Seasonal Variation of Virioplankton in a Eutrophic Shallow Lake

Abstract

Lake Donghu is a typical eutrophic freshwater lake in which high abundance of planktonic viruses was recently revealed. In this study, seasonal variation of planktonic viruses were observed at three different trophic sites, hypertrophic, eutrophic, and mesotrophic regions, and the correlation between their abundances and other aquatic environmental components, such as bacterioplankton, chlorophyll a, burst size, pH, dissolved oxygen, and temperature, was analyzed for the period of an year. Virioplankton abundance detected by transmission electron microscope (TEM) ranged from 5.48 Â 10 8 to 2.04 Â 10 9 ml )1 in all the sites throughout the study, and the high abundances and seasonal variations of planktonic viruses were related to the trophic status at the sampled sites in Lake Donghu. Their annual mean abundances were, the highest at the hypertrophic site (1.23Â10 9 ml )1 ), medium at the eutrophic site (1.19Â10 9 ml )1 ), and the lowest at the mesotrophic site (1.02Â10 9 ml )1 ). The VBR (virus-to-bacteria ratio) values were high, ranging from 49 to 56 on average at the three sampled sites. The data suggested that the high viral abundance and high VBR values might be associated with high density of phytoplankton including algae and cyanobacteria in this eutrophic shallow lake, and that planktonic viruses are important members of freshwater ecosystems.

Spatial and temporal dynamics of virioplankton in a high mountain tropical reservoir, El Neusa (Cundinamarca, Colombia)

“…The VPR values observed here were slightly higher than the average range described for continental environments (20-25;Maranger & Bird, 1995;Wommack & Colwell, 2000), and possibly similar to those reported in some systems with mesotrophic to eutrophic conditions, where a strong viral control has been attributed by a high rate of contact between viral particles and hosts (Bettarel et al, 2003;Weinbauer, 2004;Liu et al, 2006;Almeida et al, 2015). Thus, the trophic status or sporadic events of enrichment may promote the growth rates and/or the increase in biovolume of the host cell community, which in turn influence positively the assembly of viral particles and the burst size (Weinbauer & Höfle, 1998;Middelboe, 2000;Choi et al, 2003).…”

“…The VLP values from El Neusa reservoir were within the same order of magnitude as those observed in lentic ecosystems of temperate and tropical latitudes with different trophic states, especially those with moderate to high levels of nutrients and biological productivity (Wilhelm & Smith, 2000;Bettarel et al, 2003;Liu et al, 2006;De Araújo & Godinho, 2009;Ram et al, 2011;Hardbower et al, 2012;Almeida et al, 2015). However, the variability of this study was relatively higher than in other studies, probably due to differences in temporal and spatial scales of the sampling design.…”

The under‐ice microbiome of seasonally frozen lakes

“…Virus densities are typically lower under ice and during the winter months (Liu et al 2006) but in some cases are equivalent to virus densities reported in warmer seasons (Filippini et al 2008;Lymer et al 2008;Wilhelm and Matteson 2008). Some studies have found that the virus to bacteria ratio can even be higher in winter than in summer (Filippini et al 2008).…”

Optimization of viral profiling approaches reveals strong links between viral and bacterial communities in a eutrophic freshwater lake

“…While several studies have found viral abundance in freshwater lakes to be strongly correlated to chl a levels (Madan et al 2005, Liu et al 2006, Tijdens et al 2008, other studies have found viral abundance in certain lakes (Personnic et al 2009, Cheng et al 2010) and many marine systems (Maranger & Bird 1995) to be significantly correlated with bacterial abundance. These differences could indicate differences in the dominance of certain types of virioplankton (bacteriophages vs. cyanophages or algal viruses, for example) among different ecosystems.…”