SA National Parks said tests done on water samples from the Indian Ocean where it meets the Knysna Estuary have confirmed the presence of Red Tide.
However, SanParks spokesperson, Nandi Ngwadlamba, said further tests are being conducted to determine if its a toxic red tide.
"There is a definite presence of dinoflagellates in the water which is a red tide. Ongoing testing is taking place in Knysna and in the Garden Route to determine if it's toxic or not," she said.
'We are conducting further water samples to determine its toxicity as it was not certain last year whether the red tide was in fact toxic or not' said Professor Allanson of the Knysna Basin Project.
SanParks said while tests are ongoing, it is "cautioning anglers not to collect shellfish from affected areas. Users of the coastal environment are advised not to eat any fish that wash up on the shore. SANParks has also put up signage to this effect close to all affected areas."
Ngwadlamba said experts have attributed the red tide to sea conditions that are currently optimal for such a bloom formation.
The Institute for Coastal and Marine Research at Nelson Mandela Metropolitan University said it teamed up with the SA Environmental Observation Network last week to take samples of several red tide blooms in Algoa Bay and St Francis Bay.
According to a posting on its website, the Institute confirmed that the harmful bloom had made a "return to our shores."
It saids sea conditions were currently optimal for bloom formation with high surface temperatures of above 22 degrees celcius, and cold nutrient-rich bottom water of below 12 degrees.
According to a Marine and Coastal Management Guideline from the Department of Environmental Affairs, a red tide is an algal bloom. Phytonplankton are 'microscopic, single-celled organisms that float in the sea.
"They are able to photosynthesize and form the basis of food chains in the oceans. There are three types of red tide organisms, dinoflagellates, diatoms and ciliates."
"Dinoflagellates usually lie dormant on the seabed until they are lifted to the surface during upwelling where the ideal conditions of temperature and light trigger their germination."
