AME 64:135-147 (2011)  -  DOI: https://doi.org/10.3354/ame01511

Low water column nitrogen fixation in the Mediterranean Sea: basin-wide experimental evidence

Nona S. R. Agawin1,*, Antonio Tovar-Sanchez2, Lucas J. Stal3,4, Marta Alvarez2,5, Susana Agustí2, Carlos M. Duarte2

1Interdisciplinary Ecology Group, Biology Department, Universidad de las Islas Baleares, 07122 Palma de Mallorca, Spain
2Department of Global Change Research, IMEDEA (UIB-CSIC), Instituto Mediterraneo de Estudios Avanzados, 07190 Esporles, Mallorca, Spain
3Department of Marine Microbiology, Netherlands Institute of Ecology (NIOO KNAW), Yerseke, The Netherlands
4Department of Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
5Present address: IEO, Centro de A Coruña, Apdo. 130, 15080, A Coruña, Spain
*Email:

ABSTRACT: The abundance and nitrogen fixation rates of Trichodesmium sp. integrated down to the deep chlorophyll maximum as well as nitrogen fixation rates in size-fractionated discrete surface water samples were measured across the Mediterranean Sea. The abundance of Trichodesmium sp. was generally low (<50 trichomes m–3), except at one station in the Tyrrhenian Sea where the water temperature was >20°C and Trichodesmium sp. was present at a higher density (ca. 700 trichomes m–3). Across the basin, size-fractionated nitrogen fixation rates were low (<250 nmol N2 m–3 h–1). The highest rate was measured at a station characterized by relatively high concentrations of total ­dissolved P and dissolved Fe. High δ15N values (8.04 ± 2.03‰) of the particulate organic nitrogen were in accordance with the observed low water column nitrogen fixation rates across the Mediterranean Sea.


KEY WORDS: Nitrogen fixation · Trichodesmium sp. · Mediterranean Sea


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Cite this article as: Agawin NSR, Tovar-Sanchez A, Stal LJ, Alvarez M, Agustí S, Duarte CM (2011) Low water column nitrogen fixation in the Mediterranean Sea: basin-wide experimental evidence. Aquat Microb Ecol 64:135-147. https://doi.org/10.3354/ame01511

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