Learn how plants respond to higher atmospheric CO2 concentrations

How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

On the Impact of 'Blue Carbon' Disturbance Within Seagrass Beds

Paper Reviewed
Macreadie, P.I., York, P.H., Sherman, C.D.H., Keough, M.J., Ross, D.J., Ricart, A.M. and Smith, T.M. 2014. No detectable impact of small-scale disturbances on 'blue carbon' within seagrass beds. Marine Biology 161: 2939-2944.

Noting that "seagrass habitats are considered one of the most efficient carbon sinks on the planet," -- as per the studies of McLeod et al. (2011) and Fourqurean et al. (2012) -- Macreadie et al. (2014) introduce their study of the subject by noting that seagrass meadows are also "among the most long-term carbon sinks on Earth." But they additionally state that "disturbances could threaten this capacity," so that "understanding the impacts of disturbance on carbon stored within seagrass meadows -- 'blue carbon' -- is of prime importance."

Hearkening to their own implied advice, the seven scientists describe how they "experimentally created several kinds of small-scale disturbances, representative of common grazer and boating impacts, within seagrass (Zostera nigracaulis) meadows in Port Phillip Bay (Australia) and measured the impacts on sediment organic carbon stocks." And what did their work reveal?

Macreadie et al. report that "disturbance had no detectable effect on Corg levels within seagrass sediments, even for high-intensity disturbance treatments, which remained bare (i.e. no seagrass recovery) for two years after the disturbance," noting that "these findings challenge the widely held assumption that disturbance and concomitant loss of seagrass habitat cause release of carbon, at least for small-scale disturbances." And they thus conclude that "larger (e.g. meadow scale) disturbances may be required to trigger losses of 'blue carbon' from seagrass meadows," stating that "the significance of this finding is that it challenges a common assumption in the field of 'blue carbon' research that loss of seagrass habitat causes release of stored organic carbon."

Clearly, common assumptions can often be misleading, as they appear to have been in this case.

Fourqurean, J.W., Duarte, C.M., Kennedy, H., Marba, N. Holmer, M., Mateo, M.A., Apostolaki, E.T., Kendrick, G.A., Krause-Jensen, D. and McGlathery, K.J. 2012. Seagrass ecosystems as a globally significant carbon stock. Nature Geosicence 5: 505-509.

McLeod, E., Chmura, G.L., Bouillon, S., Salm, R., Bjork, M., Duarte, C.M., Lovelock, C.E., Schlesinger, W.H. and Silliman, B.R. 2011. A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment 9: 552-560.

Posted 1 April 2015