Limited resilience of relatively high-latitude coral reefs: Structural complexity degradation under climate change and anthropogenic impacts

Structural complexity is a critical factor in maintaining the key ecosystem services of coral reefs, such as fisheries, biodiversity, coastal protection, and ecotourism. However, the resilience of coral reefs to climate change and anthropogenic disturbances remains poorly understood owing to a lack of long-term data. This study used data from field surveys at Weizhou Island in the northern South China Sea, conducted from 2019 to 2024, to record the response trajectories of the coral community and structural complexity, and to estimate the key drivers in a relatively high-latitude coral reef. Following a bleaching event in 2020 and disturbance by two cyclones in 2023, live coral cover (LCC) initially declined but later recovered, suggesting a gain in thermal tolerance. Corals in the marine protected area (MPA) were less impacted than those in the non-protected area. However, the structural complexity decreased continuously, from 1.200 to 1.076, signifying simplification in coral morphological composition. Despite the decline in structural complexity, a significant positive correlation with fish density was observed in the MPA (R2=0.91, p​