# Linkages Between Trace Elements and Bacterial Communities in Glacial Freshwater Systems of Zhongar Alatau National Park, Kazakhstan

## TL;DR

This study explores how trace elements and bacterial communities interact in glacial freshwater systems in Kazakhstan, showing that these ecosystems are sensitive to environmental changes.

## Contribution

The study identifies unique bacterial assemblages and their link to chemical elements in glacial ecosystems, emphasizing their vulnerability to glacier retreat.

## Key findings

- Lake and sedimentary lake samples showed the highest bacterial diversity and richness.
- Glacier samples had the lowest diversity and highest proportion of habitat-specific OTUs.
- Chemical elements like Rb, Fe, Mn, K, and Ba were linked to spatial structuring of microbial communities.

## Abstract

Glacial ecosystems of Central Asia represent extreme environments where microbial communities are shaped by both physicochemical conditions and hydrological dynamics. In this study, we analysed 21 surface and meltwater samples collected in September 2023 from a lake, river, glacier, glacial river, and sedimentary lake in the Zhongar Alatau National Park (Kazakhstan, 1 040–3 360 m a.s.l.). Bacterial community structure was assessed using ARISA profiling, while spectrometric methods determined concentrations of chemical elements. Alpha diversity indices revealed the highest richness and diversity in lake and sedimentary lake samples, moderate diversity in river samples, and the lowest values in glacier samples. The glacial river samples showed the strongest variability among the samples. Unique operational taxonomic units (OTUs) were most abundant in the lake, but the glacier exhibited the highest relative proportion of habitat-specific OTUs. Principal component analysis revealed that DNA yield, along with heavy metals and other elements (Rb, Fe, Mn, K, Ba), covaried along the major axes, primarily reflecting differences driven by habitat. Overall, our results demonstrate that glacial valley habitats host distinct bacterial assemblages and that the chemical environment is consistent with the observed spatial structuring of microbial communities. These findings highlight the vulnerability and sensitivity of mountain freshwater ecosystems to glacier retreat and associated changes in water chemistry.