Foul-smelling algae sickens dozens along Miagao coast

By Rjay Zuriaga Castor

At least 36 residents from three coastal barangays in Miagao, Iloilo, sought medical attention after exposure to a harmful algal bloom that emitted a pungent, irritating odor, prompting authorities to advise the public to avoid coastal waters and observe health precautions.

The affected residents came from Barangays Sapa, Mambatad, and Narat-an, where an unusual black, plant-like substance was reported along the shoreline on Monday night, June 22.

Iloilo Provincial Health Office (IPHO) chief Maria Socorro Colmenares-Quiñon said that, based on the rapid health assessment report of the Miagao Municipal Health Office (MHO), all affected individuals were treated on an outpatient basis and none required hospitalization.

“Thirty-six patients were seen at the outpatient department, and so far, none of them needed admission to a hospital. They were provided first aid by the MHO and brought to a medical post established by the MHO,” Colmenares-Quiñon said.

She said residents observed decaying black algal mats along portions of the coastline, accompanied by a strong smell described as chemical-like and similar to “pepper” and “burnt” material irritating the nose.

The affected individuals experienced mild to severe symptoms, including nasal and throat irritation, sneezing, a runny nose, headache, difficulty in breathing, chest tightness, and other respiratory complaints.

The College of Fisheries and Ocean Sciences of the University of the Philippines Visayas (UPV) identified the organism responsible for the bloom as Lyngbya majuscula, a filamentous cyanobacterium commonly found in shallow coastal waters.

UPV researchers said the bloom may have been triggered by a combination of nutrient runoff from recent rains, warm seawater temperatures, and favorable sunlight and water conditions that accelerated the organism’s growth.

Initial findings showed the organism formed dark olive-green to black mats along the shoreline.

The cyanobacterium also produces toxins that can cause various health effects.

One toxin, debromoaplysiatoxin, may cause skin irritation through contact with seawater and gastrointestinal problems if accidentally ingested.

Another toxin, lyngbyatoxin A, can trigger skin and eye irritation as well as breathing difficulties when airborne particles are inhaled.

Lyngbya majuscula blooms have been documented in tropical and subtropical coastal waters worldwide and are a recognized cause of skin and respiratory irritation in affected communities, with outbreaks often associated with nutrient pollution and warming seas.

In response, the local government advised residents, fishermen, beachgoers, and visitors to avoid all water activities in the affected coastal areas until further assessments are completed.

“Some algae blooms can release toxins or airborne irritants that may affect human health, particularly when sea spray carries these particles into the air,” the local government said in an advisory.

Authorities said the bloom could persist from several days to weeks, depending on weather conditions, water currents, and other environmental factors.

The local government advised the public to avoid areas with discolored water, foam, or dead fish, refrain from swimming or consuming seafood from affected areas, and seek medical attention if severe respiratory symptoms develop.

On Wednesday, June 24, the local government launched an intensive coastal cleanup operation in the affected barangays.

All volunteers were instructed to avoid direct skin contact with the algae and were required to wear proper personal protective equipment during the cleanup.