The Sentosa South Cove waterway turned pinkish-purple on Jan 12, alarming residents.
Warning signs first emerged on Jan 5 in the form of a foul smell. Then dead fish like rabbitfish, moonyfish and batfish were found from Jan 6 to Jan 9.
A RESIDENT OF SEASCAPE CONDO AT SENTOSA COVE
By Jan 11, residents were told dead fish were no longer found, and the foul smell went away. But the waters turned pinkish-purple the next day.
MR DAN PARIS, RESIDENT OF SOUTH COVE’S TURQUOISE CONDO
Experts say the coloured water was caused by a form of algae bloom. It’s caused when a big amount of algae or cyanobacteria accumulates, resulting from high amounts of nutrients such as phosphorus and nitrogen.
The heavy rain over the past weeks may have contributed to the bloom. Rain washes off nutrients from land into the water bodies, which helps algae multiply faster.
Algae blooms can remove dissolved oxygen from the water, harming marine life. Investigations into the fish die-off found it may be caused by altered conditions due to heavy rain.
Places in Singapore which have seen algae blooms include Marina Bay. In 2020, this was spotted in the waters near Customs House.
The Marina Bay waters turned emerald green in 2015 too. Elsewhere in Singapore that year, a bloom wiped out more than 500 tonnes of fish stocks, causing farmers to lose millions of dollars.
Over at the Singapore River, an algae bloom turned parts of it emerald green in 2017.
An expert said algae blooms will keep on happening until the underlying causes behind nutrients getting into the water are corrected.
PRODUCED BY: DENISE CHONG