251
© Springer Nature Singapore Pte Ltd. 2019
T. Kuwae, M. Hori (eds.), Blue Carbon in Shallow Coastal Ecosystems,
https://doi.org/10.1007/978-981-13-1295-3_9
Chapter 9
Quantifying the Fate of Captured Carbon:
From Seagrass Meadows to the Deep Sea
Katsuyuki Abo, Koichi Sugimatsu, Masakazu Hori, Goro Yoshida,
Hiromori Shimabukuro, Hiroshi Yagi, Akiyoshi Nakayama,
and Kenji Tarutani
Abstract To help evaluate the sequestration and carbon dioxide storage function of
seagrass meadows, we describe the processes by which carbon is sequestered in
eelgrass beds and transported from shallow coastal waters to the deep sea. A part of
the carbon taken up by eelgrass is decomposed and returned to biological production or the water column’s dissolved inorganic carbon pool, some is accumulated
and stored in the shallow sea bottom, and the rest flows out into the deep sea. Here,
we describe the growth of eelgrasses and the processes of decomposition, sedimentation, and transportation of eelgrass-derived organic carbon using the Seto Inland
Sea as a model site. We estimated the amount of carbon sequestered and stored in
eelgrass beds, the fate of eelgrass-derived organic carbon, and the amounts accumulated in the shallow coastal water and transported to the deep sea. According to our
estimates based on calculations from tracking carbon over a 1-year period, of the
73,000 tons of carbon sequestered by eelgrass annually in the Seto Inland Sea,
40.9% is accumulated in the Seto Inland Sea and 8.3% flows out to the deep sea. In
other words, the eelgrass beds in the Seto Inland Sea have an annual potential capacity of 36,000 tons of carbon storage. In addition, most of the organic carbon was
accumulated in the shallow coastal waters rather than in the deep sea.
K. Abo (*) · M. Hori · G. Yoshida · H. Shimabukuro
National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries
Research and Education Agency, Hatsukaichi, Hiroshima, Japan
e-mail: abo@fra.affrc.go.jp
K. Sugimatsu
National Research Institute of Fisheries Engineering, Fisheries Research Agency,
Kamisu, Ibaraki, Japan
H. Yagi
School of Systems Engineering, National Defense Academy, Yokosuka, Japan
A. Nakayama
Alpha Hydraulic Engineering Consultants Co. Ltd., Chuoh-ku, Tokyo, Japan
K. Tarutani
Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki, Japan
© Springer Nature Singapore Pte Ltd. 2019
T. Kuwae, M. Hori (eds.), Blue Carbon in Shallow Coastal Ecosystems,
https://doi.org/10.1007/978-981-13-1295-3_9
Chapter 9
Quantifying the Fate of Captured Carbon:
From Seagrass Meadows to the Deep Sea
Katsuyuki Abo, Koichi Sugimatsu, Masakazu Hori, Goro Yoshida,
Hiromori Shimabukuro, Hiroshi Yagi, Akiyoshi Nakayama,
and Kenji Tarutani
Abstract To help evaluate the sequestration and carbon dioxide storage function of
seagrass meadows, we describe the processes by which carbon is sequestered in
eelgrass beds and transported from shallow coastal waters to the deep sea. A part of
the carbon taken up by eelgrass is decomposed and returned to biological production or the water column’s dissolved inorganic carbon pool, some is accumulated
and stored in the shallow sea bottom, and the rest flows out into the deep sea. Here,
we describe the growth of eelgrasses and the processes of decomposition, sedimentation, and transportation of eelgrass-derived organic carbon using the Seto Inland
Sea as a model site. We estimated the amount of carbon sequestered and stored in
eelgrass beds, the fate of eelgrass-derived organic carbon, and the amounts accumulated in the shallow coastal water and transported to the deep sea. According to our
estimates based on calculations from tracking carbon over a 1-year period, of the
73,000 tons of carbon sequestered by eelgrass annually in the Seto Inland Sea,
40.9% is accumulated in the Seto Inland Sea and 8.3% flows out to the deep sea. In
other words, the eelgrass beds in the Seto Inland Sea have an annual potential capacity of 36,000 tons of carbon storage. In addition, most of the organic carbon was
accumulated in the shallow coastal waters rather than in the deep sea.
K. Abo (*) · M. Hori · G. Yoshida · H. Shimabukuro
National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries
Research and Education Agency, Hatsukaichi, Hiroshima, Japan
e-mail: abo@fra.affrc.go.jp
K. Sugimatsu
National Research Institute of Fisheries Engineering, Fisheries Research Agency,
Kamisu, Ibaraki, Japan
H. Yagi
School of Systems Engineering, National Defense Academy, Yokosuka, Japan
A. Nakayama
Alpha Hydraulic Engineering Consultants Co. Ltd., Chuoh-ku, Tokyo, Japan
K. Tarutani
Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki, Japan