Urban coral communities and water quality parameters along the coasts of Guangdong Province, China.

Coral communities in China's Great Bay Area (GBA) have experienced severe degradation, but only limited information is available about their community structure. We surveyed 20 sites across three regions (Daya Bay, Dapeng Bay, Wanshan Islands) in GBA to provide an updated baseline of these urban coral communities. Live coral cover varied substantially, with the lowest values (<2 %) found inside the highly urbanized Daya Bay, and highest values (40-47 %) from offshore islands that are less affected by human activities. The two sites with the lowest live coral cover had a high percentage of dead coral. Five groups of coral communities could be identified, with most of them characterized by dominance of massive and encrusting coral species. Both coral cover and generic richness were negatively correlated with dissolved inorganic nitrogen in the water column, indicating that nutrient pollution could potentially constrain the development of these urban coral communities.