Temporal distribution of viruses, bacteria and phytoplankton throughout the water column in a freshwater hypereutrophic lake

Abstract

Analytical flow cytometry (AFC) and denaturing gradient gel electrophoresis (DGGE) were used to investigate the diversity and dynamics of viruses, bacteria and phytoplankton communities in a hypereutrophic freshwater lake. Samples were taken from different depths throughout the water column over an annual cycle. Priest Pot is a small lake in the Lake District in NW England (UK), and has been well characterised in previous studies; however, little is known of the diversity and dynamics of the virus community. Virus abundance was shown to change over both spatial and temporal scales, and appeared to be closely linked to other biotic and abiotic parameters. The highest virus concentrations occurred in the deepest part of the lake at a depth of 3.2 m, in the anoxic layer, at the same time as a peak of abundance of green sulphur bacteria. Sequence analysis of a DGGE band that occurred at the same time suggested a bacterium similar to Chlorobium spp., a green sulphur bacterium, comprised part of this bacterial bloom.

Stratification of the microbial community inhabiting an anchialine sinkhole

“…Neither population exhibited detectable orange fluorescence, characteristic of Synechococcus or Synechocystis-type cyanobacteria, and their cell size was comparable to pico-eukaryotic phytoplankton populations often identified in seawater and lake samples (Olson et al 1989, Goddard et al 2005.…”

“…A dense body of literature has examined the spatial distributions of zooplankton, phytoplankton, bacteria and viruses within lake systems and has demonstrated the re-occurrence of stratification of planktonic abundance, community composition and activity, which occurs in concomitance with a variety of biophysical parameters (e.g. Gasol et al 1991, Weinbauer & Hofle 1998, Goddard et al 2005. Anchialine systems, however, often incorporate unique physicochemical characteristics, including polymodal oxygen profiles (Humphreys 1999) possibly generated by the subterranean tidal influx of marine waters, and the manner that microbial populations are distributed and interact within these complex physical settings is virtually unknown.…”

Seasonal patterns of viral, microbial and planktonic communities in Sidi Salem: a freshwater reservoir (North of Tunisia)

“…Based on side scatter and green DNA dye complex fluorescence, FCM data allowed us to distinguish three Chen et al, 2001;Jacquet et al, 2002;Goddard et al, 2005;Duhamel and Jacquet, 2006). The abundance of VLP1 was higher than the abundance of VLP2 and also than the abundance of VLP3.…”

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“…Abiotic components include geography, lake landscape position, hydrology (drainage or seepage lake classification), seasonal and weather events, trophic status, mixing regime, and clarity (Yannarell and Triplett 2005). Biotic factors may include competition and trophic interactions Newton et al 2006), or the effect of virioplankton (Goddard et al 2005). These forces vary in relative importance at different spatial and temporal scales.…”