AB 22:77-93 (2014)  -  DOI: https://doi.org/10.3354/ab00590

Effect of CO2, nutrients and light on coastal plankton. IV. Physiological responses

C. Sobrino1,*, M. Segovia2, P. J. Neale3, J. M. Mercado4, C. García-Gómez2, G. Kulk5, M. R. Lorenzo2, T. Camarena6,7, W. H. van de Poll5, K. Spilling6,7, Z. Ruan8,9

1Department of Ecology and Animal Biology, Faculty of Sciences, University of Vigo, Campus Lagoas-Marcosende s/n, 36310 Vigo, Spain
2Department of Ecology, Faculty of Sciences, University of Málaga, Bulevar Louis Pasteur s/n, 29071 Málaga, Spain
3Smithsonian Environmental Research Center, Edgewater, Maryland 21037, USA
4Spanish Institute of Oceanography, 29640 Fuengirola, Spain
5Department of Ocean Ecosystems, Energy and Sustainability Research Institute Groningen, University of Groningen, 9747 AG Groningen, The Netherlands
6Finnish Environment Institute, Marine Research Center, 00251 Helsinki, Finland
7Tvärminnen Zoological Station, University of Helsinki, 10900 Hanko, Finland
8Marine Biology Institute & Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, Guangdong 515063, China
9Dipartimento di Scienze dell'Ambiente e della Vita, Università Politecnica delle Marche, via Brecce Bianche, 60131 Ancona, Italy
*Corresponding author:

ABSTRACT: We studied the physiological response of phytoplankton to the interacting effects of 3 factors affected by global climate change: CO2, nutrient loading and irradiance. Treatments had a high and low level for each factor: CO2 was bubbled at 1000 ppm by volume versus present atmospheric values; high nutrient treatments had a combination of inorganic and organic nutrients; and light treatments were obtained by covering the tanks with a single or double layer of screen. We measured esterase activity, oxidative stress (ROS), cell death, DNA damage, photosynthetic efficiency and 14C assimilation as particulate or dissolved organic material (POC and DOC respectively). Conditions simulating future global change scenarios showed similar chlorophyll-normalized primary productivity as present conditions. The main effect driving phytoplankton physiology was the downregulation of the photosynthetic apparatus by elevated CO2, which decreased esterase activity, ROS, cell death and DNA damage. Nutrient concentration and light acted as additional modulators, upregulating or contributing to downregulation. The percentage of DO14C extracellular release (PER) was low (0 to 27%), significantly lower under ultraviolet radiation (UVR) than under photosynthetically active radiation (PAR), and acted mainly to re-equilibrate the internal balance when cells grown under UVR were exposed to PAR. PER was almost 3 times lower under high CO2, confirming a higher resource use efficiency of phytoplankton under future CO2 concentrations.

KEY WORDS: CO2 · Downregulation · Nutrients · Microcosms · Photosynthesis · Phytoplankton · Ultraviolet radiation

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Cite this article as: Sobrino C, Segovia M, Neale PJ, Mercado JM and others (2014) Effect of CO2, nutrients and light on coastal plankton. IV. Physiological responses. Aquat Biol 22:77-93. https://doi.org/10.3354/ab00590

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