A5000861010- Polar Research and Ecology
- Microbial Community Ecology and Physiology
- Geology and Paleoclimatology Research
- Planetary Science and Exploration
- Cryospheric studies and observations
- Methane Hydrates and Related Phenomena
- Climate change and permafrost
- Space Science and Extraterrestrial Life
- Genomics and Phylogenetic Studies
- Biocrusts and Microbial Ecology
- Paleontology and Stratigraphy of Fossils
- Astro and Planetary Science
- Protist diversity and phylogeny
- Spaceflight effects on biology
- Geological Studies and Exploration
- Space Exploration and Technology
- Marine and coastal ecosystems
- Hydrocarbon exploration and reservoir analysis
- Atmospheric and Environmental Gas Dynamics
- Microbial Metabolism and Applications
- Arctic and Antarctic ice dynamics
- Microbial Natural Products and Biosynthesis
- Geochemistry and Geologic Mapping
- Marine Biology and Ecology Research
- Marine and coastal plant biology
Search for Extraterrestrial Intelligence
2015-2024
McGill University
2000-2005
Ames Research Center
1992-2003
National Aeronautics and Space Administration
1993
We studied the fluorescence properties of fulvic acids isolated from streams and rivers receiving predominantly terrestrial sources organic material lakes with microbial material. Microbially derived have fluorophores a more sharply defined emission peak occurring at lower wavelengths than in terrestrially acids. show that ratio intensity wavelength 450 nm to 500 nm, obtained an excitation 370 can serve as simple index distinguish aquatic In our study, this has value ~1.9 for microbially...
The Atacama along the Pacific Coast of Chile and Peru is one driest possibly oldest deserts in world. It represents an extreme habitat for life on Earth analog dry conditions Mars. We report four years (September 1994-October 1998) climate moisture data from arid region Atacama. Our are focused understanding sources their role creating suitable environments photosynthetic microorganisms desert surface. average air temperature was 16.5°C 16.6°C 1995 1996, respectively. maximum recorded...
Geomorphic evidence suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near surface in geologically times. Irrespective ultimate source fluid carving gullies, we seek to understand behavior this after it reaches surface. We find contrary popular belief, fluvially carved consistent with formation conditions such as now occur Mars, outside temperature‐pressure stability...
Mars has undergone three main climatic stages throughout its geological history, beginning with a water-rich epoch, followed by cold and semi-arid era, transitioning into present-day arid very desert conditions. These global eras also represent different of planetary habitability: an early, potentially habitable stage when the basic requisites for life as we know it were present (liquid water energy); intermediate extreme stage, liquid solutions became scarce or challenging life; most recent...
The search for evidence of life on Mars is the primary motivation exploration that planet. results from previous missions, and Phoenix mission in particular, indicate ice-cemented ground north polar plains likely to be most recently habitable place currently known Mars. near-surface ice provided adequate water activity during periods high obliquity, ∼5 Myr ago. Carbon dioxide nitrogen are present atmosphere, nitrates may soil. Perchlorate soil together with iron basaltic rock provides a...
The springs at Gypsum Hill and Colour Peak on Axel Heiberg Island in the Canadian Arctic originate from deep salt aquifers are among few known examples of cold thick permafrost Earth. discharge anoxic brines (7.5 to 15.8% salts), with a mean oxidoreduction potential -325 mV, contain high concentrations sulfate sulfide. We surveyed microbial diversity sediments seven by denaturing gradient gel electrophoresis (DGGE) analyzing clone libraries 16S rRNA genes amplified Bacteria Archaea-specific...
Abstract Lake Untersee is one of the largest (11.4 km 2 ) and deepest (>160 m) freshwater lakes in East Antarctica. Located at 71°S lake has a perennial ice cover, water column that, with exception small anoxic basin southwest lake, well mixed, supersaturated dissolved oxygen, alkaline (pH 10.4) exceedingly clear. The floor covered photosynthetic microbial mats to depths least 100 m. These are primarily composed filamentous cyanophytes form two distinct macroscopic structures, which –...
Perennial springs located on west central Axel Heiberg Island in the Canadian High Arctic occur a region with mean annual air temperature of −15°C and flow through continuous permafrost 600 m thick. The spring water is low‐temperature (up to 6°C) brine that maintains constant discharge temperatures rates throughout year. Here we report observations rate these develop combined thermal model subsurface using measured geothermal gradient. We also consider implications have for search similar...
