Cape Town - The cause of a red-brown discolouration of the water in the Knysna estuary will be determined through analysis of water samples, the Garden Route National Park said on Tuesday.

“Reddish-brown currents were identified in the Knysna estuary at Leisure Isle, Lake Pleasant (Sedgefield), Lake Brenton, and at the Heads over the weekend,” spokeswoman Nandi Mgwadlamba said in a statement.

She said marine and aquatic scientist retired professor Brian Allanson believed the change in water colour could be attributed either to decreased salinity or red tide.

Allanson said: “Salinity is the saltiness of dissolved content of a body of water. It is an important determining factor of numerous aspects of the chemistry of natural waters and biological processes within it.”

Recent warm weather could also have caused a red tide. This was the common name for an algal bloom involving large concentrations of red or brown-coloured micro organisms.

These micro organisms could become concentrated in filter feeders, such as mussels and oysters, making them poisonous to humans.

Knysna marine rangers collected samples from various points in the estuary and these would be analysed to determine the cause of the water discolouration. - Sapa