AME 62:153-163 (2011)  -  doi:10.3354/ame01467

Seasonal dynamics of aerobic anoxygenic phototrophs in a Mediterranean coastal lagoon

D. Lamy1,2,5,*, P. De Carvalho-Maalouf1,2,6, M. T. Cottrell3, R. Lami1,2, P. Catala1,2, L. Oriol1,2, J. Caparros1,2, J. Ras4, D. L. Kirchman3, P. Lebaron1,2

1UPMC Univ Paris 06, Observatoire Océanologique de Banyuls, 66650 Banyuls-sur-mer, France
2CNRS, UMR 7621, Laboratoire d’Océanographie Microbienne, LOMIC, Observatoire Océanologique de Banyuls,
66650 Banyuls-sur-mer, France
3School of Marine Science and Policy, University of Delaware, Lewes, Delaware 19958, USA
4Laboratoire d’Océanographie de Villefranche-sur-mer, UMR 7093 CNRS et Université Pierre et Marie Curie, Villefranche-sur-mer Cedex, France
5Present address: University of Vienna, Department of Marine Biology, Althanstrasse 14, 1090 Vienna, Austria
6Present address: Centre d’Ingénierie des Protéines, Institut de Chimie, B6, Université de Liège, 4000 Liège, Belgium

ABSTRACT: Aerobic anoxygenic phototrophic (AAnP) bacteria are bacteriochlorophyll a (BChl a)-containing prokaryotes that can use both dissolved organic matter and light as energy sources. AAnP bacteria are widely distributed in aquatic environments where they are expected to play an important role in carbon cycling. However, little is known about their spatio-temporal distribution in marine ecosystems. In this study we examined the dynamics of AAnP bacteria in a coastal saline lagoon from November 2007 to September 2008. AAnP cells were enumerated by infrared (IR) microscopy, and BChl a concentrations were measured by both IR kinetic fluorometry and high-performance liquid chromatography (HPLC). The distribution of AAnP bacteria varied seasonally, but no clear spatial pattern emerged. The abundance of these bacteria ranged from 1.0 to 13.5 × 104 cells ml–1 from winter to summer, comprising 0.1 to 3% of total bacterial abundance. Size fractionation of the BChl a fluorescence signal showed that AAnP bacteria were mainly particle-attached in winter and free-living in spring and summer. BChl a concentrations (up to 108.7 ng l–1), BChl a content per cell (up to 1.7 fg cell–1) and the ratios of BChl a to chlorophyll a (chl a) (up to 15%) were high in spring and summer, suggesting that AAnP bacteria contributed significantly at this time to photosynthetically driven energy production in the lagoon. Temperature and light were the main factors driving seasonal variations in the abundance of AAnP bacteria, while total bacterial abundance was closely related to variations in the concentration of dissolved organic carbon. These results highlight for the first time the numerical importance and the dynamics of AAnP bacteria in a coastal lagoon.

KEY WORDS:  Aerobic anoxygenic phototrophic bacteria · AAnP · Photoheterotrophy · Bacteriochlorophyll a · Seasonal dynamics · Coastal lagoon

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Cite this article as: Lamy D, De Carvalho-Maalouf P, Cottrell MT, Lami R and others (2011) Seasonal dynamics of aerobic anoxygenic phototrophs in a Mediterranean coastal lagoon. Aquat Microb Ecol 62:153-163

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