Earth has experienced periodic local to global glaciation for nearly 3 billion years, providing supra- and subglacial environments for colonization by microbial communities. A number of studies have reported on the role of microbial communities in glacial ecosystems including their influence on element cycling and weathering, but there is a paucity data on volcanic rock-hosted glacial ecosystems. Glaciers on stratovolcanoes in the Pacific Northwest override silica-rich rocks which represent analogues to an early Martian cryosphere. On these glaciers, blooms of photosynthetic snow algae support supraglacial microbial communities as has been observed on snowfields, glaciers, and ice sheets. In subglacial environments of volcanic rock-hosted glacial systems, weathering is driven, at least in part, by carbonic acid, suggesting a link between supraglacial carbon sources and subglacial heterotrophic microbial communities. Here, we report inorganic carbon assimilation and microbial community composition on glaciers across three stratovolcanoes ranging in composition from dacitic to mafic in the Pacific Northwest of the United States to begin to constrain the role of supraglacial primary productivity in subglacial weather processes. These data, coupled to contextual carbon and nitrogen isotope analyses of biomass and aqueous geochemistry, indicate snow algae drive light dependent carbon uptake across supraglacial and periglacial environments. Furthermore, snow algae microbial communities are supported by fixed nitrogen predominantly from deposition via precipitation. Our data highlight intense cycling of carbon and nitrogen driven by supraglacial microbial communities that feeds subglacial microbial communities which in turn may drive weathering processes. These results further underscore the role of glacial ecosystems in global biogeochemical cycling, especially during past global glaciations. Finally, these results lend support for glaciers as refugia for biodiversity on Earth and potentially on other bodies such as Mars where evidence exists for widespread and long-lived cryosphere including glaciers and ice sheets.
|Original language||English (US)|
|Number of pages||23|
|Journal||Geochimica et Cosmochimica Acta|
|State||Published - Feb 15 2019|
Bibliographical noteFunding Information:
JRH and TLH would like to acknowledge Courtney Motley for her help in sample processing, Jordyn Miller for her help and assistance in field work and sample collection, Helen Rogers for assistance, Dr. Aaron Diefendorf for his generous assistance in analyzing samples, and Robert and Sally Havig for their generous help and use of their garage as a lab during expeditions. JRH would like to acknowledge the University of Cincinnati and the University of Minnesota for financial support. JRH and TLH would also like to thank the National Forest Service for access to Wilderness Areas. JRH and TLH would like to acknowledge the Yakima, Chinook, Wasco and Wishram, and Molalla First Nations peoples, on whose traditional lands this work was conducted (source: Native-Land.ca).
© 2018 The Author(s)
- Carbon isotopes
- Carbon uptake
- Pacific Northwest
- Snow algae