Dry Valley Streams in Antarctica: Ecosystems Waiting for Water

• Published in: BioScience
• Main Authors: McKnight, Diane M., Niyogi, Dev, Alger, Alexander S., Bomblies, Arne, Conovitz, Peter A., Tate, Cathy M.
• Format: Text
• Language: unknown
• Published: Scholars' Mine 1999
• Subjects: Rivers; Cyanobacteria; Microbial Cultures; Temperature; McMurdo Dry Valleys (Antarctica); Antarctica; Biology; McMurdo Dry Valleys; Antarc*
• Online Access: https://scholarsmine.mst.edu/biosci_facwork/218; https://doi.org/10.1525/bisi.1999.49.12.985

An axiom of ecology is: "Where there is water, there is life." In dry valley ecosystems of Antarctica, this axiom can be extended to: "Where there has been and will be water, there is life." Stream communities in the dry valleys can withstand desiccation on an annual basis and also for longer periods - as much as decades or even centuries. These intact ecosystems, consisting primarily of cyanobacteria and eukaryotic algae, spring back to life with the return of water. Soil organisms in the dry valleys also have remarkable survival capabilities (Virginia and Wall 1999), emerging from dormancy with the arrival of water. Streams in the dry valleys carry meltwater from a glacier or ice-field source to the lakes on the valley floors and generally flow for 4-10 weeks during the summer, depending on climatic conditions. Many of these streams contain abundant algal mats that are perennial in the sense that they are in a freeze-dried state during the winter and begin growing again within minutes of becoming wetted by the first flow of the season. The algal species present in the streams are mainly filamentous cyanobacteria (approximately 20 species of the genera Phormidium, Oscillatoria, and Nostoc), two green algal species of the genus Prasiola, and numerous diatom taxa that are characteristic of soil habitats and polar regions. Algal abundances are greatest in those streams in which periglacial processes, acting over periods of perhaps a century, have produced a stable stone pavement in the streambed. This habitat results in a less turbulent flow regime and limits sediment scour from the streambed. Because dry valley glaciers advance and retreat over periods of centuries and millennia and stream networks in the dry valleys evolve through sediment deposition and transport, some of the currently inactive stream channels may receive flow again in the future. Insights into the process of algal persistence and reactivation will come from long-term experiments that study the effects of reintroducing water flow to channels in ...