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Hundreds of plastic items found in deceased sea turtles

In a recent study led by the University of Exeter and the North Cyprus Society for the Protection of Turtles (SPOT), researchers have uncovered distressing evidence of plastic pollution’s impact on sea turtles in the Mediterranean. 

The experts found hundreds of plastic items, including a Halloween toy, within the intestines of deceased sea turtles. 

Deceased sea turtles ingested plastics

The study was focused on 135 loggerhead turtles found washed ashore or accidentally entangled in fishing nets off the coast of northern Cyprus. 

The research revealed that a significant portion of these marine creatures had ingested “macroplastics” – plastic pieces larger than 5mm, ranging from bottle caps to a rubber witch’s finger from a Halloween costume.

Long-lasting pressure on marine systems

“High densities of marine plastic pollution are now present across oceanic gyres, coastal waters and beaches, putting long-lasting pressure on marine systems,” wrote the study authors.

“An estimated 8 million metric tons of plastic enter the ocean each year, which is predicted to increase 2.6-fold by 2040. The widespread dispersion and mobility of plastic pollution and its presence in all marine habitats allows it to interact with a wide variety of biota.”

“Plastic represents a threat to multiple marine vertebrate species through ingestion, entanglement and degradation of key habitats, although population-scale impacts have been more difficult to determine.”

Loggerhead turtles as bioindicators of ecosystem health

The research highlights the loggerhead turtle as a potential “bioindicator” for gauging the breadth and ramifications of plastic pollution in marine environments. 

“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 lead author Emily Duncan, an ecologist at Exeter.

“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.”

Varied levels of plastic ingestion 

The investigation identified a total of 492 macroplastic pieces, with a single turtle containing as many as 67 pieces, although the reason for such varied levels of plastic ingestion among turtles sharing the same habitat remains unclear. 

The study further observed a “strong selectivity” by the turtles for specific types, colors, and shapes of plastic, predominantly sheet-like (62%), clear (41%), or white (25%) pieces, with polypropylene (37%) and polyethylene (35%) being the most commonly ingested polymers. 

“It’s likely that turtles ingest the plastics that mostly closely resemble their foods,” Duncan explained. “We still don’t know the full impacts of macroplastic on turtles’ health, but negative effects could include causing blockages and limiting nutrition.”

Broader implications 

The study spanned a decade, from 2012 to 2022, during which the rate of macroplastic ingestion remained constant, showing no discernible increase over time and no significant difference between turtles that were stranded and those caught as bycatch.

This research sheds crucial light on the issue of plastic pollution in the eastern Mediterranean, yet it underscores the necessity for further study. 

To establish loggerhead turtles as an effective “bioindicator,” larger sample sizes are required, and the inclusion of green turtles in future research is recommended by senior author Brendan Godley, leader of the Exeter Marine research group. 

This approach aims to provide a more comprehensive understanding of the ecological threat posed by plastics to marine biodiversity.


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