scholarly journals Characteristics of genetically diverse Antarctic sea ice bacteriophages allow adaptation to changing environmental conditions

2021 ◽  
Author(s):  
Tatiana A. Demina ◽  
Anne-Mari Luhtanen ◽  
Simon Roux ◽  
Hanna Oksanen
Keyword(s):  
Sea Ice ◽  
Global Climate ◽  
Bacterial Species ◽  
Host Recognition ◽  
Global Changes ◽  
Viral Genomes ◽  
Antarctic Sea Ice ◽  
Virus Diversity ◽  
Wide Range ◽  
The Impact

Despite generally appreciated significant roles of microbes in sea ice and polar waters, detailed studies of virus-host systems from such environments have been so far limited by only a few isolates. Here, we investigated infectivity under changing conditions, infection cycles, and genetic diversity of four bacteriophages isolated from Antarctic sea ice: PANV1, PANV2, OANV1, and OANV2, infecting common sea ice bacterial species Paraglaciecola or Octadecabacter. Although the phages are marine and cold-active, replicating at 0-5 C, they all survived temporal incubations at 30 C or above and remained infectious without any salts or supplemented only with magnesium, suggesting a robust virion assembly maintaining integrity under a wide range of conditions. Host recognition in the cold proved to be effective, and the release of progeny viruses occurred as a result of cell lysis or host growth retardation. The analysis of viral genomes showed that nearly half of the gene products of each virus are unique, highlighting that sea ice harbors unexplored virus diversity. Based on predicted genes typical for tailed dsDNA phages, we suggest placing the four studied viruses in the class Caudoviricetes. Searching against viral sequences from metagenomic assemblies revealed that related viruses are not restricted to Antarctica, but also found in distant marine environments, indicating possible virus movement between biotopes. Importance. Very little is known about sea ice microbes despite the significant role of sea ice in the global oceans as well as microbial input into biogeochemical cycling. The impact of possible climatic changes on Antarctic sea ice microbial communities is also poorly understood. Studies on the sea ice viruses have been typically limited to -omics-based approaches and microscopic examinations of sea ice samples. Up to date, only four cultivable viruses have been isolated from Antarctic sea ice. Our study of these unique isolates advances the understanding of the diversity of viruses in sea ice environments, their interactions with host microbes, adaptation potential in the realm of global climate change, and possible links to other biomes. Such information contributes to more accurate future predictions on microbial feedback loops as the response to global changes.

scholarly journals How reversible is sea ice loss?

2011 ◽  
Vol 5 (5) ◽  
pp. 2349-2363 ◽  
Author(s):  
J. K. Ridley ◽  
J. A. Lowe ◽  
H. T. Hewitt
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Rate Of Change ◽  
Atmospheric Co2 ◽  
Antarctic Sea Ice ◽  
The Impact

Abstract. It is well accepted that increasing atmospheric CO2 results in global warming, leading to a decline in polar sea ice area. Here, the specific question of whether there is a tipping point in the sea ice cover is investigated. The global climate model HadCM3, is used to map the trajectory of sea ice area under idealised scenarios. The atmospheric CO2 is first ramped up to four times pre-industrial levels (4 × CO2) then ramped down back to pre-industrial levels. We also examine the impact of stabilising climate at 4 × CO2 prior to ramping CO2 down to pre-industrial levels. Against global mean temperature Arctic sea ice area has little hysteresis while the Antarctic sea ice shows significant hysteresis – its rate of change slower, with falling temperatures, than its rate of change with rising temperatures. However, we show that the driver of the hysteresis is the hemispherical differences in temperature change between transient and stabilisation periods. We find no irreversible behaviour in the sea ice cover.

scholarly journals East Antarctic sea ice: observations and modelling

1998 ◽  
Vol 27 ◽  
pp. 427-432 ◽  
Author(s):  
Anthony P. Worby ◽  
Xingren Wu
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Numerical Models ◽  
Global Climate ◽  
Thickness Distribution ◽  
Ice Thickness ◽  
Antarctic Sea Ice ◽  
Pack Ice ◽  
Concentration Sensitivity ◽  
Sensitivity Studies

