They are a very important species of semi-aquatic plant. They grow along the edges of salt-water rivers and estuaries, and they are capable of growing in either salty or brackish water. Their roots extend deep into the mud and help to stabilise the shoreline. In areas of the world where mangrove swamps have been removed for development purposes, the coastline has become subject to rapid erosion. They also provide a habitat for wildlife.
Mangroves are very resistant to pollution. Like coconuts, Mangrove seeds are encased in tough shells that require long soaking in seawater before they will germinate. This is because the fruits drop from the parent plant into the water and float away to start a new mangrove colony elsewhere.
External link
more on this biome (http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/pages/habitat/habitat14.htm)