Various ecological theories have been floated in the wake of last weeks lethal tsunami, which killed more than 150,000 people and left areas of South and Southeast Asia unimaginably devastated. Some have blamed the severity of the earthquake-spawned waves on global warming and its effects on the Indian Oceans sea level; others have targeted the U.S. Navys undersea sonar experiments for the intensity of the earthquake itself. But while the current level of the Indian Ocean can be debated (some argue its actually lower than usual this year), and the earthquake-generating power of sound in the ocean is dubious, there is no question that one human activity on the regions developed coastlines contributed to the death toll: the cultivation of cheap shrimp, for which vast swaths of protective mangrove forests have been claimed and cleared.
According to a December 30 report by the Science and Development Network in India, the tsunami did less damage and swept away fewer lives in the Pichavaram and Muthupet regions in the southern Indian state of Tamil Nadu than it did in the Nagapattinam District. The difference: Pichavaram and Muthupets forests have been kept intact, while Nagapattinams had been replaced by more than 200 shrimp farms. (Most of them were illegal: India bars shrimp farming within 1,500 feet of the coastline, but the law is often ignored.) Similar reports resonated in the days following the disaster from around the Indian Ocean rim: On Penang Island in Malaysia, according to the international environmental organization Friends of the Earth, the Penang Inshore Fishermen Welfare Association acknowledged that mangrove forests reduced the impact of the tsunami; environmental activist Hemantha Withanage of the Sri Lankan Centre of Environmental Justice noted that forested areas suffered little damage compared to their clear-cut surroundings.
Mangroves, the diverse, salt-tolerant forests that grow in the intertidal zone between land and ocean, once covered three-fourths of the earths tropical coastlines. They typically provide coastal areas with two stages of protection, first with a lower-growth area where sediment collects in roots and gives the ocean floor a shallow shape that slows incoming swells, next with a layer of taller trees that break the force of the surf. Less than 50 percent of the forests that were present in 1960 remain, according to Alfredo Quarto of the Washington statebased Mangrove Action Project. Quarto calls mangroves "the rainforests of the sea," but unlike rainforests, mangroves are disappearing without much public attention as Quarto points out, governments have until recently considered them wastelands. And while tsunamis are infrequent enough that no one could have predicted the effects of the December 26 disaster, scientists in the recent past have noted the consequences of other natural disasters on coastlines stripped of their mangroves. In 1991, tropical Cyclone Marian struck Chittagong, Bangladesh, sending up a massive "tidal bore" that claimed 138,000 lives; eight years later, a "super-cyclone" in Orissa on Indias east coast killed 10,000 people. In both instances, scientists around the world blamed the human toll on regional deforestation. Tom Spencer of the Cambridge Coastal Research Unit at Cambridge University, in an interview with New Scientist, claimed that the destruction of Orissas mangroves "left it wide open to attack by the wind and waves of the cyclones that regularly lash the coast of eastern India and neighboring Bangladesh.
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"I am quite sure," he said, "that the loss of the mangroves was a contributory factor in the extent of the damage. In the past [they] would have dissipated the incoming wave energy."
Those mangroves were mostly cleared for cheap shrimp: "Prawn culture" has been a burgeoning industry in both Orissa and Chittagong in the past 15 years. Four protesters were killed in Orissa in a 1999 demonstration against what Quarto calls a "boom and bust industry" that leaves "devastating ruin in its wake."
Like Orissa, Thailand also specializes in the tiger prawns so popular in this country, and many of its own mangroves have been sacrificed in recent years to the 250,000 tons of shrimp the country produces for the world every year. At the time of the tsunami, shrimp farms dotted the coastal provinces of Ranong, Phangga, Phuket and Krabi on Thailands coast. The regions coral reefs have also deteriorated along with the mangroves, disturbing another protective barrier that, where it remained, saved lives. In the Surin Islands off Thailands west coast, where coral reefs remain largely intact, very few people died, even though the islands were directly in the tsunamis path. Thai marine environmentalist Thon Thamrongnavasawadi told Andrew Browne of The Wall Street Journal that "most scrambled to safety as the first wave exploded against the coral." Coral demonstrated the same buffer effect in the Maldives, an island only three or four feet above sea level, where reefs were said to have broken up the tsunami. The death toll in the Maldives was 69.
No one is arguing that mangroves and coral could have stopped the tsunamis devastation altogether, and no one is willing to speculate as to just how many lives could have been saved by virgin forests and undisturbed reefs. But tourism and cheap shrimp have both been cited before by conservationists as devastating to local ecologies and economies for less dramatic reasons: Both pollute local waters and distort small economies. Alternatives to both exist, such as farming the shrimp away from the coast, and vacationing in environmentally responsible resorts. But the best solution now may be for humans simply to reduce their consumption of shrimp and understand that, even if you camp in the rainforest, theres really no such thing as environmentally benign tourism.