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133562 - Temperature modulates coccolithophorid sensitivity of growth, photosynthesis.pdf (499 kB)

Temperature modulates coccolithophorid sensitivity of growth, photosynthesis and calcification to increasing seawater pCO2

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posted on 2023-05-20, 05:04 authored by Sett, S, Lennart BachLennart Bach, Schulz, KG, Koch-Klavsen, S, Lebrato, M, Riebesell, U

Increasing atmospheric CO2 concentrations are expected to impact pelagic ecosystem functioning in the near future by driving ocean warming and acidification. While numerous studies have investigated impacts of rising temperature and seawater acidification on planktonic organisms separately, little is presently known on their combined effects. To test for possible synergistic effects we exposed two coccolithophore species, Emiliania huxleyi and Gephyrocapsa oceanica, to a CO2 gradient ranging from ∼0.5–250 µmol kg−1 (i.e. ∼20–6000 µatm pCO2) at three different temperatures (i.e. 10, 15, 20°C for E. huxleyi and 15, 20, 25°C for G. oceanica). Both species showed CO2-dependent optimum-curve responses for growth, photosynthesis and calcification rates at all temperatures. Increased temperature generally enhanced growth and production rates and modified sensitivities of metabolic processes to increasing CO2. CO2 optimum concentrations for growth, calcification, and organic carbon fixation rates were only marginally influenced from low to intermediate temperatures. However, there was a clear optimum shift towards higher CO2 concentrations from intermediate to high temperatures in both species. Our results demonstrate that the CO2 concentration where optimum growth, calcification and carbon fixation rates occur is modulated by temperature. Thus, the response of a coccolithophore strain to ocean acidification at a given temperature can be negative, neutral or positive depending on that strain's temperature optimum. This emphasizes that the cellular responses of coccolithophores to ocean acidification can only be judged accurately when interpreted in the proper eco-physiological context of a given strain or species. Addressing the synergistic effects of changing carbonate chemistry and temperature is an essential step when assessing the success of coccolithophores in the future ocean.

History

Publication title

PLoS ONE

Volume

9

Article number

e88308

Number

e88308

Pagination

1-9

ISSN

1932-6203

Department/School

Institute for Marine and Antarctic Studies

Publisher

Public Library of Science

Place of publication

United States

Rights statement

Copyright 2014 Sett et al. 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

Expanding knowledge in the earth sciences

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