The DOST-PCAMRD and the UP-MSI study on mitigating harmful algal blooms (HABs) shows that HAB—commonly known as red tide—which is suspended on the water surface can easily be bound together by a ball of clay which then sinks to the sea bottom.
“Algal cells die when they stick to clay particles,” Dr. Rhodora Azanza, program leader of PhilHABs and co-project leader for the ball clay technology, said. “Clay minerals further entrail the algal cells as they settle at the sea floor.”
Azanza also said the clays are purely natural.
PhilHABs, a UP-led program supported by DOST-PCAMRD, is the country’s HABs Research and Development Program, which contributes to the improvement of the prediction and management of HABs occurrence through the determination of its ecological and oceanographic conditions.
It monitors and manages the occurrence, movement, toxicity, and other environmental effects of algal blooms in different locations within the country.
In actual Pyrodinium bloom in Masinloc Bay, Zambales, earlier this year, the efficiency of ball clay application was tested. A prototype clay-dispersal unit mixed ball clay particles with seawater drawn from the area and formed the balls which were applied on algal bloom.
Mixing clay with seawater will improve the efficiency of ball clay to collide and eventually aggregate with algal cells, Azanza said.
Common algal blooms in the Philippines are attributed to Pyrodinium bahamense var. compressum, the organism that causes paralytic shellfish poisoning (PSP).
During the project’s initial phase, the researchers used 100 kilograms of clay soil from Camarines province for clay application in Zambales and Pangasinan. In the future, clay materials native to affected areas will be used.
Azanza’s team found that the cells of Pyrodinium at the surface and bottom of the sea were not present after clay application. The study also showed no negative effects on other marine organisms, such as green mussels and milkfish, among others.
The DOST-PCAMRD, through PhilHABs, has been working with the UP-MSI and the National Institute of Geological Sciences (NIGS), as well as DOST’s Philippine Nuclear Research Institute (PNRI), on different projects to mitigate the occurrence and proliferation of major algal blooms in the tropics.
The program has done intensive studies in 10 areas affected by HABs, namely: Manila Bay; Sorsogon Bay, Sorsogon; Bolinao and Anda, Pangasinan; Matarinao Bay, Eastern Samar; Cancabato Bay, Leyte; Murcielagos Bay, Zamboanga del Norte; Balete Bay, Davao Oriental; Pujada Bay, Davao Oriental; and Benoni Lagoon, Camiguin.
The program has enhanced community mitigating mechanisms in efforts like training and seminars on HABs facilitated by the UP-MSI, culturing of causative organisms for research and development, and PhilHABs emergency response, including ball-clay application on actual blooms.
In the Philippines some 540 outbreaks of harmful algal blooms have been reported since 1983. The most recent outbreaks were in Masinloc Bay, Zambales; Bolinao and Anda, Pangasinan; Murcielagos Bay in Zamboanga del Norte; and Dumanquillas Bay, Zamboanga del Sur.
The DOST-PCAMRD and UP-MSI will host the third National Harmful Algal Bloom Conference and East Asia HAB 7 International meeting in November 2011 in Tagbilaran City, Bohol. The conference will focus on recent developments on HAB research, monitoring, and management, and their implications to the national concerns on harmful algal blooms.
(Marilou Guieb and Ramon Lazaro)
