scholarly journals Low Salinity and High-Level UV-B Radiation Reduce Single-Cell Activity in Antarctic Sea Ice Bacteria

2009 ◽  
Vol 75 (23) ◽  
pp. 7570-7573 ◽  
Author(s):  
Andrew Martin ◽  
Julie Hall ◽  
Ken Ryan
Keyword(s):  
Sea Ice ◽  
Metabolic Activity ◽  
Cell Activity ◽  
Ice Formation ◽  
Freeze Thaw ◽  
Low Salinity ◽  
Antarctic Sea Ice ◽  
Single Cell Activity ◽  
Fast Ice ◽  
High Level

ABSTRACT Experiments simulating the sea ice cycle were conducted by exposing microbes from Antarctic fast ice to saline and irradiance regimens associated with the freeze-thaw process. In contrast to hypersaline conditions (ice formation), the simulated release of bacteria into hyposaline seawater combined with rapid exposure to increased UV-B radiation significantly reduced metabolic activity.

Preliminary evidence for the microbial loop in Antarctic sea ice using microcosm simulations

2012 ◽  
Vol 24 (6) ◽  
pp. 547-553 ◽  
Author(s):  
Andrew Martin ◽  
Andrew McMinn ◽  
Simon K. Davy ◽  
Marti J. Anderson ◽  
Hilary C. Miller ◽  
...  
Keyword(s):  
Community Structure ◽  
Sea Ice ◽  
Metabolic Activity ◽  
Bacterial Growth ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Preliminary Evidence ◽  
Antarctic Sea Ice ◽  
Cell Counts ◽  
Gradient Gel Electrophoresis ◽  
Fast Ice

AbstractSea ice microalgae actively contribute to the pool of dissolved organic matter (DOM) available for bacterial metabolism, but this link has historically relied on bulk correlations between chlorophylla(a surrogate for algal biomass) and bacterial abundance. We incubated microbes from both the bottom (congelation layer) and surface brine region of Antarctic fast ice for nine days. Algal-derived DOM was manipulated by varying the duration of irradiance, restricting photosynthesis with 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) or incubating in the dark. The bacterial response to changes in DOM availability was examined by performing cell counts, quantifying bacterial metabolic activity and examining community composition with denaturing gradient gel electrophoresis. The percentage of metabolically active bacteria was relatively low in the surface brine microcosm (10–20% of the bacterial community), the treatment with DCMU indirectly restricted bacterial growth and there was some evidence for changes in community structure. Metabolic activity was higher (35–69%) in the bottom ice microcosm, and while there was no variation in community structure, bacterial growth was restricted in the treatment with DCMU compared to the light/dark treatment. These results are considered preliminary, but provide a useful illustration of sea ice microbial dynamics beyond the use of ‘snapshot’ biomass correlations.

High single-cell metabolic activity in Antarctic sea ice bacteria

2008 ◽  
Author(s):  
A Martin ◽  
JA Hall ◽  
R O’Toole ◽  
SK Davy ◽  
KG Ryan
Keyword(s):  
Sea Ice ◽  
Single Cell ◽  
Metabolic Activity ◽  
Cell Metabolic Activity ◽  
Antarctic Sea Ice

scholarly journals Thermodynamics of slush and snow–ice formation in the Antarctic sea-ice zone

2016 ◽  
Vol 131 ◽  
pp. 75-83 ◽  
Author(s):  
Mathilde Jutras ◽  
Martin Vancoppenolle ◽  
Antonio Lourenço ◽  
Frédéric Vivier ◽  
Gauthier Carnat ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ice Formation ◽  
Antarctic Sea Ice ◽  
The Antarctic

scholarly journals Climate Influence on Antarctic Sea Ice Formation Recorded through Remote Sensing

2020 ◽  
Vol 43 (1) ◽  
pp. 151-161
Author(s):  
F. L. HILLEBRAND ◽  
C. N. ROSA ◽  
J. B. JESUS ◽  
U. F. BREMER
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Ice Formation ◽  
Antarctic Sea Ice

scholarly journals Visualization is crucial for understanding microbial processes in the ocean

2019 ◽  
Vol 374 (1786) ◽  
pp. 20190083 ◽  
Author(s):  
Marta Sebastián ◽  
Josep M. Gasol
Keyword(s):  
Single Cell ◽  
Metabolic Activity ◽  
Cell Activity ◽  
Level Of Activity ◽  
Single Cell Activity ◽  
Recent Developments ◽  
Insight Into ◽  
Do So

