Bacterial Community Structure, Function and Diversity in Antarctic Sea Ice

Ice Thickness ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Antarctic sea ice is an important feature of the southern ocean where at its maximum it can cover 8 % of the Southern Hemisphere. It provides a stable environment for the colonisation of diverse and highly specialised microbes which play a central role in the assimilation and regulation of energy through the Antarctic food web. Polar environments are sensitive to changes in the environment. Small changes in temperature can have large effects on sea ice thickness and extent and Antarctic sea ice cover is expected to shrink by 25 % over the next century. It is unknown how the sea ice microbiota will respond. In order to understand the effects of climate change on the sea ice ecosystem it is necessary to obtain information about the community structure, function and diversity and their reactions with the environment. Studies have focused on algal diversity and physiology in Antarctic sea ice and in comparison studies on the prokaryotic community are few. Although prokaryotic diversity has been investigated using clone libraries and culture based methods, it is likely that certain species have still not been described. Almost nothing is known about the Antarctic sea ice bacterial community spatial and temporal dynamics under changing abiotic and biotic conditions or their role in biogeochemical cycles. This is the first study linking Antarctic bacterial communities to function by using statistics to investigate the relationships between environmental variables and community structure. Bacterial community structure was investigated by extracting both the DNA and RNA from the environment to understand both the metabolically active (RNA) and total (DNA) bacterial community. The thickness of the sea ice and nutrient concentrations were key factors regulating bacterial community composition in Antarctic sea ice. Sea ice thickness is likely to have an effect on the physiological responses of algae leading to changes in photosynthate concentrations and composition of dissolved organic matter (DOM). Further investigations into the relationships between enzymatic activity and community structure revealed that the composition of the DOM drove variation between bacterial communities. There was no relationship between bacterial abundance and chlorophyll-a (as a measure of algal biomass), suggesting a un-coupling of the microbial loop. However bacteria were actively involved in the hydrolysis of polymers throughout the sea ice core. Investigations using quantitative PCR (qPCR) found that the functional genes involved in denitrification and light energy utilisation were in low abundance therefore these processes are minor in Antarctic sea ice. These results confirm that sea ice bacteria are predominantly heterotrophs and have a major role in the cycling of carbon and nitrogen through the microbial loop ...

Bacterial Community Structure, Function and Diversity in Antarctic Sea Ice

10.26686/wgtn.16992562.v1 ◽

2021 ◽

Author(s):

◽

Rebecca Olivia MacLennan Cowie

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Sea Ice ◽

Structure Function ◽

Bacterial Communities ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

A comparison between Envisat and ICESat sea ice thickness in the Antarctic

10.5194/tc-2020-48 ◽

2020 ◽

Author(s):

Jinfei Wang ◽

Chao Min ◽

Robert Ricker ◽

Qinghua Yang ◽

Qian Shi ◽

...

Keyword(s):

Sea Ice ◽

European Space Agency ◽

Weddell Sea ◽

Ice Thickness ◽

Radar Altimeter ◽

Average Deviation ◽

Absolute Deviation ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Abstract. The crucial role that Antarctic sea ice plays in the global climate system is strongly linked to its thickness. While in situ observations are too sparse in the Antarctic to determine long-term trends of the Antarctic sea ice thickness on a global scale, satellite radar altimetry data can be applied with a promising prospect. A newly released Envisat-derived product from the European Space Agency Sea Ice Climate Change Initiative (ESA SICCI), including sea ice freeboard and sea ice thickness, covers the entire Antarctic year-round from 2002 to 2012. In this study, the SICCI Envisat sea ice thickness in the Antarctic is firstly compared with a conceptually new proposed ICESat ice thickness that has been derived from an algorithm employing modified ice density. Both data sets have been validated with the Weddell Sea upward looking sonar measurements (ULS), indicating that ICESat agrees better with field observations. The inter-comparisons are conducted for three seasons except winter based on the ICESat operating periods. According to the results, the deviations between Envisat and ICESat sea ice thickness are different considering different seasons, years and regions. More specifically, the smallest average deviation between Envisat and ICESat sea ice thickness exists in spring by −0.03 m while larger deviations exist in summer and autumn by 0.86 m and 0.62 m, respectively. Although the smallest absolute deviation occurs in spring 2005 by 0.02 m, the largest correlation coefficient appears in autumn 2004 by 0.77. The largest positive deviation occurs in the western Weddell Sea by 1.03 m in summer while the largest negative deviation occurs in the Eastern Antarctic by −0.25 m in spring. Potential reasons for those deviations mainly deduce from the limitations of Envisat radar altimeter affected by the weather conditions and the surface roughness as well as the different retrieval algorithms. The better performance in spring of Envisat has a potential relation with relative humidity.

