Mangroves Are Nature’s Superheroes, but They’re Not Invincible

The world's largest block of mangrove forests is disappearing.

llegal loggers load the wood they cut from a mangrove forest before being detained by the Selangor Forestry Department in Port Klang, Malayasia. (Photo: Reuters / Bazuki Muhammad)

Jan 16, 2013· 2 MIN READ
The director of the Public Trust Project, Alison Fairbrother has written for Grist and Politics Daily, among others.

Mangrove forests are the X-Men of the environment: persecuted, little understood, but protecting innocents from death and destruction. Mangroves provide coastal areas with natural barriers from the devastation of hurricanes, cyclones, tsunamis, and tidal waves—superstorms that threaten to become the new normal if manmade climate change continues unmitigated.

Superheroes they may be, but mangroves are declining worldwide due to human activity. A report published this month shows that the largest tract of mangrove forest in the world, the Sundarbans in India and Bangladesh, is degrading rapidly. According to the research, conducted by the Zoological Society of London, as much as 200 meters—that’s one-eighth of a mile—of mangrove forest is disappearing from the coastline each year, weakening the region’s natural protection from extreme weather events.

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Sundarbans translates as “beautiful forests” in the Bengali language. It is home to nearly 500 species of reptiles, amphibians, and mammals, including the endangered Bengali tiger—all of which are threatened by the loss of the mangroves.

Mangroves are coastal wetlands found in tropical and subtropical areas, characterized by a rich diversity of tree, palm, and plant life that can live in salty, tidal conditions. Mangroves are relatively rare, comprising less than one percent of all forest areas.

But they are also some of the most valuable ecosystems in the world, and they’re far more efficient at sequestering carbon than terrestrial tropical forests. Their disappearance releases stored carbon into the atmosphere; scientists are still debating how much. Intact, mangrove forests may be a key element in the fight against climate change.

“Mangroves can hold carbon in place for hundreds of years. Most inland forests only hold carbon for about 50 years,” said Alfredo Quarto, executive director of the Mangrove Action Project. “When mangroves are disturbed by shrimp farming or by coastal developments, they release carbon at a high rate.”

Unfortunately, disturbances to mangrove forests are common.

An international team of researchers led by the U.S. Geological Survey (USGS) and NASA recently published the results of a project that mapped the deforestation of mangroves over a 25-year time period. The researchers found that 35 percent of the world’s mangrove forests were lost between 1980 and 2000. Just 6.9 percent of mangroves currently exist within protected areas.

“The current estimate of mangrove forests of the world is less than half what it once was, and much of that is in a degraded condition,” lead author Chandra Giri of USGS told Science Daily.

In North America, several species of mangroves surround parts of the Gulf of Mexico. Florida has an estimated 469,000 acres of mangroves, according to the state’s department of environmental protection, providing protected nursery areas for fish, crustaceans, and shellfish, nesting areas for coastal birds, and ecosystem services like nutrient trapping and cycling.

The devastating 2004 tsunami in the Indian Ocean showed what mangroves could do for human settlements too. The tsunami killed more than 200,000 people—and experts say the scale of disaster would have been even larger without the mangrove forests, which shielded coastal inhabitants from the sheer force of the tsunami’s waves.

Agricultural production, tourist development, urban expansion, and especially shrimp farming make it hard for these valuable forests to do their work. Think of these activities as the kryptonite of mangroves, threatening their effectiveness and range.

The Mangrove Action Project is leading a campaign to restore lost mangroves and educate the public about what they can do to help stop the decimation. Alfredo Quarto says shrimp farming in the global south is a major cause of mangrove deforestation—and that to help mangroves, we have to cut back on the shrimp scampi.

“We’re seeing a huge demand growing in the U.S. for shrimp from Southeast Asia, South Asia, and Latin America,” Quarto told TakePart. “Shrimp farmers in many countries move into new areas every few years, causing the loss of mangroves. We want people to know about the problem and play an active role in what they consume. We could cut back our shrimp consumption and not be hurting in terms of the possibilities on our plate.”