Diel and daily fluctuations in virioplankton production in coastal ecosystems

Abstract

SummaryViruses saturate the world around us, yet a basic understanding of how viral impacts on microbial host organisms vary over days to hours, which typify the replication cycles of aquatic viruses, remains elusive. Thus, diel patterns of viral production (VP) in Chesapeake Bay surface waters were examined on five sampling dates. Day-to-day variations in VP in the Chesapeake and coastal California surface waters were also investigated. Significant variations in VP were detected over 24 h cycles during four of five studies, but rates did not vary significantly over the course of a few days in either location. Diel patterns of VP displayed seasonality with shorter viral assemblage turnover times and shorter times to maximum viral abundance in summer, implying shorter replication cycles for virus-host systems in warmer months. No correlation was found between VP and time of day, likely due to seasonal changes in the diel patterns of VP. This analysis significantly increases our knowledge of the short-term patterning of in situ VP, and thus viral impacts, and suggests that variations in viral biology in response to changes in host communities or physio-chemical properties affect both diel and seasonal cycles and magnitudes of VP.

Bacterial Growth and Mortality after Deposition of Saharan Dust and Mixed Aerosols in the Eastern Mediterranean Sea: A Mesocosm Experiment

“…During the time of increased bacterial growth, low levels of %BP-VIR were measured in A and SD. Initial levels for VPlytic and %BP-VIR were in agreement with published data for the Mediterranean Sea (Bettarel et al, 2002;Boras et al, 2009) and other coastal systems (Winget and Wommack, 2009). At T1, VPlytic was particularly low in A and SD, and, while it still fell within the published range for the oligotrophic Northwestern Mediterranean (Boras et al, 2009), it was lower than anticipated FIGURE 4 | Frequency of lytically infected cells (% FLIC, A) and lysogenic cells (% FLC, B) in the different treatments at T-1, T1, T4 and T8.…”

“…Viruses do not all have the same latent period and the possibility that lysis did not occur during the incubation or occurred during a long time interval (e.g., between 12 and 24 h) cannot be excluded. Winget and Wommack (2009) found that maximum VLP abundance was recorded at different times between spring and winter in coastal-system incubations. Cell death or inactivation due to intense light conditions at the sampling time and area may have also contributed to low VPlytic.…”

“…The high bacterial production in A and SD further led to the estimation of exceptionally low %BP-VIR, which is among the lowest published levels for coastal systems (Winget and Wommack, 2009). For the calculation of %BP-VIR we used an average burst size value for the Mediterranean Sea (Weinbauer et al, 2003a).…”

Coral Mucus Is a Hot Spot for Viral Infections

“…Strong interactions between viruses and bacterial diversity have been previously evidenced under both natural and experimental conditions (67)(68)(69)(70). Here, the frequent occurrence of lysogenic and lytic infections in coral mucus (compared with the water column) could then be also partially responsible for the temporal variability of BCS, as shown by the Mantel test and the positive and significant correlation detected between this parameter and the abundance of mucosal viruses in F. repanda (Table 4).…”

Viral and microbial community dynamics in four aquatic environments

“…Most such studies have focused on artificial experimental systems that contain only one, or at most two, virus/host pairs, with a few recent reports exploring natural environments (Chen et al, 2009;Short and Short, 2009;Winget and Wommack, 2009). However, to the best of our knowledge, no one has previously studied the dynamics of these interactions over time in complex communities at a depth comparable to that provided by this study.…”