Dynamic of Virioplankton Abundance and Its Environmental Control in the Charente Estuary (France)

• Published in: Microbial ecology Vol. 50; no. 3; pp. 337 - 349
• Main Authors: Auguet, J. C., Montanié, H., Delmas, D., Hartmann, H. J., Huet, V.
• Format: Journal Article
• Language: English
• Published: New York, NY Springer Science + Business Media, Inc 01.10.2005; Springer; Springer Nature B.V
• Subjects: Bacteria; Bacteria - isolation & purification; Bacteriology; Bacterioplankton; Biological and medical sciences; Brackish; Ecosystem; Environment, Controlled; Environmental agencies; Environmental control; Estuaries; France; Fundamental and applied biological sciences. Psychology; Microbiology; Microorganisms; Miscellaneous; Mixing processes; Nutrient concentrations; Plankton - isolation & purification; River basins; Rivers - chemistry; Rivers - microbiology; Salinity; Seasons; Summer; Suspended solids; Virology; Viruses; Viruses - isolation & purification; Water Microbiology; Winter; Charente; France; Europe; Poitou Charentes; ANE, France, Poitou-Charentes, Charente Estuary; France, Charente R; Virus; Temperature; Microbiology; Samplings; Pigments; Bacteria; Environment; Ecology; Identification; Microorganism; Chlorophyll a
• ISSN: 0095-3628; 1432-184X
• DOI: 10.1007/s00248-005-0183-2

The Charente River provides nutrient- and virus-rich freshwater input to the Marennes Oléron Basin, the largest oyster-producing region in Europe. To evaluate virioplankton distribution in the Charente Estuary and identify which environmental variables control dynamic of virioplankton abundance, five stations defined by a salinity gradient (0-0.5, 0.6-5, 13-17, 20-24, and higher than 30 PSU) were surveyed over a year. Viral abundance was related to bacterioplankton abundance and activities, photosynthetic pigments, nutrient concentration, and physical parameters (temperature and salinity). On a spatial scale, virus displayed a decreasing pattern seaward with abundance ranging over the sampling period from 1.4 × 10⁷ to 20.8 × 10⁷ viruses mL⁻¹ making virioplankton the most abundant component of planktonic micro-organisms in the Charente Estuary. A good correlation was found between viral and bacterial abundance$(r_{{\rm s}}=0.85)$. Furthermore, bacterial abundance was the most important predictor of viral abundance explaining alone between 66% (winter) and 76% (summer) of viral variability. However, no relation existed between viral abundance and chlorophyll a. Temporal variations in viral distributions were mainly controlled by temperature through the control of bacterial dynamics. Spatial variations of viral abundance were influenced by hydrodynamic conditions especially during the winter season where virioplankton distribution was entirely driven by mixing processes.