Farewell to IceBridge: 10 years of polar sea ice remote sensing

10.5194/egusphere-egu2020-12019 ◽

2020 ◽

Author(s):

Linette Boisvert ◽

Joseph MacGregor ◽

Brooke Medley ◽

Nathan Kurtz ◽

Ron Kwok ◽

...

Keyword(s):

Sea Ice ◽

The Arctic ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Ice Drift ◽

Laser Altimeters ◽

Sea Ice Drift ◽

To Come ◽

NASA&#8217;s Operation IceBridge (OIB) was a multi-year, multi-platform, airborne mission which took place between 2009-2019. OIB was designed and implemented to continue monitoring the changing sea ice and ice sheets in both the Arctic and Antarctic by &#8216;bridging the gap&#8217; between NASA&#8217;s ICESat (2003&#8211;2009) and ICESat-2 (launched September 2018) satellite missions. OIB&#8217;s instrument suite most often consisted of laser altimeters, radar sounders, gravimeters and multi-spectral imagers. These instruments were selected to study polar sea ice thickness, ice sheet elevation, snow and ice thickness, surface temperature and bathymetry. With the launch of ICESat-2, the final year of OIB consisted of three campaigns designed to under fly the satellite: 1) the end of the Arctic growth season (spring), 2) during the Arctic summer to capture many different types of melting surfaces, and 3) the Antarctic spring to cover an entirely new area of East Antarctica. Over this ten-year period a coherent picture of Arctic and Antarctic sea ice and snow thickness and other properties have been produced and monitored. Specifically, OIB has changed the community&#8217;s perspective of snow on sea ice in the Arctic. Over the decade, OIB has also been used to validate other satellite altimeter missions like ESA&#8217;s CryoSat-2. Since the launch of ICESat-2, coincident OIB under flights with the satellite were crucial for measuring sea ice properties. With sea ice constantly in motion, and the differences in OIB aircraft and ICESat-2 ground speed, there can substantial drift in the sea ice pack over the same ground track distance being measured.Therefore, we had to design and implement sea ice drift trajectories based on low level winds measured from the aircraft in flight, adjusting our plane&#8217;s path accordingly so we could measure the same sea ice as ICESat-2. This was implemented in both the Antarctic 2018 and Arctic 2019 campaigns successfully. Specifically, the Spring Arctic 2019 campaign allowed for validation of ICESat-2 freeboards with OIB ATM freeboards proving invaluable to the success of ICESat-2 and the future of sea ice research to come from these missions.&#160;

A model reconstruction of the Antarctic sea ice thickness and volume changes over 1980–2008 using data assimilation

Ocean Modelling ◽

10.1016/j.ocemod.2013.01.003 ◽

2013 ◽

Vol 64 ◽

pp. 67-75 ◽

Cited By ~ 55

Author(s):

François Massonnet ◽

Pierre Mathiot ◽

Thierry Fichefet ◽

Hugues Goosse ◽

Christof König Beatty ◽

...

