Impact of Cyclones on Ecosystems

General Impacts

The impact of the 2008 cyclone on coastal ecosystems in Myanmar and Thailand will take a long time and significant resources to assess. Predictions about likely disturbance, based on scientific research following other cyclones, are as follows: There is likely damage to the structure and function of the coastal ecosystems (mangroves, sea grasses, estuarine mudflats and localized corals):
  • The physical structure will have been damaged by the force of the storm surge, physical removal of flora and fauna and increased sediment load which will have killed sediment sensitive organisms by smothering. The extent of this damage is being assessed and will likely vary considerably depending on the local topography and hydrology.
  • Chemical changes may have included saltwater intrusion, eutrophication (enrichment) of the water resulting from increased runoff, raw sewage and decomposition of flora and fauna including dead fish, livestock and unrecovered bodies. There will be the slower decomposition of timber from mangroves, fishing boats and buildings.
  • Non biodegradable waste such as plastics will have contributed to a build up in marine debris.
  • Toxic wastes, which were inadequately stored, may have been dispersed.
  • Exotic (introduced) species used for aquaculture may have escaped.
Finally, the biological structure of the ecosystem could be disrupted as various species at different trophic levels were differentially removed. With the structure altered, ecosystem functions could be altered.
Long Term Ecological Research (LTER) is required.

Mangroves as bio-guards

Destruction of mangrove forests in Burma left coastal areas exposed to the devastating force of Cyclone Nargis. Coastal developments had resulted in mangroves, which act as a natural defence against storms, being lost. A study of the 2004 Asian tsunami found that areas near healthy mangroves suffered less damage and fewer deaths. Most of the mangroves in Burma had suffered as a result of being overexploited. "There are very limited areas that you would describe as pristine or densely covered mangrove in the Irrawaddy area," according to the FAO Forestry, referring to the region of Burma where Cyclone Nagris first made landfall. "There are some efforts in place to try to rehabilitate and replant mangroves, but we do know that the loss rate is quite substantial still. During the 1990s, they lost something like 2,000 hectares each year, which is about 0.3% being lost annually. But that does not give you the whole picture because the majority of these tidal habitats are being degraded, even if they are not being completely destroyed."
Based on BBC News, 8 May 2008. Full story at See More.

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