A Survey Report on the Coral Reef Ecosystem of Tiexian Jiao and Niu’e Jiao was released on 25th April, 2025, which is co-authored by South China Sea Development Research Institute of the Ministry of Natural Resources, South China Sea Ecological Center, South China Sea Survey Center, Nansha Islands Coral Reef Ecosystem National Observation and Research Station, Technology Innovation Center for South China Sea Remote Sensing, Surveying and Mapping Collaborative Application. For the first time, based on satellite remote sensing and field survey, a comprehensive and systematic assessment of the status of coral reef ecosystems of Tiexian Jiao and Niu’e Jiao was conducted, the development and formation process of cays at Tiexian Jiao and Niu’e Jiao, as well as the key reason for the serere degradation of coral reef ecosystem of Tiexian Jiao was scientifically and accurately analyzed.

The report reveals that the coral reef ecosystem of Tiexian Jiao has degraded severely. Firstly, From 2016 to 2024, the reef-building coral coverage area at the atoll reef platform where Tiexian Jiao is located has declined continuously. Compared with 2016, the reef-building coral coverage area decreased by about 68.9% in 2024. Secondly, the average reef-building coral coverage is at an extremely low level at Tiexian Jiao, with a small variety of reef-building corals which are mostly massive corals dominantly prevailed by Porites lutea. Dead corals and broken coral branches were found at all stations, sporadic corals have bleached due to the water temperature increasing seasonally. Benthic macro-invertebrates, like gastropods and crustaceans which are usually widely distributed in coral reef ecosystems, are rarely seen at any survey station. Thirdly, Philippine and other foreign fishing vessels were found carrying out illegal fishing operations in waters around Tiexian Jiao without China’s permission. Moreover, illegal construction activities by the Philippines were detected on China’s Zhongye Dao. Meanwhile, anthropogenic disposals such as fishing wires, fishing nets, plastic packages, iron barrels, and glass bottles were detected at certain survey stations of Tiexian Jiao. Some disposals are labeled in the Filipino language or bear Philippine markings.

The report shows that the coral reef ecosystem of Niu’e Jiao is in a healthy state. The average reef-building coral coverage of Niu’e Jiao is quite high with an average value 37.7%. There are 172 reef-building coral species belong to 46 genera and 14 families found at Niu’e Jiao, accounting for 46.6% of all reef-building coral species recorded in Nansha Qundao. The dominant species of corals are mostly branching corals. Niu’e Jiao is home to a rich variety of coral reef fishes. Benthic macro-invertebrates, like bivalves, gastropods and crustaceans, are found in large quantities at Niu’e Jiao survey stations, and giant clams are found at 75.0% of the stations. Mobula alfredi, listed on the IUCN Red List of threatened species, was found at Niu’e Jiao where the reef habitat is of good quality. However, seasonal, sporadic heat-induced coral bleaching and human activities still create some stressful influence. Coral bleaching exist at all survey stations on Niu’e Jiao, especially patches of corals in the reef flat area outcrop at low tide with local bleaching. Moreover, fishing vessels were found anchoring in waters around Niu’e Jiao, and anthropogenic disposals such as fishing wires, fishing nets were detected at certain survey stations. From 2016 to 2024, the reef-building coral coverage area at Niu’e Jiao reef platform displays an overall tendency of slow reduction.

The report shows that Tiexian Jiao currently has three cays and Niu’e Jiao has one cay. All the four cays are naturally formed and above water at high tide. The highest points of the four cays are about 1.34m, 1.14m, 1.10m and 1.47m above the local mean high water springs, respectively. Groups of Thalasseus bergii, a national second-class protected wildlife, are found on the cays of both Tiexian Jiao and Niu’e Jiao. Sediments from Tiexian Jiao and Niu’e Jiao are separately highly homologous with no land-based substances found. The four cays display apparent natural characteristics, their position and form indicate regular changes, and there are sufficient materials fostering their growth and formation. Therefore, the formation of the four cays is a normal physical geographic phenomenon. 

The report reveals that the false remarks by the Philippines that China dumped coral debris at Tiexian Jiao, and the rumors spread by relevant countries that the formation of the cays is due to China’s “Sea reclamation”, are without any scientific or factual basis.

The report indicates that the coral reef ecosystem of Tiexian Jiao has degraded severely, for which the outbreak of crown-of-thorns starfishes is a primary reason, followed by tropical cyclone strike and frequent human activities, especially the Philippines’ persistent and illegal construction on Zhongye Dao. As the sea surface temperature continues to rise under the background of global climate change, the reefs in Nansha Qundao, including Tiexian Jiao and Niu’e Jiao, are exposed to the risk of large-scale coral bleaching. Next, efforts will be made to further intensify the survey, research, evaluation and protection for Tiexian Jiao, Niu’e Jiao, and their adjacent waters. Studies must be deepened on the early warning, prevention and control of outbreaks of crown-of-thorns starfishes, and the negative effects exerted by human activities and other external factors should be minimized to improve the diversity, stability and sustainability of the coral reef ecosystems of Tiexian Jiao and Niu’e Jiao.