This region has only moderate levels of floating plastic pollution. But shearwaters, as well as petrels and albatrosses, are part of a class known as tube-nosed seabirds, with tubular nostrils and an excellent senses of smell. As I have found in my own research, tube-nosed seabirds are highly skilled at seeking out plastic debris, which may smell like a good place to find food because of algae that coats it in the water. Indeed, the flesh-footed shearwater has one of the highest plastic ingestion rates of any species yet studied.
Marine ecologist Jennifer Lavers, head of the Adrift Lab, has been studying plastic debris consumption in this wild shearwater population for over a decade. In 2014 the lab began publishing research linking ingested plastic to sublethal health effects.
In 2019, Lavers led a study that described correlations between ingested plastic and various aspects of blood chemistry. Birds that ingested more plastic had lower blood calcium levels, along with higher levels of cholesterol and uric acid.
In January 2023, Lavers’ group published a paper that found multiorgan damage in these shearwaters from ingesting both microplastic fragments, measuring less than a quarter inch (five millimeters) across, and larger macroplastic particles. These findings included the first description of overproduction of scar tissue in the birds’ proventriculus – the part of their stomach where chemical digestion occurs.
This process, known as fibrosis, is a sign that the body is responding to injury or damage. In humans, fibrosis is found in the lungs of longtime smokers and people with repeated, prolonged exposure to asbestos. It also is seen in the livers of heavy drinkers. A buildup of excessive scar tissue leads to reduced organ function, and may allow diseases to enter the body via the damaged organs.
The Adrift Lab’s newest paper takes these findings still further. The researchers found a positive relationship between the amount of plastic in the proventriculus and the degree of scarring. They concluded that ingested plastic was causing the scarring, a phenomenon they call “plasticosis.”
Many species of birds purposefully consume small stones and grit, which collect in their gizzards – the second part of their stomachs – and help the birds digest their food by pulverizing it. Critically, however, this grit, which is sometimes called pumice, is not associated with fibrosis.
Scientists have observed associations between plastic ingestion and pathogenic illness in fish. Plasticosis may help explain how pathogens find their way into the body via a lacerated digestive tract.
Seabirds were the first sentinels of possible risks to marine life from plastics: A 1969 study described examining young Laysan albatrosses (Phoebastria immutabilis) that had died in Hawaii and finding plastic in their stomachs. So perhaps it is fitting that the first disease attributed specifically to marine plastic debris has also been described in a seabird. In my view, plasticosis could be a sign that a new age of disease is upon us because of human overuse of plastics and other long-lasting contaminants, and their leakage into the environment.
In 2022, United Nations member nations voted to negotiate a global treaty to end plastic pollution, with a target completion date of 2024. This would be the first binding agreement to address plastic pollution in a concerted and coordinated manner. The identification of plasticosis in shearwaters shows that there is no time to waste.
My art uses plastic recovered from beaches around the world to understand how our consumer society is transforming the ocean
Will we eventually have to send our trash into space if we run out of room on Earth?
Matthew Savoca does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.