scale of plastic pollution.
“The journey of that Halloween toy – from a child’s costume to the inside of a sea turtle – is a fascinating glimpse into the life cycle of plastic,” said Dr Emily Duncan, from Centre for Ecology and Conservation on Exeter’s Penryn Campus in Cornwall. “These turtles feed on gelatinous prey such as jellyfish and seabed prey such as crustaceans, and it’s easy to see how this item might have looked like a crab claw.”
The team found a total of 492 macroplastic pieces, including 67 inside a single animal. Turtles prefer certain types of shapes and colors. “The plastics we found were largely sheetlike (62%), clear (41%) or white (25%) and the most common polymers identified were polypropylene (37%) and polyethylene (35%),” said Dr Duncan. “It’s likely that turtles ingest the plastics that mostly closely resemble their foods. We still don’t know the full impacts of macroplastic on turtles’ health, but negative effects could include causing blockages and limiting nutrition.”
The turtles were found over a 10-year period between 2012 and 2022, and initial results seem to show that ingestion of macroplastic remained stable during that period. Also, no differences were found between stranded and bycaught turtles.
“Much larger sample sizes will be needed for loggerheads to be an effective ‘bioindicator’ species, and we recommend studies should also include green turtles – allowing a more holistic picture to be gathered,” concluded Professor Brendan Godley from the Exeter Marine research group.
Duncan EM, Akbora HD, Baldi P, Beton D, Broderick AC, Cicek BA, Crowe-Harland C, Davey S, DeSerisy T, Fuller WJ, Haywood JC, Hsieh YJ, Kaya E, Omeyer LCM, Ozkan M, Palmer JL, Roast E, Santillo D, Schneider MJ, Snape RTE, Sutherland KC, Godley BJ. Marine turtles as bio-indicators of plastic pollution in the eastern Mediterranean. Mar Pollut Bull. 2024 Apr;201:116141. doi: 10.1016/j.marpolbul.2024.116141