Effects of calcification on air-water CO 2  fluxes in tropical seagrass meadows: A mesocosm experiment

Seagrass meadows deliver a range of ecosystem services, where one of the more important is the capacity to store carbon and serve as sinks for atmospheric carbon dioxide. The capacity of seagrass meadows for carbon storage might, however, be modified and complicated by several factors; one important...

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Bibliographic Details
Published in:Journal of experimental marine biology and ecology 2023, Vol.561
Main Authors: Ismail, Rashid O., Asplund, Maria E., Gullström, Martin, George, Rushingisha, Dahl, Martin, Buriyo, Amelia S., Mtolera, Matern S.P., Björk, Mats
Format: Article
Language:English
Subjects:
Biogeochemistry
biogeokemi
blue carbon
calcification
carbon sinks
climate change mitigation
marin ekologi
marinbiologi
Marine Biology
Marine Ecology
plant community composition
Plant Ecology
Plant Physiology
primary productivity
Seagrass ecosystem
växtekologi
växtfysiologi
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Summary:Seagrass meadows deliver a range of ecosystem services, where one of the more important is the capacity to store carbon and serve as sinks for atmospheric carbon dioxide. The capacity of seagrass meadows for carbon storage might, however, be modified and complicated by several factors; one important factor is the possible effects of calcification within the meadows. In tropical areas, seagrass meadows can contain high proportions of calcareous organisms, which through their calcification may cause release of CO 2 . To study this aspect of the CO 2 balance within tropical seagrass systems, we investigated the air-water CO 2 flux in seagrass mesocosms with different plant community compositions, i.e. mixtures of seagrass and calcifying macroalgae, having similar overall photosynthetic oxygen evolution rates. The measured CO 2 fluxes changed both in rate and direction over the day and were significantly related to plant community composition. Downward fluxes of CO 2 were found only over vegetation with high proportion of seagrass and in the afternoon, whereas occurrence of calcifying algae appeared to reverse the flow. A partial least squares (PLS) regression model indicated that pH, pCO 2 and dissolved inorganic carbon (DIC) were the primary environmental variables predicting the CO 2 fluxes. Our findings show that algal calcification might partly counteract the carbon sequestration in seagrass meadows.
ISSN:1879-1697
0022-0981
DOI:10.1016/j.jembe.2022.151864