PHILIPPINES – Ever thought that your love for seafood could actually cost you your memory? On the densely populated island of Luzon, where shellfish is a staple for many, scientists have made a concerning discovery: two species of microscopic diatoms that produce a dangerous neurotoxin have been found in shellfish farms. These diatoms belong to the Pseudo-nitzschia family and produce domoic acid (DA), a toxin known to cause severe stomach issues and, in rare cases, memory loss—a condition known as amnesiac shellfish poisoning (ASP).
Diatoms in Luzon’s shellfish farms
Often described as “algae that live in glass houses,” diatoms are tiny organisms surrounded by milk-colored silica shells. While most of them are harmless, half of the 58 species from the genus Pseudo-nitzschia produce DA. Eating DA-infected shellfish could lead to symptoms like vomiting, nausea, and stomach cramps. In extreme cases, some people have lost short-term memory due to ASP.
Uncovering toxic diatoms in Luzon
A group of scientists from Ateneo de Manila University and Universiti Malaysia Sarawak took on a study to understand the extent of Pseudo-nitzschia’s spread in the Philippines. They gathered water samples from shellfish farms in Bacoor Bay and Pagbilao Bay, aiming to analyze both the physical and genetic traits of these diatoms. Their findings were clear: they confirmed the presence of two DA-producing diatoms, Pseudo-nitzschia pungens and Pseudo-nitzschia brasiliana—the latter being spotted in Luzon for the first time.
Red tide and the dangers of HABs
During harmful algal blooms (HABs) or “red tide” events, DA can build up in filter-feeding shellfish like mussels and clams. This can make these shellfish highly toxic. Monitoring and identifying DA-producing diatoms, especially from the genus Pseudo-nitzschia, is crucial for food safety in the Philippines, the scientists emphasized.
FAQs
What are diatoms?
Diatoms are microscopic algae with silica shells, commonly found in marine and freshwater environments.
Why are some diatoms dangerous?
Some diatoms produce domoic acid (DA), a neurotoxin that can cause severe symptoms if ingested through shellfish.
What health risks does domoic acid pose?
Consuming DA-infected shellfish can lead to vomiting, nausea, diarrhea, and in rare cases, amnesiac shellfish poisoning, causing memory loss.
Where in Luzon were these diatoms found?
The DA-producing diatoms were found in shellfish farms in Bacoor Bay and Pagbilao Bay, Luzon.
Is this the first discovery of such diatoms in the Philippines?
Yes, this is the first documented presence of the Pseudo-nitzschia brasiliana species in Luzon, adding to the concern.
