How does the ubiquitous waste plastic waste in the environment affect seabirds? You may have heard that plastic has entered the food chain of seabirds or that seabirds have died because they have been wrapped in plastic bags, but plastic pollution may pose a far greater threat to the survival and health of seabirds.
A study published in the Marine Pollution Bulletin recently found that on the Scottish island of Lady isle, the proportion of plastic in the nests of five species of seabirds is as high as 24.5% to 80%, of which the european cormorant (scientific name: phalacrocorax aristotelis) has reached 80% plastic content in the nest. Not only are seabirds prone to eating plastic by mistake, but more and more plastic is accumulating in their nests.
From food packaging to toiletries to clothes, furniture, computers and cars, plastic is everywhere. However, durable plastics are difficult to biodegrade, and once they enter the ocean, they take hundreds of years to decompose and destroy marine biodiversity. Seabirds are one of the species threatened by plastic.
In recent years, the number of seabirds of different species has been in steep decline. According to the 1986-2018 Seabird Monitoring Programme (SMP) report published by the Joint Conservation Commission (JNCC), the number of European cormorants has decreased by 24% in the UK alone in the last 18 years, the number of black-footed three-toed plovers (scientific name: rissa tridactyla) has been halved, and the number of short-tailed skuas (scientific name: stercorarius parasiticus) has decreased by 70%.
Why has the population of these seabirds declined dramatically? Still a mystery. Overfishing and climate change are considered the main causes, in addition to plastics being one of the key factors that cannot be ignored. So, how does plastic affect seabirds? How big is the impact? Only by solving this problem can humans propose targeted solutions to effectively deal with the threat posed by plastics to seabirds. But previously, there was a lack of a basic database on the above problems.
The prevalence and source of plastic incorporated into nests of five seabird species on a small offshore island, published in the Marine Pollution Bulletin, quantifies some of the key issues.
Courtesy of dani Thompson, one of the authors of the paper
On lady isle, 5.6 kilometres off the coast of Scotland, researchers used cameras to photograph 625 seabird nests and their surroundings and analyze the plastic content and variety in the nests through software calculations.
Use software to analyze the nest of the silver gull
The five recorded Species of European seabirds include: the silver gull (larus argentatus), the small black-backed gull (larus fuscus), the large black-backed gull (larus marinus), the european cormorant (phala-crocorax aristotelis) and the common corcorax carbo. Among them, the latter four have been listed by the Royal Society for the Protection of Birds (RSPB) as a "species of environmental concern" in the UK due to the sharp decline in their populations.
The results showed that the European cormorant had the highest plastic content in its nest, reaching 80%, followed by the large black-backed gull at 53%, the silver gull nest with a plastic content of 39%, and the small black-backed gull and ordinary cormorant with the lowest plastic content in the nest also exceeded 20%.
Plastic content in five bird nests on lady isle
What are the dangers of plastic in nests? For many seabirds, the nest keeps the eggs in them warm and dry, and any environmental changes brought by plastic to the nests can fail the hatching of the eggs. In addition, the plastic changes the color of the nest, making the original camouflage effect of the nest ineffective, eventually causing the eggs and chicks to be exposed to the predator's field of vision, increasing the chance of predation.
By further analyzing the type and source of plastic, the study found that the plastic in the nest came not only from the feeding sites of seabirds, but also from the environment around the nest. That is, seabirds not only ingest plastic through food, but also collect plastic as nest material.
Building on the findings, the researchers recommend targeted beach cleanups before the start of the seabird breeding season to minimize the amount of plastic seabirds are exposed to, and to use the amount of plastic in nests as long-term monitoring data. In recent years, the amount of beach garbage has increased significantly, and the need to prevent plastic from damaging the environment has become increasingly urgent.
Source: The Paper