‘Red tides’ reported in Western Mindanao

ZAMBOANGA CITY, Philippines (Mindanao Examiner / Sept. 7, 2011) – Philippine authorities have banned the harvesting of shellfish on three provinces in western Mindanao because of the presence of algal blooms or so-called “red tide” toxins.

To the human eye, blooms can appear greenish, brown, and even reddish- orange depending upon the algal species, the aquatic ecosystem, and the concentration of the organisms.

The Bureau of Fisheries and Aquatic Resources (BFAR) said Dumaguillas Bay in Zamboanga del Sur and Murcielagos Bay in Zamboanga del Norte and Misamis Occidental have been tested positive for paralytic shellfish poison.

The agency said that Masinloc Bay in Zambales, and Matarinao Bay in Eastern Samar are also positive for paralytic shellfish poison.

“All types of shellfish and Acetes sp. (krill) gathered from the three areas are not safe for human consumption. Fish, squids, shrimps, and crabs are safe for human consumption provided that they are fresh and washed thoroughly, and internal organs such as gills and intestines are removed before cooking,” said BFAR Director Asis Perez said in a bulletin issued on Tuesday.

Last month, the BFAR also banned the gathering of shellfish in those areas after water samples were tested positive for red tide toxins.

Red Tide is caused by naturally occurring microscopic plankton. “Blooms” of the poison-producing plankton are coastal phenomena caused by environmental conditions - warm surface temperatures, high nutrient content, low salinity, and calm seas - promote explosive growth.

Eating toxic shellfish can cause paralytic shellfish poisoning in humans. After ingestion, this poison immediately affects the nervous system, with symptoms usually occurring within 30 minutes.

Initial reactions are tingling of the lips and tongue, which spreads to the face, neck, fingertips and toes. Headache, dizziness and nausea follow. And in severe cases, muscular paralysis and respiratory difficulty may occur within 5 to 12 hours.

Cooking does not destroy the red tide toxin and testing is the only way to determine if shellfish contain unsafe levels of toxin. (Mindanao Examiner)