Plankton Poop Might Be Moving Plastic to the Bottom of the Ocean

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Microplastic might be spread farther throughout the ocean with a little help from plankton poop, a new study suggests. According to research published in the journal Environmental Science & Technology, environmental scientists from the UK’s University of Exeter and Plymouth Marine Laboratory found that zooplankton have no issues gobbling up microbeads, those pieces of plastic smaller than one millimeter that are often included in exfoliating face wash and other hygiene products (and recently banned in the U.S.). Then, they poop out the pieces of plastic, leaving them for coprophagous biota (a.k.a. poop-eating creatures) to gobble up.

Observing captured zooplankton in the lab, the experimenters found that two species of small crustaceans, called copepods, were more than willing to ingest pieces of plastic introduced to their environment. And when they did, it changed their feces. The plastic-laced poop was lighter than typical plankton poop, floating to the bottom of the glass beakers more slowly.

Since plankton and their waste products are such an important food source for other ocean dwellers, the researchers suggest that these slow-floating, plastic-laced feces could be spreading plastic to different layers of the ocean as other animals consume them. If the microbead-filled feces drift to the bottom of the ocean more slowly than regular poop, there’s more time for animals to eat them and swim away, later depositing the same plastic somewhere else through their own waste.

This study was done in the lab and the microbeads were introduced to the water. However, considering how much plastic there is in the ocean, it’s not a stretch to assume similar conditions might play out in the wild.