Image credit: Tycho Anker-Nilssen / NINA

Contrary to what was previously thought, new research has shown that microplastics are not a significant source of environmental pollutants in fulmars and seabirds ingest most of these pollutants through food.

Littering of the world’s oceans is a major environmental problem and millions of tons of waste material have been worn down by waves, wind and weather into microscopic particles known as micrplastics that remain in the sea for a long time.

It is not unusual for the microplastics to end up in the stomachs of marine organisms, where it can do great harm. An additional cause of concern is the environmental pollutants linked to plastic, because although not all plastics contain hazardous substances, plastic has the ability to bind to fat-soluble organic pollutants from the environment and therefore reflects the concentration of environmental pollutants in the sea.

Fulmars (Fulmarus glacialis) belong to the order Procellariformes or "tubenoses", a group of long-ranging seabirds that spend most of their time on the open sea, only seeking land during breeding season.

Fulmars feed on fish, crustaceans and other food in surface waters and can easily confuse waste with food. Studies have shown that most fulmars have plastic in their digestive systems, and the amount of plastics in fulmars is regarded as a representative indicator of ocean littering.

A team of interdisciplinary group of researchers from Norway and the Netherlands has investigated the relationship between the amount of plastic and environmental contaminants found in fulmars.

Dorte Herzke, senior scientist and section leader at the Norwegian Institute for Air Research (NILU) who along with Tycho Anker-Nilssen a senior scientist at the Norwegian Institute for Nature Research (NINA), led the study, said, "Microplastics may remain in the bird's stomach for weeks and months. We wanted to examine the extent to which environmental contaminants from plastic are absorbed by the birds' tissues."

The team examined 75 fulmars and compared the amount of environmental contaminants in plastic from the birds’ stomachs with the levels of the same substances in the birds’ livers and muscular tissues and to their surprise found no correlation.

"We found no significant differences in the pollutant concentrations in birds that had eaten a lot of plastic, compared to birds that had less plastic in their stomachs. Plastic is apparently not a major source of environmental pollutants in these birds," Dr. Herzke concluded.

However, the study did show that the environmental pollutant levels found in the fulmars most likely reflects the level of pollutants in their prey.

Dr. Herzke explained, “Contrary to what we had expected, we found that the plastic does not release environmental pollutants to the fulmar's stomach to a big extent. What happens to a much larger degree is that the plastic actually absorbs such contaminants from food the bird has eaten, and thus reflects the pollutant levels in the prey.

"This study also shows that it is not sufficient to look at either plastic pieces from bird stomachs, or to just examine the organs of birds with plastic in their stomachs. To get the full picture, it must be seen in context. We are the first to do that in Norway."

Since seabirds are top predators, they ingest environmental pollutants from all stages of the food chain. High contaminant levels could have a number of negative effects on seabirds leading to hormonal disturbances and thinner eggshells for example.

Despite their findings, the scientists want to make it clear that they are not acquitting plastic.

"That the plastic does not increase the birds' pollutant load is obviously good news in an otherwise bleak reality for most of our seabirds," Dr. Anker-Nilssen added.

"We cannot exclude the possibility that plastic may transfer some environmental pollutants to the birds. But, now we know that it does so to a far lesser degree than the fulmars' prey. In addition, the plastic takes up space in the stomach, and may thus cause the birds to starve to death."

Although this study was directed specifically towards seabirds, the scientists believe that the results may have relevance for other vertebrates.

NILU was founded in 1969 and is one of the leading specialized scientific laboratories in Europe researching issues related to air pollution, climate change and health. Their teams of specialized scientists work on over 200 projects a year for research councils, industries, international banks and local, national and international authorities and organizations.

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