Illustrating the importance of particulate organic matter to pelagic microbial abundance and community structurean Arctic case study

Hodges, Lisa R.; Bano, Nasreen; Hollibaugh, James T.; Yager, Patricia L.

doi:10.3354/ame040217

Cited by 41 publications

(17 citation statements)

References 74 publications

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“…Pre-or postbloom values reported for the Arctic have typically been lower (~5; Yager et al 2001, Middelboe et al 2002. In the present study, correlations of VLP with POC and particle concentrations in bottom samples suggested the importance of particles to VLP dynamics in Arctic winter, as observed in previous Arctic work during summer (Hodges et al 2005) and in other estuaries (Hewson et al 2001). We note that the recent demonstration that virus abundance can decline significantly in formaldehyde-fixed samples (Wen et al 2004) suggests that these viral counts should be considered underestimates.…”

supporting

confidence: 73%

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Wells¹,

Deming²

2006

Aquat. Microb. Ecol.

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Little information is currently available about water column microbial processes or mortality during Arctic winter. To address this paucity, we used epifluorescence microscopy and dilution experiments to determine the abundance of flagellates, bacteria and virus-like particles (VLP) and the rates of bacterial growth, bacterivory and virus-induced mortality in subzero-temperature bottom waters (≤ 230 m) of Franklin Bay during February and March 2004, when ice-covered surface waters were highly oligotrophic (maximum chlorophyll a value of 0.09 µg l -1 ). We focused on bottom waters due to the possible importance of sediment resuspension as a source of organic matter. While flagellates were present at low densities (1.5 to 3.1 × 10 2 ml -1 ), bacterial concentrations resembled those from other seasons in the region and increased over the 5 wk sampling period, from 1.4 × 10 5 to 3.0 × 10 5 ml -1 . VLPs were typically an order of magnitude more abundant than bacteria (range of 1.4 to 4.5 × 10 6 VLP ml -1 ) and, like the fraction of particle-associated bacteria (but not total bacteria), correlated with particulate organic carbon concentration (r s = 0.82, p < 0.04, n = 7). Grazing rates, whether measured in dilution experiments or calculated from flagellate abundance, were low or undetectable (maximum of -0.004 h -1 ). Of 3 parallel experiments, 2 yielded substantial virus-induced mortality (-0.006 to -0.015 h -1 ), comparable to or exceeding the intrinsic bacterial growth rate (0.010 h -1 in both experiments) and suggesting viruses were the more important agents of bacterial mortality under these conditions. Using a viral reduction approach, VLP production measured in the water column or ice-moored sediment traps was commonly low (0.3 to 7.7 × 10 4 VLP ml -1 h -1 ) or undetectable, highly variable among replicates and, when measurable, implied viral turnover times between 0.9 and 12 d. In general, our results show that, despite the oligotrophy of Arctic winter, bottom water bacterial communities can remain active and subject to viral predation.KEY WORDS: Virus · VLP · Lysis · Bacterivory · Arctic · Winter · Franklin Bay · Particles Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 43: [209][210][211][212][213][214][215][216][217][218][219][220][221] 2006 ditions with high (> 50%) virus-induced mortality (Murray & Eldridge 1994). Yet such conditions favor lower concentrations of bacteria and viruses (compared to eutrophic circumstances, e.g. Cochlan et al. 1993, Hewson et al. 2001, correspondingly lower encounter rates (Murray & Jackson 1992), reduced virus production and/or virus-induced mortality , Weinbauer & Peduzzi 1995, Guixa-Boixereu et al. 2002 and, perhaps, a greater likelihood of lysogeny (Weinbauer & Suttle 1999, Weinbauer et al. 2003.Viruses may exert a more subtle influence by generating a relatively labile lysate which, though a small component of DOM, may nonetheless be an important source of organic matter to other microorganisms (Middelboe et ...

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supporting

confidence: 73%

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Wells¹,

Deming²

2006

Aquat. Microb. Ecol.

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“…The abundance of organic aggregates in the polynya system could partly explain high levels of bacterial activity in the ASP despite low observed DOM concentrations, similar to algal blooms in the Chukchi Sea (Yager et al, 2001;Hodges et al, 2005). In the ASP, BP was found to correlate with both PON and POC, and size-fractionation experiments confirmed variable degrees of particle association in open water stations.…”

