Antarctic climate cooling and response of diatoms in glacial meltwater streams

• Published in: Geophysical research letters Vol. 33; no. 7; pp. L07406 - n/a
• Main Authors: Esposito, R. M. M., Horn, S. L., McKnight, D. M., Cox, M. J., Grant, M. C., Spaulding, S. A., Doran, P. T., Cozzetto, K. D.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.04.2006; Blackwell Publishing Ltd
• Subjects: Bacillariophyceae; Benthic processes; Biodiversity; Biogeosciences; Climate dynamics; Earth sciences; Earth, ocean, space; Exact sciences and technology; Life in extreme environments; Limnology; Antarctica; Antarctica, Victoria Land, McMurdo Dry Valley; trend-surface analysis; habitat; Plantae; abundance; streams; algae; solar radiation; ice; dry valleys; meltwater; Atmospheric temperature; diatoms; polar regions; climate cooling; Thallophyta
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2006GL025903

To understand biotic responses to an Antarctic cooling trend, we analyzed diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice‐free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40–60% of relative diatom abundance. Decreased solar radiation and air‐temperatures reduce annual stream flow, raising the dominance of these Antarctic species to levels above 60%. Thus, cooling favors the Antarctic species, and lowers diatom species diversity in this region.