Hong Kong's "Red Tide" spreads

The huge blooms of algae affecting the waters around Hong Kong have spread to a Stanley beach on the south of the island. The government warned people not to swim off Stanley Beach after the red tide was spotted there.

The latest sighting takes the number of affected beaches to 15, and local media said the latest outbreak was the biggest since 1998, when 90 percent of the city's farmed fish were wiped out.

Red tides are caused by the rapid multiplication of microscopic algae which discolour the water. Authorities said the latest outbreak was caused by a rare but non-toxic form of algae. Although the algae are not poisonous but they can deprive fish of oxygen.

Could the sudden lack of oxygen in the serangoon river that killed those fishes the doing of this microscopic algae?