Dry Valley Streams in Antarctica: Ecosystems Waiting for Water

McKnight, Diane M.; Niyogi, Dev K.; Alger, Alexander S.; Bomblies, Arne; Conovitz, Peter A.; Tate, Cathy M.

doi:10.1525/bisi.1999.49.12.985

Cited by 154 publications

(194 citation statements)

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“…The McMurdo Dry Valleys (DV) of Antarctica comprise the largest (approximately 15 000 km 2 ) perpetually icefree regions in the Antarctic continent (Hopkins et al, 2006b;McKnight et al, 1999). A combination of prevailing katabatic winds and extremely low precipitation rates renders the DV arguably one of the coldest, driest deserts on Earth (Barrett et al, 2002;Hopkins et al, 2006b;Cary et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Ephemerally wet soils of the DV are documented as hotspots of microbial activity; however, previous studies have focused on measurements of bulk geochemical processes as opposed to identifying the microbial members involved in these processes (Vincent, 1988;Runkel et al, 1998;McKnight et al, 1999McKnight et al, , 2004McKnight et al, , 2007Virginia & Wall, 1999;Maurice et al, 2002;Gooseff et al, 2004;Hopkins et al, 2006a;Takacs-Vesbach et al, 2010). From classical morphological-based observations, cyanobacteria have been postulated to be the dominant primary producer and N 2 fixer, with black biomass dominated by Nostoc sp., green-colored by Prasiola sp.…”

Section: Introductionmentioning

confidence: 99%

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Diverse and highly active diazotrophic assemblages inhabit ephemerally wetted soils of the Antarctic Dry Valleys

Niederberger

Sohm

Tirindelli

et al. 2012

FEMS Microbiol Ecol

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Eolian transport of biomass from ephemerally wetted soils, associated with summer glacial meltwater runoffs and lake edges, to low‐productivity areas of the Antarctic Dry Valleys (DV) has been postulated to be an important source of organic matter (fixed nitrogen and fixed carbon) to the entire DV ecosystem. However, descriptions and identification of the microbial members responsible for N2 fixation within these wetted sites are limited. In this study, N2 fixers from wetted soils were identified by direct nifH gene sequencing and their in situ N2 fixation activities documented via acetylene reduction and RNA‐based quantitative PCR assays. Shannon‐index nifH diversity levels ranged between 1.8 and 2.6 and included the expected cyanobacterial signatures and a large number of phylotypes related to the gamma‐, beta‐, alpha‐, and delta‐proteobacteria. N2 fixation rates ranged between approximately 0.5 and 6 nmol N cm−3 h−1 with measurements indicating that approximately 50% of this activity was linked with sulfate reduction at some sites. Comparisons with proximal dry soils also suggested that these communities are not ubiquitously distributed, and conditions unrelated to moisture content may define the composition, diversity, or habitat suitability of the microbial communities within wetted soils of the DVs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diverse and highly active diazotrophic assemblages inhabit ephemerally wetted soils of the Antarctic Dry Valleys

Niederberger

Sohm

Tirindelli

et al. 2012

FEMS Microbiol Ecol

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“…Although common in desert environments, dry riverbeds can be found in a wide range of ecosystems. For example, almost 50% of the network of the 2700-km-long Tagliamento River, an alpine river in northeast Italy, is temporary (Döring et al 2007), whereas streams in Antarctica flow for several months and are dry for the remainder of the year (McKnight et al 1999). Dry riverbeds can be created or inundated by anthropogenic influences (Figure 2).…”

Section: In a Nutshellmentioning

confidence: 99%

“…Values of dry riverbeds: (a) cultural significance -the Henley-on-Todd Regatta (Todd River, Northern Territory, Australia); (b) vehicle transport route(Mitchell River, Queensland, Australia); (c) egg banks for aquatic biota, such as clam shrimp (Branchiopoda: Spinicaudata) (Northern Territory, Australia); (d) habitat for terrestrial biota, such as wolf spiders (Araneae: Lycosidae) (Northern Territory, Australia); (e) wildlife corridors(Tagliamento River, Friuli-Venezia Giulia, Italy); and (f) storage sites for organic matter, such as leaf litter(Riera de Fuirosos, Catalonia, Spain). Society of America the wet phase(Robson et al 2008), or as freeze-dried mats that naturally form during winter in the frozen riverbeds of Antarctica(McKnight et al 1999).…”

mentioning

confidence: 99%

When the river runs dry: human and ecological values of dry riverbeds

Steward¹,

Schiller²,

Tockner³

et al. 2012

Frontiers in Ecol & Environ

258

255

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Temporary rivers and streams that naturally cease to flow and dry up can be found on every continent. Many other water courses that were once perennial now also have temporary flow regimes due to the effects of water extraction for human use or as a result of changes in land use and climate. The dry beds of these temporary rivers are an integral part of river landscapes. We discuss their importance in human culture and their unique diversity of aquatic, amphibious, and terrestrial biota. We also describe their role as seed and egg banks for aquatic biota, as dispersal corridors and temporal ecotones linking wet and dry phases, and as sites for the storage and processing of organic matter and nutrients. In light of these valuable functions, dry riverbeds need to be fully integrated into river management policies and monitoring programs. We also identify key knowledge gaps and suggest research questions concerning the values of dry riverbeds.

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“…In any environment, the existence and number of organisms are determined by factors within the tolerance range of the organisms. Antarctic organisms must be able to endure the intense abiotic pressures of extreme environments such as in the McMurdo Dry Valleys, where physical and chemical factors determine biological presence [3]. Antarctic lithobiontic microorganisms can withstand the harsh environmental conditions through two different strategies.…”

Section: Introductionmentioning

confidence: 99%

Exploring the physiological state of continental Antarctic endolithic microorganisms by microscopy

Rı́os¹,

Wierzchos

Sancho

et al. 2004

FEMS Microbiology Ecology

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In this microscopy study, we show that microorganisms comprising many endolithic communities of the McMurdo Dry Valleys of Antarctica appear in different physiological states. Live/dead microbial fluorescence stains were used to identify the state of microorganisms in the biofilms. The ultrastructures of these microorganisms were then characterized by transmission electron microscopy. Cyanobacteria were associated with heterotrophic bacterial cells, while fungal cells were free-living or formed partners with green alga as lichens. The extracellular polymeric substances, in which the endolithic microorganisms were embedded, formed an integral part of the biofilms observed. Extracellular polymeric substances probably play a significant role in nutrient interactions and protection of microorganisms from the environmental conditions outside the film. Living, moribund, dormant and dead microorganisms shared this microhabitat. The ecological impacts of the observed physiological dynamics are discussed.

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Dry Valley Streams in Antarctica: Ecosystems Waiting for Water

Cited by 154 publications

References 19 publications

Diverse and highly active diazotrophic assemblages inhabit ephemerally wetted soils of the Antarctic Dry Valleys

Diverse and highly active diazotrophic assemblages inhabit ephemerally wetted soils of the Antarctic Dry Valleys

When the river runs dry: human and ecological values of dry riverbeds

Exploring the physiological state of continental Antarctic endolithic microorganisms by microscopy

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