Viruses in Marine Planktonic Systems

Fuhrman, Jed A.; Suttle, Curtis A.

doi:10.5670/oceanog.1993.14

Cited by 280 publications

(226 citation statements)

References 41 publications

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“…Proctor and Fuhrman [37] 1991-1993 Estimates of virus abundance exceeding bacteria abundance by 5-10 fold from a series of papers (this observation noted in Fuhrman and Suttle [25])…”

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Re-examination of the relationship between marine virus and microbial cell abundances

et al. 2016

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Marine viruses are critical drivers of ocean biogeochemistry and their abundances vary spatiotemporally in the global oceans, with upper estimates exceeding 10 8 per ml. Over many years, a consensus has emerged that virus abundances are typically 10-fold higher than prokaryote abundances. The use of a fixed-ratio suggests that the relationship between virus and prokaryote abundances is both predictable and linear. However, the true explanatory power of a linear relationship and its robustness across diverse ocean environments is unclear. Here, we compile 5671 prokaryote and virus abundance estimates from 25 distinct marine surveys to characterize the relationship between virus and prokaryote abundances. We find that the median virus-to-prokaryote ratio (VPR) is 10:1 and 16:1 in the near-and sub-surface oceans, respectively. Nonetheless, we observe substantial variation in the VPR and find either no or limited explanatory power using fixed-ratio models. Instead, virus abundances are better described as nonlinear, power-law functions of prokaryote abundances -particularly when considering relationships within distinct marine surveys. Estimated power-laws have scaling exponents that are typically less than 1, signifying that the VPR decreases with prokaryote density, rather than remaining fixed. The emergence of power-law scaling presents a challenge for mechanistic models seeking to understand the ecological causes and consequences of marine virusmicrobe interactions. Such power-law scaling also implies that efforts to average viral effects on microbial mortality and biogeochemical cycles using "representative" abundances or abundanceratios need to be refined if they are to be utilized to make quantitative predictions at regional or global ocean scales.

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“…Proctor and Fuhrman [37] 1991-1993 Estimates of virus abundance exceeding bacteria abundance by 5-10 fold from a series of papers (this observation noted in Fuhrman and Suttle [25])…”

mentioning

confidence: 99%

“…Cochlan et al [17], Hara et al [26], Paul et al [34,35], Wommack et al [58] 1995 Maranger and Bird [31] survey 22 Quebec lakes and collect literature from 14 studies [4, 5, 7, 17, 26-28, 34, 41, 51, 58] and report VBR higher in freshwater (20)(21)(22)(23)(24)(25) than marine systems (1-5).…”

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confidence: 99%

Re-examination of the relationship between marine virus and microbial cell abundances

et al. 2016

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“…Mortality increased in parallel with the cell division rate, and as a result Prochlorococcus abundance did not increase following iron fertilization. We assume that mortality was probably dominated by microzooplankton grazing , as direct losses due to sinking would be minimal for such small cells (Pedros-Alio et al 1989), and the importance of viral lysis in mortality is unclear (Fuhrman and Suttle 1993;Waterbury and Valois 1993). Cell number data from midnight to 1650 and 0645 h to 1730 were used to calculate the mortality rates of 1.0 and 1.7 d Ϫ1 in the site survey and in the iron patch, respectively.…”

Section: Resultsmentioning

confidence: 99%

Iron limits the cell division rate of Prochlorococcus in the eastern equatorial Pacific

