Prokaryotic Diversity and Distribution in Different Habitats of an Alpine Rock Glacier-Pond System

Abstract

Rock glaciers (RG) are assumed to influence the biogeochemistry of downstream ecosystems because of the high ratio of rock:water in those systems, but no studies have considered the effects of a RG inflow on the microbial ecology of sediments in a downstream pond. An alpine RG-pond system, located in the NW Italian Alps has been chosen as a model, and Bacteria and Archaea 16S rRNA genes abundance, distribution and diversity have been assessed by qPCR and Illumina sequencing, coupled with geochemical analyses on sediments collected along a distance gradient from the RG inflow. RG surface material and neighbouring soil have been included in the analysis to better elucidate relationships among different habitats. Our results showed that different habitats harboured different, well separated microbial assemblages. Across the pond, the main variations in community composition (e.g. Thaumarchaeota and Cyanobacteria relative abundance) and porewater geochemistry (pH, DOC, TDN and NH4 +) were not directly linked to RG proximity, but to differences in water depth. Some microbial markers potentially linked to the presence of meltwater inputs from the RG have been recognised, although the RG seems to have a greater influence on the pond microbial communities due to its contribution in terms of sedimentary material.

Rock glaciers and related cold rocky landforms: Overlooked climate refugia for mountain biodiversity

“…It is unclear if CRLs will promote refugia in lakes and ponds similar to that of alpine streams. For instance, while microbial diversity typical of glacier‐fed lakes has been observed in rock glacier‐fed water bodies (Mania et al, 2019), only one study has made a direct comparison. In the Italian Alps, primary producer communities are comparable between lakes influenced by rock glaciers and those not influenced by them (Thaler et al, 2015).…”

Habitat filtering shapes the differential structure of microbial communities in the Xilingol grassland

“…In fact, mountainous studies have focused on the microbial assemblages among different habitats in a range of systems including forests 21 , rock glacier-ponds 22 , peatland systems 23 , terrestrial- freshwater gradients 24 , and the human body 25 . Although the crossing of boundaries between differential habitats enables microorganisms to occupy novel niches and explore accessible nutrient resources, it is a large challenge for microorganisms 26 .…”

Ecosystem shifts in Alpine streams under glacier retreat and rock glacier thaw: A review

“…While most research on microbial communities has focused on glacial environments and streams, only few studies have been conducted to date on permafrost-fed waters in the Alps. Preliminary studies on bacterial diversity in rock glacier ponds (Mania et al, 2018) and running waters (Tolotti et al, 2018) agree with the outcomes of studies conducted in North America (Fegel et al, 2016), which show that rock glacier outflows host more abundant and diverse bacterial communities than kryal streams, with a high proportion of typical soil taxa in streambed sediments.…”