The importance of monitoring sea ice for studies of global climate has been well noted for several decades. Observations have shown that sea ice exhibits large seasonal variability in extent, concentration and thickness. These changes have a significant impact on climate, and the potential nature of many of these connections has been revealed in studies with numerical models. An accurate representation of the sea-ice distribution (including ice extent, concentration and thickness) in climate models is therefore important for modelling global climate change. This work presents an overview of the observed sea-ice characteristics in the East Antarctic pack ice (60-150° E) and outlines possible improvements to the simulation of sea ice over this region by modifying the ice-thickness parameterisation in a coupled sea-ice-atmosphere model, using observational data of ice thickness and concentration. Sensitivity studies indicate that the simulation of East Antarctic sea ice can be improved by modifying both the “lead parameterisation” and “rafting scheme” to be ice-thickness dependent. The modelled results are currently out of phase with the observed data, and the addition of a multilevel ice-thickness distribution would improve the simulation significantly.

scholarly journals Brief communication: lack of agreement in remote sensing detection of cyclonic drift caused by Atlantic weather in Antarctic sea ice

2021 ◽  
Author(s):  
Wayne de Jager ◽  
Marcello Vichi
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Alternative Methods ◽  
Polar Regions ◽  
Sea Ice Concentration ◽  
Sea Ice Extent ◽  
Ice Dynamics ◽  
Antarctic Sea Ice ◽  
Ice Drift ◽  
The Impact

Abstract. Sea-ice extent variability, a measure based on satellite-derived sea ice concentration measurements, has traditionally been used as an essential climate variable to evaluate the impact of climate change on polar regions. However, concentration- based measurements of ice variability do not allow to discriminate the relative contributions made by thermodynamic and dynamic processes, prompting the need to use sea-ice drift products and develop alternative methods to quantify changes in sea ice dynamics that would indicate trends in Antarctic ice characteristics. Here, we present a new method to automate the detection of rotational drift features in Antarctic sea ice at daily timescales using currently available remote sensing ice motion products from EUMETSAT OSI SAF. Results show that there is a large discrepancy in the detection of cyclonic drift features between products, both in terms of intensity and year-to-year distributions, thus diminishing the confidence at which ice drift variability can be further analysed. Product comparisons showed that there was good agreement in detecting anticyclonic drift, and cyclonic drift features were measured to be 1.5–2.2 times more intense than anticyclonic features. The most intense features were detected by the merged product, suggesting that the processing chain used for this product could be injecting additional rotational momentum into the resultant drift vectors. We conclude that it is therefore necessary to better understand why the products lack agreement before further trend analysis of these drift features and their climatic significance can be assessed.

A circumpolar coupled ocean – Antarctic ice sheet configuration for investigating recent changes in Southern Ocean heat content

2020 ◽  
Author(s):  
Charles Pelletier ◽  
Lars Zipf ◽  
Konstanze Haubner ◽  
Hugues Goosse ◽  
Frank Pattyn ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ice Sheet ◽  
Heat Content ◽  
Ice Shelf ◽  
Sea Ice Extent ◽  
Antarctic Ice Sheet ◽  
Antarctic Sea Ice ◽  
Physical Phenomena ◽  
The Impact

