Warming and CO2 enrichment drive contrasting CO2-concentrating mechanism responses in two Mediterranean marine macrophytes
Abstract
Mixed meadows of the seagrass Cymodocea nodosa and the green macroalga Caulerpa prolifera are commonly found in Mediterranean coastlines. These two marine macrophytes are increasingly exposed to ocean warming and increased dissolved CO2 conditions, but how the interactive effects of these stressors remodel their photosynthetic physiology remains poorly resolved. We conducted a 15-day full factorial flow-through microcosm experiment crossing two temperatures (25 and 30 °C) with two CO2 concentrations (400 and 1000 ppm), to analyse the responses in growth, photophysiology and operation of their biophysical CO2-concentrating mechanisms (CCMs). The two species operated fundamentally different CCMs, with proton extrusion coupled to extracellular carbonic anhydrases as the major CCM component in C. nodosa, and anion-exchange HCO3- transport in C. prolifera. Warming was the main driver of the reorganization of CCM components in both species, whereas elevated CO2 had comparatively minor effects on the individual components. Notably, combined warming and elevated CO2 interactively restored several CCM components of the seagrass to control levels, suggesting that CO2 enrichment did not deactivate CCMs. Warming stimulated net photosynthesis and leaf elongation in C. nodosa whereas in C. prolifera neither warming nor elevated CO2 significantly modified net photosynthesis or rhizoid elongation, and the additional fronds formed under warming did not translate into biomass gain. These divergent physiological trajectories, observed under microcosm conditions after a 15-day incubation, suggest that near-future climate conditions may favour the ecophysiological performance of the seagrass over that of the macroalga in co-occurring Mediterranean meadows.
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BibTeX
@article{capobauca2026warming,
title = {{Warming and CO2 enrichment drive contrasting CO2-concentrating mechanism responses in two Mediterranean marine macrophytes}},
author = {Sebastià Capó-Bauçà and Concepción Iñiguez and Pere Aguiló-Nicolau and Jeroni Galmés},
journal = {Frontiers in Plant Science},
year = {2026},
month = nov,
doi = {10.3389/fpls.2026.1958510},
url = {https://www.frontiersin.org/articles/10.3389/fpls.2026.1958510},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Warming and CO2 enrichment drive contrasting CO2-concentrating mechanism responses in two Mediterranean marine macrophytes
AU - Sebastià Capó-Bauçà
AU - Concepción Iñiguez
AU - Pere Aguiló-Nicolau
AU - Jeroni Galmés
PY - 2026
DA - 2026/11/05
JO - Frontiers in Plant Science
DO - 10.3389/fpls.2026.1958510
UR - https://www.frontiersin.org/articles/10.3389/fpls.2026.1958510
AB - Mixed meadows of the seagrass Cymodocea nodosa and the green macroalga Caulerpa prolifera are commonly found in Mediterranean coastlines. These two marine macrophytes are increasingly exposed to ocean warming and increased dissolved CO2 conditions, but how the interactive effects of these stressors remodel their photosynthetic physiology remains poorly resolved. We conducted a 15-day full factorial flow-through microcosm experiment crossing two temperatures (25 and 30 °C) with two CO2 concentrations (400 and 1000 ppm), to analyse the responses in growth, photophysiology and operation of their biophysical CO2-concentrating mechanisms (CCMs). The two species operated fundamentally different CCMs, with proton extrusion coupled to extracellular carbonic anhydrases as the major CCM component in C. nodosa, and anion-exchange HCO3- transport in C. prolifera. Warming was the main driver of the reorganization of CCM components in both species, whereas elevated CO2 had comparatively minor effects on the individual components. Notably, combined warming and elevated CO2 interactively restored several CCM components of the seagrass to control levels, suggesting that CO2 enrichment did not deactivate CCMs. Warming stimulated net photosynthesis and leaf elongation in C. nodosa whereas in C. prolifera neither warming nor elevated CO2 significantly modified net photosynthesis or rhizoid elongation, and the additional fronds formed under warming did not translate into biomass gain. These divergent physiological trajectories, observed under microcosm conditions after a 15-day incubation, suggest that near-future climate conditions may favour the ecophysiological performance of the seagrass over that of the macroalga in co-occurring Mediterranean meadows.
SN - 1664-462X
ER -