An expert is urging to revert 44,000 hectares, or 80 percent of Manila Bay ponds into mangroves to restore coastal protection, regulate flooding, control soil erosion, and promote fisheries production in the national capital’s coastal area.
Internationally known Filipina mangrove scientist and chief mangrove scientific advisor at the Zoological Society of London (ZSL) Dr. Jurgenne Primavera has recommended returning these ponds to mangroves and improving ecosystem services they provide to the environment, especially in areas which they were adversely by “build-up structures in the name of progress and development.”
She noted that before 1890, mangroves covered 74,000 hectares of Manila Bay’s 200-kilometer coastline. To date, this has been reduced to 55,000 hectares of fishponds and 1,000 hectares of mangroves.
This means that 18,000 hectares have been converted to infrastructures in the name of “economic growth.”
A paper published in Science, the world’s top scientific journal, reviewed dozens of mangrove research and concluded that a ratio of 4:1 of mangroves to ponds or other uses is needed to attain the “highest economic value of all uses combined,” including coastal protection, aquaculture, and fisheries.
In response to claims that the ratio may harm livelihoods, Primavera emphasized that reverted mangroves would support fisheries directly as sources of onsite clams, crabs, and shrimp. Indirectly, mangroves also act as nurseries for bigger fish caught offsite like snappers and mullets, noting that 1,000 hectares of fishponds can produce 2,000 tons of fish yearly.
Primavera further explained that mangroves are valuable resources, not only as coastal protection but for many other significant uses. A hectare of mangrove has a value of US$14,166 to US$16,142 (₱779,130 – ₱887,810) based on the value of ecosystem services of mangroves, she added.
Ironically, as fishponds increase, mangroves also have gone down. As an example, the province of Pangasinan had 450,000 hectares of mangrove forest in 1918, but withered to only 240,000 hectares in 2003, making the mangrove-fishpond ratio parity.
“The present mangrove-fishpond ratio is 1:1. The ideal should be 4:1 for mangrove hectare and fishpond hectare for ecological sustainability. Obviously, we need to rehabilitate a lot of mangroves to bring back the 4:1 ratio,” Primavera said.
She also pointed out that informal settlers who have built their houses in coastal areas contribute to the destruction and denudation of the once lush mangroves, paving the way to the houses sprouting within the coastlines.
Primavera likewise observed that the national government installed warning signages in storm surge-prone areas after Typhoon Yolanda hit many parts of the country.
“Towns in the provinces that experience chronic flooding will require political will over years and decades to come for their relocation to higher ground, to the more inland portions of the ponds that are to be reverted.
This is what needs to be done for an ecological and economically sustainable future of Manila Bay, its marine habitats, and coastal communities,” she added.
Recent typhoons in the country have caused countless deaths and economic damages.
“While proper drainage and flood control systems are vital, greenbelts of mangroves are ultimately needed for a country that averages 20 typhoons yearly,” Primavera said.
