Influence of ocean acidification on plankton community structure during a winter-to-summer succession: An imaging approach indicates that copepods can benefit from elevated CO2 via indirect food web effects

Taucher, J., Haunost, M., Boxhammer, T., Bach, L. T., Algueró-Muñiz, M. and Riebesell, U. (2017) Influence of ocean acidification on plankton community structure during a winter-to-summer succession: An imaging approach indicates that copepods can benefit from elevated CO2 via indirect food web effects. PLoS ONE, 12(2), e0169737. (doi: 10.1371/journal.pone.0169737) (PMID:28178268) (PMCID:PMC5298333)

Abstract

Plankton communities play a key role in the marine food web and are expected to be highly sensitive to ongoing environmental change. Oceanic uptake of anthropogenic carbon dioxide (CO2) causes pronounced shifts in marine carbonate chemistry and a decrease in seawater pH. These changes–summarized by the term ocean acidification (OA)–can significantly affect the physiology of planktonic organisms. However, studies on the response of entire plankton communities to OA, which also include indirect effects via food-web interactions, are still relatively rare. Thus, it is presently unclear how OA could affect the functioning of entire ecosystems and biogeochemical element cycles. In this study, we report from a long-term in situ mesocosm experiment, where we investigated the response of natural plankton communities in temperate waters (Gullmarfjord, Sweden) to elevated CO2 concentrations and OA as expected for the end of the century (~760 μatm pCO2). Based on a plankton-imaging approach, we examined size structure, community composition and food web characteristics of the whole plankton assemblage, ranging from picoplankton to mesozooplankton, during an entire winter-to-summer succession. The plankton imaging system revealed pronounced temporal changes in the size structure of the copepod community over the course of the plankton bloom. The observed shift towards smaller individuals resulted in an overall decrease of copepod biomass by 25%, despite increasing numerical abundances. Furthermore, we observed distinct effects of elevated CO2 on biomass and size structure of the entire plankton community. Notably, the biomass of copepods, dominated by Pseudocalanus acuspes, displayed a tendency towards elevated biomass by up to 30–40% under simulated ocean acidification. This effect was significant for certain copepod size classes and was most likely driven by CO2-stimulated responses of primary producers and a complex interplay of trophic interactions that allowed this CO2 effect to propagate up the food web. Such OA-induced shifts in plankton community structure could have far-reaching consequences for food-web interactions, biomass transfer to higher trophic levels and biogeochemical cycling of marine ecosystems.

• Item Type: Articles
• Additional Information: Funding: This work was supported by the German Federal Ministry of Science and Education (BMBF): BIOACID II project (FKZ 03F06550) https://www. bmbf.de (all authors); Leibniz Award 2012 by the German Science Foundation (DFG) (UR); Swedish Academy of Sciences (MAM).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Alguero-Muniz, Dr Maria
• Authors: Taucher, J., Haunost, M., Boxhammer, T., Bach, L. T., Algueró-Muñiz, M., and Riebesell, U.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• Published Online: 08 February 2017
• Copyright Holders: Copyright © 2017 Taucher et a
• First Published: First published in PLoS ONE 12(2): e0169737
• Publisher Policy: Reproduced under a Creative Commons License