Integrating geochemical, microbiological, and molecular techniques to characterize and constrain the role of snow algae in local and global biogeochemical cycles.

Alpine glaciers are primary contributors of drinking and agricultural water in mid-latitude regions such as the Pacific Northwest (PNW) in the USA, but recent global warming predictions suggest as many as 77 % of PNW glaciers will cease to exist in the coming 100 years. These endangered systems are currently under-studied, making characterizing supraglacial ecosystems imperative to better constrain the role of supraglacial ecosystems in global biogeochemical cycles and subglacial weathering. To begin to address this knowledge gap, we have conducted integrative studies of geochemistry, microbial community composition, and primary productivity in supra- and peri-glacial systems at Mt. Adams (WA), Mt. Hood (OR), and North Sister (OR) in Cascade Range of the PNW. Our work has demonstrated: 1) snow algae communities drive primary productivity across a range of supra- and peri-glacial regions; 2) snow algae biomass contributes to subglacial weathering; 3) snow algae communities incorporate fixed nitrogen from anthropogenic sources; and 4) increasing dissolved inorganic carbon concentration correlates with increase algal activity. These results have implications for improving modern global climate models, understanding past snowball Earth events, and searching for evidence of life on Mars.