Why Hong Kong's remarkably diverse marine ecosystem is in peril

People who have lived in Hong Kong for some time know it is full of surprises. For conservationists currently marking the city's inaugural Ocean Appreciation Month, the occasion for a stocktake shows how special our surrounding marine environment is. But these qualities are a cause for concern as much as celebration, and may hold salutary lessons for the world.

Keen divers often rave about the kaleidoscope of marine life seen around reefs in Southeast Asia or the Maldives. Yet the species per unit area in Hong Kong waters is "at least a hundred times higher than many other regions in the world", according to a joint report by the Swire Institute of Marine Science (Swims) and the University of Hong Kong's School of Biological Sciences.

Titled "A review of marine biodiversity and ecological surveys in Hong Kong", the 2014 study found that our seas are home to more than 5,600 species of marine life.

In fact, although Hong Kong waters cover about 1,600 sq km, they boast 84 species of hard coral - more than all of the Caribbean, which covers an expanse of 2.75 million sq km, says David Baker, a coral expert and an assistant professor at the university.

Several factors account for this wealth of species, mainly related to Hong Kong's position.