Caddis Fly Larvae Are Now Building Shelters Out of Microplastics

An anonymous reader quotes a report from Ars Technica: Crawling along the world's river bottoms, the larvae of the caddis fly suffer a perpetual housing crisis. To protect themselves from predators, they gather up sand grains and other sediment and paste them all together with silk, forming a cone that holds their worm-like bodies. As they mature and elongate, they have to continuously add material to the case -- think of it like adding rooms to your home for the rest of your life, or at least until you turn into an adult insect. If the caddis fly larva somehow loses its case, it's got to start from scratch, and that's quite the precarious situation for a defenseless tube of flesh. And now, the microplastic menace is piling onto the caddis fly's list of tribulations.

Microplastic particles -- pieces of plastic under 5 millimeters long -- have already corrupted many of Earth's environments, including the formerly pristine Arctic and deep-sea sediments. In a study published last year, researchers in Germany reported finding microplastic particles in the cases of caddis flies in the wild. Then, last month, they published the troubling results of lab experiments that found the more microplastic particles a caddis fly larva incorporates into its case, the weaker that structure becomes. That could open up caddis flies to greater predation, sending ripple effects through river ecosystems. In the lab, the researchers found that the larvae chose to use two kinds of microplastics to build their cases, likely because the plastic is lighter than the sand, so it's not as hard to lift. The problem is that the cases with more plastic and less sand collapse more easily, weakening the larvae's protection from predatory fish, among other things.

A more long-term concern is bioaccumulation. "A small fish eats a larva, a bigger fish eats the smaller fish, all the way on up, and the concentrations of microplastic and associated toxins accumulate over time," the report says. "The bigger predators that people eat, like tuna, may be absorbing those microplastics and the chemicals they leach."

The study has been published in the journal Environmental Science and Pollution Research.

Read more of this story at Slashdot.