Mangroves, present in at least 124 countries, provide a number of ecosystem services including habitats for many species of fish and shellfish, storm protection, influences on water quality, aesthetics, and biodiversity. Ecosystem services of mangroves are estimated to be worth US$33,000 to $57,000 per hectare per year to the national economies of developing countries with mangroves. Another important ecosystem service of coastal ecosystems is that of a significant global carbon sink. This is important because of their potential to assist countries (or corporations) in meeting their emissions reductions goals or meeting corporate social and environmental responsibility goals. Because the numerous values of mangroves are well known, it is ironic that rates of degradation, largely relating to land use/land cover change, are among the highest of any ecosystem on earth.
Results/Conclusions
Throughout the world mangroves have exceptionally large carbon stocks. Based upon field studies conducted in Africa, Asia and the Americas, the global average ecosystem carbon stock in mangroves is about 869 Mg C ha-1. This is much higher than the current IPCC default values for mangroves which is about 525 Mg C ha-1.
Land cover change in mangrove due to agricultural or aquacultural development translates to a very significant source of greenhouse gasses to the atmosphere. The greenhouse emissions arising from conversion of mangroves to other uses is from carbon that has been accumulating in the wetlands for thousands of years. The global mean greenhouse gas emissions due to land use in mangroves is 1800 Mg CO2e ha-1. In low input shrimp ponds of the developing world, this equates to a land use carbon footprint of 1603 kg CO2e for every kg of shrimp produced. There is a social cost of $6.52 associated with the carbon emissions arising from a single shrimp cocktail.
Synergistic interactions of land use and climate change have the potential to drastically reduce the environmental quality of coastal ecosystems in the future. The combination of very high C stocks, susceptibility to land cover change, and numerous ecosystem services makes mangroves potentially ideal candidates for inclusion in mitigation strategies involving the coastal resources and forest sectors. Proactive mitigation strategies that result in the conservation/restoration of intact mangroves would have numerous co-benefits relating to quality of life and resource sustainability.