scholarly journals The biogeochemical role of a microbial biofilm in sea ice

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Arnout Roukaerts ◽  
Florian Deman ◽  
Fanny Van der Linden ◽  
Gauthier Carnat ◽  
Arne Bratkic ◽  
...  
Keyword(s):  
Sea Ice ◽  
Algal Blooms ◽  
Nutrient Concentrations ◽  
Community Attachment ◽  
Microbial Biofilm ◽  
Autotrophic Biomass ◽  
High Concentrations ◽  
Landfast Sea Ice ◽  
Carbon Concentrations

A paradox is commonly observed in productive sea ice in which an accumulation in the macro-nutrients nitrate and phosphate coincides with an accumulation of autotrophic biomass. This paradox requires a new conceptual understanding of the biogeochemical processes operating in sea ice. In this study, we investigate this paradox using three time series in Antarctic landfast sea ice, in which massive algal blooms are reported (with particulate organic carbon concentrations up to 2,600 µmol L–1) and bulk nutrient concentrations exceed seawater values up to 3 times for nitrate and up to 19 times for phosphate. High-resolution sampling of the bottom 10 cm of the cores shows that high biomass concentrations coexist with high concentrations of nutrients at the subcentimeter scale. Applying a nutrient-phytoplankton-zooplankton-detritus model approach to this sea-ice system, we propose the presence of a microbial biofilm as a working hypothesis to resolve this paradox. By creating microenvironments with distinct biogeochemical dynamics, as well as favoring nutrient adsorption onto embedded decaying organic matter, a biofilm allows the accumulation of remineralization products (nutrients) in proximity to the sympagic (ice-associated) community. In addition to modifying the intrinsic physicochemical properties of the sea ice and providing a substrate for sympagic community attachment, the biofilm is suggested to play a key role in the flux of matter and energy in this environment.

scholarly journals Role of GerKB in Germination and Outgrowth of Clostridium perfringens Spores

2009 ◽  
Vol 75 (11) ◽  
pp. 3813-3817 ◽  
Author(s):  
Daniel Paredes-Sabja ◽  
Peter Setlow ◽  
Mahfuzur R. Sarker
Keyword(s):  
Clostridium Perfringens ◽  
Spore Germination ◽  
Nutrient Concentrations ◽  
Wild Type ◽  
Spore Viability ◽  
Colony Forming Efficiency ◽  
Forming Efficiency ◽  
High Concentrations ◽  
Auxiliary Role

ABSTRACT Previous work indicated that Clostridium perfringens gerKA gerKC spores germinate significantly, suggesting that gerKB also has a role in C. perfringens spore germination. We now find that (i) gerKB was expressed only during sporulation, likely in the forespore; (ii) gerKB spores germinated like wild-type spores with nonnutrient germinants and with high concentrations of nutrients but more slowly with low nutrient concentrations; and (iii) gerKB spores had lower colony-forming efficiency and slower outgrowth than wild-type spores. These results suggest that GerKB plays an auxiliary role in spore germination under some conditions and is required for normal spore viability and outgrowth.

scholarly journals Green Edge ice camp campaigns: understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

2020 ◽  
Vol 12 (1) ◽  
pp. 151-176 ◽  
Author(s):  
Philippe Massicotte ◽  
Rémi Amiraux ◽  
Marie-Pier Amyot ◽  
Philippe Archambault ◽  
Mathieu Ardyna ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Zooplankton Abundance ◽  
Biological Variables ◽  
Relevant Variables ◽  
Key Variables ◽  
Field Campaigns ◽  
Landfast Sea Ice

Abstract. The Green Edge initiative was developed to investigate the processes controlling the primary productivity and fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797∘ N, 63.7895∘ W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea-ice cover from the surface to the bottom (at 360 m depth) to better understand the factors driving the PSB. Key variables, such as conservative temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured at the ice camp. Meteorological and snow-relevant variables were also monitored. Here, we present the results of a joint effort to tidy and standardize the collected datasets, which will facilitate their reuse in other Arctic studies. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a).

scholarly journals Carbon and nitrogen uptake rates and macromolecular compositions of bottom-ice algae and phytoplankton at Cambridge Bay in Dease Strait, Canada

2020 ◽  
Vol 61 (82) ◽  
pp. 106-116
Author(s):  
Kwanwoo Kim ◽  
Sun-Yong Ha ◽  
Bo Kyung Kim ◽  
C. J. Mundy ◽  
Kathleen M. Gough ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Carbon Uptake ◽  
Ice Algae ◽  
Carbon And Nitrogen ◽  
Uptake Rates ◽  
Marine System ◽  
Landfast Sea Ice

AbstractOur understanding of ice algal responses to the recent changes in Arctic sea ice is impeded by limited field observations. In the present study, environmental characteristics of the landfast sea-ice zone as well as primary production and macromolecular composition of ice algae and phytoplankton were studied in the Kitikmeot Sea near Cambridge Bay in spring 2017. Averaged total chlorophyll-a (Chl-a) concentration was within the lower range reported previously for the same region, while daily carbon uptake rates of bottom-ice algae were significantly lower in this study than previously reported for the Arctic. Based on various indicators, the region's low nutrient concentrations appear to limit carbon uptake rates and associated accumulation of bottom-ice algal biomass. Furthermore, the lipids-dominant biochemical composition of bottom-ice algae suggests strong nutrient limitation relative to the distinctly different carbohydrates-dominant composition of phytoplankton. Together, the results confirm strong nitrate limitation of the local marine system.

scholarly journals Role of environmental factors on phytoplankton bloom initiation under landfast sea ice in Resolute Passage, Canada

2014 ◽  
Vol 497 ◽  
pp. 39-49 ◽  
Author(s):  
CJ Mundy ◽  
M Gosselin ◽  
Y Gratton ◽  
K Brown ◽  
V Galindo ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Sea Ice ◽  
Phytoplankton Bloom ◽  
Landfast Sea Ice

scholarly journals Green Edge ice camp campaigns: understanding the processes controlling the under-ice Arctic phytoplankton spring bloom

2019 ◽  
Author(s):  
Philippe Massicotte ◽  
Rémi Amiraux ◽  
Marie-Pier Amyot ◽  
Philippe Archambault ◽  
Mathieu Ardyna ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spring Bloom ◽  
The Arctic ◽  
Nutrient Concentrations ◽  
Data Sets ◽  
Zooplankton Abundance ◽  
Biological Variables ◽  
Key Variables ◽  
Field Campaigns ◽  
Landfast Sea Ice

Abstract. The Green Edge initiative was developed to investigate the processes controlling the primary productivity and the fate of organic matter produced during the Arctic phytoplankton spring bloom (PSB) and to determine its role in the ecosystem. Two field campaigns were conducted in 2015 and 2016 at an ice camp located on landfast sea ice southeast of Qikiqtarjuaq Island in Baffin Bay (67.4797N, 63.7895W). During both expeditions, a large suite of physical, chemical and biological variables was measured beneath a consolidated sea ice cover from the surface to the bottom at 360 m depth to better understand the factors driving the PSB. Key variables such as temperature, salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, carbon stocks and fluxes were routinely measured at the ice camp. Here, we present the results of a joint effort to tidy and standardize the collected data sets that will facilitate their reuse in other Arctic studies. The dataset is available at http://www.seanoe.org/data/00487/59892/ (Massicotte et al., 2019a).

scholarly journals Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
François Fripiat ◽  
Klaus M. Meiners ◽  
Martin Vancoppenolle ◽  
Stathys Papadimitriou ◽  
David N. Thomas ◽  
...  
Keyword(s):  
Microbial Community ◽  
Sea Ice ◽  
Silicic Acid ◽  
Algal Blooms ◽  
Inorganic Nitrogen ◽  
Ice Cores ◽  
Nutrient Concentrations ◽  
Phosphate Adsorption ◽  
Dissolved Inorganic Nitrogen ◽  
Pack Ice

Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (Cw), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* < Cw), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (C* > Cw). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.

Trends in Arctic sea ice and the role of atmospheric circulation

2013 ◽  
Vol 14 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Masayo Ogi ◽  
Ignatius G. Rigor
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
Arctic Sea Ice ◽  
Arctic Sea

scholarly journals Spectral albedo of coastal landfast sea ice in Prydz Bay, Antarctica

2020 ◽  
pp. 1-11
Author(s):  
Guanghua Hao ◽  
Roberta Pirazzini ◽  
Qinghua Yang ◽  
Zhongxiang Tian ◽  
Changwei Liu
Keyword(s):  
Sea Ice ◽  
Near Infrared ◽  
Elevation Angle ◽  
Early Summer ◽  
Prydz Bay ◽  
Katabatic Wind ◽  
Surface Conditions ◽  
Zhongshan Station ◽  
Landfast Sea Ice ◽  
Two Phases

Abstract The surface spectral albedo was measured over coastal landfast sea ice in Prydz Bay (off Zhongshan Station), East Antarctica from 5 October to 26 November of 2016. The mean albedo decreased from late-spring to early-summer, mainly responding to the change in surface conditions from dry (phase I) to wet (phase II). The evolution of the albedo was strongly influenced by the surface conditions, with alternation of frequent snowfall events and katabatic wind that induce snow blowing at the surface. The two phases and day-to-day albedo variability were more pronounced in the near-infrared albedo wavelengths than in the visible ones, as the near-infrared photons are more sensitive to snow metamorphism, and to changes in the uppermost millimeters and water content of the surface. The albedo diurnal cycle during clear sky conditions was asymmetric with respect to noon, decreasing from morning to evening over full and patchy snow cover, and decreasing more rapidly in the morning over bare ice. We conclude that snow and ice metamorphism and surface melting dominated over the solar elevation angle dependency in shaping the albedo evolution. However, we realize that more detailed surface observations are needed to clarify and quantify the role of the various surface processes.

scholarly journals Environmentally persistent free radicals are ubiquitous in wildfire charcoals and remain stable for years

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Gabriel Sigmund ◽  
Cristina Santín ◽  
Marc Pignitter ◽  
Nathalie Tepe ◽  
Stefan H. Doerr ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Free Radicals ◽  
Reactive Oxygen ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Pyrogenic Carbon ◽  
Spin Resonance ◽  
Long Time ◽  
High Concentrations

AbstractGlobally landscape fires produce about 256 Tg of pyrogenic carbon or charcoal each year. The role of charcoal as a source of environmentally persistent free radicals, which are precursors of potentially harmful reactive oxygen species, is poorly constrained. Here, we analyse 60 charcoal samples collected from 10 wildfires, that include crown as well as surface fires in forest, shrubland and grassland spanning different boreal, temperate, subtropical and tropical climate. Using electron spin resonance spectroscopy, we measure high concentrations of environmentally persistent free radicals in charcoal samples, much higher than those found in soils. Concentrations increased with degree of carbonization and woody fuels favoured higher concentrations. Moreover, environmentally persistent free radicals remained stable for an unexpectedly long time of at least 5 years. We suggest that wildfire charcoal is an important global source of environmentally persistent free radicals, and therefore potentially of harmful reactive oxygen species.

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