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Thursday, August 30, 2012

Overlooked Species Theatre presents: Eelgrass

Carrie Robb is the Geographic Information Systems (GIS) Specialist at Living Oceans.

Eelgrass perhaps doesn’t really qualify as overlooked.  Its importance as a nursery for fish, a feeding ground for birds, a shoreline stabilizer and a water filtration system has been widely acknowledged by researchers and marine planning processes alike.  Here in British Columbia, the Marine Planning Partnership for the North Pacific Coast planning process includes eelgrass beds as an important ecological feature.

However, for the past few years eelgrass has been getting an increasing amount of attention for its role in the battle against climate change and ocean acidification.  Terrestrial forests have long been known as important carbon sinks but marine habitats, such as eelgrass beds and coastal wetlands, are now gaining in prominence.  Known as ‘blue carbon’, the importance of these habitats has been highlighted in the just released Ocean Health Index, as well as reports from a diverse array of organizations, including the Sierra Club of BC, the United Nations Environment Programme, and the World Bank, who suggests that blue carbon should be better incorporated into the international conversation on climate change, perhaps in a manner similar to the REDD program for forests.

But blue carbon it isn’t just about the plants.  In the marine realm, carbon stores are predominantly found in the soil.  Because oxygen-poor soils have slow decomposition rates and never experience fires (a means of carbon release in forests), if undisturbed they can store carbon for millennia at depths up to 11 m.  The soil supporting the eelgrass – now that is an overlooked part of our world.  Recent research in Nature Geoscience documents the first global assessment of the carbon stored in seagrass ecosystems and determined that seagrass meadows (in large part due to their soils) are a ‘global hotspot’ for carbon storage, on a level with terrestrial forests.

However, the same global assessment also highlighted the scarcity of information on the distribution and carbon storage capacities of eelgrass and their soils.  In British Columbia, the BC Marine Conservation Analysis compiled spatial data on the distribution of eelgrass beds along our coast.  In addition, many local groups are working to map eelgrass beds in their areas.  Perhaps combining these inventories with research into the stores of carbon in the soils below the eelgrass will bring an increasing awareness of yet another service that eelgrass beds provide, and highlight the value of conserving these coastal habitats.

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