Condition of coral communities in Victoria Harbour, Hong Kong as determined by mapping seascape metrics.

Victoria Harbour, located at the centre of densely populated Hong Kong, has historically suffered from significant marine pollution. In response, the Harbour Area Treatment Scheme was fully implemented by the end of 2015, effectively treating over 2 million tonnes of sewage daily from two sides of the harbour and substantially improving water quality. This study investigated coral communities in seven sites along the natural coastline and five sites along the artificial breakwater in Victoria Harbour. Five coral habitats were identified along the natural coastlines, with areas ranging from 2.02 to 10.42 ha, and recorded a total of 35 coral species, including 4 black coral species, 16 stony coral species, and 15 octocoral species. Using seascape metrics, we also assessed habitat and ecological conditions across sites. This first comprehensive underwater survey of benthic ecosystems in Victoria Harbour provides a baseline for long-term monitoring of future coral recovery.