Keyword(s):

Data Assimilation ◽

Sea Ice ◽

Ice Thickness ◽

Model Reconstruction ◽

Volume Changes ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Using Data ◽

Responses of Baltic Sea Ice and Open-Water Natural Bacterial Communities to Salinity Change

Applied and Environmental Microbiology ◽

10.1128/aem.71.8.4364-4371.2005 ◽

2005 ◽

Vol 71 (8) ◽

pp. 4364-4371 ◽

Cited By ~ 27

Author(s):

Hermanni Kaartokallio ◽

Maria Laamanen ◽

Kaarina Sivonen

Keyword(s):

Community Structure ◽

Bacterial Community ◽

16S Rrna ◽

Sea Ice ◽

Baltic Sea ◽

Bacterial Communities ◽

Bacterial Abundance ◽

Open Water ◽

Salinity Change

ABSTRACT To investigate the responses of Baltic Sea wintertime bacterial communities to changing salinity (5 to 26 practical salinity units), an experimental study was conducted. Bacterial communities of Baltic seawater and sea ice from a coastal site in southwest Finland were used in two batch culture experiments run for 17 or 18 days at 0°C. Bacterial abundance, cell volume, and leucine and thymidine incorporation were measured during the experiments. The bacterial community structure was assessed using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA genes with sequencing of DGGE bands from initial communities and communities of day 10 or 13 of the experiment. The sea ice-derived bacterial community was metabolically more active than the open-water community at the start of the experiment. Ice-derived bacterial communities were able to adapt to salinity change with smaller effects on physiology and community structure, whereas in the open-water bacterial communities, the bacterial cell volume evolution, bacterial abundance, and community structure responses indicated the presence of salinity stress. The closest relatives for all eight partial 16S rRNA gene sequences obtained were either organisms found in polar sea ice and other cold habitats or those found in summertime Baltic seawater. All sequences except one were associated with the α- and γ-proteobacteria or the Cytophaga-Flavobacterium-Bacteroides group. The overall physiological and community structure responses were parallel in ice-derived and open-water bacterial assemblages, which points to a linkage between community structure and physiology. These results support previous assumptions of the role of salinity fluctuation as a major selective factor shaping the sea ice bacterial community structure.

Sensitivity of the Antarctic sea-ice distribution to oceanic heat flux in a coupled atmosphere-sea-ice model

Annals of Glaciology ◽

10.3189/172756401781818545 ◽

2001 ◽

Vol 33 ◽

pp. 577-584 ◽

Cited By ~ 3

Author(s):

Xingren Wu ◽

W. F. Budd ◽

A. P. Worby ◽

Ian Allison

Keyword(s):

Heat Flux ◽

Sea Ice ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Oceanic Heat Flux ◽

Ice Concentration ◽

Microwave Radiometers ◽

The Antarctic ◽

Ice Model

AbstractA coupled atmosphere-sea-ice model is used to study the sensitivity of the Antarctic sea-ice distribution to oceanic heat flux (OHF). Remote sensing of sea ice from microwave radiometers provides data on ice extent and ice concentration. The ice-thickness data used are from ship-based observations. Our simulations suggest that OHF values of 0−5 W m−2 will cause sea ice to be too thick in the model. A value of 20−25 Wm−2 throughout the year causes sea ice to be too thin in the model. The model results indicate that a seasonally varying OHF is required to match the modelled thickness with observations. Values of 5−30 Wm with an annual mean of 10−15 Wm−2, give a reasonable distribution of sea-ice thickness. This agrees with the limited observations of OHF available for the Antarctic. The model results also indicate that the OHF should be varied spatially. When a seasonally and spatially variable OHF is applied to the coupled atmosphere-sea-ice model a still better simulation of the sea-ice distribution is obtained. Our results also suggest that the role of ice advection is very important in the determination of the sea-ice distribution, and it can be quantified by the model.

A comparison between Envisat and ICESat sea ice thickness in the Antarctic

10.5194/tc-2021-227 ◽

2021 ◽

Author(s):

Jinfei Wang ◽

Chao Min ◽

Robert Ricker ◽

Qian Shi ◽

Bo Han ◽

...

