Nieves penitentes are a new habitat for snow algae in one of the most extreme high-elevation environments on Earth

Figures & data

Figure 1. (a, b) Photographs of Llullaillaco penitente field at 5,277 m a.s.l., Jack Darcy and Lara Vimercati are pictured for scale in (b). (c, d) Closeup pictures of red patches in penitente ice close to the tephra ground. Figure 1c and 1d have been modified with Adobe Photoshop CS5 to enhance the color of the red patch. Input levels of the image were adjusted using the quick selection tool to select the area of interest (red ice) and selective color percentages were adjusted by increasing magenta and yellow to make the red ice stand out. Photos by G. Zimmerman and S. K. Schmidt.

Figure 2. Alpha rarefaction curves based on the number of operational taxonomic units (OTUs) observed for penitente ice and soils within and below penitentes based on a 97 percent similarity clustering: (a) eukaryotes and (b) bacteria. Soil within and below penitentes had two times the number of eukaryotic OTUs and about four times the number of bacterial OTUs compared to the penitente ice (18S ANOVA p < .001, F = 63; 16S ANOVA p < .001, F = 66.24). Data shown are means ± s.e. (soil within penitentes n = 5; soil below penitentes n = 4; red ice n = 5; clear ice n = 2). Note that the scale of the y-axis changes between the panels.

Figure 3. Cluster diagram-based PCoA plot using weighted Unifrac of eukaryotes (a) and bacteria (b). Both eukaryotic and bacterial soil communities and ice communities are significantly different from each other (18S ADONIS p < .001, R² = 0.63; 16S ADONIS p < .001, R² = 0.46). Polygons surround total soil and total ice communities in both figures.

Table 1. Sequences count, GenBank ID of the closest blast hit, identity percent, and tentative taxonomic affiliation of most abundant phylotypes retrieved in red and clear penitentes ice samples: top= eukaryotes; bottom = bacteria.

Eukaryotic Sequence Count
Red Ice	Clear Ice	GenBank ID	Identity%	Closest Blast Hit
8879.4 ± 1486	363.5 ± 1.5	JQ790560	100	Chlamydomonas nivalis (algae)
1355.6 ± 263.3	940 ± 345	AB906342	96	Chloromonas sp.1 (algae)
1499 ± 1430	0	LC012710	95	Chloromonas sp. 2 (algae)
785 ± 642	4737 ± 3210	JX844984	99	Periptyctus sp. (insect)
415.4 ± 313	5682 ± 2429	AB032630	100	Naganishia friedmannii (fungi)
132.8 ± 118	249.5 ± 116.5	MG569511	100	Dothideomycetes (fungi)
0	588 ± 558	KX757779	99	Magnoliophyta (plant)
57.6 ± 40.31	292.5 ± 157.5	MH628292	100	Deschampsia antarctica (plant)
Bacterial Sequence Count
Red Ice	Clear Ice	GenBank ID	Identity%	Closest Blast Hit
313 ± 86	0	KR846626	77	Unassigned (uncultured bacterium)
0	73 ± 73	MF527140	100	Microcoleus sp. (Cyanobacteria)
1.8 ± 1.8	45 ± 45	JQ776471	100	Nostocales (Cyanobacteria)
14.6 ± 13.4	4.5 ± 1.5	MK041527	100	Pseudomonadales (γ-Proteobacteria)
9 ± 7.3	80 ± 60	MF670897	100	Chitinophagaceae (Bacteroidetes)
11.4 ± 10.4	37 ± 35	KP109895	100	Burkholderiales (β-Proteobacteria)
26.6 ± 14.6	11.5 ± 11.5	MH196469	100	Myxococcales (Δ-Proteobacteria)
2.2 ± 1.9	74 ± 72	MG642784	100	Bacillales (Firmicutes)

Figure 4. Relative abundance of the main eukaryotic phylotypes as a percentage of total sequences retrieved from penitente ice and soil samples based on polymerase chain reaction (PCR) amplifications of the 18S rRNA gene using Euk1391F/EukBr primer sets. Snow algae make up most of the diversity in red ice samples and they are abundant in soil samples within and just downhill from the penitente field.

Figure 5. Photomicrograph (1000x magnification) of a spore of a Chlamydomonas sp. from red penitente ice.