Biogeosciences, 8, 973-985, 2011
www.biogeosciences.net/8/973/2011/
doi:10.5194/bg-8-973-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea
D. Lamy1,2,*, C. Jeanthon3,4, M. T. Cottrell5, D. L. Kirchman5, F. Van Wambeke6, J. Ras7, O. Dahan3,4, M. Pujo-Pay1,2, L. Oriol1,2, L. Bariat2,8, P. Catala1,2, V. Cornet-Barthaux9, and P. Lebaron1,2
1INSU-CNRS, UMR 7621, Laboratoire d'Océanographie Microbienne, LOMIC, Observatoire Océanologique de Banyuls, 66651 Banyuls-sur-mer, France
2UPMC Univ Paris 06, Observatoire Océanologique de Banyuls, 66651 Banyuls-sur-mer, France
3UPMC Univ Paris 06, UMR 7144, Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, 29680 Roscoff, France
4INSU-CNRS, Observatoire Océanologique, UMR 7144, Groupe Plancton Océanique, Station Biologique, 29680 Roscoff, France
5School of Marine Science and Policy, University of Delaware, Lewes, Delaware 19958, USA
6INSU-CNRS, Université de la Méditerranée, UMR 6117, LMGEM, Laboratoire de Microbiologie, Géochimie et Ecologie Marines, Centre d'Océanologie de Marseille, Campus de Luminy, Case 901, 13288 Marseille cedex 9, France
7Laboratoire d'Océanographie de Villefranche-sur-mer, UMR 7093, CNRS, Université Pierre et Marie Curie, Villefranche-sur-mer Cedex, France
8CNRS, UMS 2348, Observatoire Océanologique de Banyuls, 66651 Banyuls-sur-mer, France
9Laboratoire d'Océanographie Physique et Biogéochimique (LOPB), UMR 6535, CNRS-IRD-Université de la Méditerranée, Centre d'Océanologie de Marseille, Campus de Luminy, Case 901, 13288 Cedex 09 Marseille, France
*present address: University of Vienna, Department of Marine Biology, Althanstrasse 14, 1090 Vienna, Austria

Abstract. Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic prokaryotes able to use both light and organic substrates for energy production. They are widely distributed in coastal and oceanic environments and may contribute significantly to the carbon cycle in the upper ocean. To better understand questions regarding links between the ecology of these photoheterotrophic bacteria and the trophic status of water masses, we examined their horizontal and vertical distribution and the effects of nutrient additions on their growth along an oligotrophic gradient in the Mediterranean Sea. Concentrations of bacteriochlorophyll-a (BChl-a) and AAP bacterial abundance decreased from the western to the eastern basin of the Mediterranean Sea and were linked with concentrations of chlorophyll-a, nutrient and dissolved organic carbon. Inorganic nutrient and glucose additions to surface seawater samples along the oligotrophic gradient revealed that AAP bacteria were nitrogen- and carbon-limited in the ultraoligotrophic eastern basin. The intensity of the AAP bacterial growth response generally differed from that of the total bacterial growth response. BChl-a quota of AAP bacterial communities was significantly higher in the eastern basin than in the western basin, suggesting that reliance on phototrophy varied along the oligotrophic gradient and that nutrient and/or carbon limitation favors BChl-a synthesis.

Citation: Lamy, D., Jeanthon, C., Cottrell, M. T., Kirchman, D. L., Van Wambeke, F., Ras, J., Dahan, O., Pujo-Pay, M., Oriol, L., Bariat, L., Catala, P., Cornet-Barthaux, V., and Lebaron, P.: Ecology of aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea, Biogeosciences, 8, 973-985, doi:10.5194/bg-8-973-2011, 2011.
 
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