Dr. Danilo B. Largo, research director and Biology professor at the University of San Carlos Cebu, during the NRCP Visayas Regional Cluster plenary scientific session.

Results of the latest research that examined the quality of marine waters of Boracay and Mactan Islands claim that the minimum concentrations of hazardous pollutants allowed in the existing Water Quality Guidelines and Effluent Standards could still be high.

“The new Water Quality Guidelines which set the limits for nitrate, ammonia and phosphate for Class SB marine waters need to be urgently reviewed,“ said Dr. Danilo B. Largo, director for Research and professor of Biology of the University of San Carlos, Cebu City, during the plenary scientific session of the National Research Council of the Philippines (NRCP) Visayas Regional Cluster Scientific Conference on 29 May 2018 at the University of the Philippines Visayas Tacloban College in Tacloban City.

Largo revealed that water samples from Boracay and Cebu after having been examined were found to have high levels of nitrogen (nitrate, ammonia) and phosphorus (phosphate), which are beyond the limits set by the Water Quality Standards in this country. The limits set by the government for nitrate is at 10 mg per liter and 0.5 mg per liter for both ammonia and phosphate. “An even more striking finding is that even below these levels, lab experiments showed that nutrients in marine waters can still trigger green algae blooms. This suggests that the allowed limits should be lowered,” Largo pointed out. 

Nitrate, ammonia and phosphate are nutrients that enter our water bodies and which when form in excessive amounts can pollute and imbalance the ecosystem of lakes, streams, and marine waters. Common sources of these excess compounds include septic systems, commercial animal feeds, agricultural fertilizers, untreated industrial and household waste waters, and garbage dumps.

 Green algal blooms in Boracay documented in 2015. Photo Souce: Danilo Largo

Dr. Largo said that these same nutrients are blamed for the growth and proliferation of the green algae called Ulva that spoiled the Boracay’s beautiful beaches. It may be recalled that President Rodrigo Duterte has approved a 6-month shutdown of the popular tourist destination starting April 26, 2018 as part of the island rehabilitation and massive cleanup program.   

While occurring almost naturally and with a growth peak during summer season, the growth and persistence of this green algae is made worse by eutrophication, added Largo.

Eutrophication is a condition in which water bodies experience increased load of nutrients that cause algal blooms, low-oxygen waters, structural damage in lake and in many cases, fish kills.

Dr. Largo recounted that his research team first assessed Boracay’s water quality in 2002 when green algal blooms was first documented. The research team that inspected the island noted discharge pipes installed in Boracay Station 2 discharging effluents directly into the sea. Also, they found septic tanks constructed close to the beach and an open dumpsite situated on top of Mt. Luho in the eastern part of the island. The problem of green algal blooms in Boracay continues to persist up to this year, Largo added.

The western coast of Boracay is more likely to continue experiencing “green tides” if sewage high in inorganic nutrients disposed directly into the sea will not be regulated, thus a review of the existing water quality parameters is needed Largo stressed.

Largo said that same scenario has been observed in the Mactan Channel, a now considered “sink hole” of metro Cebu’s rivers, wherein green tide events are also rampant because of untreated waste waters that go directly into the sea.

Largo recommended installing sewage treatment facilities at the community level because households are the major source of untreated wastewaters that leach out into the sea. He added that water quality parameters should be gauged according to the levels below the detrimental thresholds of the marine ecosystem.

Dr. Largo’s research is one of the four papers discussed during this NRCP regional conference that cohesively call for strengthening state policies and crafting new legislations that are based on empirical or scientific evidences.