The joint Swire Institute of Marine Science, Hong Kong, and Natural History Museum, London, Hong Kong Submarine Caves Expedition, 2002: discussion, conclusions and recommendations for conservation

Abstract

Some two hundred taxa have been recorded from Hong Kong's submarine caves. Of these, at least eleven are new to science. The majority of species occurring on the walls and roofs in particular, however, are not cave endemics and have been recorded from other habitats in Hong Kong and elsewhere. Unlike the Tethyan karsted limestone caves of Japan and the Philippines in the Asian region, and elsewhere, Hong Kong's cave fauna is similar to other local sea bed habitats at similar depths, probably because of their modernity. Although the sediments that make up the cave's floors appear more stable (in terms of their faunistic composition), there is evidence that they are periodically infilled and flushed out. This may be either on a seasonal basis or following severe tropical storm and typhoon events. It is therefore likely that the infaunal taxa of the cave's floors are partly sustained by episodic colonization. Notwithstanding the lack of an identifiable endemicity, the caves act as refugia for a number of otherwise rare taxa, for example, the ahermatypic corals Balanophyllia eguchii and Tubastrea falkneri, and fishes gain protection within them from locally intense fishing activities. The caves also appear to contain epifaunal communities that are representative of earlier, undisturbed times and environmental conditions in Hong Kong. It is recommended that (i) the two caves on Conic Island and Steep Island be designated as Sites of Special Scientific Interest; (ii) that other caves be searched for and studied and (iii) more long‐term studies be made of their physical environments and the communities they support.