title: Influence of Ocean Acidification on a Natural Winter-to-Summer Plankton Succession: First Insights from a Long-Term Mesocosm Study Draw Attention to Periods of Low Nutrient Concentrations.
abstract: Every year, the oceans absorb about 30% of anthropogenic carbon dioxide (CO2) leading to a re-equilibration of the marine carbonate system and decreasing seawater pH. Today, there is increasing awareness that these changes-summarized by the term ocean acidification (OA)-could differentially affect the competitive ability of marine organisms, thereby provoking a restructuring of marine ecosystems and biogeochemical element cycles. In winter 2013, we deployed ten pelagic mesocosms in the Gullmar Fjord at the Swedish west coast in order to study the effect of OA on plankton ecology and biogeochemistry under close to natural conditions. Five of the ten mesocosms were left unperturbed and served as controls (~380 μatm pCO2), whereas the others were enriched with CO2-saturated water to simulate realistic end-of-the-century carbonate chemistry conditions (~760 μatm pCO2). We ran the experiment for 113 days which allowed us to study the influence of high CO2 on an entire winter-to-summer plankton succession and to investigate the potential of some plankton organisms for evolutionary adaptation to OA in their natural environment. This paper is the first in a PLOS collection and provides a detailed overview on the experimental design, important events, and the key complexities of such a "long-term mesocosm" approach. Furthermore, we analyzed whether simulated end-of-the-century carbonate chemistry conditions could lead to a significant restructuring of the plankton community in the course of the succession. At the level of detail analyzed in this overview paper we found that CO2-induced differences in plankton community composition were non-detectable during most of the succession except for a period where a phytoplankton bloom was fueled by remineralized nutrients. These results indicate: (1) Long-term studies with pelagic ecosystems are necessary to uncover OA-sensitive stages of succession. (2) Plankton communities fueled by regenerated nutrients may be more responsive to changing carbonate chemistry than those having access to high inorganic nutrient concentrations and may deserve particular attention in future studies.
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Lennart T
authors.identifier: http://orcid.org/0000-0003-0202-3671
authors.initials: LT
authors.lastname: Bach
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Taucher
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Boxhammer
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Eric P
authors.initials: EP
authors.lastname: Achterberg
authors.affiliation: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, Helgoland, Germany.
authors.forename: María
authors.initials: M
authors.lastname: Algueró-Muñiz
authors.affiliation: Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Leif G
authors.initials: LG
authors.lastname: Anderson
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.|Ocean and Earth Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Jessica
authors.initials: J
authors.lastname: Bellworthy
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Büdenbender
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Czerny
authors.affiliation: The University Centre in Svalbard (UNIS), Longyearbyen, Norway.
authors.forename: Ylva
authors.initials: Y
authors.lastname: Ericson
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.|Ocean and Earth Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Mario
authors.initials: M
authors.lastname: Esposito
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Fischer
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Haunost
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.|Department of Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Dana
authors.initials: D
authors.lastname: Hellemann
authors.affiliation: Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Biologische Anstalt Helgoland, Helgoland, Germany.
authors.forename: Henriette G
authors.initials: HG
authors.lastname: Horn
authors.affiliation: Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Experimental Limnology, Stechlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Hornick
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Jana
authors.initials: J
authors.lastname: Meyer
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Sswat
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment (ICBM), Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Carl von Ossietzky University, Oldenburg, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Zark
authors.affiliation: GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Riebesell
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010933:Plankton / Q000254:growth & development / Q000378:metabolism*; D012621:Seasons; D012623:Seawater / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide