The rainforests by the sea

Mangrove forests literally live in two worlds at once. Growing in the intertidal areas and estuary mouths between land and sea, mangroves are comprised of salt-tolerant tree and other plant species from a range of plant families. They thrive in intertidal zones of sheltered tropical shores, islands, and estuaries.

Mangroves have specially adapted aerial and salt-filtering roots and salt-excreting leaves which enable them to occupy the saline wetlands where other plant life cannot survive.

Where in the world do mangroves occur?

These complex forests are found between the latitudes of 32º N and 38º S, along the tropical and subtropical coasts of Africa, Australia, Asia, and the Americas.

The largest remaining tract of mangrove forest in the world is found in the Sundarbans (NASA image, left), on the edge of the Bay of Bengal, stretching from SW Bangladesh to SE India.

Maps of Mangrove Distribution

Check out the following links for world maps of mangrove distribution

National Geographic Magazine (pdf 1.5 MB)

World Conservation Monitoring Centre

The countries with the largest area of mangroves are:

1) Indonesia
2) Brazil
3) Australia
4) Nigeria
5) Mexico

Estimates of mangrove diversity indicate that there are 16-24 families and 54-75 species worldwide. The greatest mangrove species diversity exists in SE Asia.

Only 12 mangrove species are found in the Americas, with 4 of these occurring along portions of the SE USA (Florida) coast.

Ecosystem Services

The provision of habitat for aquatic and terrestrial fauna and flora cannot be overlooked.
75% of all tropical commercial fish species pass part of their lives in the mangroves, where they encounter:

• nursery grounds
• shelter
• food
  
  

Other ecosystem services provided by mangroves include:

• protection from strong winds & waves;

Mangroves’ protective buffer zone helps shield coastlines from storm damage and wave action, minimizing damage to property and losses of life from hurricanes and storms.

• soil stabilization & erosion protection;

The stability mangroves provide is essential for preventing shoreline erosion. By acting as buffers catching materials washed downstream, they help stabilize land elevation by sediment accretion, thereby balancing sediment loss. In regions where these coastal fringe forests have been cleared, tremendous problems of erosion and siltation have arisen.

• nutrient retention and water quality improvement through filtration of sediments and pollutants;

Mangroves have been useful in treating effluent, as the plants absorb excess nitrates and phosphates, thereby preventing contamination of nearshore waters.

• flood mitigation;
• sequestration of carbon dioxide;

Mangroves absorb carbon dioxide and store carbon in their sediments, thereby lessening the impacts of global warming; and

• protection of associated marine ecosystems

Ecosystem Goods

Traditional and indigenous coastal populations have found sustenance from mangroves, collecting products and resources in a sustainable manner for hundreds or even thousands of years, including:

• firewood
• medicines
• fibers & dyes
• food
• charcoal
• construction materials

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