The world is being inundated with microplastics. They are in our drinking water, soil, and air. They’re deep in the Mariana Trench, on the top of Everest, and in our bodies. Now, they are being found in fully protected marine areas.
A new study led by Brazilian and Australian scientists reveals that even Areas of Integral Protection (API) – the most restrictive class of Marine Protected Areas (MPAs), where all human activity is prohibited – are contaminated by microplastics.
There are over 16,500 marine protected areas (MPAs) globally, encompassing approximately 8.36% of the world’s oceans. But only 2.9% are under full or high protection, such as no-take zones.
The team used bivalve molluscs – oysters and mussels – to detect contamination.
“Bivalve molluscs feed by filtering seawater,” explains Italo Braga, coordinator of the research and professor at the Institute of Marine Science of the Federal University of São Paulo.
“The food in the water is retained in their gills, which act as sieves. And tiny cilia carry it to their stomachs. If that water contains contaminants, such as microplastics, the bivalves will retain them as well. So instead of taking water samples, which vary all the time, we analyse the bivalves because they accumulate pollutants over time and provide a more reliable history of contamination.”
Microplastics were found in all 10 integral protection areas studied, with an average concentration of 0.42 ± 0.34 particles per gram of wet tissue.
The chemical analysis identified 59.4% of the microplastics, the main components being alkyd polymers (28.1%), used in paints and varnishes; cellulose (21%), which may be of natural origin or of anthropogenic origin such as paper or cardboard; polyethylene terephthalate (14%), commonly found in plastic packaging and synthetic fibres; and polytetrafluoroethylene (12.3%), present in non-stick and industrial coatings. The remaining 40.6% could not be described.
“Our study showed that microplastic contamination occurs even in the most restrictive environmental protection areas,” says Braga. “For example, in Atol das Rocas, where there’s no economic activity and tourists aren’t allowed to visit. Microplastics can reach places like this by being carried by the wind or ocean currents.”
The presence of microplastics in MPAs raises concern because they can be ingested by a wide range of marine organisms — from plankton to top predators — and have been associated with physiological and neurological harm.
The author say “targeted mitigation strategies” are needed, including enhancing waste management systems near MPAs, reducing plastic inputs from terrestrial sources, and implementing education and awareness programs to minimize plastic consumption and discard.
“Moreover, long-term monitoring programs within MPAs assessing changes in contamination levels, effectiveness of management strategies, and identifying emerging threats should be implemented.
“The creation of MPAs alone isn’t enough to stop pollution”, says researcher Beatriz Zachello Nunes, a marine biologist and PhD student at the Federal University of Rio Grande. “It’s essential that these areas have efficient environmental management and strict enforcement. But even this isn’t enough if we consider that the microplastics may not be generated locally but brought in from afar by the atmosphere and ocean currents.
“To mitigate this, only global measures, such as the Global Plastics Treaty currently being negotiated and developed under the coordination of the United Nations Environment Program, can make a difference.”
These results were published in Environmental Research.
Microplastics and health
Do you care about the oceans? Are you interested in scientific developments that affect them? Then our email newsletter Ultramarine is for you.