Microbial Ecology

, Volume 54, Issue 2, pp 217–231

Diel and Seasonal Variations in Abundance, Activity, and Community Structure of Particle-Attached and Free-Living Bacteria in NW Mediterranean Sea

Authors

    • Observatoire Océanographique de Banyuls, Laboratoire d’Océanographie BiologiqueUniversité Pierre et Marie Curie-Paris6, Institut National des Sciences de l’Univers (INSU), CNRS (UMR 7621)
  • G. Mevel
    • Station Biologique de RoscoffUniversité Pierre et Marie Curie-Paris6, Institut National des Sciences de l’Univers (INSU), CNRS (UMR 7144)
  • M. Pujo-Pay
    • Observatoire Océanographique de Banyuls, Laboratoire d’Océanographie BiologiqueUniversité Pierre et Marie Curie-Paris6, Institut National des Sciences de l’Univers (INSU), CNRS (UMR 7621)
  • L. Mousseau
    • Observatoire Océanologique de Villefranche-sur-merUniversité Pierre et Marie Curie-Paris6, Institut National des Sciences de l’Univers (INSU), CNRS (UMR 7093)
  • P. Lebaron
    • Observatoire Océanographique de Banyuls, Laboratoire d’Océanographie BiologiqueUniversité Pierre et Marie Curie-Paris6, Institut National des Sciences de l’Univers (INSU), CNRS (UMR 7621)
  • M. Goutx
    • Laboratoire de Microbiologie, Géochimie et Ecologie MarinesUniversité de la Méditerranée, Centre d’Océanologie de Marseille, CNRS (UMR 6117)
Article

DOI: 10.1007/s00248-006-9189-7

Cite this article as:
Ghiglione, J.F., Mevel, G., Pujo-Pay, M. et al. Microb Ecol (2007) 54: 217. doi:10.1007/s00248-006-9189-7

Abstract

Diel and seasonal variations in abundance, activity, and structure of particle-attached vs free-living bacterial communities were investigated in offshore NW Mediterranean Sea (0–1000 m). Attached bacteria were always less abundant and less diverse but generally more active than free-living bacteria. The most important finding of this study was that the activity of attached bacteria showed pronounced diel variations in the upper mixed water column with higher activities at night. Under mesotrophic conditions, the contribution of attached bacteria to total bacterial activity increased from less than 10% at day time to 83% at night time. At high chlorophyll a concentration, the highest cell-specific activities and contribution to total bacterial activity were due to free-living bacteria at day and to attached bacteria at night. Under summer oligotrophic conditions, free-living bacteria dominated and contributed to the most important part of the bacterial activity at both day and night, whereas attached bacteria were much less abundant but presented the highest cell-specific activities. These diel and seasonal variations in activities were concomitant to changes in bacterial community structure, mainly in the upper layer. The number of attached ribotypes was fairly constant suggesting that particles are colonized by a relatively limited number of ubiquitous ribotypes. Most of these ribotypes were also free-living ribotypes suggesting that attached bacteria probably originate from colonization of newly formed particles by free-living bacteria in the upper layer. These results reinforce the biogeochemical role of attached bacteria in the cycling of particulate organic carbon in the NW Mediterranean Sea and the importance of diel variability in these processes.

Copyright information

© Springer Science+Business Media, LLC 2007