Algae that causes memory loss discovered in Philippine waters

Scientists have discovered two species of microscopic algae that produce toxins that can cause memory loss in the waters of the Philippines .

According to ScienceAlert on November 17, a research team from Ateneo de Manila University (Philippines) and University of Malaysia Sawawak (Malaysia) collected seawater samples from Sotto's Tahong seafood farm in Bacoor Bay, which supplies mussels to the capital Manila and neighboring provinces, and Pagbilao Bay, which cultivates populations of Magallana bilineata oysters.

The team isolated 15 strains of Pseudo-nitzschia from the samples and cultured them in the lab. They found that two of these, Pseudo-nitzschia pungens and Pseudo-nitzschia brasiliana, were capable of producing domoic acid.

Seafood is displayed for sale at a market in Manila, Philippines - (Photo: AFP).

This is the first time that Pseudo-nitzschia brasiliana, a species widely distributed throughout the tropics, has been discovered on Luzon Island and was found in seawater samples from Pagbilao Bay. Of the millions of species of diatoms, only 28 species of the genus Pseudo-nitzschia are known to produce a neurotoxin called domoic acid .

Domoic acid can accumulate in shellfish, sardines, and anchovies because they feed primarily on marine algae such as diatoms.

It's rare for seafood containing this toxin to make it to our dinner tables. However, human activities are creating more frequent algal blooms , increasing the risk that seafood could accumulate domoic acid at levels that cause a number of worrying side effects, from vomiting and diarrhea to dementia and death.

In 1987, three people died and at least 100 were hospitalized in Prince Edward Island, Canada, due to mollusk poisoning, including seafood containing domoic acid, which causes permanent short-term memory loss. The disaster is believed to have originated from the green-lipped mussel Mytulis edulis.

The seafood industry has since closely monitored Pseudo-nitzschia blooms. However, the team says more research is needed in the Philippines, after finding amnesic diatoms in shellfish from aquaculture sites off the island of Luzon.

Prior to this study, two other studies examined the presence of Pseudo-nitzschia in the Philippines, one of which found domoic acid at four times the safe level in shellfish tissue in Masinloc Bay of Luzon Island.

Most recently, in May 2023, a bloom of various algae was detected near Pangasinan, Luzon Island.

The team hopes their findings could help seafood producers monitor harmful algal blooms in the future, and limit outbreaks of amnesia poisoning in shellfish.

The study was published in the journal Diatom Research .

The Philippines is known to be the 11th largest seafood producer in the world, contributing more than 4 million tons of seafood to the global market.