Keyword(s):

Sea Ice ◽

Snow Depth ◽

Spatial Variations ◽

Weddell Sea ◽

Ice Thickness ◽

Sea Ice Thickness ◽

Temporal And Spatial Variations ◽

Antarctic Sea Ice ◽

Temporal And Spatial ◽

Abstract. The crucial role that Antarctic sea ice plays in the global climate system is strongly linked to its thickness. While field observations are too sparse in the Antarctic to determine long-term trends of the Antarctic sea ice thickness (SIT) on a hemispheric scale, satellite radar altimetry data can be applied with a promising prospect. European Space Agency Climate Change Initiative – Sea Ice Project (ESA SICCI) includes sea ice freeboard and sea ice thickness derived from Envisat, covering the entire Antarctic year-round from 2002 to 2012. In this study, the SICCI Envisat SIT in the Antarctic is first compared with a conceptually new ICESat SIT product retrieved from an algorithm employing modified ice density. Both data sets are compared to SIT estimates from upward-looking sonar (ULS) in the Weddell Sea, showing mean differences (MD) and standard deviations (SD) of 1.29 (0.65) m for Envisat-ULS, while we find 1.11 (0.81) m for ICESat-ULS, respectively. The inter-comparisons are conducted for three seasons except winter, based on the ICESat operating periods. According to the results, the differences between Envisat and ICESat SIT reveal significant temporal and spatial variations. More specifically, the smallest seasonal SIT MD (with SD shown in brackets) of 0.00 m (0.39 m) for Envisat-ICESat for the entire Antarctic is found in spring (October–November) while larger MD of 0.52 m (0.68 m) and 0.57 m (0.45 m) exist in summer (February–March) and autumn (May–June), respectively. It is also shown that from autumn to spring, mean Envisat SIT decreases while mean ICESat SIT increases. Our findings suggest that overestimation of Envisat sea ice freeboard, potentially caused by radar backscatter originating from inside the snow layer, primarily accounts for the differences between Envisat and ICESat SIT in summer and autumn, while the uncertainties of snow depth product are not the dominant cause of the differences.To get a better understanding of the characteristics of the Envisat-derived sea ice thickness product, we firstly conduct a comprehensive comparison between Envisat and ICESat-1 sea ice thickness. Their differences reveal significant temporal and spatial variations. Our findings suggest that overestimation of Envisat sea ice freeboard primarily accounts for the differences in summer and autumn, while the uncertainties of snow depth product are not the dominant cause of the differences.

Effects of Plastic Debris on the Biofilm Bacterial Communities in Lake Water

Water ◽

10.3390/w13111465 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1465

Author(s):

Chao Shen ◽

Liuyan Huang ◽

Guangwu Xie ◽

Yulai Wang ◽

Zongkai Ma ◽

...

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Bacterial Communities ◽

Diversity Index ◽

Plastic Substrate ◽

Simpson Index ◽

Plastic Debris ◽

Plastic Substrates ◽

Wiener Diversity Index

Increasing discharge of plastic debris into aquatic ecosystems and the worsening ecological risks have received growing attention. Once released, plastic debris could serve as a new substrate for microbes in waters. The complex relationship between plastics and biofilms has aroused great interest. To confirm the hypothesis that the presence of plastic in water affects the composition of biofilm in natural state, in situ biofilm culture experiments were conducted in a lake for 40 days. The diversity of biofilm attached on natural (cobble stones (CS) and wood) and plastic substrates (Polyethylene terephthalate (PET) and Polymethyl methacrylate (PMMA)) were compared, and the community structure and composition were also analyzed. Results from high-throughput sequencing of 16S rRNA showed that the diversity and species richness of biofilm bacterial communities on natural substrate (observed species of 1353~1945, Simpson index of 0.977~0.989 and Shannon–Wiener diversity index of 7.42~8.60) were much higher than those on plastic substrates (observed species of 900~1146, Simpson index of 0.914~0.975 and Shannon–Wiener diversity index of 5.47~6.99). The NMDS analyses were used to confirm the taxonomic significance between different samples, and Anosim (p = 0.001, R = 0.892) and Adonis (p = 0.001, R = 808, F = 11.19) demonstrated that this classification was statistically rigorous. Different dominant bacterial communities were found on plastic and natural substrates. Alphaproteobacterial, Betaproteobacteria and Synechococcophycideae dominated on the plastic substrate, while Gammaproteobacteria, Phycisphaerae and Planctomycetia played the main role on the natural substrates. The bacterial community structure of the two substrates also showed significant difference which is consistent with previous studies using other polymer types. Our results shed light on the fact that plastic debris can serve as a new habitat for biofilm colonization, unlike natural substrates, pathogens and plastic-degrading microorganisms selectively attached to plastic substrates, which affected the bacterial community structure and composition in aquatic environment. This study provided a new insight into understanding the potential impacts of plastics serving as a new habitat for microbial communities in freshwater environments. Future research should focus on the potential impacts of plastic-attached biofilms in various aquatic environments and the whole life cycle of plastics (i.e., from plastic fragments to microplastics) and also microbial flock characteristics using microbial plastics in the natural environment should also be addressed.

