Why do seabirds eat plastic? How a citizen science project in Poland is helping to find answers

Children are interested in nature and cause-and-effect relationships. They, therefore, represent enormous potential. Photo by Michał Karmelita, used with permission.

When I was a child, I always wondered why seabirds ate plastic garbage. Many of us have seen those pictures of albatrosses dying from eating loads of plastic. But birds have perfect eyesight! So why do they eat something that looks nothing like their natural meal? This is the story of what I discovered as I was determined to find an answer.

When as a little girl I used to conduct tests giving different kinds of food to ducks or swans. For example, oatmeal: they ate that right away. If I threw a leaf in the water, they would immediately know that it was not good and would not eat it. It took them a fraction of a second to recognize whether I was throwing some oatmeal or a carrot in pieces into the water. So why is this perfect vision failing the birds when they are to distinguish fish or krill (their natural food) from a piece of plastic?

The answer to this question came gradually. First, scientists understood that sea birds use not just sight, but smell as well. Using their sense of smell, these animals navigate, search for food, and even recognize parts of the world. Then, a few years ago scholars discovered that sea birds can eat plastic, not necessarily because it looks like their food, but because it actually smells like it. It turned out that plastic garbage that floats on the surface of the oceans begins to release a very characteristic substance after some time. It is called dimethyl sulfide – DMS for short.

The wrack line is a common place for plastic in coastal areas. Photo by Michał Karmelita, used with permission.

A whole ecosystem of microorganisms, small plants and animals quickly begins to form on the plastic waste drifting in the ocean. It is some of them that produce DMS. You probably know this smell: it emits in our kitchen when we cook, for example, cabbage or seafood. Unfortunately, DMS is a substance that is found in large amounts in the feeding grounds of seabirds. For example, where there is a lot of krill swimming. Therefore, seabirds associate this sulfur smell with dinner.  As they fly long miles guided by their noses and then fly hungry to a place where it smells like dimethyl sulfide, they are easily fooled. They conclude that if something smells like food, it probably is food. They also cannot afford to starve; sometimes they look for feeding grounds for a long time, so when they arrive, they are really very hungry.

Community science

So we know that plastic is harmful to animals. And that we should find some solutions: not only to limit its production and use but also to remove these synthetic fragments that are already circulating in the environment. However, to come up with solutions, we first need to find out exactly how much plastic can be found in seas and on coastlines, and how this plastic migrates in nature.

Beach in Gdynia on Poland's Baltic coast. Photo by: Michał Karmelita, used with permission.

Unfortunately, looking for small plastic pieces (mesoplastic) requires a lot of precision and data volume. In order to count the mesoplastic on shores, it is necessary to carefully sift the sand, and not just look at its surface. Scientists themselves are unable to do this because they have too few hands to work. Therefore, the importance of “citizen science,” also known as community science.

Citizen science is an initiative where ordinary non-scientists, as well as the local community, can help professional researchers. Their tasks are very different: sometimes they help analyze data (like NASA Feature Hunter), sometimes they count animals in reserves (like Iguanas from Above) and sometimes they collect samples. The latter example worked very well for analyzing mesoplastic. I have always believed that the best results are achieved when you think globally and act locally because then you benefit not only the planet but also your local community. The same assumption was made when I started coordinating the mesoplastic citizen science project at the science center where I work.

Citizen scientists help in the search for mesoplastics. Photo by: Michał Karmelita, used with permission.

The methodology of the project was planned by the Institute of Oceanology of the Polish Academy of Sciences, based in Sopot in northern Poland. The project is coordinated by the partner Experiment Science Centre in Gdynia (Gdynia, Sopot and Gdańsk together form the Tricity). The tasks of the Polish Academy of Sciences in the project consist mainly in developing the methodology, analysis and interpretation of data. The Gdynia science centre, on the other hand, primarily took on: raising awareness of the local community, organizing volunteers, leading the community through the project, organizing joint trips to the beach, conducting mesoplastic field lessons with schools, and informing about the project in seniors clubs, etc. Both organizations carry out their tasks pro bono, and the data obtained during the research is of the Open Science type: everyone has access to it and can use it in any way.

Huge response

The project of searching for mesoplastic on the Polish coast became very popular with the local community. The first cycle of the project ran from September 2021 until this July, and therefore lasted an entire school year, with over 500 inhabitants of the Tricity and its vicinity applying to participate. The youngest participant was two years old, the oldest over 60. Together, they organized over 300 field trips and sifted a total of over 500 liters of sand in search of miniature plastic particles. They all volunteered to search for the mesoplastic and to get as much information as possible about its distribution.

What are the results of this research conducted by community scientists so far? I think, that the most important value is the change of social attitudes of people who took part in the project, including 15-year-old Ola:

 I think that for me a turning point was finding artificial, acrylic… nail in the sand. A plastic nail, can you imagine that ?!–  It's hard to find a more useless invention, something we don't really need, something we use because we find our own nails… too natural or something. And then we go to the beach, such a plastic, artificial nail will fall into the sand, and then some seagull or tern will mistake it for food and die because of it. It made me think a lot.

The volunteers did not come only from Poland, however. As the Experiment Science Centre cooperates with the European Solidarity Centre (an international program of the European Commission, in which young people can take part in volunteering projects), some of the citizen scientists on the project came from other countries: Spain, France or Turkey. Eva, a volunteer from Spain talked about her experience:

As a citizen science project it doesn’t require very complicated materials or methods, you can find everything you need to use at home and it’s accessible to anyone, even if you don’t like science! You can participate with your family, your friends or even alone. It just takes around an hour, in which you can also see the beach from another point of view than the usual one: observing the sand composition, the biodiversity present or just paying attention to the sound of the sea. For me it was a way to be more aware of the amount of mesoplastic we could find in the beach and to better understand the problems they can cause, making me to think twice when I buy or I’m going to throw away any plastic bag or packing.

Emilie from France added:

I would say that collecting mesoplastics is not only useful but also fun to do. It's like going on a treasure hunt, while helping science!

But the change in social attitudes is not the only result of the project. The analyzes show that among the mesoplastic found by volunteers of the Experiment Science Centre in Gdynia, there are no fragments of disposable straws, cutlery or cups. What does this show? The fact that the ban on placing single-use plastic products on the market, introduced by the European Commission in 2021, is bringing early results. In previous studies, this type of disposable accessories accounted for a large proportion of garbage. Currently, there are none at all.

So what's the next step? First of all — keep going. It is possible to join the project by contacting Experyment Gdynia.

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