Last month’s tsunami inundated Sri Lanka’s water supplies and agricultural land with salt water, warns a report on the Science and Development Network (www.scidev.net).
Despite concerns raised by United Nations officials, Sri Lankan authorities claim the island’s food security is not threatened. The tsunami waves contaminated water and damaged crops most heavily on Sri Lanka’s east coast, whose rice fields produce more than one-third of the country’s total harvest.
Initial surveys by government agencies show that rice fields in the eastern districts of Trincomalee and Batticoloa have been heavily damaged and coconut plantations are also expected to suffer a slight decline. According to sources at UNICEF in the Sri Lankan capital Colombo, the extent of crop damage has been underestimated.
Staff at the UN agency said that salt has affected several thousand rice and fruit farms, and is beginning to form a crust on the soil. ”These fields cannot be used for at least another year,” says one UNICEF official. Government agencies, however, are downplaying the tsunami’s impact on agriculture.
”Crop production may face some difficulties in the next few months, but it will not affect the nation’s food security,” says S. L. Weerasena, director-general of the Department of Agriculture. Weerasena also said that though parts of the east were affected, most agricultural areas have been spared, and he predicts a ”bumper harvest” of rice this March despite the devastation caused by the tsunami.
He adds that a bigger concern was that the tsunami death toll means there is a labour shortage, which could impede the harvest. A senior official from the Department of National Planning who asked not be named commented that contamination of wells in the south and east of the island is a greater, longer-term problem than immediate crop damage.
”Sea water has seeped into wells and other water resources in Trincomalee, Amparai, Batticaloa and Hambantota districts,” he says.
”The water distribution network is partially damaged in some places and completely destroyed elsewhere. Not only do people have a scarcity of drinking water, but also a shortage of water for agricultural purposes.” Several areas in southern Sri Lanka are experiencing serious shortages of drinking water, and most water purifying plants there have been damaged beyond repair.
Most people in rural Sri Lanka still rely on wells for their drinking water. The International Water Management Institute, based in Colombo, warns that saltwater could seep into the wells and should be pumped out. ”We are worried about the quality of water people drink, as we cannot restore the water distribution network that soon,” says the minister of health, Nimal Siripala de Silva.
This process of decontaminating wells has begun in the south of the country, where machines are being used to suck out seawater. But according to the health official, ”only rainwater could flush out the aquifers — but that means having to wait for the monsoons [in April]”.
Currently, the island is using portable desalting machines to decontaminate wells. In some areas, water purification tablets are being used. Despite disagreements about the threat to crop yields following the tsunami, what has disappeared from the Sri Lankan menu are its famous seafood platters. According to fisheries minister, Chandrasena Wijesinghe, the stretch of sea between the islands of Kachchathivu and Delft Island off the Jaffna peninsula of north-western Sri Lanka — a belt known for jumbo prawns — was hit hardest.
The tsunami destroyed more than 2 000 boats and Wijesinghe says it will be one year before they can return to the sea. 60% of dietary protein in Sri Lanka comes from consumption of fish.
Meanwhile, ecosystems destroyed around much of the globe by last month’s tsunami urgently need to be restored, say environmental organisations. Damage caused by the tsunami, such as pollution of freshwater with saltwater and the uprooting of mangrove forests that act as buffers against typhoons, could have serious consequences for communities who depend on healthy coastal ecosystems for food, fuel, work and shelter.
A news story in the journal Nature says some organisations are using satellite images and divers to document the tsunami’s impact, while he United Nations Environment Programme has committed $1-million towards assessment efforts. Monitoring the damage is proving to be difficult, however, because some local research facilities that could have helped were also damaged by the tsunami. Researchers have commented that the tsunami’s effects were greatest where the environment was already damaged.
They stress the need for preventive measures to protect against future natural disasters. Already, disappearing mangroves have threatened fish populations as far away as the Caribbean, which has been badly affected by several recent hurricanes. A study published in Nature suggests that mangroves — areas with trees growing in shallow saltwater — play an important role in protecting young coral-reef fish from predators.
When the fish mature, they leave the swamps and move on to reefs. ”These swamps are thought to be no great loss when there are local pressures to build shrimp farms, new houses or tourist resorts,” says one of the researchers, Peter Mumby of the University of Exeter, United Kingdom. Mangroves are one of the world’s most threatened ecosystems, destroyed even faster than tropical rainforests.
”Urgent action needs to be taken to preserve mangroves if Caribbean fishers and coral reefs are to be preserved,” Mumby says. More than 100 000 fish from 64 different species were tracked as part of the study, which involved researchers from Canada, Mexico, the United Kingdom and the United States.
The tsunami’s ecological impact is likely to have caused long-term ecological damage to the coastlines it struck, say scientists.
The worst damage is expected to be found between 100 and 1 000 metres from the shore and species living on the shoreline would have been badly affected, they told the PlanetArk website.
Fragile coral reefs are likely to have suffered significant damage and could take years to recover as they only grow about half a centimetre a year. Diving resorts in the Maldives renowned for their rich marine life were destroyed completely. Mangrove forests — which fringe the coasts of tropical and subtropical countries — are also likely to have been affected.
Although these forests can help mitigate the effect of tsunamis by absorbing some of their energy, they are likely to have suffered considerable disturbance. This would have affected species of fish that live and breed among mangroves roots.
Larger marine species such as whales and dolphins are unlikely to have been badly affected by the tsunami, as they will have headed towards deeper water where the tsunami measured only about 18 centimetres in height. — www.scidev.net