Section: The Role Of Particlesmentioning

confidence: 68%

Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica

Williams

Dupont

Loevenich

et al. 2016

Elementa: Science of the Anthropocene

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Heterotrophic bacteria play a key role in marine carbon cycling, and understanding their activities in polar systems is important for considering climate change impacts there. One goal of the ASPIRE project was to examine the relationship between the phytoplankton bloom and bacterial heterotrophy in the Amundsen Sea Polynya (ASP). Bacterial abundance, production (BP), respiration, growth efficiency, and extracellular enzyme activity (EEA) were compared to nutrient and organic matter inventories, chlorophyll a (Chl a), viral and microzooplankton abundance, and net primary production (NPP). Bacterial production and respiration clearly responded (0.04-4.0 and 10-53 µg C L −1 d −1 , respectively) to the buildup of a massive Phaeocystis antarctica bloom (Chl a: 0.2-22 µg L −1 ), with highest rates observed in the central polynya where Chl a and particulate organic carbon (POC) were greatest. The highest BP rates exceeded those reported for the Ross Sea or any other Antarctic coastal system, yet the BP:NPP ratio (2.1-9.4%) was relatively low. Bacterial respiration was also high, and growth efficiency (2-27%; median = 10%) was similar to oligotrophic systems. Thus, the integrated bacterial carbon demand (0.8-2.8 g C m −2 d −1 ) was a high fraction (25-128%; median = 43%) of NPP during bloom development. During peak bloom, activity was particle-associated: BP and EEA correlated well with POC, and size fractionation experiments showed that the larger size fraction (> 3 µm) accounted for a majority (∼ 75%) of the BP. The community was psychrophilic, with a 5x reduction in BP when warmed to 20°C. In deeper waters, respiration remained relatively high, likely fueled by the significant downward particle flux in the region. A highly active, particle-associated, heterotrophic microbial community clearly responded to the extraordinary phytoplankton bloom in the ASP, likely limiting biological pump efficiency during the early season.

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“…Laurion et al 1995, Gradinger & Zhang 1997) during spring and summer. High contributions of attached bacteria are known from various marine environments (reviewed in Simon et al 2002) and are important in particulate organic matter degradation, bacterial production (Crump et al 1998) and for overall diversity in bacterial communities (Hodges et al 2005). Bacteria in Arctic and Antarctic sea ice can attach to algae (McGrath Grossi et al 1984, Smith et al 1989, Archer et al 1996, EP (Meiners et al 2004) and ice surfaces (Junge et al 2004).…”

Section: Bacteriamentioning

confidence: 99%

Exopolymer particles: microbial hotspots of enhanced bacterial activity in Arctic fast ice (Chukchi Sea)

Meiners¹,

Krembs²,

Gradinger³

2008

Aquat. Microb. Ecol.

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Sea ice is an important structuring element of Arctic marine ecosystems and provides a vast low-temperature habitat for ice-associated bacteria. While it is now known that sea ice sequesters large amounts of extracellular polymeric substances (EPS) contributing significantly to its particulate organic carbon pool, the ecological role of EPS in sea ice is poorly understood. Using in situ incubations combined with a newly developed triple-staining method (Alcian Blue, DAPI, CTC), we determined the number of CTC-reducing (i.e. actively respiring) sea-ice bacteria living freely or attached to gel-like exopolymer particles. Samples were collected at 6 depths from Chukchi Sea coastal fast ice in April, May and June 2003. Concentrations of exopolymer particles ranged between 1.8 × 10 6 and 149.1 × 10 6 particles l -1 (average 4.7 × 10 6 particles l -1) and showed strong vertical gradients with maximum concentrations at the ice-water interface. Total bacterial numbers (TBN) ranged from 0.18 × 10 9 to 8.48 × 10 9 cells l -1 with an average fraction of 7.4% of actively respiring cells (range 3.0 to 17.2% of TBN). The attached bacterial fraction (range 4.6 to 28.5%, average 15.0% of TBN) showed a significantly, approximately 4 times higher proportion of actively respiring cells (average 19.6%, range 7.8 to 37.6%) when compared to the free-living fraction that had an average of 5.4% (range 1.1 to 11.2%) of actively respiring cells. In conclusion, exopolymer particles in sea ice are microbial hotspots of increased bacterial activity able to foster enhanced biogeochemical cycling.

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Illustrating the importance of particulate organic matter to pelagic microbial abundance and community structurean Arctic case study

Cited by 41 publications

References 74 publications

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica

Exopolymer particles: microbial hotspots of enhanced bacterial activity in Arctic fast ice (Chukchi Sea)

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Illustrating the importance of particulate organic matter to pelagic microbial abundance and community structurean Arctic case study

Cited by 41 publications

References 74 publications

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Significance of bacterivory and viral lysis in bottom waters of Franklin Bay, Canadian Arctic, during winter

Pelagic microbial heterotrophy in response to a highly productive bloom of Phaeocystis antarctica in the Amundsen Sea Polynya, Antarctica

Exopolymer particles: microbial hotspots of enhanced bacterial activity in Arctic fast ice (Chukchi Sea)

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Illustrating the importance of particulate organic matter to pelagic microbial abundance and community structurean Arctic case study