Do you think that mangroves should take precedence over developments?

Mangroves

Photo courtesy of NOAA NOS

Mangroves are trees, shrubs or palms which live in oxygen-poor soils. They are all adapted to salt water. There are more than 60 species. Different species live at different distances form the water edge, in zones. The most noticeable thing about them is the visible tangle of roots. Parts of the roots are above ground so that they can take in oxygen, as there is little oxygen in the soil. A lot of roots are needed to support the plants in such unstable soils. More than 8% of coasts are lined with mangroves, including one quarter of tropical coastlines, making up a total of about 181,000 km². They shelter the coastlines from tsunamis, storms, tides, currents, surges and erosion, and protect coral reefs from suspended solids. In return, the corals or islands protect them from high energy waves which prevent saplings from taking root. Areas which still had mangroves came off relatively unscathed in the December 26 2004 tsunami.

Many mangrove plants filter out most of the salt at root level. Others excrete it as soon as possible from special salt glands on the leaves. Others concentrate it in the bark or old layers, where it stays. They do not appear to actually need salt, though they do best in water which is half salt and half fresh. They benefit from the lack of competition in salty water.

Mangroves act as nurseries for a wide range of fish species (up to 75 percent of fish caught commercially, or food that they eat), so they are critical to the productivity of tropical fisheries. They provide protection for the young fish, crabs and shrimp which also eat the fruit and other litter that falls. The floating fruit, and therefore most mangroves, are dispersed by the water. Some grow attached to the parent for a few years. Mangroves help to stabilise coastlines and provide timber and wood for fuel for local communities. They also provide food and medicines and are places of great biodiversity. They provide nesting paces for many resident birds and roosting places for migratory birds. Some mangrove plants can absorb some pollution, even heavy metals.

Mangrove ecosystems can be damaged by fishing, bird hunting, crab catching, waste dumping, excessive tree cutting (for fuel wood, timber or making charcoal) and spraying pesticides to try to eliminate mosquitoes. Oil can suffocate the trees by preventing them from taking in oxygen with their exposed roots, though some species will grow aerial roots to compensate. Many countries have lost more than 50% of their mangroves, with Thailand having lost 84 percent.

Recent news stories involving mangroves include:

• Tsunami May Have Spread Alien Species June 17 2005
• Indonesia Wants to Ban Coastal Rebuilding April 30 2005
• Report: Human Damage to Earth Worsening Fast March 30 2005
• U.N. Study: Earth's Health Deteriorating March 30 2005
• Maldives Coral Reef Left Unscathed by Tsunami -Report March 16 2005
• Asia Quake, Tsunami Moved Islands, Shortened Days February 14 2005
• Dogs Search for Victims, Paying Back Thais January 09 2005
• Asians Invent Ways to Survive Disasters December 30 2004
• Senegal Signs Peace Deal with Casamance Rebels December 30 2004
• Global Warming, Pollution Add to Coastal Threats December 27 2004
• 'Climate Witnesses' Testify About Warming December 11 2004
• EU Seeks More Talks on Kyoto Protocol December 10 2004
• Bangladesh Sees Tiger Numbers Up in Mangrove Swamps October 09 2004
• Group: Tigers Live on Bangladesh Border October 09 2004
• Nigerian Security Improves After Deal October 03 2004
• Nigerian Oil Delta Rebels Agree to Cease-Fire September 29 2005
• Nigerian Rebels to Widen Conflict, Target Agip September 26 2005

Development threatens Malaysia's mangroves

For thousands of years mangrove swamps have protected parts of Malaysia from tsunamis and provided food, fuel and income for the local people. Now commercial shrimp farms are damaging the ecosystem.

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