When envisioning the problem of plastic pollution in our oceans, scenes of beaches strewn with single-sue water bottles, cigarette butts and other trash often come to mind.
You may recall viral videos that tug on the heartstrings, such as the clip of biologists removing a straw from the nostril of an olive ridley sea turtle.
But the most damaging plastics in the ocean and other water bodies may ones that are almost too small to see — and they’re even being found here on the Central Coast.
A recent study by researchers at Monterey Bay Aquarium Research Institute (MBARI) and Monterey Bay Aquarium found tiny particles called microplastics at wide-ranging ocean depths and within all marine organisms they examined. The results reconfirm that microplastics can be widespread and are making their way into ocean food webs.
What are microplastics and where do they come from?
Microplastics are particles less than 5 millimeters in length — about four times the length of a grain of sand, and they come in two types.
Secondary microplastics are the remnants that are created when larger “macro” plastics break down over time, from the usual suspects like plastic bags, bottles, containers and knick-knacks.
Primary microplastics are those bits of material produced at a tiny size and directly released into the ocean. A well-known example is microbeads, found in “rinse-off” products like shampoo and soap. While the federal 2015 Microbead-Free Waters Act curbed their use in those products, microbeads and other microplastics like glitter can still be present in non “rinse-off” products like makeup and detergents.
Synthetic clothes that shed fibers in your washing machine are another important but perhaps surprising source of primary microplastics. According to a 2019 study published in Scientific Reports, many of these could be just the right size to bypass wastewater treatment and enter downstream aquatic systems.
What did the Monterey study find?
The team of researchers in Monterey, helmed by lead author Anela Choy, used one of MBARI’s remotely operated vehicles, Ventana, to retrieve water samples from intervals ranging from 5 to 1,000 meters.
The scientists found a similar concentration of particles in both the shallowest and deepest depths they sampled, while finding almost four times that occurring between mid-depths of 200 and 600 meters. Weathering of the plastic also suggested it had been adrift in the marine environment for long periods of time.
Gear used by local fishermen was ruled out as a significant source of plastic pollution. Rather, the study described the material as mostly polyethylene terephthalate (PET), polyamide and polycarbonate — components associated with single-use beverage and food containers, nylon clothing and eyewear.
In addition, the team also looked for and found microplastics within two filter-feeding organisms — pelagic red crabs and giant larvaceans, transparent invertebrates that build temporary nets of mucus to filter particles from the surrounding water.
MBARI principal engineer and study co-author Kakani Katija said these particular ocean animals were chosen because “the way they eat brings them in contact with large volumes of water.”
Because these creatures are ingesting microplastics and contribute to food webs at multiple depths in the ocean, they can help move plastic particles from the ocean’s surface to its lower reaches.
While this is not the first study to look at microplastic concentrations across multiple depths, marine scientist La Daana Kanhai, who is unaffiliated with the study but has done similar work in the Arctic, wrote in an email that “studies like this emphasize the pervasiveness of microplastics in the oceans as well as highlight the fact that these particles are interacting with the marine organisms that inhabit our oceans. More than ever, studies like this are a call to action to address the issue of plastic pollution in the oceans.”
What does this mean for SLO County?
The results from the Monterey Bay study join a body of research documenting the presence of plastic throughout the extent of the world’s oceans and more generally in the environment around us.
This suggests there are likely microplastics in waters adjacent to San Luis Obispo County, but study co-author Katija says it can be difficult to suggest how much and where without further sampling and research.
“I think this local study on microplastics is important because it is easy to be disconnected from this problem,” Chelsea Potter, current chair of the Rise Against Plastics Initiative for the SLO chapter of Surfrider, said in an email. “When we see more local studies, it really ‘hits home’ and makes us realize that this effects us personally as well as our future generations.”
Though there continues to be large data gaps in study around the effects of microplastics on aquatic organisms, according to a 2018 Science of the Total Environment research review, scientists have documented impacts on sea life ranging from neurotoxicity in fish to reduced survival and fertility of marine zooplankton.
Concentrations of micro-pollutants can also be amplified when larger animals, such as fish, load up on smaller plastic-containing organisms. A 2019 Environmental Science and Technology study characterizes seafood as one of the top three contributors to human consumption of microplastics.
The United Nations Food and Agricultural Organization advises this is more of a concern in seafood that is typically consumed whole, as is the case for shellfish, crustaceans, and small fish like sardines. For example, Belgian researchers estimate that European shellfish consumers may be ingesting up to 11,000 microplastic particles every year when eating cultured blue mussels and Pacific oysters.
Potter also wrote in her email that “In human and animal studies, different types of plastic exposure have been associated with certain cancers, hormonal disruptions and other serious health problems. Continued research is important to further understand the detrimental effects of plastics on human health.”
What can you do to reduce microplastics?
The first adds microplastics to the California Safe Drinking Water Act and requires that the State Water Resources Control Board adopt a standard methodology by July 2020 to test for microplastics in drinking water for four years while disclosing the results publicly. The second directs the state’s Ocean Protection Council to develop and submit a Statewide Microplastics Strategy to the Legislature by December of 2021.
Katija found the fact that the study team measured plastic in locations both easy and difficult to access makes the “idea of removing plastics from the ocean much more challenging.” She suggests it is important these plastics don’t make it into the water supply, and ultimately the ocean in the first place.
Katija urges people to consider other materials for single-use needs. SLO has already embraced this notion in the form of two city ordinances enacted last year regulating single-use plastic bottles, straws and cups, as reported by The Tribune.
Carlie Herring from NOAA advises being a selective consumer, including searching for ingredients like “polyethylene” on labels to help identify products that still contain plastics. She also recommends disposing of larger plastic debris when out at parks or the beach “so we remove them before they become microplastics.”
Consumers can further make choices related to the types of textiles they buy or turn toward products, like those Ocean Clean Wash describe on their website, that capture fibers during the wash cycle. Industry is also tackling the program as evidenced by a 2017 summit held in California that brought together producers of apparel and outdoor goods, scientists, nonprofits and other groups associated with microfiber pollution.
Responding by email, Ximena Waissbluth, Monterey Chapter coordinator for Surfrider, thinks more needs to happen at the commercial level: “We can each do better at the consumer level with our choices, but as, if not more, importantly, the companies who make this stuff need to step up and go full bore into the world of truly compostable materials, returnable systems, thoughtful design.”