Samut Prakan, 6 March 2023: Mangrove is known to be a powerful carbon sink, which is essential in mitigating climate change. However, large areas of mangrove forests face tremendous threats from plastic pollution, including the ones in Bang Pu mangrove conservation at the south of Bangkok city, Thailand.

Spreading across an area of 102 ha, the mangrove forest lies at the mouth of the Chao Phraya River, which carries an estimated 4,000 tonnes of plastic waste annually into the Gulf of Thailand. Some of this plastic waste ended up in the mangrove forest, jeopardising the habitat for more than 200 bird species and 70 species of benthic fauna.

During the visit by the Regional Knowledge Centre for Marine Plastic Debris (RKC-MPD) team, the shore of the mangrove forest was covered with plastic waste in the forms of food packaging (bottles, bags, sachets) and fishing equipment (fishing nets and buoys). This waste might have come from either direct littering by people or through the water current from the Chao Phraya River.

The condition of plastic pollution was no different than that of 2019, despite a clean-up activity performed on 6 July 2019. Organised by Toyota and the International Union for Conservation Nature (IUCN), a total of 2.8 tons of waste was collected by more than 2,000 participants coming from NGOs, schools, and private companies during the event. However, due to the COVID-19 pandemic, there has been no similar clean-up activities organised in Bang Pu, which could explain the plastic waste piling up along the shoreline.


Plastic pollution in mangrove forest in 2019

The condition in 2019.


Plastic pollution in Bang Pu mangrove forest in 2023.

The condition in 2023.

Rising Concern of Plastic Pollution in Mangrove Forests

This condition is not unique to Bang Pu mangrove forest in Thailand. Throughout Southeast Asia, more and more plastics of different forms—including macroplastics and microplastics—are widely distributed in the ecosystem. An increase in plastic production, coupled with insufficient waste management, resulted in surging plastic waste leakage to the aquatic environments. As mangroves primarily grow in the estuarine area between river and sea, they are more vulnerable to plastic pollution that may come from both sources. In addition, as quoted by Luo in 2021, mangrove’s spatial complexity can easily enhance the trapping and retaining of plastic debris, causing detrimental impacts unique to the mangrove ecosystem.

Due to the nature of ocean tides, plastics might be trapped among mangrove’s branch during high tide or on the forest floor during low tide. Overtime, plastics on the forest floor—especially of small sizes—could become sequestered inside the sediment, leaving traces for years to come. Studies on the extent of microplastics burial in mangrove sediments have been performed in different locations in Southeast Asia, leading to conclusion confirming mangrove sediments as long-term sinks for plastics.


Plastic waste on the forest floor will be fragmented into microplastic overtime.


Mangrove forests are hotspots of biodiversity that offer a multitude of ecological functions and ecosystem services beneficial not only to the organisms inhabiting it, but also to communities surrounding it. Mangroves provide nature-based coastal protection from storm surges, tsunami, and flooding, as well as shelter for diverse biota that are commercially valuable for fisheries. More importantly, mangroves act as major ‘blue carbon’ sinks, sequestering much CO2 that is crucial for mitigating global climate change.

A study by Brander et al. in 2021 showed that in Southeast Asia alone—where the most extensive and diverse mangrove forests are found—the value of ecosystem services from mangroves are estimated to be 4,185 US$/ha/year on average. Despite their high values, mangrove ecosystems are rapidly declining due to anthropogenic influences, of which plastic pollution is thought to be one of the causes.

For the reasons above, protecting mangroves from plastic pollution is therefore of high importance. The Regional Knowledge Centre for Marine Plastic Debris is taking up the challenge to gather good practices around the ASEAN+3 region, with the aim of providing recommendations for different stakeholders to reduce plastic pollution in mangrove ecosystems.