Toxic red tide spreads across Cape peninsula

There is now a toxic red tide stretching from Blouberg to Kommetjie and the authorities have warned the public not to eat shellfish collected from this area.

The red tide, an algal bloom, contains dense concentrations of toxic organisms which can cause paralysis if eaten. Filter-feeding shellfish, like mussels and oysters, consume the organisms and so become poisonous themselves if they are eaten.

Cases of severe poisoning can be fatal.

Grant Pitcher, a red tide expert from Marine and Coastal Management, said on Wednesday they had not had any recent reports of people being poisoned from eating shellfish.

Last month at least four people were treated in hospital for paralytic shellfish poisoning after eating shellfish collected during the red tide on the West Coast.

"The warnings to the public about paralytic shellfish poisoning still apply and have done so since March. The municipalities and marine inspectors are all well informed about the toxic red tide, which is probably why there have been no more incidents of poisoning," Pitcher said.

He said the toxic red tide seemed to have moved south of Cape Columbine.

"At the weekend satellite images showed it very well, with high concentrations in Table Bay. It has broken up a bit with the wind, and has lost a bit of colour. It is a dark red to maroon-brown," said Pitcher.

Typical symptoms of paralytic shellfish poisoning include tingling and numbness of the mouth, lips and fingers, difficulty in breathing, accompanied by general muscular weakness and lack of coordination. In severe cases it can cause paralysis and death.