An invisible threat to Arctic birds

Exactly how much plastic are we surrounded by? The answer is: quite a bit, but it’s hard to quantify because so much of it is invisible. Unfortunately, the fact that we can’t see it doesn’t stop it from causing irreversible—sometimes fatal—harm to wildlife. As DAVIDE TAUROZZI explains, this problem is widespread in the Arctic, and birds are among the main victims.

As one of the most inhospitable places on Earth for humans, the Arctic has long been a well-preserved ecosystem characterized by areas with high biodiversity.

But in recent years, the Arctic has been undergoing unprecedented change as it is exposed to a wide range of human pressures from climate change, maritime commercial activities, industrial fisheries, oil and gas platforms, plastic pollution and more. Some of these impacts have local sources, but others are regional or global in origin. The resulting pollutants find their way north with oceanic currents.

As a result, plastic pollution in the polar regions is a growing threat. Plastics—which are among the most dangerous of anthropogenic, or human-made, materials—can take anywhere from 20 to 500 years to decompose. While pieces larger than five centimetres (known as macroplastics) can be removed from the environment fairly easily, microplastics (0.1 micrometre to five millimetres in size) are almost impossible to eliminate.

More than 60 seabird species currently inhabit the Arctic, feeding and breeding mainly at sea—and they are harbingers of change in the environment. Generally, each bird species is associated with a particular habitat type, food resource, and optimum temperature and vegetation cover—and both their presence in an area and their general fitness levels are deeply influenced by changes in these ecological variables. Plastics represent one of the most high-impact anthropogenic pollutants for birds.

Threats to seabirds come mainly from two types of interactions with plastic: ingestion and entanglement, such as in fishing lines or nets, plastic bags, or plastic strings, bands and ropes.

The effects of a plastic diet

The smallest plastic particles—which are generally derived from the degradation of larger ones—can have a range of negative effects on wildlife. They can block the gastrointestinal tract, move from the intestines into other tissues, cause particle toxicity and oxidative stress, provoke inflammation, and damage immune cells like cytokines (molecules that protect against pathogenic bacteria).

I co-authored a 2024 synthesis of peer-reviewed literature published from the late 1980s to 2023 on seabirds’ ingestion of microplastics in polar regions. As you would expect, it paints a troubling picture. Overall, 374 samples were investigated, including stomach contents, pouch contents, guano and pellets. The stomach contents represent what a bird had in its digestive system at the moment of death. Pouch contents are the foods that little auks and a few other birds store beneath their beaks during foraging trips. Guano is the complex excrement of seabirds, containing a mixture of food residues and metabolic waste products, with uric acid as the main component. Pellets are regurgitations of indigestible food.

Among all of the samples investigated, 90 per cent contained at least one piece of microplastic. Looking at stomach contents specifically, 82 per cent contained microplastics.

The northern fulmar is a case in point: the results showed that 200 individuals had ingested more than 2,500 microplastic particles. Northern fulmars are predators and scavengers, feeding on fish, squid and small crustaceans. This tells us that microplastic pollution can reach seabirds both directly (when they ingest water, soil or rocks) and indirectly (when they feed on contaminated food).