Recent developments in community and single-cell genomic approaches have provided an unprecedented amount of information on the ecology of microbes in the aquatic environment. However, linkages between each specific microbe's identity and their in situ level of activity (be it growth, division or just metabolic activity) are much more scarce. The ultimate goal of marine microbial ecology is to understand how the environment determines the types of different microbes in nature, their function, morphology and cell-to-cell interactions and to do so we should gather three levels of information, the genomic (including identity), the functional (activity or growth), and the morphological, and for as many individual cells as possible. We present a brief overview of methodologies applied to address single-cell activity in marine prokaryotes, together with a discussion of the difficulties in identifying and categorizing activity and growth. We then provide and discuss some examples showing how visualization has been pivotal for challenging established paradigms and for understanding the role of microbes in the environment, unveiling processes and interactions that otherwise would have been overlooked. We conclude by stating that more effort should be directed towards integrating visualization in future approaches if we want to gain a comprehensive insight into how microbes contribute to the functioning of ecosystems. This article is part of a discussion meeting issue ‘Single cell ecology’.

scholarly journals Antarctic Sea Ice Control on the Depth of North Atlantic Deep Water

2019 ◽  
Vol 32 (9) ◽  
pp. 2537-2551 ◽  
Author(s):  
Louis-Philippe Nadeau ◽  
Raffaele Ferrari ◽  
Malte F. Jansen
Keyword(s):  
Sea Ice ◽  
Deep Water ◽  
Formation Rate ◽  
Deep Ocean ◽  
Meridional Overturning Circulation ◽  
Ice Formation ◽  
Overturning Circulation ◽  
Antarctic Sea Ice ◽  
Meridional Overturning

Abstract Changes in deep-ocean circulation and stratification have been argued to contribute to climatic shifts between glacial and interglacial climates by affecting the atmospheric carbon dioxide concentrations. It has been recently proposed that such changes are associated with variations in Antarctic sea ice through two possible mechanisms: an increased latitudinal extent of Antarctic sea ice and an increased rate of Antarctic sea ice formation. Both mechanisms lead to an upward shift of the Atlantic meridional overturning circulation (AMOC) above depths where diapycnal mixing is strong (above 2000 m), thus decoupling the AMOC from the abyssal overturning circulation. Here, these two hypotheses are tested using a series of idealized two-basin ocean simulations. To investigate independently the effect of an increased latitudinal ice extent from the effect of an increased ice formation rate, sea ice is parameterized as a latitude strip over which the buoyancy flux is negative. The results suggest that both mechanisms can effectively decouple the two cells of the meridional overturning circulation (MOC), and that their effects are additive. To illustrate the role of Antarctic sea ice in decoupling the AMOC and the abyssal overturning cell, the age of deep-water masses is estimated. An increase in both the sea ice extent and its formation rate yields a dramatic “aging” of deep-water masses if the sea ice is thick and acts as a lid, suppressing air–sea fluxes. The key role of vertical mixing is highlighted by comparing results using different profiles of vertical diffusivity. The implications of an increase in water mass ages for storing carbon in the deep ocean are discussed.

scholarly journals Seasonal changes of sea-ice characteristics off East Antarctica

1994 ◽  
Vol 20 ◽  
pp. 195-201 ◽  
Author(s):  
Ian Allison ◽  
Anthony Worby
Keyword(s):  
Sea Ice ◽  
Ice Cores ◽  
Open Water ◽  
Ice Formation ◽  
Ice Thickness ◽  
Spatial And Temporal Variability ◽  
Growth Season ◽  
Ice Growth ◽  
Antarctic Sea Ice ◽  
Ice Edge

