So much ado about mangroves

by Admin-Phmp

Text and Photos by Henrylito D. Tacio

“It is worthy to note how crucial these ecosystems are in supporting the interconnectivity of key biodiversity areas. As they link the land and the sea, mangrove systems receive nutrients and organic matter from terrestrial ecosystems, estuaries, and marine systems.”

Dr. Theresa Mundita S. Lim, executive director of the Laguna-based ASEAN Centre for Biodiversity (ACB), was referring to mangrove ecosystems. In fact, she said those words during the International Day for the Conservation of the Mangrove Ecosystem, which was observed last July 26.

Mangroves are found in tropical and sub-tropical regions, on the boundary between land and sea. Globally, they cover a surface of just 14.8 million hectares, or roughly equivalent to the size of Greece. 

Among the members of the Association of Southeast Asian Nations (ASEAN), the mangroves are rich and diverse, “armoring communities against the cruel impacts of climate change and, at the same time, underpinning community livelihoods as well as economies,” Dr. Lim stated. 

The ASEAN – composed of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam – hosts 42 percent of mangrove forests in the world, with an estimated total area of 42,914 square kilometers as of 2020.

At least 47 out of the 70 known mangrove species in the world can be found in the region, according to the database of the ASEAN Clearing House Mechanism.

Mangroves grow well in tropical countries, including the Philippines. But 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,” wrote Jurgenne Primavera and Resurreccion Sadaba in the book Beach Forest Species and Mangrove Associates in the Philippines. “They’ve long gone unreported in the yearly Philippine Forestry Statistics.”

Actually, mangroves are communities of trees in the tidal flats in coastal waters, extending inland along rivers where the water is tidal, saline, or brackish. “There are 25 to 30 species of true mangrove trees and an equal number of associated species,” says Dr. Miguel Fortes, a professor of Marine Science Institute at the College of Science of the University of the Philippines in Diliman Quezon City.

Mangroves are very important to marine life, says Dr. Rafael D. Guerrero III, former head of the Philippine Council for Aquatic and Marine Research and Development. They serve as sanctuaries and feeding grounds for fish that nibble on detritus (fallen and decaying leaves) trapped in the vegetation and on the bark and leaves of living trees.

“(Mangroves) are important feeding sites for many commercially important fish species (mullet, tilapia, eel, and especially milkfish), shrimps, prawns, mollusks, crabs, and sea cucumbers,” a World Bank report on environment adds. “Fry that gather in mangrove areas are very important for aquaculture.”

Unknowingly, mangroves also help protect people and even properties from destruction brought about by typhoons. Moises Neil V. Seriño, assistant professor of the Department of Economics at the Visayas State University, found this out after he and co-researchers conducted a study on the aftermath of super typhoon Yolanda (international name: Haiyan) in 2013.

“Our study shows that mangrove vegetation reduced the number of deaths and damaged houses during the Yolanda incident,” Seriño said. “This property and lifesaving effects of mangrove is robust. Mangroves can protect us (our lives, livelihood and properties) from damaging effects of typhoons.”

Mangroves also help in arresting the consequences of climate change. Mangroves, along with tidal marshes and seagrass meadows, sequester and store substantial amounts of coastal blue carbon from the atmosphere and ocean. As such, they “are now recognized for their role in mitigating climate change,” said Ma. Josella Pangilinan of Conservation International-Philippines.

“If rainforests can store a ton of carbon per hectare, mangrove forests can store up to four times more acting as effective carbon sinks deterring global warming,” the “Times” feature said.

The Science Daily further explained the role of mangroves in carbon sequestration: “The mangrove forest’s ability to store such large amounts of carbon can be attributed, in part, to the deep organic-rich soils in which it thrives. Mangrove-sediment carbon stores were on average five times larger than those typically observed in temperate, boreal and tropical terrestrial forests, on a per-unit-area basis.”

 Yet despite these benefits, the United Nations Educational, Scientific and Cultural Organization (UNESCO) estimated that some countries lost more than 40% of their mangroves between 1980 and 2005, often due to coastal development. 

This is true in the Philippines. From its original area of approximately 450,000 hectares in 1918, the mangrove areas went down to 140,000 hectares in 1991. It decreased further in 1994 to 120,000 hectares, according to Dr. Carmelita I. Villamor of the Ecosystems Research and Development (ERDB).

In her paper, she summarized the culprits of mangrove denudation in the country, among which were logging for firewood, harvesting for tanbarks, and the conversion of mangroves to fishponds for milkfish and prawn culture.

“In the 1950s, mangrove firewood was the preferred fuel source in coastal villages and most bakeries because of its high heating value,” Villamor reported. “But a greater volume was exported to Japan as firewood, which reportedly became the source of rayon.”

Large tracks of mangrove forests were lost and degraded when the government encouraged the development of aquaculture to increase food production in the 1960s. Around half of the 279,000 hectares disappeared between 1961 and 1988 due to conversion into milkfish or shrimp ponds, according to other reports.

Although human health has always depended on the health of the planet, UNESCO Director-General Audrey Azoulay said the importance of mangrove systems is now increasingly clear. “The world is now waking up to the importance of mangroves – and other blue carbon ecosystems, including salt marshes, seagrass beds and coastal wetlands,” she said.

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