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FROM THE SEA TO THE AIR: microplastics in marine and coastal birds

By Júlia Jacoby de Souza

Everyone has seen the consequences of plastic in the sea. From litter on the beach to interactions with marine animals. But what about microplastics, which can be hard to see? How do they affect marine fauna? 

Microplastics are small particles (< 5mm), which can either be manufactured in this size, such as pellets and cosmetic microbeads, or can originate from the degradation of larger plastics (packaging, various plastic objects, synthetic fabrics). The final destination of plastic waste, through transport by wind and various bodies of water, is usually the ocean.

Microplastics found in beach sand on the North Coast of Rio Grande do Sul. (Photo: Derek Blaese de Amorim with CC BY 4.0 license)

These particles, which can reach sizes invisible to the naked eye, are available to a wide variety of organisms, from microscopic zooplankton to large fish, to birds and mammals, for example. But why do these animals interact with microplastic? Well, the simple reason is because microplastics are everywhere in the sea: from the surface water to the depths, in beach sediment and on the seabed. In addition, they can be ingested by organisms that serve as food for others, creating somewhat of a snowball, or rather, plastic ball effect. So it's hard not to come into contact with something that is practically omnipresent!

Diagram of microplastic accumulation through direct ingestion of this material, or indirect ingestion through prey. (Image by Júlia Jacoby de Souza with CC BY 4.0 license)

I started studying this subject about two years ago, when I was halfway through my degree in Marine Biology. It was at this time that I became interested in birds. So I got in touch with the professor who became my advisor, Dr. Guilherme Tavares Nunes from the Federal University of Rio Grande do Sul (UFRGS), and he proposed that we study the issue of plastic contamination in marine and coastal birds in southern Brazil. 

Seabirds are organisms that depend entirely on the oceans for at least part of their lives[1] and generally breed on islands. This group has been shown to be especially susceptible to the presence of plastics in the environment: of all the bird species ever recorded with some interaction with this material, almost 80% of them are marine[2]! Although high, this percentage is not surprising, since there is plastic everywhere in the sea. Another contributing factor is that these species identify feeding areas by detecting dimethyl sulfide (DMS), a substance released by the consumption of phytoplankton by zooplankton. In the marine environment, DMS acts as a "restaurant smell," indicating that food is available there. However, phytoplankton that adhere to floating pieces of plastic also release DMS, so that areas with a high concentration of plastic are also identified as "restaurants," creating a trap for these birds[3].

One of the first records of seabirds ingesting plastic dates back to the 1960s, when researchers found pieces of plastic in the stomachs of Laysan albatrosses[4] that breed on Midway Atoll in the Pacific Ocean. This location is more than 3,000 kilometers away from the American continent, but receives huge amounts of garbage carried by ocean currents. The fact that this species of albatross is dying on this atoll from ingesting plastic material was portrayed in Chris Jordan's documentary "Albatross''. However, this species is just one of a group (Procellariiformes) whose interaction with plastic has been widely studied, including in Brazil.

Dead Laysan albatross chick with ingested

pieces of plastic (Photo by Lindsay C. Young,

However, for our research, we chose to move away from the most studied groups and focus on others whose contamination is little known, both in Brazil and worldwide: coastal birds. Have you ever paid attention to the birds you see when you go to the beach? Well, that's exactly what we're trying to study! Our study group includes birds that use the coastal environment, whether resident or migratory, which feed on the coast of Rio Grande do Sul during non-reproductive periods. Among these, there are organisms with different body shapes, diets and behaviors. There are species that eat fish (piscivores), such as terns and black skimmers, others that eat invertebrates buried in the sediment (benthivores), such as sandpipers and stilts, and there are also species, such as gulls, that eat practically any food available (generalists). This means that, among the birds that use the coastal environment, there are different functional trophic groups, i.e. groups of species that feed on similar forms and foods.

Functional trophic groups: 1- Common Tern / 2- Black Skimmer / 3- White-rumped Sandpiper / 4- White-backed Stilt / 5 - Brown-hooded Gull / 6 - Kelp Gull. (Images by Daniela Martins with CC BY 4.0 license)

So, assuming that there is microplastic practically everywhere in marine and coastal environments, including in beach sediment and potentially in the food of these birds, are these species also being contaminated? Do different diets and forms of feeding alter this contamination? Are shorebirds, or any specific trophic group, good indicators for detecting the presence of plastic in the environment? Well, these are some of the questions we're trying to answer! 

Using shorebirds as a model has been challenging, as we are working with groups that have been poorly studied and very small particles. Therefore, there is no "recipe" that shows "how to find and identify microplastics in shorebirds." So we had to test what other researchers had already done, with different methodologies and animal groups (fish, mollusks, other bird species) in order to adapt the "recipes" already developed to our study group. We are working with samples of both live birds (feces) and birds that have died at the Center for the Rehabilitation of Wild and Marine Animals at the Center for Coastal, Limnological and Marine Studies (CECLIMAR/UFRGS). In our preliminary tests, it was possible to see colored fibers in some samples. Subsequently, we intend to carry out the chemical identification of this material through a partnership with the Laboratory of Environmental Processes of Emerging Contaminants (LAPACE) at the UFRGS Chemistry Institute. With this analysis, it will be possible to know from what type of plastic the microplastic originated, whether from fabrics, bags, or packaging, for example. Unfortunately, due to the COVID-19 pandemic, we have had to pause our activities, but we intend to resume them as soon as possible.

Blue fiber found in the feces sample of a tern

(Photo by Júlia Jacoby de Souza, CC BY SA 4.0)

Plastics comprise a group of incredible materials and it is practically impossible not to depend on them for our daily activities, as they are everywhere, including in the device you are reading this post on! But the research that has been and is being carried out shows just how much the mismanagement of this material, from the individual to the global level, has impacted all organisms, including us humans. Science is key to exposing and understanding its consequences in order to develop solutions and alternatives. Small changes in our day-to-day actions are essential; rethinking and avoiding the use of one plastic a day could mean millions of microplastics less! 


Our research is funded by the Rio Grande do Sul Research Foundation (FAPERGS).



1]Votier, S. C; Sherley, R. B. 2017. Seabirds. Current Biology, v. 27, n. 11, p. R448–R450.

[2]Battisti, C; Staffieri, E; Poeta, G; Sorace, A; Luiselli, L; Amori, G. 2019. Interactions between anthropogenic litter and birds: A global review with ‘black-list’ of species. Marine Pollution Bulletin, vol 138.

[3]Savoca, M. S; Wohlfeil, M. E; Ebeler, S. E; Nevitt, G. A. 2016. Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds. Science Advances, vol 2, n.11. DOI: 10.1126/sciadv.1600395

[4]Kanyon, KW; Kidler, E. 1969. Laysan albatrosses swallow indigestible matter. The Auk.

Suggested content

 - Video "Microplastic: where it comes from and where it goes" produced by the author and colleagues (in portuguese): 


About the author:

I'm a Marine Biology student and I'm part of the team behind the Aves da Praia Extension Project, which seeks to publicize bird biodiversity and address the issue of plastic pollution for the community of the North Coast of Rio Grande do Sul. I love going out on field trips, they are incredible opportunities to get to know new places and have lots of stories to tell afterwards. I love to draw and ride my bike with my dog Galgo. 

Contact email:

Instagram: @juliajacobys @avesdapraia

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