Geographical variability of bacterial communities of cryoconite holes of Andean glaciers

Abstract

Cryoconite holes, ponds full of melting water with sediment on the bottom, are hotspots of biodiversity on glacier surfaces and host dynamic micro-ecosystems. They have been extensively investigated in different areas of the world (e.g., the Arctic, Antarctic, Alps, and Himalaya), but so far no study has described the bacterial communities of the glaciers in the Andes, the world’s longest mountain range. In this study, we describe the bacterial communities of three small (< 2 km2) high-elevation (< 4200 m a.s.l.) glaciers of the Central Andes (Iver, East Iver and Morado glaciers) and two large (> 85 km2) glaciers of the Patagonian Andes (Exploradores and Perito Moreno glaciers) whose ablation tongues reach low altitude (< 300 m a.s.l.). Results show that the bacterial communities were generally similar to those observed in the cryoconite holes of other continents, but with few cyanobacteria (0.5% of sequences). The most abundant orders were Betaproteobacteriales, Cytophagales, Chitinophagales, Acetobacterales, Frankiales, Armatimonadales, Sphingobacteriales, Rhizobiales, Bacteroidales, Sphingomonadales, and Micrococcales. The bacterial communities differed between glaciers and both water pH and O2 concentration appeared to influence the bacterial community composition. This work thus provides the first description of the bacterial communities in cryoconite holes of South American glaciers.

A preliminary investigation of microbial communities on the Athabasca Glacier within deposited organic matter

“…Alphaproteobacteria were mainly composed of the orders Rhizobiales (cryoconite holes 2.5 ± 0.9%; ice 1.0 ± 0.3%, sediment 0.88%) and Sphingomonadales (cryoconite holes 2.2 ± 0.6%; ice 1.2 ± 0.4%, sediment 4.4%), which have been previously detected on other glaciers. 57–59 The order Sphingomonadales is known for its ability to degrade a wide range of aromatic hydrocarbons, particularly PAHs. 60 Differences between samples were also seen in their eukaryotic composition.…”

Linking the composition of cryoconite prokaryotic communities in the Arctic, Antarctic, and Central Caucasus with their chemical characteristics

“…The focus of our research was to study and compare the composition of cryoconite prokaryotic communities from remote regions across the globe, and to connect their variation with the chemical parameters of the sediment material. The studies on cryoconite microbiomes are limited by their inaccessibility and are mostly focused on the Arctic and Antarctic regions, and several mountain ridges, including Alps 7 , 8 , 11 and Andes 29 , while information on other regions is scarce 58 . Here, along with these locations, sampling sites introduced glaciers from the poorly covered areas of Northern Ural and Central Caucasus Mountains.…”

“…Some of the works cover the Andes 29 , the results of which showed that bacterial communities in cryoconites of South American glaciers were similar to those observed on other continents but they have fewer percentages of Cyanobacteria. They also revealed the linkage of the cryoconite bacterial community composition differences with geographical isolation and chemical characteristics of the substrate.…”

“…Even more scarce are the studies connecting the microbial diversity of cryoconites with the chemical composition of the substrate on the global and local scale. An earlier study used pH and O 2 concentrations of cryoconite holes for comparing the composition of their microbial communities across five glaciers, all from the same mountain range 29 .…”