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Six Months Later: Mangroves in the Tsunami Zone
Emily Gertz, 27 Jun 05

mangroveSix months ago, I wrote here on Worldchanging that one measure of success in post-tsunami reconstruction around the Indian Ocean rim would be "restoration of what the region had 50 years ago: a coast lined with healthy, productive, protective mangroves."

There was a lot of anecdotal evidence that where healthy mangrove greenbelts -- and coral reefs -- still lined the coast, they blunted the impact of the tsunami and saved lives.

In the June 21 issue of the journal Current Biology, (sadly behind a paywall, but a good summary can be found here) an international team of researchers have published results from one of the first detailed studies ever of the protective qualities of mangroves. The team of scientists from Kenya, India, Sri Lanka and Belgium confirm that initial rush of intuition back in December: Mangroves did offer protection from the tsunami.

Where the tsunami hit healthy mangroves, the leading edge of the forest took the brunt of the wave's energy, and few trees were uprooted. However, where mangroves were weakened even relatively slightly by human-caused "cryptic ecological degradation," they were profoundly less protective of the inner coastline -- even where the total area of mangroves was not lessened.

The United Nations Environment Program (UNEP) is encouraging assessing the "unseen value" of healthy ecosystems, which might in turn encourage governments to factor them into development plans.

The second report in the U.N.'s Millennium Ecosystem Assessment, Biodiversity and Human Well-being, (PDF link) estimates that about two and a half intact acres (one hectare) of mangrove swamp in Thailand is worth about $1,000 a year in benefits such as fishing and soil protection, but worth only $200 a year if converted to intensive farming.

According to the Mangrove Action Project, the tsunami damaged or destroyed at least 750 acres of mangroves along Thailand's coast.

In its recent draft "Principles for a Code of Conduct for Mangrove Management," the World Bank has failed to recommend involvement of local and indigenous peoples who live and work in mangrove zones, according to Bretton Woods Project, a watchdog NGO. In the areas affected by the tsunami, as well as other developing nations, this threatens to perpetuate the emphasis on projects that will generate hard currency, like shrimp aquaculture for export, instead of protecting or restoring mangroves for the sake of local needs and economies.

Findings on damage to mangroves and loss of sea life are trickling in -- MAP News is a good place to keep up with these reports.

As we've been seeing lately in the American press, linking environmental green to greenbacks appears to be taking hold in the Western mainstream -- notably in venture and institutional investing in clean energy development, and also (as in the case of the GE announcement) reducing exposure to economic risks from climate change.

Now we have to figure out how to get through to investors -- domestic and international, venture and development -- about the economic benefits of saving ecosystems.

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Great post, Em! Thanks!

Posted by: alex Steffen on 27 Jun 05

I'm a reefkeeper, meaning that I keep a living coral reef aquarium in my home. It's interesting that in recent years the hobby has turned to a very natrual philosophy - we're using biological filtration of various sorts these days instead of the bad old days of basically 'dead' aquariums with coral skelatons and lots of fish. Now we've found that if we keep our systems very natural we can keep (and in fact not only keep, but they often abundantly multiply!) corals that were impossible to keep alive in captivity just a few years ago.

Anyway, part of the new natural approach is to include a mangrove 'swamp' in your system. Practically speaking, that means keeping a seperate tank often referred to as a sump that is plumbed into the main tank so there is water exchange between them. The sump tank is often lit at night when the main tank is dark and dark during the day when the main tank is lit - this helps keep oxygen levels high and ph levels consistent in a very natural way. The mangrove plants growing in the sump tank help to remove waste products from the system.

BTW: I know that we aquarists sometimes get a bad wrap as having a hobby which isn't considered to be ecolocally sound, however, these days we're actually getting most of the inhabitants of our aquariums from captive grown sources. In fact, I think it's possible that as the oceans become more polluted and warmer (thus leading to coral bleaching all over the world) there could be a time when the only coral reefs to be found on earth will be those found in our aquariums. Responsible reef keepers are not having a negative impact on the earth's reefs - we're in fact trying to preserve them.

Posted by: Phil on 27 Jun 05

A long time ago, I remember reading about people "seeding" new coral reefs. Basically, having noticed that old sunken ships and other structures attracted all sorts of life, they started creating structures that might be colonized. Apparently it worked and helped increase fish catches (healthy reefs are important for fish reproduction).

It's a bit like planting trees in clearcuts, but the economic may be worth it. If there's also safety issues, the case may be even stronger. Is anyone better versed in this domain that could shed some light on this? I'm afraid it's been so long I wouldn't even know where to start looking anymore.

Posted by: Daniel Haran on 28 Jun 05



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