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Extreme streams: flow intermittency as a control on diatom communities in meltwater streams in the McMurdo Dry Valleys, Antarctica

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Abstract:

In the McMurdo Dry Valleys of Antarctica, stream biota is limited by the brief availability of liquid water. The benthic microbial mats harbor diatoms that have adapted to hydrologic stresses, including numerous endemic species. We found a strong relationship between diatom community composition and flow intermittency in a data set including seven streams that spanned a gradient in flow intermittency. In particular, two genera represented by numerous endemic species in Dry Valley habitats, Hantzschia and Luticola, had high abundances in moderately and highly intermittent streams, respectively. The Shannon Index of diversity was greatest in streams with intermediate flow intermittency, with lower diversity in more stable streams resulting from lower evenness, and lower diversity in highly intermittent streams resulting from lower richness. These results indicate that multiple metrics of biodiversity may be useful in assessing the response of diatom communities to changing hydrologic regime. We propose that flow intermittency acts as a species filter that increases habitat heterogeneity in Dry Valley streams and may allow endemic species to persist. Future Antarctic warming may alter diatom community composition and habitats that act as refugia for desiccation-tolerant taxa.

Document Type: Research Article

DOI: http://dx.doi.org/10.1139/f2012-022

Affiliations: 1: Environmental Studies Program, Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Campus Box 450, Boulder, CO 80309, USA. 2: Biology Department, University of Louisiana at Lafayette, Lafayette, LA 70504, USA. 3: Division of Natural Sciences and Mathematics, East Georgia College, Swainsboro, GA 30401, USA. 4: Natural Resource Ecology Laboratory and Department of Biology, Colorado State University, Fort Collins, CO 80523, USA. 5: Department of Civil and Environmental Engineering, Institute of Arctic and Alpine Research, University of Colorado, 1560 30th Street, Campus Box 450, Boulder, CO 80309, USA.

Publication date: August 20, 2012

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  • Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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