Hong Kong hit by 10 red tides as heavy rain lashes city over past week

Ten red tides have been spotted in Hong Kong over the past week amid persistent heavy rain, with five remaining at Repulse Bay, Stanley Bay and other beaches.

Just two red tides were spotted the week before. Among coastal areas hit by the natural phenomenon this week were Silverstrand Beach, South Bay Beach, Turtle Cove Beach, Shek O Beach, Repulse Bay Beach and Deep Water Bay Beach, Stanley Bay and Repulse Bay, the interdepartmental Red Tide Working Group said on Friday.

“The above red tides were formed by Noctiluca scintillans, which is commonly found in Hong Kong waters and is non-toxic,” a working group spokesman said, adding no associated fish deaths had been reported so far.

Red tides are areas of seawater discoloured by large concentrations of microorganisms that may deplete levels of dissolved oxygen. Sightings of the natural phenomenon – which can be brown, pink or red in colour – usually peak in the spring.

Rising temperatures or rainy weather could facilitate the growth of red tides, experts said.

The working group said red tides remained at South Bay Beach, Repulse Bay Beach, Stanley Bay, Repulse Bay and Clear Water Bay to Joss House Bay, while the others had dissipated.

The Agriculture, Fisheries and Conservation Department urged workers at fish culture zones affected by the red tides, such as those at Tai Tau Chau, Po Toi O and Tung Lung Chau, to monitor the situation closely and increase aeration where necessary.