Laguna de Bay’s algal bloom

RECENTLY, the country’s largest lake Laguna de Bay opened out in news broadcasts and newspapers because of the reported algal bloom, a high-speed increase in algae density in the 2.8-meter deep lagoon.

Algal blooms are natural phenomena, but their frequency, duration and intensity are increased by nutrient pollution.

Good thing the Muntinlupa City Health Office was quick on the draw and assured lakeshore residents the algal bloom in the 900-square-km Laguna de Bay does not pose a threat to public health.

Experts have said exposure to high levels of blue-green algae and their toxins can cause diarrhea, nausea or vomiting; skin, eye or throat irritation; and allergic reactions or breathing difficulties.

Drinking algae-affected water or consuming food (such as fish or shellfish) containing toxins can lead to gastroenteritis, which can induce vomiting, diarrhea, fevers and headaches.

These toxins may also affect the liver or nervous system, according to experts.

Concerns associated with blue-green algae include discolored water, reduced light penetration, taste and odor problems, dissolved oxygen depletions during dieoff and toxin production.

Government data showed about 60 percent of the estimated 8.4 million people residing in the Laguna de Bay Region discharge their solid and liquid wastes indirectly to the lake through its tributaries.

Shaped like a crow’s foot, with two peninsulas jutting out from the northern shore and filling the large volcanic Laguna Caldera, it drains its water to Manila Bay via the Pasig River.

Environmental concerns like water quality problems created by population pressure and industrialization, invasive species and over-fishing are round the lake, hurting its economic importance to the country.

As population expands in the Bay, it’s expected to rely more heavily on the lake for freshwater supply, thus water quality directly affects human populations.

The latest algal bloom suggests authorities should rethink development plans to protect water quality and fish stocks for Metro Manila’s 16 million people.

It also supports agriculture, industry and hydro-power generation, and is a welcome getaway for rest and recreation for many Filipinos.

Time was when the lake’s importance was placed in peril from problems, including pollution from untreated sewage and industrial waste, over-fishing and the sedimentation and illegal reclamation eroding its capacity.

In recent years the Laguna Lake Development Authority gave the lake an overall ranking of “C-” for water quality and “F” for fisheries (on a scale of A-F, with F being the worst).

Environmental threats have also sparked repeated attempts to clean up the lake and ease the pressure on its overstretched ecosystem so it continues to deliver its benefits to a growing human population.

And now the algal bloom.

The latest algal bloom suggests authorities should rethink development plans to protect water quality and fish stocks for Metro Manila’s 16 million people