Significant Differences in the Gut Bacterial Communities of Hooded Crane (Grus monacha) in Different Seasons at a Stopover Site on the Flyway

Animals ◽

10.3390/ani10040701 ◽

2020 ◽

Vol 10 (4) ◽

pp. 701 ◽

Cited By ~ 1

Author(s):

Fengling Zhang ◽

Xingjia Xiang ◽

Yuanqiu Dong ◽

Shaofei Yan ◽

Yunwei Song ◽

...

Keyword(s):

Community Structure ◽

Bacterial Community ◽

Community Composition ◽

Bacterial Communities ◽

Bacterial Community Composition ◽

Stopover Site ◽

Intestinal Bacterial Community ◽

Hooded Crane ◽

Grus Monacha

Intestinal bacterial communities form an integral component of the organism. Many factors influence gut bacterial community composition and diversity, including diet, environment and seasonality. During seasonal migration, birds use many habitats and food resources, which may influence their intestinal bacterial community structure. Hooded crane (Grus monacha) is a migrant waterbird that traverses long distances and occupies varied habitats. In this study, we investigated the diversity and differences in intestinal bacterial communities of hooded cranes over the migratory seasons. Fecal samples from hooded cranes were collected at a stopover site in two seasons (spring and fall) in Lindian, China, and at a wintering ground in Shengjin Lake, China. We analyzed bacterial communities from the fecal samples using high throughput sequencing (Illumina Mi-seq). Firmicutes, Proteobacteria, Tenericutes, Cyanobacteria, and Actinobacteria were the dominant phyla across all samples. The intestinal bacterial alpha-diversity of hooded cranes in winter was significantly higher than in fall and spring. The bacterial community composition significantly differed across the three seasons (ANOSIM, P = 0.001), suggesting that seasonal fluctuations may regulate the gut bacterial community composition of migratory birds. This study provides baseline information on the seasonal dynamics of intestinal bacterial community structure in migratory hooded cranes.

Estimating the thickness of ridged sea ice from ship observations in the Ross Sea

Antarctic Science ◽

10.1017/s0954102003001056 ◽

2003 ◽

Vol 15 (1) ◽

pp. 47-54 ◽

Cited By ~ 5

Author(s):

TINA TIN ◽

MARTIN O. JEFFRIES ◽

MIKKO LENSU ◽

JUKKA TUHKURI

Keyword(s):

Sea Ice ◽

Ross Sea ◽

Low Cost ◽

Thickness Distribution ◽

Ice Thickness ◽

Equivalent Thickness ◽

Sea Ice Thickness ◽

Antarctic Sea Ice ◽

Using Data ◽

Original Formula

Ship-based observations of sea ice thickness using the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol provide information on ice thickness distribution at relatively low cost. This protocol uses a simple formula to calculate the mass of ice in ridges based on surface observations. We present two new formulae and compare these with results from the “Original” formula using data obtained in the Ross Sea in autumn and winter. The new “r-star” formula uses a more realistic ratio of sail and keel areas to transform dimensions of sails to estimates of mean keel areas. As a result, estimates of “equivalent thickness” (i.e. mean thickness of ice in ridged areas) increased by over 200%. The new “Probability” formula goes one step further, by incorporating the probability that a sail is associated with a keel underwater, and the probability that keels may be found under level surfaces. This resulted in estimates of equivalent thickness comparable with the Original formula. Estimates of equivalent thickness at one or two degree latitude resolution are sufficiently accurate for validating sea ice models. Although ridges are small features in the Ross Sea, we have shown that they constitute a significant fraction of the total ice mass.