An eerie blue glow is lighting up the shores of a northern Hong Kong village, the stunning iridescence against the quiet nightscape making for a true photographers’ dream.
Over the last week, pictures have circulated on local Facebook photography groups showing the natural phenomenon. The shots were taken in Sam Mun Tsai, a fishing village in Tai Po’s Tolo Harbor.
But the idyllic sight is not quite what meets the eye. According to reports, the glow is caused by a single-celled organism called Noctiluca scintillans. Known more innocuously as “sea sparkle,” the algae bloom could be an indicator—and cause—of marine pollution.
Kenneth Leung, an environmental toxicology and chemistry professor at City University of Hong Kong, told Coconuts that algae blooms are formed when there is an excessive amount of nutrients, including ammonia and nitrate nitrogen, in the water. Because the Tolo Harbor is a nearly landlocked body of water, the nutrients can easily accumulate.
Leung warned that the microalgae could cause oxygen levels in the water to deplete. When the microalgae die, they sink to the bottom of the seabed, and bacteria will use dissolved oxygen to consume them. This results in reduced oxygen supply for other marine organisms, such as corals, which could be deadly.
“The consequence of harmful algae blooms can cause significant negative impacts to marine ecosystems,” Leung said. (Leung and his team have launched a project called “Oysters Save Our Seas” to introduce oysters, which are capable of consuming microalgae and thereby removing them, into Hong Kong waters with an aim of improving water quality and tackling algae bloom.)