Plastic Pollution, Seabirds, and Open-Ocean Currents: A Global Risk

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Plastic pollution in the open oceans continues to threaten seabirds and marine life

Researchers have found that a quarter of all plastics found in the world’s oceans is swallowed by seabirds, a consequence that unfolds largely because national laws and enforcement fail to reach international waters. The problem grows when plastics drift far from any coastline, making it harder to imagine who should take responsibility for solving it.

This conclusion comes from a study published in a leading science journal. After tracking the movements of 7,137 birds across 77 species, scientists confirmed that marine plastic pollution closely follows the routes these birds use to hunt for food. In other words, the debris is most concentrated where birds feed, signaling a direct link between bird foraging patterns and plastic exposure.

Massive patches of plastic accumulate in the remote open ocean, driven by giant currents and eddies that spin waste into circulating gyres. These offshore plastic islands gather material from ships and from numerous countries, creating vast zones where debris concentrates away from shorelines and jurisdictions.

According to Lizzie Pearmain of the University of Cambridge and the British Antarctic Survey, these swirling oceans of plastic exist out of sight and outside any national boundary. The study’s co-authors emphasize that such “islands of plastic” form a global problem, not confined to a single region or coast.

Birds are often photographed with plastic on or around their bodies, a stark reminder of the intimate scale of this threat. Images showing seabirds swallowing or attempting to feed plastic to their chicks have become a grim symbol of the crisis in the oceans.

This comprehensive analysis examined the behavior of a large, migratory seabird population, including species such as the northern fulmar, petrels, and Newell’s shearwater. These birds span oceans and climates, and many are listed as critically endangered. The monitoring data, paired with global maps of oceanic plastic distribution, underscore plastic pollution as one of the most significant risks facing marine life today.

Experts note that many bird species spend long periods feeding in mid-ocean eddies, areas that trap plastic waste and make ingestion more likely. As Pearmain explains, this behavior places certain species at a heightened risk of encountering and consuming debris during feeding bouts.

Even small fragments are dangerous. Birds may mistake tiny pieces for food, or they may swallow plastic indirectly through contaminated prey. Ingested plastics can travel through the digestive system, causing injury, poisoning, and, in severe cases, starvation. The problem is especially acute for seabirds because many species lack an effective way to eject or regurgitate ingested plastics, leaving the material to accumulate in the stomach and, ultimately, affecting health and reproductive success.

Petrels, a diverse and relatively understudied group of marine birds, play a crucial role in oceanic food webs. Their wide distribution across the oceans makes them valuable indicators of plastic pollution risks in marine ecosystems. When these birds feed in high-plastic areas, their well-being becomes a bellwether for broader environmental health in the seas.

Additional risks to other wildlife

Beyond seabirds, many other seabirds face extinction pressures from climate change, accidental predation, competition with fisheries, and invasive species such as rodents in breeding colonies. Ingested plastics can hasten declines by weakening the birds’ resilience to these stressors, reducing their ability to cope with multiple simultaneous threats.

Bethany Clark, a leading researcher and co-author, stresses the need for international collaboration to curb plastic pollution in the world’s oceans. She notes that migratory birds traverse waters belonging to many nations, which complicates conservation efforts and mobilization of resources. The team highlights that even species with relatively low exposure risk can still encounter plastics during migration, underscoring the widespread nature of the problem.

In the broader context, seabird populations are under pressure from several converging factors, and plastics add a harmful layer that can ripple through entire marine ecosystems. The findings call for coordinated international action, improved waste management, and stronger protections in international waters to reduce plastic inputs and protect vulnerable wildlife.

Researchers hope these insights spur policy discussions and practical measures aimed at reducing plastic leakage into the oceans. The study contributes a detailed map of exposure risks, tied to the flight paths and foraging zones of migratory seabirds, which can guide future conservation and pollution-control strategies. [Citation: Nature Communications, 2023]

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Note: environmental authorities and researchers acknowledge ongoing efforts to address plastic pollution and protect marine life through cross-border cooperation and better waste-handling practices.

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