Abstract

The accumulation of plastic waste has been recognized as a threat to the environment and wildlife all around the world. Several studies have shown that marine life, including seabirds, sea turtles, fish, and mammals, have suffered the consequences of their interaction with plastic waste.¹ This is indisputable for coastal and more generalist seabirds such as gulls that opportunistically forage from anthropogenic materials present in fishery discards and landfill wastes. The effect of the increasing plastic pollution in aquatic birds is noticeable either by the ingestion or entanglement of this waste material. Other hazardous marine debris, especially for seabirds, are discarded fishing lines, nets, and fishing hooks and lines.^1-3

For this preliminary study, in all marine birds that died during admission or treatment at the wildlife rehabilitation centre in the north of Portugal (PBG, Avintes), the postmortem examination was carried out to identify the presence of plastic (ingested or entangled), during a period of 10 years. A total of 2220 animals were necropsied, belonging to the Order Charadriiformes (n=2066), Order Pelecaniformes (n=35), Order Procellariiformes, and Order Suliformes (n=119). Of those 82 (3.7%) presented fishing hooks, nets, or plastic entangled in their limbs or ingested. The main lesions observed were hooks in the oral cavity or perforation of the oesophagus, nets entangled in the limbs associated with fracture or amputation, nets and plastic entangled in the body and neck, and portions of plastic and net in the stomach. Even though considered a small percentage (3%), it is possible that a larger number of animals could be affected since a high number presented trauma from an unknown origin. This might be due to the struggle to free themselves from anthropogenic materials. Furthermore, it is known that due to gulls’ ability to regurgitate a large part of non-edible food remnants, the probability to find plastic materials in its gastrointestinal (GI) tract is also reduced.^1,2,4 However, deleterious effects of its ingestion may include GI obstruction, ulcers, perforations, impaired nutrient assimilation, morbidity, and starvation.^5,6 Not-so-obvious effects are related to the absorption of toxins into the animal’s bloodstream which may lead to neurological symptoms, behavioral and reproductive complications, and death.⁷

Going forward, it will be important to conduct further studies and evaluate the causal relationship between the presence of these materials and the death of the animal. The impact of pollution can be immediate, but can also have medium-term toxic effects, which need to be investigated and known, in a ONE HEALTH approach.

*Presenting author

Literature Cited

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6.  Garcês A, Soeiro V, Lóio S, Prada J, Silva F, Pires I. 2018. Necropsy findings and causes of mortality in wild birds in a Center for Rehabilitation of Wild Animals in the North of Portugal. Rev Electron de Vet. 19:1–20.

7.  Basto MN, Nicastro KR, Tavares AI, McQuaid CD, Casero M, Azevedo F. 2019. Plastic ingestion in aquatic birds in Portugal. Mar Pollut Bull. 138:19–24.