This may be why her team got contrasting results in their analysis. individual Microplastics in the gut, microbial diversity is greater, mass Diversity of microplastics is low. The more particles a bird eats, the more likely it is that hitchhiking microbes will colonize the gut. However, if the birds ate more microplastics (smaller but heavier portions), they may have reduced their uptake of microbes from the outside world.
On the other hand, especially jagged microplastics may be scraping through the bird’s digestive system, causing trauma that affects the microbiome. In fact, the authors of the plasticosis paper found extensive trauma in the intestines of wild petrels that ate microplastics and macroplastics in coastal birds of Australia and New Zealand. (They also looked at plastic particles as small as a millimeter.) At the Adrift Lab, which studies the effects of plastic on marine life.
Specifically, they found that the bird’s tubular glands, which produce the mucus that protects the lining of the stomach and the hydrochloric acid that digests food, were catastrophically damaged. Without these vital secretions, birds also cannot digest and absorb the proteins and other nutrients that keep them healthy and well. It is acceptable.”
Scientists call this the “sublethal effect.” Even if an ingested piece of plastic doesn’t kill the bird immediately, it can do serious harm. Nori calls it the “one-two punch of plastic” because eating it can completely harm a bird and make it vulnerable to pathogens that they carry.
A major caveat to today’s paper, and to much of microplastic research, is that few scientists have analyzed the smallest plastic particles. could be quantified by NanoPlastic on the scale of one-millionth of a meter. These are much more numerous in the environment. (This is also why the discovery of 11 billion pounds of plastic floating on the surface of the ocean was probably greatly underestimated, because the team only considered particles up to a third of a millimeter. (Because they didn’t.) But the process of observing nanoplastics remains challenging. As such, Fackelmann’s group cannot tell how many were present in the seabirds’ digestive system or how they influenced the microbiome.
Not likely to be good news. Nanoplastics are so small that they can penetrate and harm individual cells. Experiments with fish have shown that when fish are fed nanoplastics, the particles eventually reach the brain and cause damage. Other animal studies have also found that nanoplastics can cross the intestinal barrier and move to other organs. In fact, in another of his Lavers papers published in January, microPlastic accumulated in the petrel’s kidney and spleen, causing severe damage. “The harms shown in the plastics paper may be conservative because they don’t deal with particles in the nanoplastic spectrum,” he says. “I personally think it’s very scary because the harm of plastic paper is so overwhelming.
Scientists are now racing to figure out whether ingested plastic could endanger not only individual animals, but entire populations. Is this harm at the individual level—chemical exposure, exposure to microbiome alterations, plasticity—sufficient to drive population decline?” asks Reavers.
The jury is still out on it because scientists don’t have enough evidence to form a consensus. “A lot of the evidence we have now is deeply concerning,” she says. “I think we need to spread the logic and make a fairly safe and conservative assumption that plastic is currently causing population declines in some species.”
