Microplastic Contamination Found in Fully Protected Marine Areas of Brazil

A recent scientific study reveals that Brazil’s fully protected marine areas, designated as integral protection areas (APIs) with the strictest restrictions on human activity, are contaminated by microplastics. These tiny plastic particles have been detected even in the most remote and strictly controlled locations, showing that no marine environment is completely immune to this form of pollution.

The research was carried out by a team of Brazilian and Australian scientists, focusing on ten of Brazil’s integral protection areas along the coastline. These include well-known conservation zones such as Jericoacoara National Park, Atol das Rocas Biological Reserve, Fernando de Noronha, Abrolhos National Park, Alcatrazes Archipelago Wildlife Refuge, and others. These areas are generally regarded as sanctuaries for biodiversity with minimal human interference, yet they still face contamination.

Microplastics are plastic particles ranging from one micron to five millimetres in size. They originate either from the breakdown of larger plastic items or are manufactured directly in micro-size for industrial and cosmetic uses. The study used bivalve mollusks, including oysters and mussels, as bioindicators to assess the levels of microplastic contamination. These organisms filter large amounts of seawater for feeding and thus accumulate microplastics present in their environment, providing a reliable measure of pollution over time.

The study found that microplastics were present in all ten integral protection areas examined. The average concentration detected in bivalves was 0.42 particles per gram of wet tissue. Among the locations, the Alcatrazes Archipelago Wildlife Refuge recorded the highest contamination level at 0.90 particles per gram, while Atol das Rocas showed the lowest at 0.23 particles per gram. Despite the presence of microplastics, the contamination levels were below the international average reported for marine protected areas globally, and significantly lower than those found in Brazilian non-protected coastal zones, where pollution levels can be 50 to 60 times higher.

Chemical analysis of the microplastic particles revealed a varied composition. Alkyd polymers accounted for the largest share at 28.1%; these are typically used in paints and varnishes, likely originating from boats and tourist vessels. Cellulose made up 21% of the particles, potentially derived from both natural sources like plankton and algae, and anthropogenic sources such as paper and food waste. Polyethylene terephthalate (PET), common in plastic packaging and synthetic fibres, represented 14%, likely entering the marine environment through urban runoff and laundry wastewater. Polytetrafluorethylene (PTFE or Teflon), used in industrial coatings and non-stick surfaces, comprised 12.3%. A portion of the particles, about 40.6%, remained chemically unidentified.

The detection of microplastics in integral protection areas suggests that local human activity is not the only source of this pollution. Microplastics are transported by ocean currents and atmospheric movements, allowing them to reach even the most isolated marine habitats. This means that despite the strict protection and absence of economic activity in some areas, such as Atol das Rocas where tourism and fishing are prohibited, contamination persists.

The use of bivalve mollusks as sentinels is significant because they accumulate microplastics over time, unlike water samples which can fluctuate frequently. This approach gives a more consistent picture of long-term pollution levels in marine environments. The presence of microplastics raises concerns about potential risks to marine ecosystems and food chains, as these particles can be ingested by a wide range of marine species.

The study highlights the limits of marine protected areas in combating plastic pollution. While MPAs are essential for conserving biodiversity and ecosystems, they alone cannot prevent the influx of microplastics, particularly when these pollutants are transported from distant sources. Effective environmental management and strict enforcement within these protected zones remain necessary but insufficient.

The researchers emphasise that addressing microplastic pollution requires global cooperation and measures. The ongoing negotiations under the United Nations Environment Programme (UNEP) for a Global Plastics Treaty are seen as a crucial step towards reducing plastic pollution worldwide. Without international agreements and coordinated actions, microplastics will continue to threaten marine environments, even in protected areas.

The findings of this study underline the complexity of marine pollution and the challenge of safeguarding ocean health. They also serve as a call to action for governments, industries, and society at large to intensify efforts to reduce plastic waste and prevent it from entering marine ecosystems.

Source and Credits:

This article is based on research reported by FAPESP, authored by José Tadeu Arantes, edited by Stephanie Baum, and reviewed by Robert Egan. The original study titled “Microplastic contamination in no-take Marine Protected Areas of Brazil: Bivalves as sentinels” was published in Environmental Research (2025), DOI: 10.1016/j.envres.2025.121231.