Microbial Investigations of Surface Microlayers, Water Column, Ice and Sediment in the Arctic Ocean

Dahlbäck, Björn; Gunnarsson, Låh; Hermansson, Malte; Kjelleberg, Staffan

doi:10.3354/meps009101

Cited by 25 publications

(8 citation statements)

References 28 publications

(34 reference statements)

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“…A recent paper by Cho et al (1996) found that urea production by bacteria could account for 35 to 91 % of the estimated nitrogen demand by phytoplankton in the Southern California Bight, USA; such production was also 2 orders of magnitude greater than the rate of urea degradation by bacteria in the same environment. So far as we are aware, the production of urea by bacteria in ice-related environments has not been studied, but there is ample evidence that bacteria can survive and grow in or in near contact with ice (Dahlback et al 1982, Smith et al 1989, Kottmeier & Sullivan 1990, Mordy et a1.1995. but not at a sufficiently rapid rate to seriously influence our frozen nutrient samples (Grossman & Gleitz 1993).…”

Section: 5mentioning

confidence: 99%

Sources of urea in arctic seas:seasonal fast ice?

Conover¹,

Mumm²,

Bruecker³

et al. 1999

Mar. Ecol. Prog. Ser.

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Twelve profiles for dissolved nitrogen, including nitrate, ammonia and urea, and for chlorophyll-related pigments, were taken between February 4 and November 23, 1993, as part of a seasonal study of biological oceanography of Resolute Passage, Northwest Territories, Canada. An additional 20 or 23 profiles of salinity, chlorophyll and total dissolved nitrogen obtained between January 16 and December 13, 1993, from up to 10 depths provided background data in the same area. Eight short cores from seasonal fast ice in the same environment were analyzed for dissolved nitrogen specles between January 30 and December 4, 1993, omitting the open water period from early to rnidJuly through the beginning of October. In the water column, nitrate was the predominant dissolved nitrogen source throughout most of the ice season, but it largely disappeared following break-up, as chlorophyll and its derivative pigments increased. By mid-October nitrate reappeared in the subsurface water and was the dominant nitrogen source again by late November. Ammonia and urea concentrations in the water column were relatively low and variable over the winter, declining in spring, but increasing moderately, although erratically, during June at the onset of the seasonal melt, and continuing to fluctuate through summer and fall In the ice, ammonia and especially urea were the dominant nitrogen sources, culminating in a large, but non-uniformly distributed, standing stock of regenerated nitrogen, with urea the most concentrated, in late May near the time of maxlmum ice thickness. At freeze-up, regenerated nutrients, and particularly urea, appeared in the new ice, generally at concentrations greater than in the water just under the ice. We argue that a considerable amount of carbon, as part of the urea molecule, is also incorporated into the ice seasonally.

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Section: 5mentioning

confidence: 99%

Sources of urea in arctic seas:seasonal fast ice?

Conover¹,

Mumm²,

Bruecker³

et al. 1999

Mar. Ecol. Prog. Ser.

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“…Nutrient levels in annual or first-year sea ice generally parallel salinity distributions throughout most of the ice sheet [Grainger, 1977] Table 2 are based on seasonal data for Resolute Bay from the spring of 1983 or 1984. Comparable values for amphipods and nematodes [Carey, 1985], for ciliates [Grainget and Hsiao, 1982], and bacteria [Dahlback et al, 1982' Grossi et al, 1984 have been repor.ted for similar sea ice communities. We consider only the dominant forms of heterotrophs.…”

