From the shore, the sea appears serene, but beneath the surface lies a growing crisis: an estimated 24 trillion microplastic particles, according to the United Nations. These tiny fragments, less than 5 millimetres in diameter, are nearly invisible yet pose a significant threat to marine ecosystems. To understand how scientists detect and study these pollutants, European Pulse visited the Flanders Marine Institute (VLIZ) in Ostend, on the Belgian coast.
Microplastics enter the ocean through multiple pathways: abandoned fishing nets, litter from inadequate waste management, and the gradual breakdown of larger plastic debris. Researchers at VLIZ, led by senior researcher Ana Catarino, are collecting data directly from the North Sea to unravel the complexities of this pollution.
Two Types of Microplastics, One Growing Problem
Marine microplastics fall into two categories. Primary microplastics include industrial pellets known as nurdles, while secondary microplastics result from the degradation of larger plastic items due to waves, sunlight, and temperature changes. This degradation process is closely tied to climate change. As Catarino explains, “If we have more sunny days and higher UV radiation exposure and heat waves and changes of temperature, that might impact the degradation of plastics that are stranded.”
The interaction between microplastics and climate change is also critical for marine species. On their own, ingested microplastics may not be lethal, but when combined with stressors like rising sea temperatures or ocean acidification, the effects can be cumulative. “These combined effects can be cumulative in the organism,” Catarino notes.
Innovative Detection Methods
Identifying microplastics is challenging due to their small size, irregular shapes, and varied colours. Postdoctoral researcher Nelle Meyers at VLIZ has developed a semi-automated method to speed up the process. The technique involves collecting a seawater sample with a net, cleaning it of organic material, staining it with Nile Red dye, and then examining it under a fluorescence microscope. Two automated programmes analyse the images to determine whether a particle is a microplastic and identify its polymer type.
“We wanted to automate to speed up the whole process,” Meyers says. “We wrote a code so when you upload the picture, the image analysis is done automatically.” Because fluorescence microscopes are common in laboratories, the method is both cost- and time-effective. However, it has limitations: it cannot reveal the chemical composition of particles and only identifies certain polymers.
Impact on Marine Life
Just as larger plastic debris is ingested by fish and turtles, microplastics are consumed by tiny organisms like plankton. “They can also get their stomach, their gut clogged. And then they don't eat their nutrients, they don't eat their own food,” Catarino explains. This can impair reproduction and population health. The specific effects depend on the species, the type of microplastic, and other environmental stressors. “Sometimes it’s not just one issue or another, it’s the accumulation of all these effects that may be harmful to the organisms,” she adds.
Efforts to monitor and mitigate microplastic pollution are gaining momentum across Europe. For instance, citizen scientists in the Canary Islands are helping track marine life, while projects like the Typhoon Project have cut coastal pollution by up to 75% on Greek islands. These initiatives highlight the importance of combining advanced research with community engagement to protect Europe’s seas.
