Anela Choy aboard a research vessel in Monterey Bay
Anela Choy aboard a research vessel in Monterey Bay. Courtesy Monterey Bay Aquarium Research Institute

A new study shows that plastic waste less than 5 millimeters across is common from the surface to the seafloor off California.

So-called “microplastic” refuse from consumer products may also be entering marine food webs, both at the surface and in the deep, according to the study published in the journal Scientific Reports.

The research project in California’s Monterey Bay National Marine Sanctuary is the first to look systematically at microplastic, with repeated sampling at the same locations and a range of depths, from just beneath the ocean surface to 1,000 meters.

“Our findings buttress a growing body of scientific evidence pointing to the waters and animals of the deep sea, Earth’s largest habitat, as the biggest repository of small plastic debris,” said Anela Choy, assistant professor at Scripps Institution of Oceanography and lead author of the paper.

Using underwater robots, equipped with sampling devices designed specifically for the project, the researchers filtered plastic particles out of seawater on multiple occasions at two different locations. Some samples were collected just offshore of Moss Landing Harbor, but the majority were collected about 25 kilometers from shore, in the deep waters of Monterey Canyon.

They found nearly identical concentrations of microplastic particles near the surface and in the deepest waters surveyed.

In addition to sampling the water, the researchers also looked at concentrations of microplastic particles in specimens of two marine species: pelagic red crabs and giant larvaceans. The team found microplastic in all of the animal specimens they surveyed.

“Our study demonstrates a link between microplastics distributed across the water column and entry of this foreign material into marine food webs by important marine animals, such as pelagic crabs and giant larvaceans,” said Choy.

The groundbreaking research was a joint effort by the Monterey Bay Aquarium Research Institute and Monterey Bay Aquarium. Choy conducted the research while a postdoctoral fellow at the institute.

Chris Jennewein

Chris Jennewein is Editor & Publisher of Times of San Diego.