With extensive coverage in the news media, the issue of microplastics has been appearing frequently before the public eye in recent years. Below are a few reports on microplastics to help those new to the topic build a general understanding.
This major ocean issue affecting all of humanity has prompted countries around the world to find ways to reduce the sources of marine microplastics. In Taiwan, perhaps the most tangible step for the public was the 2018 ban on microbeads in personal care products. The vast majority of microbeads in Taiwan are made of polyethylene (polyethylene) — these tiny beads, marketed by manufacturers as aids for facial and dental cleansing, have been proven to be a direct source of microplastics in the ocean. Of course, another major source of microplastics is the everyday plastic products we all use — including plastic bags, PET bottles, and cigarette butts. They end up in the ocean through various means, and under the pounding of waves and exposure to sunlight, they gradually fragment into the subject of this article: microplastics.
For this article, we are delighted to have interviewed Yu Xing-Pei from the Institute of Ecology and Evolutionary Biology at National Taiwan University (supervised by Dr. Kuo-Chin Chen, a researcher at the Biodiversity Research Center, Academia Sinica). In a recent research paper, she uses rigorous scientific methodology to help us understand what unexpected consequences may arise for us when the filter-feeding species at the very bottom of the marine food web are filled with microplastics.
Yu Xing-Pei has published multiple papers on microplastics
Having loved marine life since childhood, Yu Xing-Pei happened to have the opportunity to visit Hokkaido, Japan, where the local research institution was focused on studying microplastics. This inspired her to make microplastics the subject of her graduate thesis. At the time, most other research papers were focused on the impact of microbeads from facial cleansers, yet there was a notable lack of studies on the specific effects of these microplastics on marine organisms. As it happened, her graduate supervisor specialized in barnacle research, so she set her sights on barnacles — bottom-dwelling filter feeders — to investigate the effects of microplastics on them.
The Star of the Microplastics Study: Barnacles
Barnacles (superorder Thoracica) are often called "Buddha's hand" in casual conversation, and many people assume they are shellfish — but they are in fact crustaceans through and through. Some cling tightly to intertidal reef flats, while others attach themselves to driftwood floating on the ocean surface. Adults are incapable of movement, and they feed by using their feathery appendages (cirri) to sweep plankton from the water. Common barnacle species found in Taiwan include goose barnacles, turtle-foot barnacles (Pollicipes), and acorn barnacles. Barnacles occupy the bottom tier of the ecosystem, and some species have evolved specialized biological structures specifically to prey on them.
For this study, Yu Xing-Pei used the striped barnacle (Amphibalanus amphitrite) — widely regarded as the "lab mouse" of the barnacle world. Typical experiments feeding microplastics to organisms may only administer high concentrations over a day or two, which fails to accurately reflect real-world ocean conditions. So Yu Xing-Pei extended the experimental scale to span two generations: collecting adult barnacles, releasing their larvae, continuously feeding them microplastic concentrations matching real environmental levels, and tracking them until they grew into adults and produced offspring.
Yu Xing-Pei's barnacle study spanned two generations
Hoping to faithfully replicate real-world microplastic concentrations, she fed the barnacles four different sizes of microplastics and observed the accumulation of microplastics within their bodies. When the research began, Yu Xing-Pei admitted to feeling a bit disappointed — her initial hypothesis was that the larvae would be more vulnerable and would show some impact from the microplastics, but the baby barnacles grew up healthy and robust with no apparent effects whatsoever. She also shared an interesting fact: barnacle larvae are actually planktonic, drifting along with the ocean currents. Only after growing to a certain size do they settle onto reef surfaces, gradually forming their shells, and remain anchored there for the rest of their lives.
Microplastics of different sizes inside barnacle larvae
The initial conclusion from the research was that, without accounting for toxic substances adsorbed onto microplastics, the concentration of microplastics currently found in the environment may not have a noticeable impact on individual organisms.
