Extensive mortality of black corals Antipathes curvata along a depth gradient in Hong Kong, China

Abstract

Black corals (Antipatharia) generally occur in deep water, but in some tropical and subtropical areas, they can also be found in much shallower water. In Hong Kong, antipatharian corals can be observed starting at 4 m depth in its northeastern waters, including the semi-enclosed Tolo Harbour (22°27’50”N, 114°17’27”E). In September 2012, a clear pattern of mortality of the black coral Antipathes curvata van Pesch, 1914 was noticed along a depth gradient in this harbour. Black corals shallower than 4.8 m mean tide remained healthy (Fig. 1a), whereas those found from 4.8 to 6 m depth showed partial