Heterotrophic activity and bacterial productivity in assemblages of microbes from sea ice in the high Arctic

Smith, Ralph E. H.; Clément, Pierre

doi:10.1007/bf00237822

Cited by 50 publications

(40 citation statements)

References 40 publications

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“…A Wallac WinSpectral 1414 counter and InstaGel (Perkin-Elmer) cocktail were used in scintillation counting. Bacterial production was calculated using a cell conversion factor of 2.09 × 10 18 cell mol − 1 (Smith and Clement, 1990), a cell volume of 0.3 μm 3 (Kaartokallio, 2004;Smith and Clement, 1990) and a carbon conversion factor of 0.12 pg C μm leucine-based bacterial production was calculated using a factor of 3.0 kg C mol −1 (Bjornsen and Kuparinen, 1991).…”

Section: Bacterial Abundance and Productionmentioning

confidence: 99%

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

et al. 2014

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a b s t r a c t a r t i c l e i n f oWe investigated how physical incorporation, brine dynamics and bacterial activity regulate the distribution of inorganic nutrients and dissolved organic carbon (DOC) in artificial sea ice during a 19-day experiment that included periods of both ice growth and decay. The experiment was performed using two series of mesocosms: the first consisted of seawater and the second consisted of seawater enriched with humic-rich river water. We grew ice by freezing the water at an air temperature of −14°C for 14 days after which ice decay was induced by increasing the air temperature to −1°C. Using the ice temperatures and bulk ice salinities, we derived the brine volume fractions, brine salinities and Rayleigh numbers. The temporal evolution of these physical parameters indicates that there was two main stages in the brine dynamics: bottom convection during ice growth, and brine stratification during ice decay. The major findings are: (1) the incorporation of dissolved compounds (nitrate, nitrite, ammonium, phosphate, silicate, and DOC) into the sea ice was not conservative (relative to salinity) during ice growth. Brine convection clearly influenced the incorporation of the dissolved compounds, since the non-conservative behavior of the dissolved compounds was particularly pronounced in the absence of brine convection. (2) Bacterial activity further regulated nutrient availability in the ice: ammonium and nitrite accumulated as a result of remineralization processes, although bacterial production was too low to induce major changes in DOC concentrations. (3) Different forms of DOC have different properties and hence incorporation efficiencies. In particular, the terrestrially-derived DOC from the river water was less efficiently incorporated into sea ice than the DOC in the seawater. Therefore the main factors regulating the distribution of the dissolved compounds within sea ice are clearly a complex interaction of brine dynamics, biological activity and in the case of dissolved organic matter, the physico-chemical properties of the dissolved constituents themselves.

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Section: Bacterial Abundance and Productionmentioning

confidence: 99%

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

et al. 2014

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“…Aquat Microb Ecol 50: [25][26][27][28][29][30][31][32][33][34][35][36][37][38] 2007 production in landfast sea ice during the spring/summer period (Smith et al 1989, Smith & Clement 1990. In Arctic pack ice or in landfast sea ice during winter, bacteria can be important contributors to total sea-ice carbon biomass, potentially surpassing algal or heterotrophic protist (HP) carbon biomass (Gradinger & Zhang 1997, Gradinger et al 1999a, Kaartokallio 2004.…”

Section: Resale or Republication Not Permitted Without Written Consenmentioning

confidence: 99%

Grazing of large-sized bacteria by sea-ice heterotrophic protists on the Mackenzie Shelf during the winterspring transition

Riedel¹,

Michel²,

Gosselin³

2007

Aquat. Microb. Ecol.

