Limits...
Microbial diversity on Icelandic glaciers and ice caps.

Lutz S, Anesio AM, Edwards A, Benning LG - Front Microbiol (2015)

Bottom Line: Multivariate analyses indicated no relationships between nutrient data and microbial community structure.However, the aqueous geochemical simulations suggest that the microbial communities were not nutrient limited because of the equilibrium of snow with the nutrient-rich and fast dissolving volcanic ash.Increasing algal secondary carotenoid contents in the last stages of the melt seasons have previously been associated with a decrease in surface albedo, which in turn could potentially have an impact on the melt rates of Icelandic glaciers.

View Article: PubMed Central - PubMed

Affiliation: Cohen Laboratories, School of Earth and Environment, University of Leeds Leeds, UK.

ABSTRACT
Algae are important primary colonizers of snow and glacial ice, but hitherto little is known about their ecology on Iceland's glaciers and ice caps. Due do the close proximity of active volcanoes delivering large amounts of ash and dust, they are special ecosystems. This study provides the first investigation of the presence and diversity of microbial communities on all major Icelandic glaciers and ice caps over a 3 year period. Using high-throughput sequencing of the small subunit ribosomal RNA genes (16S and 18S), we assessed the snow community structure and complemented these analyses with a comprehensive suite of physical-, geo-, and biochemical characterizations of the aqueous and solid components contained in snow and ice samples. Our data reveal that a limited number of snow algal taxa (Chloromonas polyptera, Raphidonema sempervirens and two uncultured Chlamydomonadaceae) support a rich community comprising of other micro-eukaryotes, bacteria and archaea. Proteobacteria and Bacteroidetes were the dominant bacterial phyla. Archaea were also detected in sites where snow algae dominated and they mainly belong to the Nitrososphaerales, which are known as important ammonia oxidizers. Multivariate analyses indicated no relationships between nutrient data and microbial community structure. However, the aqueous geochemical simulations suggest that the microbial communities were not nutrient limited because of the equilibrium of snow with the nutrient-rich and fast dissolving volcanic ash. Increasing algal secondary carotenoid contents in the last stages of the melt seasons have previously been associated with a decrease in surface albedo, which in turn could potentially have an impact on the melt rates of Icelandic glaciers.

No MeSH data available.


Related in: MedlinePlus

Principal component analysis of bacterial species revealing taxonomic distance between sampling sites and species causing separation. Samples collected in 2012 and 2014 cluster together due to a higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 contain higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).
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Figure 7: Principal component analysis of bacterial species revealing taxonomic distance between sampling sites and species causing separation. Samples collected in 2012 and 2014 cluster together due to a higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 contain higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).

Mentions: Bacterial primer amplification resulted in 24,221 sequences (12 samples in total) passing the QIIME quality pipeline corresponding to 1733 operational taxonomic units clustered at 97% sequence identity. Again similar values were derived when the relative abundance of taxa for OTUs were clustered at different similarities of 99, 97, and 95% (Table S5). OTUs aligned and assigned to the Greengenes database revealed differences between the eight sampling sites. The most abundant bacterial phyla were Proteobacteria, Bacteriodetes, and Cyanobacteria (see Figure 6). Within the Proteobacteria, Betaproteobacteria were most abundant followed by Alphaproteobacteria. Betaproteobacteria were present in high abundance on Snaefellsjökull (95.1%) in 2012, Langjökull in 2013 (80.3 and 71.9%) and Eyafjallajökull in 2014 (28.7–65.4%). In contrast, Alphaproteobacteria were most abundant on Vatnajökull (49.5%) and Eyafjallajökull in 2013 (42.6%), and Drangajökull (42.0 %) in 2012. Within the Bacteriodetes, the Sphingobacteria, and Saprospirae were the most abundant representative classes in the samples collected in 2012 and 2014. Sphingobacteria showed higher relative abundance on Hofsjökull (32.2%) and on Drangajökull (18.8%) whereas Saprospirae were more present on Hofsjökull (38.4%), in the three samples collected from Eyafjallajökull in 2014 (28.0–45.5%), Laugafell (28.5%) and Drangajökull 24.1%). Cyanobacteria (Nostocophycideae and Oscillatoriophycideae) were strongly represented only on Eyafjallajökull (74.0%), Vatnajökull (56.4%), and Langjökull (24.4%) collected in 2013. The Shannon indices for most bacterial samples (Table 6) varied over a narrow range (H′ = 5.13–5.38) and showed the same trend as for algae with similar values for all glaciers. Exceptions were again the three samples collected from Eyafjallajökull in 2014 (4.52–4.64) and the pooled Snaefellsjökull sample collected in 2013, which had the lowest bacterial diversity index among all bacterial samples (H′ = 3.97). PCA analysis (Figure 7) showed samples collected in 2012 and 2014 clustering together due to higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 clustered together due to higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).


Microbial diversity on Icelandic glaciers and ice caps.

Lutz S, Anesio AM, Edwards A, Benning LG - Front Microbiol (2015)

Principal component analysis of bacterial species revealing taxonomic distance between sampling sites and species causing separation. Samples collected in 2012 and 2014 cluster together due to a higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 contain higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403510&req=5

Figure 7: Principal component analysis of bacterial species revealing taxonomic distance between sampling sites and species causing separation. Samples collected in 2012 and 2014 cluster together due to a higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 contain higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).
Mentions: Bacterial primer amplification resulted in 24,221 sequences (12 samples in total) passing the QIIME quality pipeline corresponding to 1733 operational taxonomic units clustered at 97% sequence identity. Again similar values were derived when the relative abundance of taxa for OTUs were clustered at different similarities of 99, 97, and 95% (Table S5). OTUs aligned and assigned to the Greengenes database revealed differences between the eight sampling sites. The most abundant bacterial phyla were Proteobacteria, Bacteriodetes, and Cyanobacteria (see Figure 6). Within the Proteobacteria, Betaproteobacteria were most abundant followed by Alphaproteobacteria. Betaproteobacteria were present in high abundance on Snaefellsjökull (95.1%) in 2012, Langjökull in 2013 (80.3 and 71.9%) and Eyafjallajökull in 2014 (28.7–65.4%). In contrast, Alphaproteobacteria were most abundant on Vatnajökull (49.5%) and Eyafjallajökull in 2013 (42.6%), and Drangajökull (42.0 %) in 2012. Within the Bacteriodetes, the Sphingobacteria, and Saprospirae were the most abundant representative classes in the samples collected in 2012 and 2014. Sphingobacteria showed higher relative abundance on Hofsjökull (32.2%) and on Drangajökull (18.8%) whereas Saprospirae were more present on Hofsjökull (38.4%), in the three samples collected from Eyafjallajökull in 2014 (28.0–45.5%), Laugafell (28.5%) and Drangajökull 24.1%). Cyanobacteria (Nostocophycideae and Oscillatoriophycideae) were strongly represented only on Eyafjallajökull (74.0%), Vatnajökull (56.4%), and Langjökull (24.4%) collected in 2013. The Shannon indices for most bacterial samples (Table 6) varied over a narrow range (H′ = 5.13–5.38) and showed the same trend as for algae with similar values for all glaciers. Exceptions were again the three samples collected from Eyafjallajökull in 2014 (4.52–4.64) and the pooled Snaefellsjökull sample collected in 2013, which had the lowest bacterial diversity index among all bacterial samples (H′ = 3.97). PCA analysis (Figure 7) showed samples collected in 2012 and 2014 clustering together due to higher relative abundance of Bacteriodetes (Sphingobacteria, Saprospirae), whereas samples collected in 2013 clustered together due to higher proportions of Betaproteobacteria and Cyanobacteria (Nostocophicidae, Oscillatoriophycideae).

Bottom Line: Multivariate analyses indicated no relationships between nutrient data and microbial community structure.However, the aqueous geochemical simulations suggest that the microbial communities were not nutrient limited because of the equilibrium of snow with the nutrient-rich and fast dissolving volcanic ash.Increasing algal secondary carotenoid contents in the last stages of the melt seasons have previously been associated with a decrease in surface albedo, which in turn could potentially have an impact on the melt rates of Icelandic glaciers.

View Article: PubMed Central - PubMed

Affiliation: Cohen Laboratories, School of Earth and Environment, University of Leeds Leeds, UK.

ABSTRACT
Algae are important primary colonizers of snow and glacial ice, but hitherto little is known about their ecology on Iceland's glaciers and ice caps. Due do the close proximity of active volcanoes delivering large amounts of ash and dust, they are special ecosystems. This study provides the first investigation of the presence and diversity of microbial communities on all major Icelandic glaciers and ice caps over a 3 year period. Using high-throughput sequencing of the small subunit ribosomal RNA genes (16S and 18S), we assessed the snow community structure and complemented these analyses with a comprehensive suite of physical-, geo-, and biochemical characterizations of the aqueous and solid components contained in snow and ice samples. Our data reveal that a limited number of snow algal taxa (Chloromonas polyptera, Raphidonema sempervirens and two uncultured Chlamydomonadaceae) support a rich community comprising of other micro-eukaryotes, bacteria and archaea. Proteobacteria and Bacteroidetes were the dominant bacterial phyla. Archaea were also detected in sites where snow algae dominated and they mainly belong to the Nitrososphaerales, which are known as important ammonia oxidizers. Multivariate analyses indicated no relationships between nutrient data and microbial community structure. However, the aqueous geochemical simulations suggest that the microbial communities were not nutrient limited because of the equilibrium of snow with the nutrient-rich and fast dissolving volcanic ash. Increasing algal secondary carotenoid contents in the last stages of the melt seasons have previously been associated with a decrease in surface albedo, which in turn could potentially have an impact on the melt rates of Icelandic glaciers.

No MeSH data available.


Related in: MedlinePlus