Coral Bleaching and El Nino

I had the privilege last November of travelling with my favorite dive buddies: PADI Instructor Jun Zamora and PADI

Master Instructor Ross Guzman. As we went diving in the popular sites of Anilao, Puerto Galera, Boracay and

Buruanga, we noticed patches of corals that have turned white. Conversations with other divers confirmed this

observation. When I researched about it, this phenomenon turned out to be one of the destructions brought about

by El Nino ? coral bleaching. Coral bleaching is characterized by the appearance of the coral?s white skeleton due to

the transparency of its polyps. What struck me is the fact that a bleached coral is not exactly a dead coral as what

the popular notion is.

El Nino is a change in the ocean-atmosphere system in the tropical Pacific. This name is used for its tendency to

arrive around Christmas. El Nino means The Little Boy or Christ child in Spanish. During an El Nino, the trade winds

along the equator in the Pacific dwindle or even reverse. These travelling winds bring warm surface water heated by

the tropical sun from the coast of Indonesia to the western coasts of North and South America. In a non-El Nino

condition, there is an upwelling of nutrient-rich cold water from deeper levels. A reduced efficiency in the upwelling

cuts off the supply of nutrient-rich thermocline water. In addition, the migration of extremely high sea surface

temperatures or ?hot spots? is causing coral bleaching. An increase to 86-87.8 degrees Fahrenheit can be deadly to

the corals.

It has to be stressed that coral bleaching does not necessarily kill the corals but instead makes it more vulnerable to

disease, damage or death. Corals maintain a symbiotic relationship with a microscopic organism called zooxanthallae.

These tiny one-celled plants live within the thin layer of live coral tissue. The zooxanthallae provide their hosts with

oxygen and some organic compounds for food production. They also facilitate the formation of coral skeleton. When

a coral is stressed due to high temperature, they tend to expel their zooxanthallae. The polyps of the corals are

then left without pigmentation thus its bleached appearance. Without this symbiotic relationship, corals are left to

feed by themselves and are now more vulnerable to several coral diseases. Bleached corals can rebuild their bonds

with their algal partners in two months to a year. However, if the temperature gets too high or the bleaching

becomes prolonged and frequent, the corals will be unable to recover.

Approximately 50 countries have reported the occurrence of coral bleaching since 1997. For the Philippines, it is only

in June 1998 that ?hot spots? are observed. However, concerns are mounting that the destruction can be extensive

if the elevated temperatures persist for too long a period or become too warm to permit recovery. A report from

Reef Check, an international coral assessment program, shows that there is a massive expansion of coral bleaching

wherein corals that have thrived for hundreds of years and even those that are generally more adept at adjusting to

temperature fluctuations are dying.

What divers can do is avoiding contribution to the stress of the corals. Extra care must be practiced when near

them. Refrain also from touching or breaking a coral. Remember that corals are the rainforests of the oceans. If it

goes, so does half of the sustenance of our population.