National Wetlands Update September 2012
Issue No. 21, September 2012
Coastal wetlands and blue carbon
Neil Saintilan, NSW Office of Environment and Heritage
International Blue Carbon Scientific Working Group
members on location in the mangroves of Costa
Rica. (Anissa Lawrence)
"Blue Carbon" is a term used to describe the carbon sequestered by marine, coastal and estuarine ecosystems. Mangroves, saltmarshes and seagrasses fix carbon from the atmosphere and ocean and estuarine waters, and preserve this carbon with remarkable efficiency in deep, organic-rich sediments.
They are among the most efficient ecosystems globally in burying carbon, because methane emissions are dramatically reduced in saline environments, and biogeochemical conditions in tidal wetlands are conducive to long-term carbon retention.
Reviews by Duarte et.al. (2005a) and Bouillon et.al. (2008) report a mean organic carbon burial rate of 1.51 tonnes per hectare per year for saltmarsh and 1.39 tonnes per hectare per year for mangrove, exceeding by ten and six times respectively the maximum carbon burial rate of undisturbed Amazonian forest. There is a growing interest internationally in quantifying the ecosystem service of carbon sequestration as an argument for the preservation of coastal wetlands.
The development of markets for the purchase of carbon offsets has the potential to provide new impetus to conservation and restoration initiatives in these vulnerable ecosystems.
Recently, Conservation International convened an International Blue Carbon Scientific Working Group tasked with developing protocols for estimating carbon sequestration in mangrove, saltmarsh and seagrass environments.
Australian-based members of the working group include Professor Peter Ralph (UTS), Professor Catherine Lovelock (UQ), Dr Dan Alongi (AIMS), and Dr Neil Saintilan (OEH), with Anissa Lawrence (TierraMar Consulting) participating as an observer.
The International Blue Carbon Scientific Working Group has met on four occasions during 2011-12, and expects to complete a manual by the end of the year that will guide the estimation of above and below ground carbon stores and rates of carbon accumulation and greenhouse gas emission in mangrove, saltmarsh and seagrass environments.
On the domestic front, a process is underway to develop and implement a national policy and action plan for the improved conservation, management and restoration of coastal ecosystems to assist in mitigating the impacts of climate change. Work is currently underway to scope a baseline assessment of carbon in our coastal ecosystems and explore opportunities to develop methodologies under the Carbon Farming Initiative.
Also, CSIRO and partner organisations are commencing work under a Marine and Coastal Carbon Biogeochemistry Cluster, tasked with improving carbon inventory and process understanding of sources, stocks and fluxes of carbon in Australian marine and coastal environments.
For further information contact Anissa Lawrence 0419 903 800.
Duarte, C.M. Middelburg, J.W. Caraco, N. 2005, Major role of marine vegetation on the oceanic carbon cycle. Biogeosciences 2:1-8.
Bouillon, S. Borges, A.V. Castaneda-Moya, E. Diele, K. Dittmar, T. Duke, N. C. Kristensen, E. Lee, Y. Marchand, C. Middleburg, J.J. Rivera-Monroy, V.H. Smith III, T.J. Twilley, R.R. 2008, Mangrove production and carbon sinks: a revision of global budget estimates, Global Biogeochemical Cycles 22.