In this study, we report the distribution of microbial taxa and their predicted metabolic functions observed in top (U1), middle (U2) inner (U3) decadal growth laminae a unique large conical mat from perennially ice-covered freshwater Lake Untersee East Antarctica, using NextGen sequencing 16S rRNA gene bioinformatics tools. The results showed that U1 lamina was dominated by cyanobacteria, specifically Phormidium sp., Leptolyngbya sp. Pseudanabaena U2 U3 had high abundances Actinobacteria,...
This paper documents perennial spring activity at Expedition Fiord on western Axel Heiberg Island in the Canadian High Arctic. Two groups of mineralized springs occur near McGill University Research Station located 79°26'N, 90°46'W. The first is Gypsum Hill, 3 km from terminus White and Thompson glaciers, second site Colour Peak, approximately 10 downvalley head Fiord. Each group consists 20-40 vents spread over several hundred square metres. highly nature discharge causes a freezing-point...
The saline springs of Gypsum Hill in the Canadian high Arctic are a rare example cold originating from deep groundwater and rising to surface through thick permafrost. heterotrophic bacteria autotrophic sulfur-oxidizing (up 40% total microbial community) isolated spring waters sediments were classified into four phyla (Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria) based on 16S rRNA gene analysis; isolates primarily psychrotolerant, salt-tolerant, facultative anaerobes. Some...
Lake Vostok is a large lake located 4 km beneath the East Antarctic Ice Sheet that should be supersaturated with dissolved gases in equilibrium clathrate present water column. Here we show if age of such mass has been cycled over 30 times then total gas equilibrates at about 2.5 liters (STP) per kg water; high enough to have important implications for drilling into this deep subglacial lake. Different air are preferentially incorporated and thus molar ratios column will reflect presence...
Microbial pinnacles in ice-covered Lake Vanda, McMurdo Dry Valleys, Antarctica, extend from the base of ice to more than 50 m water depth. The distribution microbial communities, their photosynthetic potential, and pinnacle morphology affects local accumulation biomass, which turn shapes morphology. This feedback, plus environmental stability, promotes growth elaborate structures. In all mats sampled greater 10 depth contained with a gradation size <1-mm-tall tufts that were centimeters...
This study describes microbial community compositions, and various cold-responsive stress genes, encompassing cold-induced proteins (CIPs) cold-associated general stress-responsive (CASPs) in selected Antarctic lake water, sediment, soil metagenomes. Overall, Proteobacteria Bacteroidetes were the major taxa all Prochlorococcus Thiomicrospira highly abundant waters, while Myxococcus, Anaeromyxobacter, Haliangium, Gloeobacter dominant sediment Among CIPs, genes necessary for DNA replication,...
Antarctic cryoconite holes (CHs) are mostly perennially ice-lidded and sediment-filled depressions that constitute important features on glaciers ice sheets. Once being hydrologically connected, these microbially dominated mini-ecosystems provide nutrients biota for downstream environments. For example, the East Anuchin Glacier gradually melts into adjacent ice-covered Lake Untersee, CH from this glacier contribute up to one third of community composition in benthic microbial mats within...
We report results from 10 years of ice thickness measurements at perennially ice‐covered Lake Hoare in southern Victoria Land, Antarctica. The cover this lake had been thinning steadily a rate exceeding 20 cm yr −1 during the last decade but seems to have recently stabilized 3.3 m. Data concerning level and degree‐days above freezing are presented show relationship between peak summer temperatures volume glacier‐derived meltwater entering each summer. From these latter data we infer that 0°C...
We have investigated the transmission and albedo of perennial ice cover on Lake Hoare, Antarctica. Our database consists year‐round measurements photosynthetically active radiation (400–700 nm) under ice, spatial variation under‐ice light in midsummer, spectrally resolved from 400 to 700 nm early (November) midsummer (January). results show that decreases first part summer, dropping by a factor ∼4 November January. suggest this is due heating upper layers formation Tyndall figures. Later...
An analysis of diatoms and fossil pigments in a sediment core from perennially ice‐covered Ward Hunt Lake at latitude 83°N Nunavut, Canada revealed striking changes diatom communities sedimentary pigment concentrations during the last two centuries. Diatoms were found only upper 2.5 cm record, where present, assemblages composed almost entirely Staurosirella pinnata . Photosynthetic present low throughout profile, consistent with ultra‐oligotrophic nutrient status lake. Pigment varied...