One of California’s Most Beautiful Bodies of Water is Filled with Plastic

The mucus “house” of a giant larvacean (Bathochordaeus charon) several hundred meters below the surface of Monterey Bay. (Photo courtesy Monterey Bay Research Aquarium Research Institute)

LOS ANGELES – Monterey Bay is one of the most beautiful and pristine-looking places on earth, but look below the surface and researchers have found evidence it’s teeming with microplastic.

The tiny pieces are smaller than a grain of rice and have been discovered floating through water columns as deep as 3,800 feet and in the guts and discharge of different sea creatures.

The findings are part of a new study published in Nature’s Scientific Reports. A team of researchers from the Monterey Bay Aquarium and the Monterey Bay Research Institute used remote operated vehicles (ROVs) and animal samples to figure out the prevalence of microplastic beneath the bay’s surface, and how it moves through the ecosystem.


“What we found was that microplastic is actually pretty pervasive,” said Anela Choy, lead author and assistant professor at the Scripps Institution of Oceanography, who was a postdoc with MBRI at the time.

“We found microplastics in 100 percent of our water samples and 100 percent of our animal samples that we looked at,” she said.


The team sampled water from 16 feet below the surface to more than 3,800 feet down, with the greatest concentrations between 650 and 2,000 feet.

They also went searching in the guts of sea creatures, looking for plastic in the digestive tracts of pelagic red crabs, tiny lobster looking omnivores that hang out in shallow waters and feed on particles that float down from above.

And they collected the discarded mucus feeding structures from giant larvaceans. These jellyfish-like filter feeders amble along, collecting whatever passes by, and then eject the structures when they’re full.


Microplastics were consumed by all of the sampled creatures.

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Microplastics can come from various sources, including the manufacturing of plastic, as well as from plastic trash floating through our oceans. The plastic gets smaller and smaller the longer it’s exposed to the elements.

Finding the evidence of microplastic is the first step in figuring out what effect it’s having on our ecosystems.

“We’re still not 100 percent there in terms of what does this mean,” said Choy. “What does it mean for a giant larvacean or a pelagic red crab to have this many pieces of microplastic in its gut? Is it harmful? Is it going to affect its ability to reproduce or to be completely alert to its function and find food, and live a happy life in the water? We just don’t know yet.”