Leveraging species distribution models to predict the impact of climate change on glacier-fed stream biofilms

Owing to climate changes, glaciers and ice sheets are rapidly shrinking worldwide, altering the geophysical properties of many ecosystems. In this context, glacier-fed streams are expected to undergo major physical and chemical modifications in the future. Lying at the glacier forefront, glacier-fed streams host a diverse, yet poorly characterised, microbial diversity. Bacteria form biofilms, along with eukaryotic algae, that develop on the streambed during the melting season and represent a major component of life in this ecosystem, even driving biogeochemical fluxes of global relevance. However, little is known about the microbes that form these biofilms, and how climate changes will impact them. The Vanishing Glaciers Project aims at unravelling the microbial life inhabiting glacier-fed streams at a global scale, coupling amplicon sequencing and metagenomics with measurements of glaciological and biogeochemical parameters. To predict the impact of climate change on the glacier-fed stream microbiome, we will use a species distribution modelling approach. First, we will use the parameters measured in this project along with climatic and geographical data to model the abundance of key bacterial taxa. Subsequently, we will use climatic and glaciological parameters to model biogeochemical parameters, and applying predictions of future scenarios of climate change, we will understand how the glacier-fed stream ecosystem will be altered by glacier retreat. Finally, we will use the distribution models and project them onto to these future scenarios, enabling us to understand how the distribution of the main bacterial taxa forming glacier-fed stream biofilms will be impacted by climate changes.