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4.3.3 Mangrove forests
Mangrove forests currently occupy 14,650,000 ha of coastline globally (Wilkie and Fortuna,
2003 ) , with an economic value in the order of US$200,000-900,000 ha −1 (UNEP-WCMC,
2006 ) . Mangroves are important habitats and are especially often important nursery grounds
and breeding sites for birds, mammals, fish, crustaceans, shellfish, and reptiles. Moreover
they represent a renewable resource of wood and sites for accumulation of sediment, nu-
trients, and contaminants (Twilley, 1995 ; Kathiresan and Bingham, 2001 ; Manson et al.,
2005 ) . Climate change components that affect mangroves include changes in sea level, high
water events, storminess, precipitation, temperature, atmospheric CO 2 concentration, ocean
circulation patterns, health of functionally linked neighbouring ecosystems, as well as hu-
man responses to climate change (Gilman et al., 2008 ). Of all the outcomes from change in
the atmospheric composition and alterations to land surfaces, relative sea-level rise may be
the greatest threat (Lovelock and Ellison, 2007 ). Based on available evidence, among all cli-
matechangeoutcomes(suchasriseinsealevel,oceanacidification andtemperature,change
in frequency and intensity of precipitation/storm patterns), relative sea-level rise may be
the greatest threat to mangroves (Gilman et al., 2008 ). The Pacific islands mangroves have
been demonstrated to be at high risk of substantial reductions (Gilman et al., 2008 ). Recent
predictions on mangrove losses reveal a 10−15% decline in global mangrove area by 2100
(Snedaker, 1995 ; Alongi, 2008 ). Reduced mangrove area and health will increase the threat
to human safety and shoreline development from coastal hazards such as erosion, flooding,
storm waves and surges, and tsunami, as most recently observed following the 2004 Indian
Ocean tsunami (Dahdouh-Guebas et al., 2005a , b ; 2006 ) . Mangrove loss also reduces coastal
water quality and biodiversity, eliminates fish and crustacean nursery habitat, adversely af-
fects adjacent coastal habitats, and eliminates a major resource for human communities that
rely on mangroves for numerous products and services (Nagelkerken et al., 2008 ). Man-
grove destruction can also release large quantities of stored carbon and exacerbate global
warming and other climate change trends (Kristensen et al., 2008 ).
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