Microplastics are harming gut health

Newswise — Researchers have harbored concerns regarding the possible perils of microplastics for an extended duration. These minute fragments of plastic, measuring under 5 mm in size, have been detected ubiquitously due to plastic contamination - spanning from the profound depths of Earth's oceans to isolated territories in Antarctica, and even within the seafood we consume. Nevertheless, do microplastics indeed pose a threat?

A global consortium of scientists, which encompasses scholars affiliated with McGill University, has uncovered proof indicating that microplastics present in the gastrointestinal system of seabirds have modified the gut's microbiome. This alteration entails an upsurge in the abundance of pathogens and antibiotic-resistant microorganisms, while concurrently reducing the levels of advantageous bacteria typically found within the intestines.

"The authors stress that our discoveries mirror the conditions experienced by wildlife. Given that humans also ingest microplastics through environmental exposure and food consumption, this study should serve as a cautionary signal," emphasize the researchers.

Julia Baak, co-author of the study and a PhD Candidate in the Department of Natural Resource Sciences at McGill University, elucidates, "The gut microbiome encompasses the entire assemblage of microorganisms residing in the gastrointestinal tract, crucially involved in regulating processes such as food digestion, immune system function, central nervous system activity, and other vital bodily functions. It serves as a pivotal indicator of overall health and well-being."

In order to acquire enhanced insights into the impacts of diets persistently contaminated with microplastics on various species, the researchers meticulously analyzed the gut microbiome of two seabird species: the northern fulmar (Fulmarus glacialis) and the Cory's shearwater (Calonectris borealis). These avian species predominantly inhabit offshore regions and rely on a diet composed primarily of marine mollusks, 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, highlights, "Until this point, there has been limited research addressing whether the quantities of microplastics existing in the natural environment have detrimental consequences on the gut microbial well-being of the affected species."

During their investigation of the seabirds, the researchers made a significant observation: the ingestion of microplastics resulted in a notable alteration of microbial communities across the entire gastrointestinal tract in both species of seabirds. Gloria Fackelmann explains, "As the quantity of microplastics in the gut increased, the presence of commensal bacteria decreased. Commensal bacteria play a crucial role in providing vital nutrients to their hosts and aiding in the defense against opportunistic pathogens. Disturbances in these microbial communities can impair numerous health-related processes and potentially give rise to diseases within the host."

The researchers note that a majority of studies investigating the influence of microplastics on the microbiome are conducted in laboratory settings utilizing exceedingly high concentrations of microplastics. Gloria Fackelmann emphasizes, "Through our examination of animals in their natural habitats, our research demonstrates that alterations in the microbiome can transpire at lower concentrations that are already prevalent in the natural environment."

About the study

“Current levels of microplastic pollution impact wild seabird gut microbiomes” by Gloria Fackelmann, Christopher Pham, Yasmina Rodríguez, Mark Mallory, Jennifer Provencher, Julia Baak, and Simone Sommer was published in Nature Ecology & Evolution.