A new study on seabird ingestion of plastics by MEOPAR researchers and colleagues finds ingested plastics did not cause ulcers or lacerations of the digestive tracts of almost 200 dovekies that perished in a storm on the coast of Newfoundland in early January, 2013. The study urges the use of standardized methods in plastic ingestion research, so that related studies can be taken together to help understand the effects of plastics on the marine food web.
Plastic pollution in the oceans is a worldwide and complex problem, with a central concern being that of longevity. Plastics may degrade into smaller pieces, eventually becoming microplastics (1 to 5 mm in size, as pictured at left), of which there are an estimated minimum 15 trillion pieces in the oceans already, but no matter the size, plastics can last forever in the ecosystem.
Many marine animals are known to ingest plastics, from tiny zooplankton ingesting microplastics, to sea turtles ingesting plastic shopping bags. Ingestion of plastics can be detrimental to animal health, and researchers are trying to identify how plastics affect individual animals, populations and the marine food web.
MEOPAR researcher Dr. Max Liboiron (pictured at right), an assistant professor in Sociology and Environmental Sciences at Memorial University of Newfoundland and co-author of the study, explains that a number of possible mechanisms for harm are being investigated. These include plastic accumulation in an animal’s digestive tract, ulcers and lacerations of the digestive tract, and, a more recent hypothesis, hormone-mimicking chemicals that transfer from plastics to animal tissues. Researchers, she says, are also working to determine the sources of marine plastics and the rates of plastic ingestion by animals.
This study, on plastic ingestion by 171 seabirds, was “opportunistic,” says Liboiron. There was a mass die-off of dovekies, the most common seabird in the North Atlantic and the smallest bird in the puffin family. The dovekies had been blown off course and were starving near the coast of Newfoundland when one of the island’s characteristic storms battered them against a cliff, killing the flock. Co-author Ian Jones collected the birds for further study.
The researchers, which include a number of students from Memorial University of Newfoundland, rinsed out the contents of the dovekies’ digestive tracts, and identified, measured, and counted pieces of plastic using a microscope. They also examined the digestive tract tissues for ulcers and lacerations.
Liboiron emphasizes one of the study’s main results: “We found no correlation between ulcers and plastics.” It has been thought that plastics could harm an animal’s tissues as pieces passed through the digestive tract. This research found that was not the case. The study also found that nearly one third of the birds had ingested plastics: “It was the highest recorded ingestion rate ever for this bird in this area, and for other birds in this area.” She says the high ingestion rate may be due to the thoroughness of their research methods, which included examining the entire stomach and esophagus, rather than the stomach only, as in some other studies.
Comparability with related research is paramount, as stressed in the paper, since each study is meant to add a piece to a global puzzle. Lead author Stephanie Avery-Gomm (pictured at left), who was with the Wildlife Research Division of Environment and Climate Change Canada when the study was conducted, says, “This Newfoundland-based study really demonstrates just how important it is for researchers around the world to use standardized methods, so that as a scientific community we can track trends in plastic pollution - and plastic ingestion in wildlife - through space and time.”
Avery-Gomm and Liboiron have begun a subsequent study, this one of fulmars, also a North Atlantic seabird. Their work on fulmars is part of MEOPAR’s Monitoring Marine Plastics in Canada’s North project. On top of investigating the digestive tract, as in the dovekie study, they plan to determine if there is a correlation between hormone-mimicking chemicals found in the animals’ tissues and plastics found in their digestive tracts.
Find the publication, "A study of wrecked Dovekies (Alle alle) in the western North Atlantic highlights the importance of using standardized methods to quantify plastic ingestion", here.
Learn more about waste and wasting at discardstudies.com, and interdisciplinary hub for research on the topics facilitated by Dr. Liboiron and her colleagues.