ENVIRONMENT: COASTAL ECOSYSTEMS ON THE BRINK (Second of Three Parts)

On land, the ecosystem that supports the greatest number of plant and animal species is the rainforest. In the sea, it’s the coral reef.

What most Filipinos don’t know that the corals they are familiar with are actually the dried and bleached skeletons of soft-bodied animals that live in the warm, sunlit waters of tropical seas and look more like plants and rocks than animals.

The main part of the real coral is the polyp – the extraordinary flower-like animal with a tube-like body and finger-like tentacles. “Coral polyps get nutrition in two ways,” explains Lindsay Bennett, author of globetrotter island guide, Philippines. “They catch their food by means of stinging tentacles that paralyze any suitable prey – microscopic creatures called zooplankton – and also engage in a symbiotic relationship with zooxanthellae that live within the polyp structure.”

Coral polyps reproduce in two ways: asexually (by the division of existing individual polyps) and asexually (by combining egg and sperm from two different polyps). “This results in a free-swimming polyp that will be carried by ocean currents to find a new colony and commence a new reef,” Bennet writes.

Coral reefs attract a diverse array of organisms in the ocean. They provide a source of food and shelter for a large variety of species including fish, shellfish, fungi, sponges, sea anemones, sea urchins, turtles and snails.

Coral reefs produce about four times more fish per unit area compared to the coastal trawl fisheries, some studies have shown. Fish, it must be pointed out, provide more than half of the protein requirements of Filipinos.

One hundred scientists have declared the Philippines as the world’s “center of marine biodiversity” because of its vast species of marine and coastal resources.

Take the case of Samal Island in Davao del Norte. It is part of Davao Gulf which the World Wildlife Fund considers as “one of the most diverse marine ecosystems in the world.” Diverse coral reefs, different mangrove species, cetaceans and a host of invertebrates contribute to the natural diversity of the gulf, it said.

Interestingly, Davao Gulf is Southern Mindanao’s fishing ground. But lately, a recent study showed that 45-50% of the total fish caught daily by most of the fishermen in the gulf are juvenile – too young, not marketable and, therefore, wasted.

Dr. Anthony Sales, regional director of the Department of Science and Technology (DOST), attributed the dwindling fish catch in Davao Gulf to the destruction of coral reefs and other fish habitats.

If the Philippines will not do something to stop the destruction of the country’s coral reefs, several experts cautioned that it may not have the fish to feed its surging population. In fact, fish catch is fast dwindling in most of the country’s fishing grounds.

According to the Department of Environment and Natural Resources (DENR), major causes of coral reef destruction include destructive fishing, overfishing, sedimentation, ill-planned coastal development, and rapid population growth.

“Coral reefs have survived tens of thousands of years of natural change, but many of them may not be able to survive the havoc brought by humankind,” the Union of Concerned Scientists (UCS) points out in its website.

The only way to save coral reefs from extinction and restore their productivity is to limit access to them, suggests Dr. Edgardo D. Gomez. “This is no mean task,” says the country’s foremost marine scientist. “But it seems it is the only means we can save our coral reefs from disappearing in this part of the world.”

According to Dr. Gomez, a number of marine parks and reserves have already been established in many parts of the country. In fact, some fishing areas have been closed periodically to enable the fish to breed.

In Davao Gulf, the BFAR imposed a three-month fishing ban “to conserve marine resources and to secure the spawning period of pelagic fishes.” “Given the decline of fishery resources, there has to be a closed season in Davao Gulf,” a government official once said.

Filipinos need to save their coral reefs. Dr. Rafael D. Guerrero, a fishery expert, urged: “We are the stewards of our nation’s resources; we should take care of our national heritage so that future generations can enjoy them. Let’s do our best to save our coral reefs. Our children’s children will thank us for the effort.”

Even if the coral reefs can be restored and rehabilitated, they still face two major stresses posed by climate change. These include further increases in ocean temperatures, which can trigger coral bleaching, and ocean acidification, which at critical thresholds makes it difficult for corals to build shells and skeletons.

“Corals’ spectacular coloration comes from symbiotic algae, which also nourish them,” the UCS explains. “When rising ocean temperatures or ultraviolet light stress the corals, they lose their colorful algae, leaving only transparent tissue covering their white calcium-carbonate skeletons. If the stresses are sustained, the corals die. Even small increases in water temperature can cause coral bleaching.”

Since 1950, global mean sea surface temperatures have risen roughly 1° F (0.6° C). “The intensity and frequency of coral bleaching has increased significantly over the past 30 years, causing death or severe damage to one-third of the world’s corals,” the UCS says.

The Philippines first suffered mass coral bleaching in 1998-99. Reefs off northern Luzon, west Palawan, the Visayas, and parts of Mindanao were affected. The worst bleaching – which affected 80% of corals – occurred around Bolinao.

That’s just for starter. “Continued acidification of the ocean as it absorbs our carbon emissions poses another danger to corals and other sea animals that need calcium carbonate to build shells or skeletons,” the UCS says. – (To be concluded)