Scientists Discover Two Tiny Marine Algae Species Producing Neurotoxin Linked to Memory Loss in Philippine Waters.
According to ScienceAlert on November 17, a research team from Ateneo de Manila University (Philippines) and Universiti Malaysia Sarawak (Malaysia) collected seawater samples from Sotto’s Tahong seafood farm in Bacoor Bay, which supplies mussels to the capital Manila and nearby provinces, as well as from Pagbilao Bay, known for its populations of Magallana bilineata oysters.
The team isolated 15 strains of Pseudo-nitzschia from the samples and cultured them in the laboratory. They discovered that among these, two species, Pseudo-nitzschia pungens and Pseudo-nitzschia brasiliana, have the ability to produce domoic acid.
Seafood sold at a market in Manila, Philippines – (Photo: AFP).
This is the first time Pseudo-nitzschia brasiliana, a species widely distributed throughout the tropics, has been found on Luzon Island and in seawater samples from Pagbilao Bay. Among millions of diatom species, only 28 species of the genus Pseudo-nitzschia are known to be capable of producing the neurotoxin known as domoic acid.
Domoic acid can accumulate in shellfish, sardines, and anchovies as they primarily feed on marine algae like diatoms.
It is rare for seafood containing this toxin to appear on our dining tables. However, human activities are causing algal blooms to occur more frequently, increasing the risk that seafood may accumulate domoic acid at levels that can lead to concerning side effects, from vomiting and diarrhea to memory loss and even death.
In 1987, three people died and at least 100 were hospitalized on Prince Edward Island (Canada) due to shellfish poisoning, including seafood containing domoic acid that caused permanent short-term memory loss. This disaster was believed to have originated from blue mussels (Mytulis edulis).
Since then, the seafood industry has closely monitored the blooms of Pseudo-nitzschia. However, the research team believes that more studies are needed in the Philippines after discovering memory loss-inducing diatoms in shellfish from offshore aquaculture areas around Luzon Island.
Prior to this study, two other studies investigated the presence of Pseudo-nitzschia in the Philippines, one of which found that domoic acid levels were four times higher than the safety threshold in shellfish tissue from Masinloc Bay on Luzon Island.
Most recently, in May 2023, a bloom of various algae was detected near Pangasinan on Luzon Island.
The research team hopes their findings can help seafood producers monitor harmful algal blooms in the future and mitigate outbreaks of memory loss poisoning in shellfish.
The study was published in the journal Diatom Research.
It is known that the Philippines is the 11th largest seafood producer in the world, contributing over 4 million tons of seafood to the global market.
