There are far more microplastics in the oceans than we’ve thought

Microplastics are pernicious pollutants with the tiny particles having spread far and wide across the planet from mountaintops to the depth of oceans. Microplastics have also entered the food chain to the extent that unknowingly we each consume a credit card’s worth of plastic every week.

And the extent of microplastic pollution is worse even than we have thought, according to research by the Scripps Institution of Oceanography, which suggests there could be a million times more pieces of plastic in the ocean than previous estimates have had it.

Concentrations of microplastic in seawater are likely much higher because previous measurements missed counting the tiniest particles, say the researchers behind a new study published in the journal Limnology and Oceanography Letters. According to the new estimates ocean water contains a shocking 8.3 million pieces of mini-microplastics per cubic meter, which is five to seven orders of magnitude more than previous estimates.

“For years we’ve been doing microplastics studies the same way, by using a net to collect samples,” explains lead researcher Jennifer A. Brandon. “But anything smaller than that net mesh has been escaping.” Instead, Brandon and her team decided to examine the stomach contents of gelatinous filter-feeding invertebrates known as salps, which propel themselves by sucking in water.

Brandon surveyed water samples collected from salps over several years. They all had high concentrations of mini-microplastics in their guts. Worse: these microplastics are resilient to environmental factors, which means they take a long time to disappear. That is to say they will remain in seawater for decades to come, contaminating marine ecosystems.

“Despite tremendous interest in microplastics, we are just beginning to understand the scale and effects of these ocean contaminants,” Dan Thornhill, a program director at the National Science Foundation’s Division of Ocean Sciences, commented on the findings.

“This study demonstrates that marine plastics are far more abundant than anyone realized and can be found potentially everywhere in the ocean,” Thornhill added. “This is troubling, especially when the consequences for the environment and human health remain largely unknown.”