Where Have All the Mangroves Gone?

Shrimp farming, urbanization and agriculture have taken a toll on the world's mangroves.

Imagine realizing you have 12 percent less money in your bank account than you thought. Scientists realized something similar while mapping the mangrove forests of the world.

A group of scientists from the U.S. Geological Survey estimated mangrove forests cover about 53,190 square miles of coast and river delta, mostly in the tropics. That's 12 percent less than the U.N. Food and Agriculture Administration estimate.

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Chandra Giri was inspired to study the protection mangroves offer after the Southeast Asian tsunami in 2004. He decided to study how mangrove forests benefit humanity, but needed an accurate estimate of how much remains.

Giri, and his team of 30 interns and visiting scientists at the U.S. Geological Survey, used more than 1,000 satellite images to make their mangrove map.

Mangrove forests grow along the shorelines of 118 countries and territories. But three-quarters grow in just 15 countries. Less than 7 percent are protected.

Mangroves are disappearing fast. Thirty-five percent of mangrove ecosystems disappeared between 1980 and 2000, according to the Millennium Ecosystem Assessment. Shrimp farms have been a primary cause of mangrove loss, as well as urbanization and agriculture.

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Local communities depend on the forests for food, fuel, fishing, and medicine. Mangroves are also breeding grounds for many fish and centers of biodiversity.

Mangroves absorb an estimated 20 million metric tons of carbon each year, making them important in slowing global warming. Ironically, mangrove forests are threatened by rising sea levels and increasingly strong storms which result from a warmer climate.

Advances have been made towards creating ecologically sensitive shrimp farms in Ecuador, Vietnam, and other countries. They'll have to act quick before we realize our ecological bank account is even smaller.

Photo: Wikimedia Commons