The Distribution, Diversity, and Indicator Species of Coral Communities Under the Influence of Environmental Changes in the Subtropical Peninsula of Southern China

Coral reefs are among the most biodiverse and economically important marine ecosystems worldwide. Recently, these ecosystems have faced threats and degradation from multiple factors. In particular, coral species living at the edges of subtropical zones are important “barometers” for indicating the global boundaries of coral communities. From 2023 to 2024, we investigated the coral species composition and coverage surrounding the Dapeng Peninsula, which is located at the northern edge of the subtropical zone, and explored the influence of environmental factors on the coral community structure. Fifty-one species belonging to 20 genera and 13 families were identified in five habitats (conservation, wind-wave, tourist, fishery, and pristine areas) across three seasons. Owing to rapid urbanization and global warming, the dominant coral species shifted from branching types, which are essential reef-builders for creating structural substrates, to clumping types, which are more adaptable to environmental pressures. Notably, compared with the first report four decades ago, our current results demonstrated that coral coverage around the Dapeng Peninsula declined at an approximate rate of 0.54% per year from 1983 to 2023. Redundancy correspondence analysis revealed that substrate type, especially rock and dead coral skeletons, nitrogen and phosphorus levels, suspended particulate matter, chemical oxygen demand, and water transparency were key environmental factors that significantly (p < 0.05) influenced the distribution of coral species. The lowest diversity of coral communities was recorded in fishery and wind-wave areas, where intense human disturbance and harsh natural environments limit the survival of sensitive coral species. In contrast, owing to stable hydrological conditions, shallow sunlit water, and diverse substrate types, coral biodiversity was the highest in the pristine habitat. Accordingly, the coral indicator species varied from Pavona decussata in the conservation area to Platygyra carnosus in the wind-wave area, to Montipora peltiformis and Leptastrea purpurea in the tourist area, to Turbinaria peltata, Porites deformi, Goniopora columna, and Goniopora lobata in the pristine area, while no indicator species were found in the fishery area. The distribution and coverage of these indicator species can effectively reflect the extent of human disturbance to local habitats. In the future, it will be important to conduct real-time monitoring of coral community characteristics around the Dapeng Peninsula to determine environmental changes in subtropical marine zones, providing insights into the response of global coral communities to anthropogenic disturbances and climate change.