Microbial Ecology

, Volume 48, Issue 1, pp 103–110

Productivity and Growth of a Natural Population of the Smallest Free-Living Eukaryote under Nitrogen Deficiency and Sufficiency

  • E. Fouilland
  • C. Descolas-Gros
  • C. Courties
  • Y. Collos
  • A. Vaquer
  • A. Gasc
Article

DOI: 10.1007/s00248-003-2035-2

Cite this article as:
Fouilland, E., Descolas-Gros, C., Courties, C. et al. Microb Ecol (2004) 48: 103. doi:10.1007/s00248-003-2035-2

Abstract

The influence of dissolved inorganic nitrogen (DIN) enrichments on cell-normalized carbon uptake rate, chlorophyll a content, and apparent cell size of a picoeukaryote (<1 μm) (Ostreococcus tauri, the smallest eukaryotic cell) from a natural summer phytoplanktonic assemblage (<200 μm) in a northern Mediterranean Lagoon (Thau Lagoon) was studied in 20-L enclosures in June 1995. The natural planktonic community was incubated in situ for 24 h with initial ammonium and nitrate enrichments and compared to a control without enrichment. O. tauri cell-normalized productivity was estimated from the combination of flow cytometric (FCM) enumeration and 2-h (radioactive) carbonate incorporation measured on post-incubation size fractions (<1μm). No difference between the effects of the two DIN sources of enrichment on the studied biological parameters was measured during this experiment. Growth of natural O. tauri was perturbed by the low DIN availability in the control with drastic changes in cell productivity, chlorophyll content, and cell cycle (from the variations in apparent cell size) as compared to the DIN sufficiency conditions. On the other hand, a very high specific growth rate for natural O. tauri, up to 8 day−1 under DIN enrichments, has been estimated from production and abundance data obtained during this experiment. This supports values measured in culture and suggests that the yearly high contribution of picophytoplankton to the total primary production in Thau Lagoon is likely to be due to their high growth rate rather than the previously suggested lack of grazing pressure.

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • E. Fouilland
    • 1
    • 3
  • C. Descolas-Gros
    • 1
    • 4
  • C. Courties
    • 1
    • 5
  • Y. Collos
    • 1
    • 6
  • A. Vaquer
    • 1
    • 6
  • A. Gasc
    • 2
    • 7
  1. 1.Laboratoire d’Hydrobiologie Marine et ContinentaleUMR 5556 CNRS, Université Montpellier IIMontpellier Cedex 05France
  2. 2.Station IFREMERLaboratoire EcologieFrance
  3. 3.The Scottish Association for Marine ScienceDunstaffnage Marine LaboratoryDunbeg, ArgyllUK
  4. 4.ISEM PaléoenvironnementsUMR 5554 CNRSMontpellierFrance
  5. 5.Laboratoire Modèles en Biologie Cellulaire et IntégréeUMR CNRS 7628Banyuls-sur-merFrance
  6. 6.Ecosystèmes LagunairesUMR 5119 CNRSMontpellierFrance
  7. 7.The Oceanic InstituteU.S.A.