AB 22:25-41 (2014)  -  DOI: https://doi.org/10.3354/ab00587

Effect of CO2, nutrients and light on coastal plankton. I. Abiotic conditions and biological responses

P. J. Neale1,*, C. Sobrino2, M. Segovia3, J. M. Mercado4, P. Leon4, M. D. Cortés4, P. Tuite4, A. Picazo5, S. Salles4, M. J. Cabrerizo6, O. Prasil7, V. Montecino8, A. Reul3, A. Fuentes-Lema2

1Smithsonian Environmental Research Center, Edgewater, Maryland 21037, USA
2Department of Ecology and Animal Biology, Faculty of Sciences, University of Vigo, 36310 Vigo, Spain
3Department of Ecology, Faculty of Sciences, University of Málaga, 29071 Málaga, Spain
4Centro Oceanográfico de Málaga, Instituto Español de Oceanografía, 29640 Fuengirola, Málaga, Spain
5Departamento de Microbiología y Ecología (Siberia II), Instituto Cavanilles de Biodiversidad y Biología Evolutiva (ICBiBE), Universidad de Valencia, 46100 Burjassot (Valencia), Spain
6Department of Ecology, Faculty of Sciences, University of Granada, 18071 Granada, Spain
7Laboratory of Photosynthesis, Center Algatech, Institute of Microbiology ASCR, 37981 Trebon, Czech Republic
8Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653 Santiago, Chile
*Corresponding author:

ABSTRACT: We report on results of a microcosm experiment to study the interactive effects of elevated CO2, high organic and inorganic nutrient loading, and high irradiance on phytoplankton and bacterioplankton from the Mediterranean coastal ecosystem of the Alboran Sea. This experiment was part of the Group for Aquatic Productivity 9th international workshop and was conducted by Working Group 1 (WG1: Phytoplankton of coastal waters, www.gap9.uma.es). Over a 7 d period, we measured the variation in physical and chemical variables and the characteristics of phytoplankton and bacterioplankton in microcosms incubated under 8 treatments, representing full factorial combinations of 2 levels each of CO2 supply, nutrient concentrations and solar radiation exposure. For each treatment combination, we incubated triplicate microcosms consisting of 20 l polyethylene bags which were transparent to ultraviolet radiation. Sustained growth of phytoplankton biomass (chl a) occurred in all treatments. The absence of mesozooplankton in the microcosms resulted in a trophic cascade. Picophytoplankton were initially stimulated but then decreased, apparently due to microzooplankton grazing, and were largely replaced by diatoms. Bacteria were also initially stimulated and then decreased, but eventually recovered. Responses were modified markedly by nutrient enrichment and light availability, with moderate effects of elevated CO2. Relative to ambient CO2, elevated CO2 resulted in higher chl a under low irradiance, but lower chl a under high irradiance.

KEY WORDS: Phytoplankton · Bacterioplankton · CO2 · Ultraviolet radiation · Nutrients · Multiple stressors · Microcosm · Trophic cascade

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Cite this article as: Neale PJ, Sobrino C, Segovia M, Mercado JM and others (2014) Effect of CO2, nutrients and light on coastal plankton. I. Abiotic conditions and biological responses. Aquat Biol 22:25-41. https://doi.org/10.3354/ab00587

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