How microplastic pollution is menacing Antarctica
By Federico Citterich
Plastic pollution continues to impact our everyday lives, threatening both our health and the environment. Plastic bags often get ingested by animals, plastic bottles accumulate in oceans and rivers, and discarded fishing gear traps kill marine life indiscriminately.
Repeatedly, Pope Francis has called on all men and women of goodwill to care for God’s creation and preserve its biodiversity and has highlighted the need to protect the oceans. In a television interview in 2022, he said “Throwing away plastic in the sea is criminal. This kills biodiversity, the Earth, everything. If things don’t change our grandchildren (…) will have to live in an uninhabitable world within 30 years.”
Yet, another plastic-derived, silent polluting item has recently worried scientists and politicians: microplastics.
The problem of microplastic pollution
Microplastics are plastic particles smaller than 5mm in size. They can either be deliberately produced of this size or result from the degradation of larger plastic items.
Microplastics are now found in almost every environment on Earth, such as water bodies, soil, and air, and have even reached the most pristine areas of the world, including Antarctica and its seas.
One important problem with microplastics is their small size, which enables them to be easily transported by atmospheric agents from one part of the world to the other.
“Due to their light weight, microplastics can be carried by wind or oceanic currents over incredibly long distances”, said Angelina Lo Giudice, a researcher at the Institute of Polar Sciences of the Italian National Research Council. “This process is known as long-range transport”.
“However, scientists and tourists are increasingly visiting Antarctic areas, and despite the environmental protection management framework, this inevitably contributes to polluting the region with plastic material”, added Lo Giudice.
According to the researcher, the most common type of plastic found in Antarctic regions is polyethene terephthalate (PET), which is used to produce soft drink bottles and clothing items.
“We use synthetic fabrics every day, and both daily wear and frequent washing processes can provide a direct pathway through which textile fibres can enter the Antarctic environment”, explained Lo Giudice.
And once there, microplastics can be erroneously ingested by animals, entering the food chain and reaching its highest levels.
The effect is that animals at the base of the food chain ingest microplastics because they mistake them for food items. These animals are then eaten by predators, which in turn become prey for other predators, continuing up the food chain until reaching the top.
For example, a study by the University of Toronto reported for the first time the presence of microplastics in the Arctic char, a cold-water fish of the same family of the salmon and native to Arctic and sub-Arctic regions, including Northern Europe. The Arctic char is commonly used for human consumption, emphasising how the spread of microplastics in Polar regions can be a significant problem for us as well.
“This is because microplastics can accumulate other pollutants such as heavy metals and toxic organic compounds”, said Maria Papale from the Institute of Polar Sciences of the Italian National Research Council. “By spreading into the food chain, these pollutants can ultimately reach our stomachs”.
Plastispheres: microplastics as micro-ecosystems
A similar procedure occurs with pathogenic microbes, that often adhere to microplastics and can hence spread between animals more easily.
“In fact, it is very common for microorganisms to colonise microplastic items”, said Papale.
In aquatic environments, microplastics provide a stable, long-lived, and mobile environment onto which microbes can grow, and thus immediately adhere to them. This creates a new plastic-based micro-ecosystem, known as plastisphere.
Plastispheres host photosynthetic organisms, predators and prey, symbionts and parasites, enabling an incredible amount of potential interactions between the microorganisms that inhabit them. “They are fully working ecosystems”, explained Papale.
The impacts of plastispheres
According to recent research, microbial communities living in plastispheres significantly differ from the free-living, independent communities of their surroundings.
“Plastispheres tend to host more consolidated and structured microbial communities”, said Papale, first author of the study. “While free-living microbial communities are exposed to variables that influence their composition – such as temperature, salinity, pH, solar radiation, presence of dissolved nutrients, etc. – plastisphere-colonising communities are protected by a solid and stable substrate”.
The plastic component of these microparticles can in fact act as a physical barrier, shielding microbes from direct exposure to external factors.
“Furthermore, microbes on plastic surfaces often form biofilms” added Lo Giudice, co-author of the study. “These are protective layers of cells and extracellular material that preserve the plastisphere-colonising communities even further”.
“Our study even demonstrates that plastispheres recovered from the surroundings of the Italian ‘Mario Zucchelli’ research station (Road Bay, Antarctica) grew abnormally, leading to a massive microbial abundance”, explained Papale.
According to the investigation, which is part of a research project in Antarctica led by Gabriella Caruso from the Institute of Polar Sciences of the Italian National Research Council, anthropogenic stressors influenced the chemical structure of the biofilm and the microbial composition in plastispheres around the station, promoting microbial growth even during winter, despite the hostile environment.
From an ecology standpoint, however, this is problematic. The presence of plastispheres alters microbial communities and, consequently, the balance of their environment, having a chain effect on the entire ecosystem.
“Plastispheres affect the normal functioning of nutrients cycles”, explained Papale. “This ultimately modifies the structure of all biological communities in the ecosystem, not just the microbial ones”.
Future implications
“Hence, it is imperative that we take urgent actions to mitigate and contrast microplastic pollution, even in remote areas such as Antarctica”, said Lo Giudice. “We need to monitor the presence and distribution of plastic material in polar regions, and we need to better evaluate the impacts they have on biodiversity”.
“It is essential to further assess the effects of plastispheres on the health of marine ecosystems and biodiversity, and to study the interactions between plastic, biofilm, and environmental contaminants”, said Papale.
“The ultimate goal is to develop strategies to mitigate the impact of plastispheres in marine environments”, she concluded. “This will clearly take some time, but we are hopeful and optimistic”.
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