Section: Desalination Nutrient Supplymentioning

confidence: 99%

Nutrient fluxes during extended blooms of Arctic ice algae

Cota¹,

Prinsenberg²,

Bennett³

et al. 1987

J. Geophys. Res.

159

119

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Estimates of nutrient demand by dense mats of ice algae in the high Arctic indicate that substantial nutrient fluxes are necessary to satisfy the observed growth over the 2-month bloom. In our study area, Barrow Strait, the quantity of nutrients in the surface-mixed layer is about 3-10 times greater than estimates of total demand during the bloom, and nutrient fluxes in the water column are estimated to be of the same order of magnitude as algal demand. The fluxes in the water column are predicted to vary by more than an order of magnitude over the fortnightly tidal cycle, assuming that fluxes depend upon the strength of tidal currents and the vertical nutrient gradients. In the latter half of the bloom, when biomass levels are high, it appears that established populations of ice algae may experience cyclic conditions of nutrient limitation during neap tides when nutrient fluxes are minimal. Contributions from regeneration and brine exclusion from the ice sheet appear to satisfy only a portion of the bloom's total requirement for nutrients. INTRODUCTIONDense growths of ice algae are a ubiquitous feature beneath annual sea ice in polar regions during the springtime. In the high Arctic these microalgae are largely concentrated at the ice-water interface on or within the skeletal layer of the congelation ice. MacroScopically, they resemble a mottled goldenbrown carpet about 1-2 cm thick. We have found that these algae grow for at least 2 months (April-May) in the central portion of the Northwest Passage. Moreover, the ice alga. e often achieve high levels of biomass (80-100 mg chlorophyll m -e) that are similar to water column values integrated over the depth of the euphotic zone in many planktonic systems.

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“…In this study, mostly first-year ice floes strongly affected by melting were investigated. Abundances of sea-ice bacteria were in the range of published data for the Barents Sea and the Laptev Sea (Dahlbäck et al 1982;Gradinger and Zhang 1997). The vertical distribution of sea-ice bacteria followed bulk salinity that gradually increased from top to bottom in most ice cores.…”

Section: Organic Matter Distribution and Heterotrophic Bacterial Actimentioning

confidence: 58%

“…Based on satellite observations, it has been estimated that Arctic net primary production increased by 30% between 1998 and 2012 mainly due to reduced ice concentration and longer growing seasons (Arrigo and van Dijken 2015). For the Eurasian Basin, estimates derived from the 14 C-bicarbonate method (Steemann Nielsen 1952) combined with an irradiance-based model revealed a doubling of net primary production between 1982(Fernández-Méndez et al 2015. Little is known about the effects of ongoing environmental changes on the heterotrophic recycling of organic matter in the Arctic Ocean.…”

mentioning

confidence: 99%

Organic matter composition and heterotrophic bacterial activity at declining summer sea ice in the central Arctic Ocean

Piontek

Galgani

Nöthig

et al. 2020

Limnology & Oceanography

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The Arctic Ocean is highly susceptible to climate change as evidenced by rapid warming and the drastic loss of sea ice during summer. The consequences of these environmental changes for the microbial cycling of organic matter are largely unexplored. Here, we investigated the distribution and composition of dissolved organic matter (DOM) along with heterotrophic bacterial activity in seawater and sea ice of the Eurasian Basin at the time of the record ice minimum in 2012. Bacteria in seawater were highly responsive to fresh organic matter and remineralized on average 55% of primary production in the upper mixed layer. Correlation analysis showed that the accumulation of dissolved combined carbohydrates (DCCHO) and dissolved amino acids (DAA), two major components of fresh organic matter, was related to the drawdown of nitrate. Nitrate-depleted surface waters at stations adjacent to the Laptev Sea showed about 25% higher concentrations of DAA than stations adjacent to the Barents Sea and in the central Arctic basin. Carbohydrate concentration was the best predictor of heterotrophic bacterial activity in sea ice. In contrast, variability in sea-ice bacterial biomass was largely driven by differences in ice thickness. This decoupling of bacterial biomass and activity may mitigate the negative effects of biomass loss due to ice melting on heterotrophic bacterial functions. Overall, our results reveal that changes in DOM production and inventories induced by sea-ice loss have a high potential to enhance the bacterial remineralization of organic matter in seawater and sea ice of the Arctic Ocean.

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Microbial Investigations of Surface Microlayers, Water Column, Ice and Sediment in the Arctic Ocean

Cited by 25 publications

References 28 publications

Sources of urea in arctic seas:seasonal fast ice?

Sources of urea in arctic seas:seasonal fast ice?

Nutrient fluxes during extended blooms of Arctic ice algae

Organic matter composition and heterotrophic bacterial activity at declining summer sea ice in the central Arctic Ocean

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