For many, thinking about what we consume is a part of managing our health. A healthy diet is a necessity, but being aware of what forms of pollutants are finding their way into our bodies is important too. Scientists, journalists, government officials, health officials, and the general public are concerned with the concentration of heavy metals, like lead and mercury, in drinking water as they pose clear threats to human health, such as causing some forms of cancer. But heavy metals are only part of a long list of contaminants that can find their way into the products we consume. Another type that is gaining more attention is the increasing proliferation of microplastics, tiny plastic fragments, that are becoming more common in our environment.
A Mt. A student, Rukiya Minnis, said: “Microplastics are a pollutant to the health of all organisms. Because they are so small, many cases are being left untreated as doctors cannot treat what they cannot see. I believe we must put a stop to microplastics before it is too late to maintain our health and ecosystem.”
The spread of microplastics within the world’s oceans is being fuelled by the usage of consumer products, such as cosmetics and cleaning agents, as well as the breakdown of large plastic waste. Research has detected microplastic across a myriad of marine environments, including inside many of the species we regard as prized seafood. But understanding how these plastics find their way into these organisms, and onto our plates, requires us to look at the lifeforms residing near the bottom of the food chain, such as ciliates, a form of microzooplankton.
Ciliates are single-celled organisms that feed on phytoplankton (think plant-plankton) and are an important prey item for larger marine life. However, if these ciliates encounter and consume microplastics, these pollutants can build up in their tiny bodies. This means that when larger organisms eat the polluted ciliates, they ingest all the microplastics along with them; then something larger eats them, and so on and so on. This is also known as a microbial loop as materials and energy are transferred. This continued transfer and accumulation of microplastic up the food chain is the reason why a delicious plate of fish and chips may contain plastic that was originally collected and consumed by a ciliate so small you would not be able to see it without the aid of a microscope.
A number of questions and concerns arise from this information. First, there is a limitation as to what we can do to eliminate microplastics within our ocean entirely. Also, there has been little research as to whether the size of the microplastic has a greater effect on the microbial loop or not. Lastly, you may be wondering whether it is proven that microzooplankton are eating microplastics.
A study by Geng and colleagues used various concentrations of microplastic to gauge the response of the planktonic ciliated protozoan Strombidium sulcatum to microplastic. Different concentrations of microplastic proved to be irrelevant as it entered the food chain through the ciliate that consumed it regardless of how large or small the microplastic was. Consequently, this means that this organism has a major impact on the food web. This just shows that small mishaps can have big consequences. After the ciliates consumed the microplastics, many of them died, could not reproduce, or had stunted growth because their body ingested harmful substances instead of receiving nutritious food.
Another Mt. A student, Shaniah Duncombe, had thoughts on this topic as well. She said: “The ocean’s health is important for our survival and sustainability because healthy waters are a necessity for food resources. If we consider this fact, the long-term implications that microplastics have on our population can be dire, and we risk losing one of the vital resources needed to sustain ourselves. Microplastics within our oceans need to be researched further because it affects our well-being and the overall health of our ocean.”
There is a clear need for us to enhance our knowledge of microplastics in our ocean, where the sources are, and how we can limit their spread. Just as we stop and think about other pollutants in the things we consume, like heavy metals in our drinking water, we need to also think about preventing microplastics from entering the ecosystems as they can severely affect the food we eat.