Just as the results were feeling somewhat discouraging, the story took a dramatic turn. Yu Xing-Pei discovered that the offspring of barnacles fed microplastics had higher mortality rates — and the smaller the microplastics they were fed, the higher the offspring mortality, in some cases more than 3 times higher than the control group that was not fed microplastics. To explain this striking finding, Yu Xing-Pei reviewed domestic and international literature and theorized that after ingesting microplastics, the body may naturally make a trade-off (Tradeoff), diverting precious energy toward expelling the microplastics or generating molecular responses such as inflammation — thereby reducing the quality of offspring produced and leading to elevated offspring mortality. As mentioned above, barnacles are a foundational species in their ecosystem. If barnacle populations in a given area decline dramatically due to microplastic exposure, the ripple effects through the interconnected food chain could cause a complete ecosystem collapse in that region.
The Hazards of Microplastics After Adsorbing Seawater Contaminants
Many experiments have already demonstrated that microplastics adsorb various man-made carcinogens from seawater, including bisphenol A (BPA) and polychlorinated biphenyls (PCBs) — environmental toxins that everyone desperately wants to avoid, associated with chronic disease, infertility, hormonal disorders, and even cancer. If bottom-dwelling filter feeders like barnacles consume microplastics coated with these environmental toxins, the toxins can diffuse into their bodies (since the internal toxin concentration is initially lower, they gradually permeate inward) and may directly affect the parent organism — or be passed on to offspring through reproduction. These toxins accumulating within organisms are also transmitted up the food chain: barnacles are eaten by small fish, small fish are eaten by large fish, large fish are eaten by humans — and ultimately the toxins return to our own bodies (in their highest concentrations). We who pride ourselves as the crown of creation, sitting at the top of the pyramid, turn out to be the final victims of microplastics' revenge. It is truly a cause for sorrow.
The findings of this research can be applied to oysters, clams, freshwater clams, razor clams, and scallops — all beloved by humans. The next time you sit down to a feast of shellfish, it may be worth pausing to wonder: are the microplastics you and I generate in daily life being swallowed back up, one by one, by ourselves?
Every Time You Do Laundry, You're Creating Microplastics!
24% comes from everyday plastic products
28% comes from tire abrasion on roads
35% comes from washing synthetic fiber clothing in washing machines
Based on data analysis by Dr. Kuo-Chin Chen, Biodiversity Research Center, Academia Sinica
Looking at the microplastic source breakdown above, it's surprising to learn that tire wear from our daily commutes and the shedding of synthetic fibers from everyday laundry actually generate more microplastics than the marine debris we see on the ocean floor. Modern civilization cannot ban people from driving or doing laundry — so does that mean we simply surrender to microplastics? Until scientists find an effective method for removing microplastics from the ocean, the only way we can reduce microplastic quantities through our own actions is to cut down on single-use plastics and start with ourselves. The ocean changes because we dive — and because we care.
Cutting Plastic From Your Life Is Simple — Here's Where to Start
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Reduce single-use plastics: carry a reusable bag and bring your own utensils
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PET bottles are not as eco-friendly as you think — the plastic labels and caps cannot be recycled, and the dioxins released when they are incinerated harm us all. Carrying your own water bottle is the only real solution
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Love bubble tea? A plastic cup, a plastic straw, and a plastic carrier bag — three types of plastic waste generated in one purchase. After reading the above, you might make a different choice next time
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Don't flick cigarette butts into drains — and quitting smoking altogether is even better for your health
Cover image: Photo by mauRÍCIO SANTOS on Unsplash
Research papers:
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Effects of polystyrene microplastics on larval development, settlement, and metamorphosis of the intertidal barnacle Amphibalanus amphitrite Sing-Pei Yua,b, Benny Kwok Kan Chana,∗（2020）
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Intergenerational microplastics impact the intertidal barnacle Amphibalanus amphitrite during the planktonic larval and benthic adult stages* Sing-Pei Yu a, b, Benny K.K. Chan a, *（2020）
Further Reading:
