Ecotourists visit pristine mangrove forest in Phang Nga Bay, Thailand.

Credits: © Mangrove Action Project

Mangrove forests are under threat in many parts of the world. These ecotourists visit a mangrove forest in the hongs or narrow tidal lagoons of Phang Nga Bay, Thailand, which has some of the country's most pristine mangrove forests.

Mangrove forests are complex ecosystems found between the latitudes of 32 degrees north and 38 degrees south, along the tropical coasts of Africa, Australia, Asia, and the Americas. There are over 50 species of mangrove, with the greatest diversity existing in South-east Asia. There are only twelve mangrove species in the New World and only four species of mangroves exist along portions of the coasts of the southern USA. Mangrove forests literally live in two worlds at once, acting as the interface between land and sea. Mangroves help protect coastlines from erosion, storm damage, and wave action. The stability mangroves provide is of immense importance. They prevent shoreline erosion by acting as buffers and catch alluvial materials, thus stabilizing land elevation by sediment accretion that balances sediment loss. Vital coral reefs and sea grass beds are also protected from damaging siltation. A primary factor of the natural environment that affects mangroves over the long term is sea level and its fluctuations.

Other shorter-term factors are air temperature, salinity, ocean currents, storms, shore slope, and soil substrate. Most mangroves live on muddy soils, but they also grow on sand, peat, and coral rock. If tidal conditions are optimal, mangroves can flourish far inland, along the upper reaches of coastal estuaries. Mangrove forests are one of the most productive and biodiverse wetlands on earth. Yet these unique coastal tropical forests are among the most threatened habitats in the world. Growing in the intertidal areas and estuary mouths between land and sea, mangroves provide critical habitat for a diverse marine and terrestial flora and fauna. Healthy mangrove forests are key to a healthy marine ecology, and their destruction in some places made the December 2004 tsunami more lethal.

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