TY - JOUR
T1 - Seaweed forests are carbon sinks that may help mitigate CO2 emissions
T2 - a comment on Gallagher et al. (2022)
AU - Filbee-Dexter, Karen
AU - Pessarrodona, Albert
AU - Duarte, Carlos M.
AU - Krause-Jensen, Dorte
AU - Hancke, Kasper
AU - Smale, Daniel
AU - Wernberg, Thomas
PY - 2023/8
Y1 - 2023/8
N2 - Recently, Gallagher et al. (2022) suggested that seaweed ecosystems are net heterotrophic carbon sources due to CO2 released from the consumption of external subsidies. Here we outline several flaws in their argument, which we believe confuse research on the blue carbon potential of seaweed ecosystems, and unjustifiably generate doubt around initiatives to protect and restore seaweed forests. Gallagher et al.'s evidence relies on 18 studies with highly variable measures of net ecosystem production, which do not statistically support their conclusion that most seaweed ecosystems are heterotrophic. This dataset is also inappropriate as it is incomplete and misrepresents seaweed ecosystems globally, particularly seaweed forests, which contribute disproportionately to global seaweed productivity. We maintain that the climate change mitigation value of an ecosystem depends on the net difference in CO2 uptake between the original ecosystem and its replacement ecosystem. We provide evidence that most seaweed ecosystems, which drawdown the largest carbon flux of any vegetated coastal habitat, are indeed net autotrophic ecosystems. We recognize that substantial uncertainties remain concerning the magnitude of CO2 drawdown by seaweed ecosystems and recommend that carbon fluxes around seaweed ecosystems should be considered more broadly and taken into account in estimates of their CO2 mitigation potential.
AB - Recently, Gallagher et al. (2022) suggested that seaweed ecosystems are net heterotrophic carbon sources due to CO2 released from the consumption of external subsidies. Here we outline several flaws in their argument, which we believe confuse research on the blue carbon potential of seaweed ecosystems, and unjustifiably generate doubt around initiatives to protect and restore seaweed forests. Gallagher et al.'s evidence relies on 18 studies with highly variable measures of net ecosystem production, which do not statistically support their conclusion that most seaweed ecosystems are heterotrophic. This dataset is also inappropriate as it is incomplete and misrepresents seaweed ecosystems globally, particularly seaweed forests, which contribute disproportionately to global seaweed productivity. We maintain that the climate change mitigation value of an ecosystem depends on the net difference in CO2 uptake between the original ecosystem and its replacement ecosystem. We provide evidence that most seaweed ecosystems, which drawdown the largest carbon flux of any vegetated coastal habitat, are indeed net autotrophic ecosystems. We recognize that substantial uncertainties remain concerning the magnitude of CO2 drawdown by seaweed ecosystems and recommend that carbon fluxes around seaweed ecosystems should be considered more broadly and taken into account in estimates of their CO2 mitigation potential.
KW - blue carbon
KW - carbon dioxide removal
KW - net ecosystem productivity
KW - respiration
KW - seaweed
KW - seaweed forest
UR - http://www.scopus.com/inward/record.url?scp=85168674968&partnerID=8YFLogxK
U2 - 10.1093/icesjms/fsad107
DO - 10.1093/icesjms/fsad107
M3 - Journal article
AN - SCOPUS:85168674968
SN - 1054-3139
VL - 80
SP - 1814
EP - 1819
JO - ICES Journal of Marine Science
JF - ICES Journal of Marine Science
IS - 6
ER -