Viral-Mediated Microbe Mortality Modulated by Ocean Acidification and Eutrophication: Consequences for the Carbon Fluxes Through the Microbial Food Web.

Autor:	Malits A; Biological Oceanography Laboratory, Austral Center for Scientific Research (CONICET), Ushuaia, Argentina.; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Boras JA; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Balagué V; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Calvo E; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Gasol JM; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain.; Center for Marine Ecosystems Research, School of Sciences, Edith Cowan University, Joondalup, WA, Australia., Marrasé C; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Pelejero C; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain.; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain., Pinhassi J; Centre for Ecology and Evolution in Microbial Model Systems, Linnaeus University, Kalmar, Sweden., Sala MM; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain., Vaqué D; Department of Marine Biology and Oceanography, Institut de Ciències del Mar (CSIC), Barcelona, Spain.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2021 Apr 14; Vol. 12, pp. 635821. Date of Electronic Publication: 2021 Apr 14 (Print Publication: 2021).
DOI:	10.3389/fmicb.2021.635821
Abstrakt:	Anthropogenic carbon emissions are causing changes in seawater carbonate chemistry including a decline in the pH of the oceans. While its aftermath for calcifying microbes has been widely studied, the effect of ocean acidification (OA) on marine viruses and their microbial hosts is controversial, and even more in combination with another anthropogenic stressor, i.e., human-induced nutrient loads. In this study, two mesocosm acidification experiments with Mediterranean waters from different seasons revealed distinct effects of OA on viruses and viral-mediated prokaryotic mortality depending on the trophic state and the successional stage of the plankton community. In the winter bloom situation, low fluorescence viruses, the most abundant virus-like particle (VLP) subpopulation comprising mostly bacteriophages, were negatively affected by lowered pH with nutrient addition, while the bacterial host abundance was stimulated. High fluorescence viruses, containing cyanophages, were stimulated by OA regardless of the nutrient conditions, while cyanobacteria of the genus Synechococcus were negatively affected by OA. Moreover, the abundance of very high fluorescence viruses infecting small haptophytes tended to be lower under acidification while their putative hosts' abundance was enhanced, suggesting a direct and negative effect of OA on viral-host interactions. In the oligotrophic summer situation, we found a stimulating effect of OA on total viral abundance and the viral populations, suggesting a cascading effect of the elevated p CO 2 stimulating autotrophic and heterotrophic production. In winter, viral lysis accounted for 30 ± 16% of the loss of bacterial standing stock per day (VMM BSS ) under increased p CO 2 compared to 53 ± 35% in the control treatments, without effects of nutrient additions while in summer, OA had no significant effects on VMM BSS (35 ± 20% and 38 ± 5% per day in the OA and control treatments, respectively). We found that phage production and resulting organic carbon release rates significantly reduced under OA in the nutrient replete winter situation, but it was also observed that high nutrient loads lowered the negative effect of OA on viral lysis, suggesting an antagonistic interplay between these two major global ocean stressors in the Anthropocene. In summer, however, viral-mediated carbon release rates were lower and not affected by lowered pH. Eutrophication consistently stimulated viral production regardless of the season or initial conditions. Given the relevant role of viruses for marine carbon cycling and the biological carbon pump, these two anthropogenic stressors may modulate carbon fluxes through their effect on viruses at the base of the pelagic food web in a future global change scenario. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2021 Malits, Boras, Balagué, Calvo, Gasol, Marrasé, Pelejero, Pinhassi, Sala and Vaqué.)
Databáze:	MEDLINE
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