Zonation of a cold-water coral garden on the northern continental slope of the South China sea

Cold-water coral (CWC) ecosystems are receiving ever-increasing attention. Here, the distribution of CWC on a single seamount off the northern continental shelf of the South China Sea (SCS) is investigated by combining video footage from manned submersible dives and high-resolution multibeam bathymetric data. An active CWC garden ecosystem, with an average density of 15.11 ± 2.25 individuals per 100 m², is identified on the seamount. Video footage analysis enabled the classification of CWC into 10 distinct families. The spatial distribution of the CWC on the seamount is significantly influenced by bottom current intensity and substrate type. At the summit of the seamount, dead coral skeletons covering a large area are found on mud substrates. The distribution pattern of the studied CWC garden reveals the important role of the seamount's elevated structure in sustaining benthic ecosystems under high sedimentation-rate conditions. The widespread occurrence of dead scleractinians further indicates the presence of significant environmental stressors that may threaten the long-term viability of the CWC garden, underscoring the need for continued ecological research and conservation efforts on the continental slopes of the South China Sea.