Philippine coral reefs - in hot water

Imagine taking a dip in a hot spring for 10 to 30 minutes — what a relaxing thought! But imagine being in a hot spring for several hours, or even days — that certainly would not be good for your health. That is the situation our coral reefs find themselves in. Since last May, the water temperature of the western Philippines (from Luzon to the Visayas, Palawan and Mindanao) has been 2 to 3°C above normal. The abnormally high water temperature is killing plenty of coral.

What is coral bleaching?

At first glance, coral simply looks like either a rock (if it is hard coral which has an outer skeleton made of limestone) or a plant (if it is soft coral which does not produce a limestone skeleton). But actually, coral is a colony of tiny animals called coral polyps. Each coral polyp can roughly be described as having a body (that looks like your wrist and hand pointing up) with tentacles (which look like your fingers) and a mouth (imagine a hole in the center of your palm). Living inside the body tissue of each coral polyp are microscopic plants (called “zooxanthellae”). These tiny algae produce nutrients for the polyp. The coral returns the favor by providing the algae with a place to live. Algae come in a rainbow of colors. It is the algae living inside the coral, which give color to the coral. 

When corals are severely stressed, these are forced to release the algae living in their tissues. This is a last ditch effort by the corals to save themselves. Without the algae, corals lose their color and turn white, hence the term “coral bleaching.”

For corals, “bleaching” means not just a change in their color, it also means they are already in a life-or-death situation. (Please note that when coral is newly bleached, it is not yet dead. If the source of stress is removed and if not too much time has passed, it may still be possible for the coral to recover.) 

Latest findings

In 1998, a significant bleaching killed over 90 percent of the corals in 19 percent of coral reefs worldwide. For the past few months, scientists from the University of the Philippines-Marine Science Institute (UP MSI) and De La Salle University’s Br. Alfred Shields Marine Station have gathered data indicating that a massive bleaching event may be unfolding in our seas. Dr. Perry Aliño of the UP MSI says that up to 75 percent of our corals may be severely affected. This is a worrisome scenario because we have so few healthy reefs left, according to Dr. Al Licuanan of the DLSU. His studies show that if major bleaching events occur every 10 years, then in 50 years, only 11 percent of our corals will remain. If major bleaching was to occur more often (i.e., every five years), only one percent of our corals will remain after 50 years. Recent analyses involving many local scientists show one third of all coral species worldwide now are more likely to go extinct because of climate change and local impacts.

Much to lose

Bleaching has a huge negative impact, not only on coral but also on man. If coral bleaches and is unable to recover, then it dies and becomes covered with long tufts of algae. Residents of the diverse marine community, whose lives revolve around the coral reef, disappear. Small fish which feed either on the coral or on algae disappear, together with the bigger fish which feed on them. Shrimps, crabs, starfish, sea cucumbers, squids, sea snails, etc. have to leave the dead reef. Ultimately, the local community suffers because fish catch is greatly affected, together with income from tourism. According to Mags Quibilan of UP MSI, the bleaching event of 1998 resulted in an income loss of $15 million for the El Nido area in Palawan.

We can help

• Report sightings of bleached coral to the Philippine Coral Bleaching Watch on Facebook. 

• To give coral as much chance as possible to recover from the high temperature of the ocean, reduce the other sources of stress for coral, such as:

• Sedimentation – Soil that goes into the ocean as a result of agricultural run-off, coastal development, and mining kills coral.

•  Pollution – Corals need clean and clear water.

•  Destructive fishing methods – overfishing, blast fishing, cyanide fishing

•  Garbage – Please do not throw litter into the sea, no matter how small. You would be surprised how many candy wrappers and sachets of shampoo are found on top of corals. These smother and kill corals.

•  Diver damage – To scuba divers: as much as possible, please avoid touching or stepping on corals.

• Support the creation and better management of more Marine Protected Areas (MPAs) — Coral bleaching has affected all reef areas, including MPAs, but better recovery has been observed in MPAs compared to unprotected sites.

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Nino Jacinto is a marine life enthusiast and scuba diver. He works both as a licensed real estate broker and as a trainer for Reef Check Philippines, a non-profit organization which trains volunteers (from all walks of life, whether diver or non-diver) on how to monitor the health of coral reefs. E-mail at [email protected].