97% of Antarctic Seabirds Have Ingested Microplastic

Antarctica and the Arctic are two places on Earth most inhospitable to human life, leaving them largely untouched and uninvestigated by mankind. But that doesn’t mean that these remote reaches of our planet are immune to anthropogenic pollution, far from it.

Previous studies have found traces of microplastics – tiny particles of plastic measuring less than 5 millimeters in size – in Antarctic snow and the Arctic deep sea. Now, a new systematic review published in Frontiers in Marine Science is shining a light on the consequences of this pollution on the regions’ seabirds.

Looking at more than 40 years of data, the review found that over 90% of the Arctic and Antarctic seabirds studied had ingested or tried to ingest at least one piece of microplastic.

Seabird exposure to microplastics

After searching literature databases for combinations of the terms “microplastic”, “nanoplastic”, “seabird”, “Arctic” and “Antarctic”, the researchers were able to identify 14 relevant research papers covering a study period from 1983 to 2023.

Collectively, these papers studied the impact of microplastics on four Arctic seabird species and nine Antarctic species, including white-chinned petrels, glaucous gulls and four different species of penguin.

More than 1,100 samples originating from these birds were captured by these studies, with the most-studied sample type being pellets – the name given to the morsels of undigested food that birds will sometimes regurgitate. The stomach contents of deceased birds and bird excrement (guano) were also frequent sample types. In some cases, food that had been stashed away by little auks and similar species into the small pouches located below their beaks was also examined.

Between the 14 studies, a total of 3,523 microplastic particles (MPs) were recovered, averaging around 3 MPs per bird. However, the actual number of MPs in each sample was highly varied, reaching up to 36 MPs in one sample. Between both locations, a median of 31.5 and 35, and an average of 7.2 and 1.1 MPs were found in Arctic and Antarctic samples, respectively.

What types of microplastic exist at the poles?

In addition to counting the number of MPs in each sample, the studies also recorded the shape and type of each particle.

Plastic fragments were the most dominant microplastic type, accounting for 79% of the MPs recorded. The remaining 21% were pieces of fiber. Notably, most of the fragments were found in the stomach contents of the birds, while fibers were mainly found in and on the regurgitated pellets.

Cellulose-based plastic was the most common plastic type observed, followed by sheet plastic, plastic thread, foam, film and plastic pellets. Further analysis identified 14 identifiable plastic polymers in these samples, including polystyrene, polypropylene, polyethylene terephthalate (PET), polyamide, polyethylene and polyester.

With microplastic pollution becoming a topic of focus within the scientific community in recent years, the researchers behind this new review say that continued monitoring of seabirds could provide valuable data.

“The importance of seabirds as biological indicators and their crucial role as top predators in the polar food chains renders them in need of protection,” the researchers wrote. “The monitoring of MP ingestion is crucial to mitigating the impacts on marine and terrestrial organisms.”

The introduction of standardized protocols for analyzing seabird microplastic exposure could also help to improve safeguarding, they said.

Reference: Taurozzi D, Scalici M. Seabirds from the poles: microplastics pollution sentinels. Front Mar Sci. 2024;11. doi: 10.3389/fmars.2024.1343617