Blue carbon: seagrass meadows as a direct sink for atmospheric CO2

A new functioning of "blue carbon": seagrass meadows can directly absorb and sequester atmospheric CO2

A collaborative research team from the Port and Airport Research Institute (PARI), Hokkaido University, and the University of Tokyo, Japan, led by Drs Tatsuki Tokoro and Tomohiro Kuwae (PARI), report that coastal shallow water inhabited by eelgrass and other seagrasses are direct sinks of atmospheric CO2. The research article was published in the scientific journal “Global Change Biology” (John Wiley & Sons Ltd) (Link). .



Identifying locations and mechanisms responsible for changing global atmospheric CO2 is still a critical challenge for predicting future interactions between the carbon cycle and climate. Coastal ecosystems have been recently identified as an important stock for organic carbon; however, such ecosystems have been regarded as a source of atmospheric CO2 due to terrestrial carbon input. This dilemma generates controversy about the function of coastal ecosystem as a measure for the climate change.

Our study is the first to empirically show the net uptake of overlying atmospheric CO2 through the air-water CO2 flux in shallow vegetated systems. A paradigm shift (i.e., coastal areas as a “direct sink”) has now been quantified by thorough in situ observations in seagrass meadows (see below). We found that whether the system was a sink or source of overlying atmospheric CO2 is determined by the community metabolism.

Our results have important implications to thinking in a variety of associated scientific as well as social disciplines. For instance, the results add a new value to coastal ecosystems as a direct atmospheric CO2 sink in addition to a significant carbon stock, indicating that coastal conservation and restoration can be a means of suppressing global climate change. Furthermore, our results should provide a rationale for both coastal ecosystem service evaluations and carbon trading, because now we are able to take the point of view that such ecosystems can take up “on-site” atmospheric CO2.


Eddy-covariance system for measuring air-sea CO2 flux


Flux-chamber system for measuring air-sea CO2 flux


Eel grass meadow in Furen lagoon, Nemuro, Japan


News article from the Mainichi Japan, released on March 24, 2014



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