Large viruses in Ross Sea late autumn pack ice habitats

Gowing, Marcia M.; Riggs, Blake E.; Garrison, David L.; Gibson, Angela H.; Jeffries, Martin O.

doi:10.3354/meps241001

Cited by 32 publications

(18 citation statements)

References 39 publications

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“…These high modelled contact rates suggest the possible significance of viruses to the ecology of winter sea ice. Low microbial diversity (as determined for upper horizons of summer sea ice; Junge et al, 2002), increasing the probability that a cell contacted by a virus is a host, and minimal grazing on viruses and bacteria (as concluded for viruses in fall ice; Gowing et al, 2002) could further accentuate that impact. As discussed above, however, the calculated contact rates are based on assumed and poorly known fractions of bacteria (f B ) and viruses (f V ) retained in sea ice following freezing.…”

Section: Modelled Contact Rates In Winter Sea-ice Brine Inclusionsmentioning

confidence: 97%

“…Although little is known about viral ecology in sea ice, some of the highest concentrations of viruses in the ocean have been found in this environment. Maximal densities of 1.0–1.3 × 10 8 viruses ml −1 were reported in Arctic sea ice during spring (numbers scaled to volume of ice sampled; Maranger et al ., 1994) and in Antarctic pack ice during summer and fall (numbers scaled to volume of melted sample; Gowing et al ., 2002; 2004). The physical process of seawater freezing, which initially includes both brine formation and rejection (until the ice becomes generally impermeable below −5°C), is unlikely to account for these high viral concentrations, because they exceed those in underlying seawater by an order of magnitude (Maranger et al ., 1994).…”

Section: Introductionmentioning

confidence: 99%

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Modelled and measured dynamics of viruses in Arctic winter sea‐ice brines

Wells

Deming

2006

Environmental Microbiology

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We describe a model based on diffusion theory and the temperature-dependent mechanism of brine concentration in sea ice to argue that, if viruses partition with bacteria into sea-ice brine inclusions, contact rates between the two can be higher in winter sea ice than in seawater, increasing the probability of infection and possible virus production. To examine this hypothesis, we determined viral and bacterial concentrations in select winter sea-ice horizons using epifluorescence microscopy. Viral concentrations ranged from 1.6 to 82 x 10(6) ml(-1) of brine volume of the ice, with highest values in brines from coldest (-24 to -31 degrees C) ice horizons. Calculated virus-bacteria contact rates in underlying -1 degrees C seawater were similar to those in brines of -11 degrees C ice but up to 600 times lower than those in ice brines at or below -24 degrees C. We then incubated native bacterial and viral assemblages from winter sea ice for 8 days in brine at a temperature (-12 degrees C) and salinity ( approximately 160 psu) near expected in situ values, monitoring their concentrations microscopically. While different cores yielded different results, consistent with known spatial heterogeneity in sea ice, these experiments provided unambiguous evidence for viral persistence and production, as well as for bacterial growth, in -12 degrees C brine.

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Section: Modelled Contact Rates In Winter Sea-ice Brine Inclusionsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Modelled and measured dynamics of viruses in Arctic winter sea‐ice brines

Wells

Deming

2006

Environmental Microbiology

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“…such as chl a measurements). Our studies of ice communities in the Ross Sea have included the consideration of a range of microbial forms from viruses (Gowing et al 2002, Gowing 2003 and bacteria (Stewart et al 2001, Gowing et al 2004) to protists. Here, we describe the community composition of the ice biota in pack ice regions of the Ross Sea during the autumn to winter transition and during the summer.…”

Section: Introductionmentioning

confidence: 99%

Sea-ice microbial communities in the Ross Sea: autumn and summer biota

Garrison¹,

Gibson²,

Coale³

et al. 2005

Mar. Ecol. Prog. Ser.

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The composition of sea ice communities in the Ross Sea region was examined during the autumn to winter transition and during the summer. The biomass of autotrophs and heterotrophs in autumn reached maximum values of 709 and 167 mg C m , respectively. During the autumn-winter cruise, most of the biomass was found within ice floes as interior and bottom layer communities. During summer, surface-layer slush communities occurred throughout the ice-covered regions. The biomass was highly variable throughout the study regions during both cruises. Diatoms dominated the autotrophic biomass; however, autotrophic dinoflagellates and autotrophic flagellates contributed significantly to the community make-up. Among heterotrophs, ciliates predominated during both cruises, followed by heterotrophic flagellates and heterotrophic dinoflagellates. Similarity analysis, based on the biomass composition of major groups, showed consistency between and within cruises, with most samples > 70% similar. The autumn to winter samples (all from within floes) showed higher similarity clusters that could be related to changing compositions of diatoms, ciliates, and autotrophic dinoflagellates. Most variable were some summer surface slush samples, where samples dominated by Phaeocystis, Pyramimonas, Gymnodinium, and the ciliate Gymnozoum formed outlying clusters. The dynamics of ice biota may be determined by relatively few taxa that are persistently found within the ice floes. Surface blooms may develop either from a biota within the ice or from opportunistic forms from the water column that are introduced during flooding events. Thus, these assemblages may show considerably more variability in composition than those that develop within the underlying ice. KEY WORDS: Sea ice community · Antarctic · ProtistsResale or republication not permitted without written consent of the publisher

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“…Studies in the autumn are rare, but the overall bacterial production is low compared to the rest of the year and exceeds that by microalgae (Grossmann and Dieckmann 1994). Grazing seems to be a minor impact, while viruses and phages are enriched 10-100 times (e.g., Gowing et al 2002;Collins and Deming 2011). Knowledge on bacterial and algal diversity and functions are rare, but the community structures seem to differ from the other seasons and are more similar to the seawater below the newly forming sea ice (Collins et al 2010).…”

Section: Autumnmentioning

confidence: 99%

Progress in Microbial Ecology in Ice-Covered Seas

Vonnahme

Dietrich

Hassett

2019

YOUMARES 9 - The Oceans: Our Research, Our Future

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Sea ice seasonally covers 10% of the earth's oceans and shapes global ocean chemistry. The unique physical processes associated with sea ice growth and development shape the associated biological diversity and ecosystem function. Microbes make up the base of all marine food webs and the overwhelming majority of biomass in the sea ice ecosystem. Despite their biomass, microbial processes are not fully integrated into marine ecosystem models. Recent applications of novel molecular biology technologies to studies of marine ecology have elucidated numerous microbial-mediated processes interfaced by previously unknown organisms and processes. These discoveries are yielding more in-depth studies on the relevance of mixotrophy, the ecology of fungi, and the interplay between major microbial clades. In ecosystem studies, the basis of the food web is frequently neglected even though the accessibility of energy, recycling of nutrients, and parasitism are crucial factors shaping the environment for grazers and higher trophic levels. In this review, we focus on the species composition, abundance, and functions of microalgae, bacteria, archaea, fungi, and viruses in the sea ice-covered seas throughout the year. A strong emphasis will be put on advances in molecular methods that empower scientists to further investigate microorganisms in more detail. Since microbes make up the majority of all oceanic biomass, we believe that it is impossible to accurately forecast the biological fate of polar marine ecosystems without placing a proportional emphasis on microbes relative to their biomass.

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Large viruses in Ross Sea late autumn pack ice habitats

Cited by 32 publications

References 39 publications

Modelled and measured dynamics of viruses in Arctic winter sea‐ice brines

Modelled and measured dynamics of viruses in Arctic winter sea‐ice brines

Sea-ice microbial communities in the Ross Sea: autumn and summer biota

Progress in Microbial Ecology in Ice-Covered Seas

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