12 March 2012 Mangrove forests and aquaculture farmers: Aspects of climate change adaptation on the central coast of Bangladesh M. Mizanur Rahman*1 and M. Shahadat Hossain1 Aquaculture production and its share of the seafood market are predicted to expand and play an increasingly important role in meeting global fish demands. The success of the sector, therefore, has important implications for food security and as a source of income for a growing number of producers. Consequently, any potential direct or indirect effects of climate change on aquaculture must be taken seriously. The major consequences of climate change include ice melting, sea-level rise, irregular drought and rain, cyclonic storms, coastal erosion, inundation of low-lying areas, salinity intrusion and groundwater contamination. Sea-level rise will have gradual impacts because of the loss of land from inundation and erosion. Salinization of groundwater may reduce the availability of freshwater for aquaculture, agriculture, domestic and industrial uses. Similar problems may arise with increasing the frequency of droughts. Severe droughts may lead to water shortages and massive forest fires. Forest fires release millions of tons of carbon into the atmosphere, creating a dangerous feedback loop that further accelerates global warming. The severity and frequency of storm surges increase from the effects of mean sea-level rise and the loss of natural defenses, such as mangrove forests. High winds and waves destroy structures used for coastal aquaculture such as embankments, pond dikes, sluice gates, hatcheries, electricity poles and cage materials, resulting in loss of stock and damage to equipment and facilities. Damage to farm infrastructure can also cause saline water intrusion in the culture pond (FAO 2008). The financial impacts of cyclonic storms on aquaculture may be severe because coastal aquaculture species are often of high value. Climate change can also increase physiological stress on cultured stock. This would reduce productivity and increase vulnerability to diseases and consequently impose higher risks and reduce returns to farmers. Bangladesh, a very low-lying country with a substantial aquaculture industry, typically experiences storm surges between 3 and 6 m, with theoretical predictions up to 7.5 m (Salam and Beveridge 2003). Future predictions for Bangladesh, in association with increased sea surface temperature of 2 °C and 4 °C, suggest maximum storm surge heights of 9.2 and 11.3 m, depending on the extent of sea level rise (Ali 1996). Annual total rainfall over Bangladesh is predicted to increase 296 mm by 2050 and 543 mm by 2100 (Karmakar and Shrestha 2000). Singh et al. (2000) showed that mean tidal level at Hiron Point (21° 48/ N, 89° 28/ E), Hatyia (22°08/ N, 91°06/ E) and Cox’s Bazar (21° 26/ N, 91° 59/ E) increased 4.0, 6.0 and 7.8 mm/year, respectively. Torrential rainfall leads to flooding and paralyzes the affected area, inundating houses, displacing and killing people, destroying infrastructure, and damaging crops, causing massive economic loss. A study was conducted in the Feni-Noakhali area, which is a centrally exposed part of coastal Bangladesh. The geographical location and geomorphological conditions of this region have made it one of the most vulnerable areas in the world to natural disasters (Fig. 1). The objectives of the study were to measure the area in aquaculture, measure the spatial distribution of mangrove forest, identify the causes and impacts of climate change on coastal aquaculture, and analyze the role of mangrove forests in mitigating climate change vulnerability. Fig. 1. Geographical location of the study area.
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