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Competitive fitness of a predominant pelagic calcifier impaired by ocean acidification

journal contribution
posted on 2023-05-20, 05:16 authored by Riebesell, U, Lennart BachLennart Bach, Bellerby, RGJ, Monsalve, JRB, Boxhammer, T, Czerny, J, Larsen, A, Ludwig, A, Schulz, KG

Coccolithophores—single-celled calcifying phytoplankton—are an important group of marine primary producers and the dominant builders of calcium carbonate globally. Coccolithophores form extensive blooms and increase the density and sinking speed of organic matter via calcium carbonate ballasting. Thereby, they play a key role in the marine carbon cycle. Coccolithophore physiological responses to experimental ocean acidification have ranged from moderate stimulation to substantial decline in growth and calcification rates, combined with enhanced malformation of their calcite platelets. Here we report on a mesocosm experiment conducted in a Norwegian fjord in which we exposed a natural plankton community to a wide range of CO2-induced ocean acidification, to test whether these physiological responses affect the ecological success of coccolithophore populations. Under high-CO2 treatments, Emiliania huxleyi, the most abundant and productive coccolithophore species, declined in population size during the pre-bloom period and lost the ability to form blooms. As a result, particle sinking velocities declined by up to 30% and sedimented organic matter was reduced by up to 25% relative to controls. There were also strong reductions in seawater concentrations of the climate-active compound dimethylsulfide in CO2-enriched mesocosms. We conclude that ocean acidification can lower calcifying phytoplankton productivity, potentially creating a positive feedback to the climate system.


Publication title

Nature Geoscience








Institute for Marine and Antarctic Studies


Nature Publishing Group

Place of publication

United Kingdom

Rights statement

Copyright 2017 Macmillan Publishers Limited, part of Springer Nature

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Expanding knowledge in the earth sciences

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