Loss of Mangrove Forests Exacerbated Tsunami Damage
Many seashores have a natural defense against the onslaught of a tsunami: the mangrove forest. Dense thickets of these trees that tolerate salt water and line the coasts of many subtropical islands and continents can absorb much of the energy of killer waves. It is entirely plausible that the enormity of the human death toll can be traced in large part to the destruction of large tracts of native mangrove, caused by the lure of beachfront property for hotels, fisheries and industry.
Mangrove forests “help protect coastlines from erosion, storm damage and wave action by acting as buffers and catching alluvial materials,” writes Nigel Williams in Current Biology.1 “They also protect reefs and sea grass beds from damaging siltation and pollution.” It appears that the hardest hit areas by December’s devastating tsunamis were those with the least mangrove protection. Williams quotes Indian sources that reported that wherever mangrove forests were intact, “the impact was mitigated and the lives and property of the communities inhabiting the region were saved.”
Unfortunately for coastal communities, the rush to clear coastlines for industry and recreation is causing these unique ecosystems to disappear faster than the rain forests. Years ago, 75% of the coastlines of tropical and sub-tropical countries were lined with mangrove forests; now, less than half remains. The devastation of the recent disaster has awakened a new interest in this “neglected yet vital marine ecosystem.”
1Nigel Williams, “Tsunami insight to mangrove value,” Current Biology, Volume 15, Issue 3, 8 February 2005, Page R73, doi:10.1016/j.cub.2005.01.015.
The mangrove has an amazing capacity for regeneration with its floating seed pods that can cross continents like rafts, then orient themselves upright and plant themselves in shallow water. The story is told in an excellent family film about seed dispersal, Journey of Life. Mangrove forests create lush habitats for many species of animals and birds. Now, we find that they also create safety nets for humans.