China’s artificial-island building accounts for about two-thirds of the damage to marine habitats in the South China Sea stemming from dredge-and-fill construction, researchers say.
China has buried more than 4,600 acres (about 19 square kilometers) of coral reef since 2013, the Asia Maritime Transparency Initiative (AMTI) reported in January 2025. The group, part of the United States-based think tank Center for Strategic and International Studies (CSIS), analyzed satellite imagery and determined China was responsible for 65% of the 8,000 acres of damaged reef.
The artificial island-building activities “cause irreparable and long-term changes to the overall structure and health of the reef,” the report said.
AMTI researchers analyzed coral reef destruction caused by South China Sea claimants — also including Malaysia, the Philippines, Taiwan and Vietnam — and determined Beijing to be the primary culprit. China arbitrarily claims almost the entire strategic waterway as its territory and disregards an international tribunal’s 2016 ruling invalidating the claim.
In the December 2023 report “Deep Blue Scars: Environmental Threats to the South China Sea,” AMTI described China’s dredging method: “Its cutter suction dredgers would slice into the reef and pump sediment through floating pipelines to shallow areas to deposit it as landfill. This process disturbed the seafloor, creating clouds of abrasive sediment that killed nearby marine life and overwhelmed the coral reef’s capacity to repair itself.”
Additionally, Chinese vessels harvesting giant clams damaged 16,353 acres (66 square kilometers) of coral reef. The clam shells are carved and sold as jewelry or statues in China. Chinese fishermen use an extremely harmful method of “dragging specially made brass propellers” to dig up reef surfaces “to more easily harvest both live and dead clams attached to the reef,” the report stated.
The most recent report came as the Philippines said it was considering a new arbitration case against China for continued violations of the United Nations Convention on the Law of the Sea (UNCLOS). Manila, which initiated the case that led to the tribunal ruling against China, said it hoped other nations would join what could become a multilateral proceeding.
The 2016 ruling found that China, through its artificial-island building at seven reefs, breached six tenets of UNCLOS, including obligations to protect and preserve the marine environment; reduce and control pollution; and work cooperatively to coordinate management of the sea’s living resources.
A new case against China under UNCLOS arbitration procedures could include similar environmental claims. The Philippines previously called for an international inquiry into environmental damage at a South China Sea shoal caused by giant clam harvesting.
The Philippines also could seek a U.N. nonbinding resolution and forward it to the International Court of Justice for an advisory opinion, AMTI Director Gregory B. Poling wrote for CSIS.
During the U.N. General Assembly in September 2024, “the Philippines gathered senior officials from more than 20 countries ‘to give a signal to China’ that Manila is not isolated on the South China Sea disputes,” Poling wrote. “Such legal and diplomatic options are mutually reinforcing. In fact, making greater use of the United Nations would expand Philippine options for arbitration.”
