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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

Distribution of 97% clustered OTUs aligned and assigned to known algal species. Values are the relative abundance of the taxa in percentage of total sequences and figure shows taxa with OTUs of a minimum total observation count of 0.05%. It is important to note that values are rounded to one digit; therefore, the abundance of a taxon with a value of 0.0 in one sample can range between 0.00 and 0.04%. A full OTU table can be found in the SI.
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Figure 4: Distribution of 97% clustered OTUs aligned and assigned to known algal species. Values are the relative abundance of the taxa in percentage of total sequences and figure shows taxa with OTUs of a minimum total observation count of 0.05%. It is important to note that values are rounded to one digit; therefore, the abundance of a taxon with a value of 0.0 in one sample can range between 0.00 and 0.04%. A full OTU table can be found in the SI.

Mentions: In order to investigate algal relative abundance all sequences corresponding to Chloroplastida were filtered from the main OTU table (Figure 4) with 567 OTUs remaining. Sequences matching Embryophyta showed low abundance with <7% for all samples with Vatnajökull being the exception and a value of 22% of total eukaryotic sequences. All sequences matching Embryophyta were removed from further analyses. The most abundant genera of algae belong to the Chlamydomonadaceae with Chloromonas polyptera being the dominant taxon. Two uncultured Chlamydomonadaceae species were also highly abundant and based on their 18S rRNA sequences they shared the highest sequence similarity (89–93% similarity) with other Chloromonas species found in our samples (Figure S2). The Trebouxiaceae were represented by Raphidonema sempervirens as the dominant taxon. Other Chloromonas species with intermediate abundance (up to 16.7%) were Chr. nivalis, Chr. alpina and Chr. tughillensis. Relative abundance of Chlamydomonas, Ancylonema, and Mesotaenium, that are typically described on glacial surfaces worldwide, was very low (<0.1%). In the Langjökull sample we also found a high number of sequences matching Prototheca cutis, a newly discovered pathogenic algae (Satoh et al., 2010), that may be derived from sledge dog feces that was abundant close to our sampling site. Full OTU tables can be found in the SI files. Shannon indices (Table 6) for algal species did not reveal large differences between sites (H′ = 3.88–4.51). The exceptions were the three samples collected from Eyafjallajökull in 2014, which showed a much lower diversity in the algae species (H′ = 1.07–1.81). The PCA analysis of the algal species (Figure 5) revealed taxonomic distance between sampling sites, however, separation was not caused by increasing geographic distance or collection time.


Microbial diversity on Icelandic glaciers and ice caps.

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

Distribution of 97% clustered OTUs aligned and assigned to known algal species. Values are the relative abundance of the taxa in percentage of total sequences and figure shows taxa with OTUs of a minimum total observation count of 0.05%. It is important to note that values are rounded to one digit; therefore, the abundance of a taxon with a value of 0.0 in one sample can range between 0.00 and 0.04%. A full OTU table can be found in the SI.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: Distribution of 97% clustered OTUs aligned and assigned to known algal species. Values are the relative abundance of the taxa in percentage of total sequences and figure shows taxa with OTUs of a minimum total observation count of 0.05%. It is important to note that values are rounded to one digit; therefore, the abundance of a taxon with a value of 0.0 in one sample can range between 0.00 and 0.04%. A full OTU table can be found in the SI.
Mentions: In order to investigate algal relative abundance all sequences corresponding to Chloroplastida were filtered from the main OTU table (Figure 4) with 567 OTUs remaining. Sequences matching Embryophyta showed low abundance with <7% for all samples with Vatnajökull being the exception and a value of 22% of total eukaryotic sequences. All sequences matching Embryophyta were removed from further analyses. The most abundant genera of algae belong to the Chlamydomonadaceae with Chloromonas polyptera being the dominant taxon. Two uncultured Chlamydomonadaceae species were also highly abundant and based on their 18S rRNA sequences they shared the highest sequence similarity (89–93% similarity) with other Chloromonas species found in our samples (Figure S2). The Trebouxiaceae were represented by Raphidonema sempervirens as the dominant taxon. Other Chloromonas species with intermediate abundance (up to 16.7%) were Chr. nivalis, Chr. alpina and Chr. tughillensis. Relative abundance of Chlamydomonas, Ancylonema, and Mesotaenium, that are typically described on glacial surfaces worldwide, was very low (<0.1%). In the Langjökull sample we also found a high number of sequences matching Prototheca cutis, a newly discovered pathogenic algae (Satoh et al., 2010), that may be derived from sledge dog feces that was abundant close to our sampling site. Full OTU tables can be found in the SI files. Shannon indices (Table 6) for algal species did not reveal large differences between sites (H′ = 3.88–4.51). The exceptions were the three samples collected from Eyafjallajökull in 2014, which showed a much lower diversity in the algae species (H′ = 1.07–1.81). The PCA analysis of the algal species (Figure 5) revealed taxonomic distance between sampling sites, however, separation was not caused by increasing geographic distance or collection time.

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