Plastics Are Devastating the Guts of Seabirds

This might be why her team got contrasting results in their analysis: The more individual microplastics in the gut, the greater the microbial diversity, but the higher mass of microplastics, the lower the diversity. The more particles a bird eats, the greater the chance that those hitchhiking microbes take hold in its gut. But if the bird has just eaten a higher mass of microplastics—fewer, but heavier pieces—it may have consumed fewer microbes from the outside world.

Meanwhile, particularly jagged microplastics might be scraping up the birds’ digestive systems, causing trauma that affects the microbiome. Indeed, the authors of the plasticosis paper found extensive trauma in the guts of wild flesh-footed shearwaters, birds that live along the coasts of Australia and New Zealand, that had eaten microplastics and macroplastics. (They also looked at plastic particles as small as 1 millimeter.) “When you ingest plastics, even small amounts of plastics, it alters the structure of the stomach, often very, very significantly,” says study coauthor Jennifer Lavers, a pollution…