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Heterotrophic bacterial dynamics were assessed in the sea ice and surface waters on the Mackenzie Shelf (Beaufort Sea), from 5 March to 3 May 2004. On 11 occasions, heterotrophic protist bacterivory was assessed from the disappearance of fluorescently labeled bacteria (FLB) in sea-ice samples collected from areas of high and low snow cover. Concurrently, sea-ice and surface water samples were analyzed for dissolved organic carbon (DOC), exopolymeric substances (EPS) and chlorophyll a concentrations, and protist and bacterial abundances. Total bacterial abundances were significantly higher in the sea ice than in surface waters. However, DOC concentrations and abundances of large (≥ 0.7 µm) bacteria were not significantly higher in the sea ice as compared to surface waters. This suggests that DOC was being released from the sea ice, potentially supporting the growth of large-sized bacteria at the ice-water interface. Heterotrophic protist (HP) bacterivory averaged 57% d -1 of large-sized bacterial abundances in the sea ice with ingestion rates averaging 768 and 441 bacteria HP -1 d -1, under high and low snow cover, respectively. High concentrations of EPS during the sea-ice algal bloom may have interfered with the grazing activities of heterotrophic protists as indicated by the significant negative correlations between ingestion rates and EPS-carbon concentrations under high (τ = -0.57, p < 0.05) and low (τ = -0.56, p < 0.05) snow cover. Bacterivory satisfied heterotrophic protist carbon requirements prior to, but not during, the sea-ice algal bloom, under high and low snow cover. EPS may have been an additional carbon source for the heterotrophs, especially during the sea-ice algal bloom period. This study provides evidence of an active heterotrophic microbial food web in first-year sea ice, prior to and during the sea-ice algal bloom. This study also highlights the significance of DOC and EPS as integral components of the microbial food web within the sea ice and surface waters of Arctic shelves. KEY WORDS: Bacteria · FLB · Grazing · DOC · EPS · Sea ice · Arctic Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 50: [25][26][27][28][29][30][31][32][33][34][35][36][37][38] 2007 production in landfast sea ice during the spring/summer period (Smith et al. 1989, Smith & Clement 1990. In Arctic pack ice or in landfast sea ice during winter, bacteria can be important contributors to total sea-ice carbon biomass, potentially surpassing algal or heterotrophic protist (HP) carbon biomass (Gradinger & Zhang 1997, Gradinger et al. 1999a, Kaartokallio 2004. In addition, bacterial secondary production can surpass primary production when sea-ice algae are light limited in thick pack ice (Grossmann & Dieckmann 1994).Bacteria in landfast Arctic sea ice can be much larger than those found in the surface water (Bunch & Harland 1990, Laurion et al. 1995. In addition, sea-ice bacteria in Arctic pack ice appear to be more active than pelagic bacteria (Junge et al. 2002) and ...

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“…Such values are of the same order as those we measured in the superficial waters of Stn 1 (228 nmol C 1-' h-'). Several studies in the Southern Ocean have shown that the melting ice may seed the water column by releasing DOM and nanoplankton and thus, the ice-edge system constitutes an important area for enhanced bacterial activity (Ackley et al 1979, Smith & Clement 1990, Talbot 1995. Similar favourable mechanisms could be considered for the Pacific opening of the Strait of Magellan (Stn l ) , characterized by low salinity and high bacterial activity.…”

Section: 2timentioning

confidence: 99%

Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

Talbot¹,

Giuliano²,

Bruni³

et al. 1997

Mar. Ecol. Prog. Ser.

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Heterotrophic activity and bacterial productivity in assemblages of microbes from sea ice in the high Arctic

Cited by 50 publications

References 40 publications

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

Grazing of large-sized bacteria by sea-ice heterotrophic protists on the Mackenzie Shelf during the winterspring transition

Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

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Heterotrophic activity and bacterial productivity in assemblages of microbes from sea ice in the high Arctic

Cited by 50 publications

References 40 publications

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

Physical and bacterial controls on inorganic nutrients and dissolved organic carbon during a sea ice growth and decay experiment

Grazing of large-sized bacteria by sea-ice heterotrophic protists on the Mackenzie Shelf during the winterspring transition

Bacterial abundance, production and ectoproteolytic activity in the Strait of Magellan

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Grazing of large-sized bacteria by sea-ice heterotrophic protists on the Mackenzie Shelf during the winterspring transition