AB 22:43-57 (2014)  -  DOI: https://doi.org/10.3354/ab00606

ABSTRACT: We conducted a microcosm experiment aimed at studying the interactive effects of high CO₂, nutrient loading and irradiance on the metabolism of a planktonic community sampled in the Western Mediterranean near the coast of Málaga. Changes in the metabolism of phytoplankton and bacterioplankton were observed for 7 d under 8 treatment conditions, representing the full factorial combinations of 2 levels each of CO₂, nutrient concentration and solar radiation exposure. The initial plankton sample was collected at the surface from a stratified water column, indicating that phytoplankton were naturally acclimated to high irradiance and low nutrient concentrations. Nutrient addition combined with high irradiance resulted in a significant increase in primary production. Nitrate uptake by phytoplankton was also stimulated under high nutrient conditions. High nutrients, high irradiance and the combination of low CO₂ and high irradiance positively affected bacterial production. Light was the main factor affecting the respiration rates of the community, which were higher at the high light level. After 7 d of incubation, nutrient loading was the only factor that significantly affected the amount of particulate organic carbon (POC) accumulated in the microcosms. Therefore, the changes in metabolic rates produced at high CO₂ had no effect on net production of particulate organic matter. If these results are extrapolated to the natural environment, it could be hypothesized that high levels of CO₂ will have a limited impact on biological pump activity in the northern Alboran Sea since it is assumed that POC export towards deeper layers determines the potential for carbon sequestration.

KEY WORDS: Acidification · Bacterioplankton · Nutrients · Phytoplankton · Primary productivity · Respiration · UVR

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Cite this article as: Mercado JM, Sobrino C, Neale PJ, Segovia M and others (2014) Effect of CO2, nutrients and light on coastal plankton. II. Metabolic rates. Aquat Biol 22:43-57. https://doi.org/10.3354/ab00606 Export citation Share:    Facebook - - linkedIn