Xiamen's once polluted mudflats turned into thriving eco-sanctuary

Xiatanwei Mangrove Park, the largest restored intertidal wetland in East China's Fujian province, launched a series of marine biodiversity activities this weekend to mark World Oceans Day on June 8, showcasing the site's transition from a polluted aquaculture zone into a world-class ecological sanctuary.

The three-day event features the debut of a new scientific illustrated guide on intertidal species conservation, anchoring a localized marine market that highlights what the United Nations has recognized as a global blueprint for coastal rehabilitation.

During the 1970s and 1980s, these natural intertidal flats were degraded by commercial aquaculture farms, with farming runoff destroying the native mangrove vegetation.

The turning point came in the early 2000s, when a research team led by the late academician Lin Peng, widely regarded as a pioneer of modern Chinese mangrove research, initiated a 5-hectare experimental forest on the polluted mudflats to test restoration feasibility.

Following successful trials, the Xiamen city government scaled the initiative into a comprehensive multiphase remediation campaign, restoring approximately 85 hectares.

According to data compiled by Xiamen University, the completed 85-hectare forest has fundamentally altered the local food web, triggering a large-scale return of native wildlife.

Yang Shengchang, an associate professor from the College of the Environment and Ecology at Xiamen University, said that restored mangroves function as primary producers to sustain a complex food web. This triggered a measured biological recovery, he added.

Recent data showed the park's total species richness has increased 2.4-fold compared to pre-restoration, with the biomass for fish up 2.99-fold, for shellfish up 4.76-fold, and crustaceans up 1.19-fold, according to Yang.

On the ground, when the tide recedes, the exposed mudflats reveal an active intertidal ecosystem. Large populations of fiddler crabs and mudskippers emerge across the patterned flats, creating an abundant feeding ground that draws flocks of egrets and herons down from the mangrove branches.

"In the past, this area only attracted waterbirds, but now as you walk along the boardwalk, you can observe a significant number of forest birds as well, with 76 bird species recorded so far," Yang said. "This direct influx is a clear result of environmental improvement."

As the biological community matured, the forest's physical and environmental functions multiplied. The dense root systems now serve as a vital storm barrier, while its carbon sequestration capacity was found to be two to five times greater than equivalent areas of terrestrial forests, he said.

Beyond biodiversity metrics, the park has established a distinct precedent in climate diplomacy.

A dedicated section of the replanted mangrove canopy was utilized to fully offset the carbon emissions generated during the 2017 BRICS Xiamen Summit. The initiative marked the first certified "zero-carbon" international meeting in BRICS history, earning the site its official designation as the "BRICS Carbon Neutral Forest".

Peter Thomson, the UN Secretary-General's Special Envoy for the Ocean, visited the park in 2018 and returned in 2023 during the 18th Xiamen International Ocean Week, praising it as a great example of mangrove restoration.

Since January 2023, the park's infrastructure — including an elevated 4.2-kilometer boardwalk system, five dedicated viewing piers, and island trails — has accommodated more than 3 million tourists.

The site also functions as an outdoor science classroom. Educational institutions have conducted over 500 interactive workshops there, allowing more than 150,000 students to personally observe mangrove viviparity, feel the unique breathing roots and trace intertidal wildlife.

"Young students are highly receptive to these ecological narratives," Yang said. "Whether they are exploring the elevated boardwalks, stepping directly onto the mudflats, or even getting pinched by a crab, this hands-on exploration effectively translates textbook knowledge into a lasting understanding of marine conservation."

Contact the writers at zhangyi1@chinadaily.com.cn