The first quantitative assessment of microplastics in seabird faeces in Northern Europe shows presence of microplastics in European shag (Gulosus aristotelis) chicks. This provides valuable baseline information and confirms that minimal-invasive sampling of faeces for plastic monitoring in seabirds is possible.
A pair of European shag (Gulosus aristotelis) at the Sklinna Archipelago, Norway. Photo credit: Nina Dehnhard, NINA.
Plastic pollution is an increasing problem in the marine environment, and microplastics are frequently ingested by wildlife, including seabirds. Once ingested, microplastics can be transferred through the food web to higher trophic levels. Once in the gastrointestinal system, it can lead to inflammatory processes and biochemical changes.
Seabirds are one of the most threatened groups of birds worldwide, undergoing severe population declines, and plastic pollution is a potential new and increasing threat. In fact, it is expected that 99 % of seabird species will be exposed to plastic ingestion by 2050.
Quantifying microplastics with minimal-invasive sampling
Faeces is an increasingly used matrix to quantify ingested microplastics, although still under development. Faeces can be sampled without harming and often without handling the animal, and microplastic analyses of faeces can also deliver information on excretion rates.
Most studies of seabirds have focused on larger microplastic particles (> 1 mm) in surface-feeding species and are based on necropsies of dead birds. With this method however, the origin of carcasses (e.g. beached or bycatch) is unknown, and hence plastic levels cannot be reliably linked to breeding populations.
Presence of microplastics in 69% of faecal samples
A team of researchers has now undertaken the first quantitative assessment of microplastics in seabird faeces in Northern Europe.
They investigated microplastics in faecal samples from chicks of European shags (Gulosus aristotelis) sampled at Sklinna, central Norway. The species is a pursuit-diving seabird, and therefore ingests plastics most likely through secondary ingestion by feeding on fish containing microplastics.
We found microplastics in more than 69% of the samples, a very high proportion unfortunately within the same range as for other seabird species around the world, says Nina Dehnhard, Senior Research Scientist at The Norwegian Institute for Nature Research (NINA).
The researchers also found a much higher proportion of small microplastic particles (100-300 μm) in the faeces than have been described by others, probably because shags are able to egest larger microplastic particles due to their behaviour of regurgitating indigestible items as pellets.
In addition, our results suggest that a faecal sample from one chick is representative for all siblings at a given moment in time. Also, as chicks receive their food from their parents, it proofs that parents transfer microplastics to their chicks, says Dehnhard.
Providing valuable baseline information
The study shows for the first time that microplastics are present in the faeces of European shags in central Norway, and provides valuable baseline information about quantity, colour- and size distribution as well as polymer composition. The study also represents the first quantitative assessment of MP in seabird faeces in Northern Europe, at the same time confirming that minimal-invasive sampling of faeces in seabirds for plastic monitoring is possible.
Read the full article: Microplastics in faeces of European shags Gulosus aristotelis in central Norway
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Contact: Nina Dehnhard