Microplastic pollution is altering the gut microbiomes of wild seabirds, and humans should be wary too

Scientists have been worried about the potential harm of microplastics for years.

These small plastic particles less than 5mm in length have been found everywhere because of plastic pollution – from the Earth’s deep oceans to remote regions in Antarctica, and even the seafood we eat.

But are microplastics really harmful?

An international team of scientists, including researchers from McGill University, has found evidence that microplastics in the digestive tract of seabirds altered the microbiome of the gut – increasing the presence of pathogens and antibiotic-resistant microbes, while decreasing the beneficial bacteria found in the intestines.

The authors stated: “Our findings reflect the circumstances of animals in the wild. Since humans also uptake microplastics from the environment and through food, this study should act as a warning for us.”

Julia Baak, co-author of the study and a PhD Candidate in the Department of Natural Resource Sciences at McGill University, added: “The gut microbiome encompasses all the microbes in the gastrointestinal tract, which help control the digestion of food, immune system, central nervous system, and other bodily processes.

“It’s a key indicator of health and wellbeing.”




Contaminated with microplastics


To gain a better understanding of how species are affected by diets chronically contaminated with microplastics, the scientists examined the gut microbiome of two seabird species, the northern fulmar (Fulmarus glacialis) and the Cory’s shearwater (Calonectris borealis) that live mainly on the high seas and feed on marine molluscs, crustaceans, and fish.

Gloria Fackelmann, who conducted the study as part of her doctoral thesis at the Institute of Evolutionary Ecology and Conservation Genomics at Ulm University in Germany, said: “Until now there was little research on whether the amounts of microplastics present in the natural environment have a negative impact on the gut microbial health of affected species.”

In studying the seabirds, the researchers discovered that microplastic ingestion changed the microbial communities throughout the gastrointestinal tract of both seabird species.

Fackelmann advised: “The more microplastics found in the gut, the fewer commensal bacteria could be detected.

“Commensal bacteria supply their host with essential nutrients and help defend the host against opportunistic pathogens.

“Disturbances can impair many health-related processes and may lead to diseases in the host.”

According to the researchers, most studies exploring the impact of microplastics on the microbiome are done in labs using very high concentrations of microplastics.

Fackelmann concluded: “By studying animals in the wild, our research shows that changes in the microbiome can occur at lower concentrations that are already present in the natural environment.”

Image 1: Cory´s Shearwaters foraging south of the island of Pico, Azores archipelago, Portugal. Credit: Christopher Pham.

Image 2: Northern fulmars attend their nest on the eroding rock face of Prince Leopold Island, Nunavut. Credit: Mark Mallory.

Research Aether / Earth Uncovered