Inorganic carbon fluxes and perturbations by ocean acidification estimated using a data-constrained, process-based model of coral physiology

Recognition that ocean acidification (OA) alters calcification rates in many tropical corals and photosynthetic processes in some has motivated research into coral’s carbon processing systems. Here, a multi-compartment coral model is used to assess inorganic carbon fluxes, accounting for carbon upta...

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Bibliographic Details
Published in:Marine biology 2021-07, Vol.168 (7), Article 116
Main Authors: Tansik, Anna L., Hopkinson, Brian M., Meile, Christof
Format: Article
Language:English
Subjects:
Acidification
Algae
Aragonite
Biomedical and Life Sciences
Calcification
Carbon
Carbon dioxide
Carbonic anhydrase
Carbonic anhydrases
Constraints
Corals
Dissolved inorganic carbon
Environmental aspects
Fluxes
Freshwater & Marine Ecology
Life Sciences
Marine & Freshwater Sciences
Marine biology
Microbiology
Ocean acidification
Oceanography
Original Paper
Perturbation
pH effects
Photosynthesis
Saturation
Seawater
Symbionts
Tissue
Transport
Tropical climate
Uptake
Zoology
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Summary:Recognition that ocean acidification (OA) alters calcification rates in many tropical corals and photosynthetic processes in some has motivated research into coral’s carbon processing systems. Here, a multi-compartment coral model is used to assess inorganic carbon fluxes, accounting for carbon uptake, photosynthesis, transport across and between coral tissue and calcification. The increased complexity of this model is enabled by incorporating recent measurements of carbonic anhydrase activity and dissolved inorganic carbon (DIC) related photosynthetic parameters, allowing the model to respond to changes in external inorganic carbon chemistry. The model reproduced measured gross photosynthesis, calcification rates and calcifying fluid pH from Orbicella faveolata at current oceanic conditions. Model simulations representing OA conditions showed an increase in net photosynthesis and modest decreases in calcification which fall within trends seen in experimental data. Photosynthesis increased due to higher diffusive influx of CO 2 into the oral tissue layers, increasing DIC where symbiotic algae reside. The model suggests that decreases in calcification result from increased fluxes of CO 2 into the calcifying fluid from the aboral tissue layer and the bulk seawater, lowering its pH and reducing the aragonite saturation state. However, modeled pH drops in the calcifying fluid exceed those observed, pointing to the need for additional empirical constraints on DIC fluxes associated with calcification and coelenteron transport.
ISSN:0025-3162
1432-1793
DOI:10.1007/s00227-021-03926-8