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In recent years, deforestation, or the cutting down of large tracts of trees, has received much attention worldwide. Scientist and citizens alike have become concerned about the loss of species and habitat as trees disappear from places like the Amazon rainforest. But in the warm tropical waters around the middle of the planet, another type of important forest is being destroyed—faster and with less fanfare.

mangroves in Belize
Mangroves protect coastlines, like this one in Belize, from erosion and storm damage. They also protect marine life and filter nutrients from run-off. Image courtesy: Eric Punkay/Marine Photobank.

Mangroves, salt-tolerant trees that thrive in swampy areas along many tropical and subtropical coasts, are rapidly being displaced by development, industrial activity, and aquaculture. Normally, their dense forest canopy and extensive root systems—above and below the water line—provide many benefits to humans and other species.

Despite their importance, mangroves are disappearing at an alarming rate from coastal areas around the world. While mangrove cover is increasing in a few places, scientists estimate that at least 35 percent of the world's mangroves have been lost in the last decade—a rate of loss that exceeds tropical rainforests.

brown boobies perched among mangrove branches
Some seabirds, like the Brown Booby, feed at sea and use the mangrove canopy for roosting and nesting . Image courtesy: Smithsonian Institution.

The rapid disappearance of these coastal forests has serious consequences. Mangrove roots stabilize sediments, helping prevent erosion. They also offer a sheltered nursery for the juveniles of many fish species valued by fishermen. As a whole, mangrove ecosystems form protective barriers against storms and tsunamis, and improve water quality by filtering upland runoff and coastal pollution. They also provide habitat for many birds, land animals, and marine organisms.

In the Caribbean, researchers have found that coral reefs with mangroves nearby tend to have more of certain fish that are valued as seafood. And some species, such as rainbow parrotfish, are dependent on mangroves, disappearing in areas where the trees have been removed. In the Gulf of California, scientists found that fisherman bring in larger catches of fish and blue crabs in areas with mangroves fringing the coast.

shrimp farm
Worldwide, mangroves are being cleared for aquaculture, urbanization, and coastal landfill at an alarming rate. Image: Candy Feller, Smithsonian Institution.

Researchers have estimated that the world's mangrove forests offer many billions of dollars worth of free services to human communities, including wastewater treatment, raw materials like fiber and wood, and seafood production. But many scientists agree that if we don't change current patterns, we could lose mangroves and the services they provide altogether within 100 years.

 

Related Links...

Smithsonian Environmental Research Center (SERC): Mangroves in the Margin
http://www.serc.si.edu/inside/07_feller.jsp

SERC Tangled Roots Project: Virtual Tour of a Caribbean Mangrove Island
http://www.serc.si.edu/labs/animal_plant_interaction/Trail/VirtualTour.html

Smithsonian Magazine: Interview with Mangrove Researcher, Dr. Candy Feller
http://www.smithsonianmag.com/specialsections/ecocenter/Roots_of_the_Sea.html

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