Data on Antarctic sea‐ice characteristics, and their spatial and temporal variability, are presented from cruises between 1986 and 1993 for the region spanning 60°−150° E between October and May. In spring, the sea‐ice zone is a variable mixture of different thicknesses of ice plus open water and in some regions only 30−40% of the area is covered with ice >0.3 m thick. The thin‐ice and open‐water areas are important for air‐sea heat exchange. Crystallographic analyses of ice cores, supported by salinity and stable‐isotope measurements, show that approximately 50% of the ice mass is composed of small frazil crystals. These are formed by rapid ice growth in leads and polynyas and indicate the presence of open water throughout the growth season. The area‐averaged thickness of undeformed ice west of 120° E is typically less than 0.3 m and tends to‐increase with distance south of the ice edge. Ice growth by congelation freezing rarely exceeds 0.4 m, with increases in ice thickness beyond this mostly attributable to rafting and ridging. While most of the total area is thin ice or open water, in the central pack much of the total ice mass is contained in ridges. Taking account of the extent of ridging, the total area‐averaged ice thickness is estimated to be about 1m for the region 60°−90° E and 2 m for the region 120°−150° E. By December, new ice formation has ceased in all areas of the pack and only floes >0.3 m remain. In most regions these melt completely over the summer and the new season's ice formation starts in late February. By March, the thin ice has reached a thickness of 0.15 0.30 m, with nilas formation being an important mechanism for ice growth within the ice edge

Detection and Collection System of Target Single Cell Based on pH and Oxygen Sensing

2010 ◽  
Vol 22 (5) ◽  
pp. 639-643 ◽  
Author(s):  
Masayasu Suzuki ◽  
◽  
Hiroyuki Tanaka ◽  
Yasunori Iribe
Keyword(s):  
Single Cell ◽  
Metabolic Activity ◽  
Chemical Sensors ◽  
Oxygen Sensor ◽  
Oxygen Sensing ◽  
Cell Activity ◽  
Collection System ◽  
Sensor Film ◽  
Single Cell Activity ◽  
Inverted Microscope

This paper describes single-cell-based detection and collection using pH and oxygen sensing with microarrayed chemical sensors we developed previously to monitor single-cell activity in parallel. Such sensors consist of optical sensor film for pH or oxygen and microwell arrays prepared with carbon-black-doped polydimethylsiloxane (PDMS). We monitored singlecell respiration in parallel using a microarrayed oxygen sensor. An automatic single-cell collector we developed can be used with a commercial inverted microscope. The single-cell-based detection and collection we developed based on respiration or metabolic activity combines these two techniques. Model experiments for single-cell-based detection and collection based on metabolic activity used urease-immobilized microbeads (6 µm i.d.). Fluorescence intensity after substrate injection increased only in wells containing urease-immobilized microbeads. Bead in target wells could be successfully collected alone, leaving other beads in their wells, by simply pushing a controller button, requiring no training or skill.

Human geographies of sea ice: freeze/thaw processes around Cape Dorset, Nunavut, Canada

Polar Record ◽  
2008 ◽  
Vol 44 (1) ◽  
pp. 51-76 ◽  
Author(s):  
Gita J. Laidler ◽  
Pootoogoo Elee
Keyword(s):  
Sea Ice ◽  
Regional Scale ◽  
Open Water ◽  
Current Strength ◽  
Ice Formation ◽  
Future Research ◽  
Baffin Island ◽  
Freeze Thaw ◽  
Ice Conditions ◽  
Inuit Knowledge

ABSTRACTSea ice has been, and continues to be, an integral component of life in the Inuit community of Cape Dorset, Nunavut. Located on an island of the same name off the southwestern coast of Baffin Island, the strong Hudson Strait currents prevent extensive ice formation around the community. Nevertheless, sea ice remains an important travel and hunting platform, enabling access to Baffin Island, hunting and fishing grounds, and nearby communities. With the combined importance, dynamism, and continuous use of this frozen ocean environment, local Inuit elders and hunters have developed a detailed and nuanced understanding of sea ice conditions, freeze/thaw processes, and the influences of winds and currents on ice conditions. Working collaboratively with the community of Cape Dorset since October, 2003, we present the results of 30 semi-directed interviews, 5 sea ice trips, and 2 focus groups to provide a baseline understanding of local freezing processes (near-shore, open water, sea ice thickening, landfast ice, floe edge, and tidal cracks), melting processes (snow melt, water accumulation and drainage, break-up, and cracks/leads), wind influences on sea ice (wind direction and strength affecting sea ice formation, and movement), and current influences on sea ice (tidal variations and current strength affecting sea ice formation, movement, and polynya size/location). Strong emphasis is placed on Inuktitut terminology and spatial delineations of localised ice conditions and features. Therefore, this paper provides insights into local scale ice conditions and dynamics around Cape Dorset that are not captured in regional scale studies of Hudson Bay and/or Hudson Strait. Results have the potential to inform future research efforts on local/regional sea ice monitoring, the relationship between Inuit knowledge, language, and the environment, and addressing community interests through targeted studies.

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