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Marine Ecology Progress Series

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MEPS 565:17-33 (2017)  -  DOI:

Iron availability modulates the effects of future CO2 levels within the marine planktonic food web

María Segovia1,*, M. Rosario Lorenzo1, María T. Maldonado2, Aud Larsen3, Stella A. Berger4,5, Tatiana M. Tsagaraki4, Francisco J. Lázaro6, Concepción Iñiguez1, Candela García-Gómez1,9, Armando Palma1, Michaela A. Mausz7,10, Francisco J. L. Gordillo1, Jose A. Fernández8, Jessica L. Ray3, Jorun K. Egge

1Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, 29071 Málaga, Spain
2Department of Earth and Ocean and Atmospheric Sciences, University of British Columbia, 2207 Main Mall, Vancouver, BC V6T 1Z4, Canada
3Uni Research Environment and Hjort Centre for Marine Ecosystem Dynamics, Thormøhlensgt 41, 5006 Bergen, Norway
4Department of Biology, Thormøhlensgt 53A/B, University of Bergen, 5020 Bergen, Norway
5Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhütte 2, 16775 Stechlin, Germany
6Department of Science and Technology of Materials and Fluids, University of Zaragoza, María de Luna 3, 50018 Zaragoza, Spain
7Institute of Inorganic and Analytical Chemistry/Bioorganic Analytics, Friedrich Schiller University Jena, 07743 Jena, Germany
8Department of Plant Biology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, 29071 Málaga, Spain
9Present address: Spanish Oceanographic Institute (IEO), Puerto Pesquero, 29640 Fuengirola, Málaga, Spain
10Present address: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
*Corresponding author:

ABSTRACT: Ocean acidification (OA) due to increased anthropogenic CO2 emissions is affecting marine ecosystems at an unprecedented rate, altering biogeochemical cycles. Direct empirical studies on natural communities are required to analyse the interactive effects of multiple stressors while spanning multiple trophic levels. We investigated the interactive effects of changes in CO2 and iron availability on functional plankton groups. We used mesocosms manipulating the carbonate system from the start to achieve present (low concentration, LC) and predicted future pCO2 levels (high concentration, HC). To manipulate dissolved iron (dFe), half of the mesocosms were amended with 70 nM (final concentration) of the siderophore desferoxamine B (DFB) on Day 7 (+DFB and -DFB treatments). Manipulation of both CO2 and DFB increased dFe compared to the control. During the 22 experimental days, the plankton community structure showed 2 distinct phases. In phase 1 (Days 1-10), only bacterioplankton abundances increased at elevated pCO2. In contrast, a strong community response was evident in phase 2 (Days 11-22) due to DFB addition. Biomass of the coccolithophore Emiliania huxleyi increased massively at LC+DFB. HC negatively affected E. huxleyi and Synechococcus sp., and high dFe (+DFB) had a positive effect on both. The rest of the plankton community was unaffected by the treatments. Increased dFe partially mitigated the negative effect of HC imposed on the coccolithophores, indicating that E. huxleyi was able to acclimate better to OA. This physiological iron-mediated acclimation can diminish the deleterious effects of OA on carbon export and the rain ratio, thus affecting food web dynamics and future ecosystem functioning.

KEY WORDS: Global change · Iron · CO2 · Mesocosms · Plankton food web · Emiliania huxleyi · Synechococcus sp.

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Cite this article as: Segovia M, Lorenzo MR, Maldonado MT, Larsen A and others (2017) Iron availability modulates the effects of future CO2 levels within the marine planktonic food web. Mar Ecol Prog Ser 565:17-33.

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