The effects of human activities on mangroves have far exceeded those of natural events over the past few decades. Economic development, rapid population growth and high population densities in coastal areas are the main drivers for mangrove degradation and loss. Although causes for loss can differ substantially amongst regions and countries, aquaculture has been the major global driver for mangrove conversion, and still represents one of the greatest global threats.
Already the environmental toll on mangroves and other coastal ecosystems from aquaculture has been severe. A 2001 study estimated that about 38% of global mangrove loss can be attributed to the clearing of mangroves for shrimp culture, while another 14% can be blamed on other forms of aquaculture (Valiela et al., 2001). With almost half (~44%) of the world’s population living within 150 km of a coastline, it is not surprising that there has been widespread clearing and degradation of mangroves for coastal development, conversion to aquaculture or other resource use, as well as pollution.
Climate change will exacerbate existing pressures; future coastal wetland (including mangroves) loss through sea level rise is predicted to reach 5–20% by 2080 (Crooks et al., 2011) and this ‘coastal squeeze’ may cause coastal wetland systems to be lost entirely locally (CBD, 2010). Armed with this knowledge, policies must change in order to halt, or reverse, the rate of mangroves loss.
Mangrove forests are a unique and rich ecosystem found along intertidal coastlines of tropical and subtropical latitudes. These forested wetlands are home to a wide variety of flora and fauna, including mammals, birds, insects, reptiles, fish and molluscs. Birds roost in the canopy, shellfish attach themselves to roots, and snakes and crocodiles use them as hunting grounds. Mangroves provide a valuable nursery habitat for fish and crustaceans; a food source for monkeys, deer, birds, even kangaroos; and a source of nectar for bats and honeybees. Typically, there are tight ecological linkages and energy flows between mangroves and adjacent ecosystems such as mudflats, coral reefs, seagrass beds and salt marshes. Mangrove forests are highly productive and support complex communities; linked to mangroves are thousands of other species which interact in a myriad of ways and with complex interdependencies.
Reference: Hanneke Van Lavieren, Mark Spalding, Daniel M. Alongi, Mami Kainuma, Miguel Clüsener-Godt, Zafar Adeel. Securing the future of mangroves (2012). United Nations University, Institute for Water, Environment and Health (UNU-INWEH)
Source: Institute for Water, Environment and Health (UNU-INWEH), 18/december/2012