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130035 - Responses of macroalgae to CO2 enrichment cannot be inferred solely.pdf (1.33 MB)

Responses of macroalgae to CO2 enrichment cannot be inferred solely from their inorganic carbon uptake strategy

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journal contribution
posted on 2023-05-19, 23:40 authored by van der Loos, LM, Matthias SchmidMatthias Schmid, Leal, PP, McGraw, CM, Damon BrittonDamon Britton, Revill, AT, Patti VirtuePatti Virtue, Peter Nichols, Catriona HurdCatriona Hurd

Increased plant biomass is observed in terrestrial systems due to rising levels of atmospheric CO2, but responses of marine macroalgae to CO2 enrichment are unclear. The 200% increase in CO2 by 2100 is predicted to enhance the productivity of fleshy macroalgae that acquire inorganic carbon solely as CO2 (non‐carbon dioxide‐concentrating mechanism [CCM] species—i.e., species without a carbon dioxide‐concentrating mechanism), whereas those that additionally uptake bicarbonate (CCM species) are predicted to respond neutrally or positively depending on their affinity for bicarbonate. Previous studies, however, show that fleshy macroalgae exhibit a broad variety of responses to CO2 enrichment and the underlying mechanisms are largely unknown. This physiological study compared the responses of a CCM species (Lomentaria australis) with a non‐CCM species (Craspedocarpus ramentaceus) to CO2 enrichment with regards to growth, net photosynthesis, and biochemistry. Contrary to expectations, there was no enrichment effect for the non‐CCM species, whereas the CCM species had a twofold greater growth rate, likely driven by a downregulation of the energetically costly CCM(s). This saved energy was invested into new growth rather than storage lipids and fatty acids. In addition, we conducted a comprehensive literature synthesis to examine the extent to which the growth and photosynthetic responses of fleshy macroalgae to elevated CO2 are related to their carbon acquisition strategies. Findings highlight that the responses of macroalgae to CO2 enrichment cannot be inferred solely from their carbon uptake strategy, and targeted physiological experiments on a wider range of species are needed to better predict responses of macroalgae to future oceanic change.

History

Publication title

Ecology and Evolution

Volume

9

Pagination

125-140

ISSN

2045-7758

Department/School

Institute for Marine and Antarctic Studies

Publisher

John Wiley & Sons Ltd.

Place of publication

United Kingdom

Rights statement

Copyright 2018 The Authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

Repository Status

  • Open

Socio-economic Objectives

Ecosystem adaptation to climate change; Expanding knowledge in the biological sciences