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Everglades National Park is a 1.5-million-acre wetlands preserve on the southern tip of the U.S. state of Florida. Everglades National Park is a 1.5-million-acre wetlands preserve on the southern tip of the U.S. state of Florida.  (AFP or licensors)

World Wetlands Day: Saving our common home, one ecosystem at a time

World Wetlands Day, marked annually on 2 February, aims to raise awareness regarding the importance of these ecosystems that contribute to biodiversity, climate mitigation and adaptation, freshwater availability, world economies and more. A recent study highlights the delicate ecological balance of wetlands and the growing threat posed by plastic pollution.

By Federico Citterich 

Sunday, 2 February, marked World Wetlands Day. The theme chosen for 2025 is “Protecting Wetlands for Our Common Future” which highlights the vital role wetlands play in our ecosystem – and the growing threats they face, including plastic pollution. Wetlands in fact, provide extremely sensitive ecosystems, yet they are often understudied, particularly in the context of plastic pollution.

“Currently, there isn’t a global solution to plastic pollution”, said Davide Taurozzi, a PhD candidate at Roma Tre’s Science Department. “Considering this, it is also important to recognise its few positive aspects”.

Amongst these, a recent study suggests that plastic materials deposited in coastal wetlands may facilitate the colonisation of primary producers and consumers, life forms at the foundation of the food chain that can, in turn, support the proliferation of higher organisms.

“Our starting point was to investigate whether macroplastics – plastic items larger than 5 cm in size – in coastal wetlands could serve as an additional substrate for colonisation by small invertebrates”, explained Taurozzi, first author of the study.

To do this, the researchers placed previously unexposed polystyrene and polyethylene terephthalate (PET) components on the surface and at a depth of up to two meters in a wetland at Torre Flavia, near Rome, and found that small invertebrates actively colonised all the samples.

“By active colonisation, we mean that the organisms reached the plastic sites by swimming towards them, rather than being transported by atmospheric agents such as winds”, highlighted Taurozzi. “This suggests that the organisms specifically selected the plastic as a substrate, indicating a preference for it over other available surfaces”.

All that glitters is not gold

“Obviously, this does not mean that from now on we have to purposely release plastics in wetlands”, said Taurozzi. “We always have to remember that plastic pollution creates colossal problems”.

Among these, the authors mentioned the release of additives in the environment, plastic entanglement, and plastic ingestion.

“In addition, macroplastics can serve as a surface onto which not only small invertebrates but also microorganisms can grow and develop”, explained Taurozzi. “They become functional plastic-based micro-ecosystems, known as plastispheres”.

Among the microorganisms found on macroplastics, viruses and bacteria are the most concerning.

"Winds and currents can carry macroplastics across vast distances, potentially introducing pathogens to areas where they were previously absent”, said Taurozzi. "This could lead to detrimental effects, as some species – having never been exposed to those pathogens – may lack the immune defences necessary to combat them”.

Furthermore, macroplastic transfer can transport invasive species into new ecosystems. Invasive species are introduced organisms that ecologically harm their new environments, having negative effects on local organisms.

Macro- and microplastics

Macroplastics can also break down into smaller fragments. When these fragments become smaller than 5 mm, they are known as microplastics.

“Due to their extremely small size and our current limitations in engineering and ecological knowledge, removing microplastics from the environment is – at present – impossible”, warned Taurozzi.

However, even when removal is theoretically possible – as in the case of macroplastics – the enormous quantities of these materials in the environment make their extraction unachievable.

Future perspectives

“Our study is the first of its kind”, highlighted Taurozzi. “It’s the first time anyone has investigated virgin macroplastic colonisation in a wetland”.

“Hence, it is essential to further assess how small invertebrates colonise not only plastic materials but also natural substrates such as wood or plant matter”, he explained. In addition, the authors believe it would be useful to compare their results to similar studies carried out in different environments.

"We present what can be considered positive results, but the goal is always to prevent and avoid pollution", concluded Taurozzi. “This is particularly true for sensitive ecosystems such as wetlands”.

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05 February 2025, 12:08