<p>From 2016 on, observed tendencies of Southern Ocean sea surface temperatures and Antarctic sea ice extent (SIE) have shifted from cooling down (with SIE increase) to warming up (SIE decrease). This change of Southern Ocean surface thermal properties has been sustained since, which indicates that it is not solely due to the interannual variability of the atmosphere, but also to modifications in the ocean itself. Among other physical phenomena, the acceleration of continental ice shelf melt, through its subsequent impact on the Southern Ocean stratification, has been proposed as one of the potential meaningful drivers of the sea ice changes. Reciprocally, recent studies suggest that besides atmosphere forcings, the upper ocean thermal content bears significant impact on ice shelf melt rates and dynamics. Here we present a new circumpolar coupled Southern Ocean – Antarctic ice sheet configuration aiming at investigating the impact of this ocean – continental ice feedback, developed within the framework of the PARAMOUR project. Our setting relies on the ocean and sea ice model NEMO3.6-LIM3 sending ice shelf melt rates to the Antarctic ice sheet model f.ETISh v1.5, who in turn responds to it and provides updated ice shelf cavity geometry. Both technical aspects and first coupled results are presented.</p>

scholarly journals Urban climate in Central European cities and global climate change

2018 ◽  
Vol 51-52 (1) ◽  
pp. 7-35 ◽  
Author(s):  
Anita Bokwa ◽  
Petr Dobrovolný ◽  
Tamás Gál ◽  
Jan Geletič ◽  
Ágnes Gulyás ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Global Climate ◽  
Urban Climate ◽  
Global Changes ◽  
Climate Modelling ◽  
Complex Data ◽  
Central European ◽  
European Cities ◽  
The Impact

Urban areas are among those most endangered with the potential global climate changes. The studies concerning the impact of global changes on local climate of cities are of a high significance for the urban inhabitants' health and wellbeing. This paper is the final report of a project (Urban climate in Central European cities and global climate change) with the aim to raise the public awareness on those issues in five Central European cities: Szeged (Hungary), Brno (Czech Republic), Bratislava (Slovakia), Kraków (Poland) and Vienna (Austria). Within the project, complex data concerning local geomorphological features, land use and long-term climatological data were used to perform the climate modelling analyses using the model MUKLIMO_3 provided by the German Weather Service (DWD).

scholarly journals Mutation rate dynamics reflect ecological change in an emerging zoonotic pathogen

PLoS Genetics ◽  
2021 ◽  
Vol 17 (11) ◽  
pp. e1009864
Author(s):  
Gemma G. R. Murray ◽  
Andrew J. Balmer ◽  
Josephine Herbert ◽  
Nazreen F. Hadijirin ◽  
Caroline L. Kemp ◽  
...  
Keyword(s):  
Genome Size ◽  
Mutation Rate ◽  
Evolutionary Dynamics ◽  
Bacterial Species ◽  
Invasive Disease ◽  
Mutation Rates ◽  
Ecological Change ◽  
Zoonotic Pathogen ◽  
Wide Range ◽  
The Impact

Mutation rates vary both within and between bacterial species, and understanding what drives this variation is essential for understanding the evolutionary dynamics of bacterial populations. In this study, we investigate two factors that are predicted to influence the mutation rate: ecology and genome size. We conducted mutation accumulation experiments on eight strains of the emerging zoonotic pathogen Streptococcus suis. Natural variation within this species allows us to compare tonsil carriage and invasive disease isolates, from both more and less pathogenic populations, with a wide range of genome sizes. We find that invasive disease isolates have repeatedly evolved mutation rates that are higher than those of closely related carriage isolates, regardless of variation in genome size. Independent of this variation in overall rate, we also observe a stronger bias towards G/C to A/T mutations in isolates from more pathogenic populations, whose genomes tend to be smaller and more AT-rich. Our results suggest that ecology is a stronger correlate of mutation rate than genome size over these timescales, and that transitions to invasive disease are consistently accompanied by rapid increases in mutation rate. These results shed light on the impact that ecology can have on the adaptive potential of bacterial pathogens.

Evaluating Antarctic sea ice variability and its teleconnections in global climate models

2002 ◽  
Vol 22 (8) ◽  
pp. 885-900 ◽  
Author(s):  
Jiping Liu ◽  
Douglas G. Martinson ◽  
Xiaojun Yuan ◽  
David Rind
Keyword(s):  
Sea Ice ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Antarctic Sea Ice
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