Taxonomic and functional analysis of proglacial water bodies of Triloknath glacier ecosystem from North-Western Himalayas

Abstract

The melting of glaciers due to global warming leads to the formation of proglacial water bodies such as streams and lakes in their downstream environment. Triloknath glacier in the North-Western Himalayas has retreated unprecedently at a rate of 180 m /decade, forming similar water bodies. Glacier meltwater is considered the primary source of microbial diversity in downstream water bodies. Documentation of such diversity is crucial to retrieve the specialized microbial population because of the shift in the aquatic system due to deglaciation. In the current study, bacterial community structure based on V3-V4 region amplicons of 16S rRNA gene of two proglacial lakes and the glacial stream of Triloknath glacier was compared. Proglacial lake I site represents the ice-contacted proglacial lake while the proglacial lake II represents an ice-distal proglacial lake generally said to be evolved from the former. Proteobacteria was the most abundant phylum across the three sites. The prevalence of Proteobacteria in the proglacial lake I, proglacial lake II and glacial stream was 43.58%, 49.91%, and 40.08%, respectively. The highest species richness based on Chao I index (656) was observed in glacial stream while, the highest species diversity based on the Shannon index (8.95) was observed in proglacial lake I. The physiochemical conditions of glacial stream and proglacial lake II were closer than the lake I. These findings were corroborated with microbial diversity results as beta diversity analysis based on the Bray-curtis matrix indicated the closeness of glacier stream and proglacial lake II ecosystem and these sites also shared maximum bacterial genera.16S rRNA gene-based functional analysis showed the occurrence of xenobiotics degrading genes exposing the presence of pollutants in glacier ecosystem. The current study generated baseline information about the change in bacterial diversity due to deglaciation and hydrological connectivity of downstream water bodies with the glacier. The study documented residential microbial population of sensitive ecological niche of proglacial water bodies of Triloknath glacier ecosystem.