The water running through coastal Sentosa South Cove has turned pinkish-purple since Tuesday afternoon, January 12, 2021, alarming residents.
Warning signs emerged on Jan. 5th when a foul, sulfurous, sewage-like smell came from the waterway. The odor became stronger over the next few days and dead fish started appearing near the banks from Wednesday last week to Sunday.
The waterways were combed on Monday morning and no dead fish were found, and the foul smell had also cleared up. But when residents thought the worst was over, the waters turned pinkish-purple on Tuesday.
“As a precautionary measure, SCRM has advised residents to refrain from water sport activities in the waterway. SCRM will continue to monitor the waters,” said the spokesman.
A biologist said the coloured water was caused by a pico-cyanobacteria bloom – a form of algae bloom, which is due to the heavy and persistent rain over the past couple of weeks.
Algae blooms can remove dissolved oxygen from the water, harming marine life. But it is unclear if the fish deaths and the strange purple water are linked. Oxygen deprivation? Toxins produced by algae blooms? High concentrations of algae species?
Officials say there is no indication of any industrial or marine pollution that could have affected the waters in the surrounding area.