Viral dynamics in two trophically different areas in the Central Adriatic Sea

Abstract

To understand the activity of marine viruses, experiments on viral production, viral decay and the percentage of lytic and lysogenic bacterial cells among the total number of bacterial cells were carried out seasonally at two stations in the Adriatic Sea with different trophic conditions. Additionally, we are providing an insight on the enrichment with dissolved and particulate organic matter by viral lysis in the studied area. Viral production was higher at the coastal station than at the open-sea station. Viral decay rates were also higher at the coastal sea station than at the open-sea station, and accounted for approximately 40% of viral production at both investigated stations. The percentage of lysogenic infection was lower than that of lytical infection, which indicates the prevalence of the lytic cycle at both stations. Viruses had a significant influence on bacterial mortality through high daily removal of the bacterial standing stock at the coastal and open-sea station. The viruses contributed to the restoration of dissolved organic carbon, nitrogen and phosphorus in the microbial loop by lysing the bacterial cells at the studied stations. All the above suggest that viruses are important in the microbial food web and an important factor in the control of bacterial populations within the study area.

Assessment of Explicit Representation of Dynamic Viral Processes in Regional Marine Ecological Models

“…Using the current scheme and parameters of our viral module, the model simulated viral decay rates of 13.7% ± 0.7% d −1 and 8.3% ± 0.7% d −1 in the surface and subsurface layers at HOT, respectively, while the rates were 40.6% ± 7.8% d −1 and 20.1% ± 2.9% d −1 at AS. These decay rates at AS were generally comparable to the observations of 39.4% ± 5.0% d −1 measured in the western Pacific Ocean [63], 43.9% ± 10.2% d −1 in the Central Adriatic Sea [34], 25.4% ± 8.4% d −1 in the North Sea [64] and 70.8% ± 30.1% d −1 in the South China Sea [31]. The low viral decay rates in extremely oligotrophic open oceans such as HOT can be expected because of their low productivity, but there have been no measurements reported in this kind of ocean environment.…”

“…These models, therefore, were largely similar to previous non-virus models in simulating the effects of viruses on other components of marine ecosystems, considering that most non-virus models also assigned constant mortality rates to the simulated bacteria. The viral infection rates of hosts, and subsequently the VMM rates, are highly variable [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ] and can be impacted by the abundance of viruses and hosts, the temperature and nutrients [ 36 ]. As a first-order estimation, the rate of viral infection depends on the contact rate between the viruses and hosts [ 37 ] and thus can be assumed to be proportional to the product of viral and host abundances [ 38 ].…”

Changes in the Trophic Pathways within the Microbial Food Web in the Global Warming Scenario: An Experimental Study in the Adriatic Sea

“…), nutrient availability, grazing, and viral lysis [11][12][13]. It is well-established that temperature significantly influences microbiological processes such as production [14], growth rate [15,16], and growth efficiency [17], as well as grazing on bacteria [9,18,19] and viral lysis [20][21][22][23]. However, these processes have shown different sensitivity to temperature increases, which ultimately determines how the microbial community will respond to warming [24,25].…”

Temperature and phosphorus interacts in controlling the picoplankton carbon flux in the Adriatic Sea: an experimental versus field study

“…Edwards and Richardson, 2004;Wiltshire et al, 2008;Montoya and Raffaelli, 2010). It is well established that temperature significantly influences microbiological processes such as production (Rivkin et al, 1996;Hoppe et al, 2008;Šoli c et al, 2018a), growth rate (White et al, 1991;Shiah and Ducklow, 1994) and growth efficiency (Rivkin and Legendre, 2001), as well as grazing on bacteria (Vaqué et al, 1994;Krstulovi c, 1994, 1995;Vázquez-Dominguez et al, 2012) and viral lysis (Danovaro et al, 2011;Lara et al, 2013;Maranger et al, 2015;Tsai et al, 2015;Ordulj et al, 2017). Furthermore, temperature influences the complex microbial trophic interactions, altering food web structure and ecosystem functioning (Petchey et al, 1999).…”