Frequency of dividing cells and viability of Microcystis aeruginosa in sediment of a eutrophic reservoir

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 36:117-122 (2004) - doi:10.3354/ame036117 Frequency of dividing cells and viability of Microcystis aeruginosa in sediment of a eutrophic reservoir Delphine Latour*, Hervé Giraudet, Jean-Louis Berthon Laboratoire de Biologie Animale et Appliquée, Université Jean Monnet, 23 rue Paul Michelon, 42023 Saint-Etienne Cedex 2, France *Email: delphine.latour@univ-st-etienne.fr ABSTRACT: Blooms of Microcystis aeruginosa occurred in summer months for several years in the reservoir of Grangent (France). Disappearance of planktonic colonies in autumn does not necessarily mean the end of the life cycle for cyanobacteria, and part of them sink down to the sediment. Frequency of dividing cells (FDC) of benthic M. aeruginosa was measured under experimental hypolimnetic conditions in winter and in spring (darkness and temperature = 4 or 8°C) to show overwintering survival and difference between seasons. Enzymatic activity (viability) of benthic cyanobacteria was controlled in situ in winter and spring. Our study revealed that in winter (4°C), benthic colonies continued to divide, with low FDC (mean % = 13.49) and low enzymatic activity (mean ratio carboxyfluorescein diacetate [CFDA] fluorescence:autofluorescence = 1.27). In contrast, when temperature increased in spring (8°C), the viability values significantly increased (mean ratio = 3.78), and a rhythmic increase of FDC appeared every 8 h with maximum of ca. 27.5%. This corresponds to an ultradian rhythm of division, which provides strong evidence that benthic cells were under the control of an endogenous component synchronized by an internal clock. Our results suggest that hypolimnetic temperature plays an important role in the return of the active form of M. aeruginosa in spring. KEY WORDS: Benthic cyanobacteria · Microcystis aeruginosa · Cell division · Enzymatic activity Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 36, No. 2. Online publication date: July 21, 2004 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2004 Inter-Research.