Microbial community composition and the transformation of dissolved organic matter in supraglacial environments

• Main Author: Smith, Heidi Jean
• Other Authors: Chairperson, Graduate Committee: Christine Foreman, Markus Dieser and Christine Foreman were co-authors of the article, 'Organic matter shapes community compositon in glacial environments' submitted to the journal 'International Society for Microbial Ecology (ISME)' which is contained within this dissertation., Rachel Foster, Diane McKnight, John Lisle, Daniela Tienken, Marcel Kuypers and Christine Foreman were co-authors of the article, 'Microbial formation of labile glacial organic carbon' submitted to the journal 'Nature geosciences' which is contained within this dissertation., Michelle Tigges, Juliana D'Andrilli, Albert Parker, Brian Bothner and Christine Foreman were co-authors of the article, 'Supraglacial dissolved organic matter: a labile but unsustainable carbon source' submitted to the journal 'Limnology and oceanography' which is contained within this dissertation., Amber Schmidt, Rachel Foster, Sten Littmann, Marcel Kuypers and Christine Foreman were co-authors of the article, 'Biofilms on glacial surfaces: hotspots for biological activity' submitted to the journal 'Nature biofilms and microbiomes' which is contained within this dissertation.
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Montana State University - Bozeman, College of Agriculture 2016
• Subjects: Microorganisms; Carbon; Biogeochemistry; Organic compounds; Cotton Glacier; Antarc*; Antarctica
• Online Access: https://scholarworks.montana.edu/xmlui/handle/1/13796

Relating microbial community composition to ecosystem function is a fundamental goal in ecological analyses, with physico-chemical parameters largely controlling this relationship. This investigation aimed to elucidate the impact of physicochemical factors on biodiversity in glacial habitats, with an emphasis on dissolved organic matter (DOM). DOM is a complex mixture of organic compounds and the primary substrate for microbial activity. Considering the variety of DOM sources in aquatic systems, little is still known about the biological release and bio-transformation of microbially-derived, autochthonous DOM. Continental Antarctica, typically lacking terrestrial carbon inputs, is largely governed by autochthonous DOM, making it an ideal site to investigate microbial biodiversity and the microbial formation of DOM. Different glacial ecosystems were selected, with a strong focus on the supraglacial Cotton Glacier stream, to investigate: i) the microbial diversity and underlying environmental factors governing biogeographical trends, ii) the contribution of exuded carbon to the DOM pool and subsequent heterotrophic uptake/transformation, and iii) how biofilm influences nutrient cycling in supraglacial environments. Findings from this study highlight distinct microbial assemblages in meltwater streams/sediments, ice, snow, and cryoconite across local and regional geographic scales. Specifically, nutrient availability and DOM quality influenced trends in microbial diversity. In situ DOM exudation was sufficiently high to support bacterial carbon demands, while the spatial organization of microorganisms in biofilms was advantageous in transferring nutrients between community members. Furthermore, compared to other more recalcitrant and chemically heterogeneous DOM sources, the highly labile supraglacial DOM was unable to sustain the same magnitude of microbial metabolism. The present study revealed dynamic carbon cycling in supraglacial environments, mediated by the tight coupling between in situ carbon fixation, DOM ...