Abstract:

Global coral reefs are undergoing continuous degradation, and it is universally acknowledged that alleviating local pressures stemming from regional coral reef degradation is crucial to counteracting the substantial impacts of escalating global stressors. The coral reefs of the Xisha Islands in the South China Sea, a vital component of the “Coral Triangle”, have exhibited varying degrees of degradation in recent years, as revealed by ecological monitoring. Analyzing coral reef degradation through relevant ecological indicators is vital for understanding coral reef trends and supporting restoration and management efforts. This paper, drawing upon existing surveys of Yongxing Island in the Xisha Islands, examines relevant ecological indicators such as coral coverage, replenishment, and bleaching rates. The results indicate that over the past 40 years, the scleractinian corals of Yongxing Island have undergone a phased pattern of degradation: healthy growth (1984-2006), rapid degradation (2006-2011), slow recovery (2011-2019), and renewed degradation (2019-2021). This trend follows a general pattern of “healthy growth→sharp degradation→slow recovery→renewed degradation”. The crown-of-thorns starfish emerges as the primary driver of rapid degradation, with coral diseases also playing a role during this stage. Human activities hindered the swift recovery of corals following the initial rapid degradation to a certain extent, while coral bleaching was the primary factor governing both slow recovery and later-stage renewed degradation. In comparison to the swift recovery of scleractinian corals in the Great Barrier Reef following its rapid degradation, the scleractinian corals of Yongxing Island have experienced more severe degradation, with a lower recovery rate over the past decade.

Key words: Yongxing Island, scleractinian coral, dynamic changes, degradation, controlling factor