资源环境科技发展态势分析平台

Hidden in and around the muddy depths of the Mekong River is a wondrous animal world.

Here you can find catfish that weigh up to 300 kilograms and measure almost the length of a car. You might come across a dolphin that is known to communicate with humans to coordinate fishing expeditions. Or you could stumble upon something completely unknown: between 1997 and 2014, over 2,000 new species were discovered in the Lower Mekong Basin.

But this critical ecosystem is under immense strain from climate change, toxic farm runoff and scientists suspect, a rising tide of plastic pollution.  To gauge just how bad the plastic problem is, the United Nations Environment Programme (UNEP), the Conservation of Migratory Species of Wild Animals and several other partners have launched an in-depth study of the Mekong River Basin.

“Most of the focus on plastic pollution to date has centered on the marine environment. But we know that plastics are found in terrestrial and freshwater environments,” said Amy Fraenkel, Executive Secretary of the Convention on the Conservation of Migratory Species of Wild Animals. “We need to better understand the scale and impact of such pollution on the species in these areas, including migratory species.” 

A tidal wave of plastic

Humanity produces 300 million tonnes of plastic waste each year, of which about 8 million tonnes ends up in the ocean. More than 800 marine and coastal species are affected by this pollution through ingestion, entanglement, and other dangers.

The Irrawaddy dolphin, which inhabits the Mekong, is a frequent victim of entanglement in plastic fishing gear. But the broad effects that plastic is having on species living in and around rivers is an open question. One study in 2017 reported that 100 per cent of freshwater fish in the La Plata River in South America had microplastics in their system. Few other studies have been undertaken.

Chemicals that are added to plastics – including harmful ones, like Bisphenol A –   also leak into the natural environment with plastic debris. Additionally, microplastics can absorb chemicals and heavy metals from the surrounding environment and transport them further. The impact on human health of ingesting microplastics via wildlife, like fish and shellfish, is not fully understood. However, some research suggests that plastic additives are retained in marine plastics and microplastics and subsequently digested and absorbed into tissue, where it accumulates.

Governments have become more aware of the urgency to address the plastic problem. At COP13 of the Convention on Migratory Species, held in February 2020 in India, parties adopted Decisions 13.122 – 13.125 and called for further research on this issue. 

Into the Mekong’s depths

As part of the CounterMEASURE project in the Mekong, UNEP and its partners, which include the Mekong River Commission Secretariat, are assessing plastic hotspots in the terrestrial and freshwater environment.

The project will also examine the effects of plastic pollution – including microplastics – on the migratory species that exist in the Mekong River Basin, such as the Irrawaddy dolphin, the Mekong giant catfish, the Bengal florican and the sarus crane.

“With this information, areas that are of high importance for migratory species can be made a priority for preventing, combating and removing plastic pollution,” said Fraenkel. “The project will also develop a biological monitoring protocol for the Mekong River Basin. Importantly, we’ll also be working to raise awareness on plastic pollution and its impact on migratory species in Mekong communities.”

The biodiversity of the Mekong River is the foundation for the food, jobs and traditions of hundreds of millions of people. Some 60 million people alone rely on the abundant Mekong freshwater fishery for their livelihoods.