MICROPLASTICS are plastic particles smaller than five millimeters that originate from the breakdown of larger plastic items or are manufactured at small sizes for industrial and consumer use. They are now widely detected in marine, freshwater and terrestrial environments, including coastal waters surrounding the Philippines.
In recent years, scientific research from The University of the Philippines, Ateneo de Manila, Central Luzon University, and foreign universities like Tel Aviv University in Israel, University of Sharjah in the United Emirates, Rhode Island University, University of Plymouth, in the US and the Chinese Academy of Sciences, examined how microplastics interact not only with marine organisms but also with processes involved in climate regulation.
One area of focus is the ocean’s role in absorbing and storing carbon dioxide from the atmosphere. Research from these educational institutions was used to develop this article.
The biological carbon pump
A 2026 study by researchers from the University of Sharjah examined how microplastics interact with organisms involved in this process. The study found that plastic particles smaller than five millimeters can disrupt planktonic organisms, interfere with feeding and reproduction, and reduce the efficiency of carbon transfer to deeper ocean layers.
The oceans absorb a significant portion of anthropogenic carbon dioxide through physical and biological processes. One of these is the biological carbon pump, in which plankton and other microorganisms incorporate carbon during photosynthesis and transport it to deeper waters when they die or are consumed.
The researchers also observed that as microplastics degrade, they can release greenhouse gases, including carbon dioxide and methane. While the quantities released at the particle level are small, the cumulative effect at large scales remains under investigation.
The study focused on global ocean systems but raised questions about how similar mechanisms may operate in coastal and tropical environments.
Blue carbon ecosystems
In the Philippines, carbon storage is not limited to the open ocean. Mangroves and seagrass beds along the country’s coastlines store carbon in plant biomass and sediments, a process commonly referred to as blue carbon sequestration.
Mangroves are particularly important where they also reduce coastal erosion, dampen storm surges and support fisheries. Their ability to store carbon depends in part on sediment stability and biological activity below the surface.
Research conducted in August 2025 by the Marine Research Institute on coastal habitats in the southern Philippines reported increased accumulation of microplastics in mangrove sediments. The study found that while mangroves in the area can sequester up to 342 grams of carbon per square meter per year, sediment samples contain as many as 6,578 microplastic particles per square meter annually.
Scientists involved in the research noted that plastic particles can alter sediment structure, porosity and microbial activity. These changes may affect how carbon is stored and retained, although the long-term consequences for sequestration rates are still being studied.
Interaction with marine food webs
Microplastics are readily ingested by marine organisms across multiple trophic levels. Particles have been documented in plankton, invertebrates and fish, either through direct ingestion or indirectly through prey.
Plastic surfaces also serve as habitats for microbial communities, sometimes referred to as the plastisphere. These communities can include bacteria capable of producing greenhouse gases or carrying chemical contaminants and pathogens.
In the Philippines, studies conducted between 2024 and 2025 reported widespread microplastic contamination in seafood. One study found microplastics present in all mussels sampled from major aquaculture sites. Separate studies in Butuan Bay and Nasipit documented microplastic ingestion in bangus (milkfish) and mud clams.
These findings demonstrate that microplastics are moving through marine food webs in Philippine waters. While ingestion does not necessarily translate into immediate harm, researchers note that plastic particles can act as carriers for additives, heavy metals and microorganisms.
The effects of chronic dietary exposure to microplastics in humans remain an active area of research.
Climate relevance and uncertainties
The relevance of microplastics to climate processes lies in their interaction with carbon cycling rather than their direct contribution to emissions. Disruption of plankton communities, alteration of sediment properties and changes in microbial activity may affect how carbon is absorbed, stored and released in marine environments.
Tropical ecosystems such as those in the Philippines differ from temperate systems in temperature, biodiversity and biological productivity. These factors may influence how microplastics behave and how their impacts manifest, but data specific to tropical regions remain limited.
As a result, many questions remain unresolved, including how widespread sediment-level changes are, whether carbon sequestration rates are measurably affected and how microplastic-related processes interact with other stressors such as warming waters and ocean acidification.
Research and policy context
In January last year, the Department of Environment and Natural Resources (DENR) launched the National Plastic Action Partnership, which seeks to reduce plastic waste through improved management and implementation of the 2023 Expanded Producer Responsibility Law.
While these measures focus primarily on waste reduction, scientists note that understanding the broader environmental effects of plastics requires long-term monitoring and interdisciplinary research. At present, links between plastic pollution, ecosystem function and climate processes are still being established.
International assessments such as the 2026 Climate Performance Index have also highlighted gaps in the Philippines’ climate policy framework, including the absence of a clearly defined net-zero emissions target. How plastic-related emissions and ecosystem impacts are incorporated into climate strategies remains unclear.
Current research shows that microplastics are present in Philippine coastal sediments, marine organisms and food systems. Studies also indicate that plastic particles can interact with biological and chemical processes involved in carbon cycling.
What remains uncertain is the scale of these effects and their significance over time. As research continues, microplastics are increasingly being examined not only as a pollution issue but as a factor influencing how marine systems function under changing environmental conditions.
