do you want to swim in that?

Manila Bay's unfiltered sea water*

I certainly don't.

Some residents along the coastal area, however, do not mind the quality of the water as much as I do. They try to relieve themselves from the sweltering summer heat by taking a dive into the murky waters amid the floating debris. I just wish that before their next dive, they stop and consider that the water really is polluted and it is unhealthy to swim there.

Aside from fecal bacteria that are dumped from untreated wastewater, there are other microorganisms that make Manila Bay their home. A 2009 study by marine scientists entitled "Pollution Study in Manila Bay: Eutrophication and Its Impact on Plankton Community" associated human activity with the presence of chemical pollutants in the water. Manila Bay (at the time of the experiment) has a high concentration of nitrogenous and phosphorus-containing chemicals, with the highest levels being near the Pasig River. Microorganisms, such as phytoplankton and zooplankton, that eat these chemicals live in big populations in the bay because of the abundant food supply.

So what if these microscopic creatures live in abundance at the Manila Bay? The authors of the study highlighted that some of the species of plankton they found are associated with the recurring algal blooms in the area. One of the species with bigger populations, Noctiluca scintillans, is not toxic. However, harmful algal blooms (what we recognize as red tide), caused by other species of plankton, is the main reason why it is periodically unsafe to eat shellfish captured in the Manila Bay.

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* The photo was taken at the Manila Ocean Park. It is one of the exhibits in the Oceanarium. Seawater that is pumped into the animal enclosures have been filtered several times, according to the guide in the glass-bottom boat ride attraction.