Text and Photos by Henrylito D. Tacio
Mangrove forests grow where saltwater meets the shore in tropical and subtropical regions, thus serving as an interface between terrestrial, fresh-water and marine ecosystems. These forests provide at least US$1.6 billion each year in ecosystem services.
“The loss of mangroves will have devastating economic and environmental consequences,” says Greg Stone, Senior Vice President of Marine Programs at the Washington-based Conservation International. “These ecosystems are not only a vital component in efforts to fight climate change, but they also protect some of the world’s most vulnerable people from extreme weather and provide them with a source of food and income.”
A couple of years ago, a powerful storm surges brought by typhoon Gener caused flooding in Manila’s bay area, forcing the Senate to shut down for a second time in a week and the US Embassy to cancel work at its chancery and suspend consular services.
Concrete seawalls that supposed to shield Roxas Boulevard were destroyed causing flood waters to submerge the area.
Concrete seawalls are not permanent solutions; they are expensive and will ultimately breakdown,” says Dr. Elmer S. Mercado, former undersecretary of the Department of Environment and Natural Resources.
Dr. Mercado cites the case of the tsunami that hit Japan recently. “The 10-meter high seawalls did not save them,” he says. “What was worst was they got complacent that they continued building infrastructures along the coastal areas.”
If it happened in Japan, he says it will also happen in the Philippines. “We are worst here,” he reminds. “So the best solution is to remove all settlements further back from main coastal areas and shorelines.”
Dr. Mercado also suggests that drainage systems be improved, natural catchment areas be built, and all obstructions in waterways be removed. “(If these recommendations are not followed) then people living in Metro Manila should be prepared to have Ondoy and Sendong scenarios every year and every time there is a typhoon.”
The Philippines is hit by an average of 20 typhoons a year.
Asked whether mangroves can help minimize the impact of storm surges, Dr. Mercado replies, “You just can’t plant mangroves anywhere. You should plant them in places where mangroves thrive.”
Mangroves can’t be planted in the whole coastal areas of Metro Manila. But should mangrove rehabilitation be done, it “should be combined with other factors I mentioned earlier,” Dr. Mercado says.
The former environment official is currently connected with a German project and helps on training local government units to integrate forest, coastal (including mangroves), and climate change/disaster risk mitigation into their community land-used programs.
Most Filipinos don’t consider mangroves – touted to be the forests in the coastal areas – as important. “Coastal forests…. are not familiar to the average Filipino due to their early loss,” write Jurgenne Primavera and Resurreccion Sadaba in the just-released Beach Forest Species and Mangrove Associates in the Philippines. “They’ve long gone unreported in the yearly Philippine Forestry Statistics.”
But the Indian Ocean tsunami in 2004 and sea level rise from brought about by global warming changed all that. These highlight the neglected but increasingly needed “bioshield” role of “beach forest-mangrove belts.”
“Mangroves serve as coastal buffers and reduce coastal erosion,” points out Dr. Rafael D. Guerrero III, a national scientist and former head of the Philippine Council for Aquatic and Marine Research and Development.
“The coastline of Manila Bay used to be full of mangroves,” he informs. “But with overexploitation and human settlements, they were denuded.”
As such, Dr. Guerrero suggests mangrove rehabilitation.
Mangroves are the best line of defense against sea level rise and storm surges. “Its three-dimension structure offers much resistance to incoming waves and wind energy,” says Dr. Miguel D. Fortes, a professor of marine science institute of the University of the Philippines in Diliman.
But there’s one problem: “It will take a lot of money and efforts to enable mangroves to grow in such degraded area,” says Dr. Fortes, the first Filipino to receive the prestigious International Biwako Prize for Ecology.
In an earlier interview, Dr. Mercado claims the government can save money if mangrove rehabilitation is done as it is cheaper than building 100-meter of protected seawalls.
“The new seawall constructed by the Department of Public Works and Highways (in Manila Bay) is estimated to cost PhP94 million for a 1.5-kilometer stretch,” he says. “That money in mangrove hectare terms would be more than 752 hectares of mangroves – enough to cover the whole stretch of Manila Bay from Luneta to all the way to Cavite City twice.”
Dr. Mercado is thinking of around 75.2-kilometer stretch of mangroves and a protective barrier of 100-meter of mangroves from the seafront area of Manila Bay – with a 100-meter by 100-meter dimension per hectare.
According to him, it only costs PhP25,000 per hectare to establish a mangrove and another PhP25,000 per hectare a year to maintain them for another 4 years. “That’s a total of only PhP125,000 per hectare in 5 years,” he says.
In the case of the mangroves as seawall in Manila Bay, “there will be minimal need for maintenance plus the added bonus that this will bring back fishes and crustaceans back to Manila Bay which would be a boon to all the marginal fishermen from Manila, Paranque, Las Pinas, Cavite and even Bataan.”
But before mangrove rehabilitation can be fully done, the government must “remove all physical obstructions and illegal settlements along the waterways and embankments and proper handling of solid wastes along the major rivers and coastal areas.”
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