Mangrove forests are being destroyed at an alarming rate, despite the many benefits and ecosystem services that they provide. It is estimated that as much as 50% of mangrove coverage has been lost in the last half century alone1. At present, about 1% of global mangrove coverage continues to be destroyed each year. It is also estimated that if these destructive trends are allowed to continue, all unprotected mangroves will be lost within the next century2.
Why are we losing mangroves?
Mangroves face numerous threats to their existence, the most imminent of which are human-induced. One of the greatest threats to mangrove forests is their deforestation and conversion for aquaculture, the fastest growing food production system in the world today3. Mangrove forests are also deforested to make room for agricultural production, as well as coastal infrastructure. A rapidly growing global population, coupled with an ever-increasing coastal population expansion, means that many coastal communities are rapidly urbanizing, often without proper development planning, and coastal ecosystems are bearing the brunt. Rapid development of roads, ports, marinas, and coastal communities means that more mangrove forests are being destroyed.
Beyond the risk of development, mangrove ecosystems suffer greatly from over-fishing and over-harvesting of their valuable resources, such as timber which can be used for firewood and construction in local communities. Agricultural and urban runoff, along with other forms of pollution, including oil spills, contribute significantly to mangrove degradation. The construction of upstream dams and irrigation systems also contribute to mangrove destruction, as they alter the water flow and can lead to over-salinization and lack of new sediment input. Weak governance and loose environmental regulations exacerbate many of these issues.
Another major threat to mangroves is anthropogenic climate change. Sea-level rise degrades mangrove ecosystems through sediment erosion, inundation stress, and over-salinization4. However, mangroves do have the ability to adapt to sea level rise if it occurs slowly enough so that they may retreat, assuming that they have space on the landward side to expand and that several other environmental conditions are met5. In addition to sea level rise, climate change endangers mangroves via more frequent and intense storms and the associated storm surge, which can lead to inundation, tree mortality, and soil erosion6.
Another critical threat to mangroves is the fact that they are consistently undervalued in cost-benefit analyses and in the minds of policymakers, governments, local communities, and individuals.
- Donato et al. (2011). Mangroves among the most carbon-rich forests in the tropics. Nature Geoscience 4, 293-297.
- The Blue Carbon Initiative. Blue Carbon. Accessed on February 14, 2017. http://thebluecarboninitiative.org/blue-carbon/.
- Responsible Aquaculture. Accessed on February 14, 2017. http://wwf.panda.org/what_we_do/how_we_work/our_global_goals/markets/mti_solutions/certification/seafood/aquaculture/index.cfm.
- Ellison, J. Climate change and sea level rise impacts on mangrove ecosystems. University of Tasmania, Australia. Available at: vliz.be/imisdocs/publications/120078.pdf.
- Wongthong, P. (2008). Potential Impacts of Sea Level Rise on Mangroves. Accessed on November 15, 2016. Available at: http://www.coastalwiki.org/wiki/Potential_Impacts_of_Sea_Level_Rise_on_Mangroves.
- Gilman, E., Ellison, J., Duke, N., and C. Field (2008). Threats to mangroves from climate change and adaptation options. Aquatic Botany. Available at: https://www.iucn.org/sites/dev/files/import/downloads/aquatic_botany_mangrove_article2008.pdf.