Mann

Chisholm

2000

Limnology & Oceanography

120

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Prochlorococcus, a small unicellular cyanobacterium, is an important member of the phytoplankton community in the eastern equatorial Pacific. When these waters were enriched with iron during IronEx II, the chlorophyll per cell and cell size of Prochlorococcus increased, implying that they were iron limited. The extent of this limitation was unclear, however, and the number of Prochlorococcus remained constant. To examine whether cell division rates were stimulated significantly by iron, we used a cell cycle analysis approach to measure them in and out of the Fe-enriched patch and in Fe-enriched bottles. The cell division rate increased from 0.6 to 1.1 d Ϫ1 over 6 d of exposure to the elevated iron concentrations in the patch. Cells incubated in bottles with additional iron had rates of 1.4 d Ϫ1 or two doublings per day. Prochlorococcus mortality rates, measured independently, nearly doubled after the addition of iron. This matched the increase in the cell division rate and maintained a relatively constant population size. Thus the cell division rates of even the smallest phytoplankton in the equatorial Pacific are significantly iron limited, but biomass is constrained by both iron limitation and microzooplankton grazing. The differential response of individual phytoplankton groups to the addition of iron during IronEx II was at least partially a result of differential mortality rates over the time course of the experiment. How the community would respond to sustained fertilization, however, is not obvious.Nitrate and phosphate concentrations are persistently high in the euphotic zone of the equatorial Pacific, and phytoplankton biomass and productivity are lower than expected based on nutrient availability (Cullen 1991;Frost and Franzen 1992). The phytoplankton community is dominated by small picoplankton (Chavez 1989), which have a large surface area to volume ratio and are less likely to be diffusion limited by either nutrients or trace metals than larger cells (Morel et al. 1991a). Measured cell division rates are often 0.5 d Ϫ1 or higher, both for the phytoplankton community as a whole (Barber and Chavez 1991;Chavez et al. 1991;Cullen 1991;Cullen et al. 1992;Landry et al. 1995;Verity et al. 1996;Latasa et al. 1997;Lindley and Barber 1998) and for the small cyanobacterium Prochlorococcus (DuRand 1995;Landry et al. 1995;Vaulot et al. 1995;Binder et al. 1996;Latasa et al. 1997;Liu et al. 1997; Vaulot and Dom-1 Corresponding author (chisholm@mit.edu). AcknowledgementsWe thank the captain and crew of the RV Melville, as well as Kenneth Coale and the Moss Landing IronEx group, for making the experiment possible. We also thank R. Michael Gordon for iron concentration measurements, and Richard Barber, William Cochlan, Michael R. Landry, and Makoto Saito for sharing unpublished data. Comments by J. Cullen, P. Falkowski, and an anonymous reviewer helped improve the manuscript.

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“…Models and empirical studies demonstrate that viral lysis can be a significant contributor to the flux of dissolved organic matter (DOM) from biomass in marine systems (Fuhrman 1992, Fuhrman & Suttle 1993, Fuhrman & Noble 1995. Changes in nutrient portioning (Middelboe et al 1996) and the DOM pool have been discussed as possible biogeochemical impacts of viral lysis.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of incubation-based methods for estimating virioplankton production in estuaries

Helton¹,

Cottrell²,

Kirchman³

et al. 2005

Aquat. Microb. Ecol.

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Assessment of the role of viral lysis in aquatic microbial communities requires a robust means of estimating viral production (VP). Here, 3 incubation-based VP methods (fluorescently labeled viruses [FLV], dilution [DIL], and thymidine incorporation [TdR]) were evaluated in water samples from the Delaware and Chesapeake Bays. In Chesapeake Bay samples, average VP rates were 10-fold higher for FLV and DIL (~3 to 25 × 10 10 viruses l -1 d -1 ) than for TdR (~0.2 to 3 × 10 10 viruses l -1 d -1 ). Estimates of viral-mediated bacterial mortality (VMM) indicate that FLV overestimates VP in eutrophic waters, since >100% of bacterial production (BP) would have been consumed through viral lysis. DIL and TdR VP methods gave more realistic estimates of VMM with respect to BP. The FLV method provides estimates of both VP and virus removal rates; however, it requires preparation of a viral tracer and twice as many microscopic enumerations as the DIL method. DIL was the least difficult and most efficient method; however, bacterial loss during vacuum diafiltration resulted in poor replicability. TdR gave similar VP estimates to DIL, but requires use of a large and poorly constrained conversion factor. With methodological improvements in bacterial cell recovery, DIL should be the most widely applicable method for estimation of VP in highly productive estuarine waters. KEY WORDS: Viral production · Bacteriophage · Marine viruses · Marine microbial ecologyResale or republication not permitted without written consent of the publisher

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Viruses in Marine Planktonic Systems

Cited by 280 publications

References 41 publications

Re-examination of the relationship between marine virus and microbial cell abundances

Re-examination of the relationship between marine virus and microbial cell abundances

Iron limits the cell division rate of Prochlorococcus in the eastern equatorial Pacific

Evaluation of incubation-based methods for estimating virioplankton production in estuaries

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