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PubMed2006

Solar modulation of Little Ice Age climate in the tropical Andes.

The underlying causes of late-Holocene climate variability in the tropics are incompletely understood. Here we report a 1,500-year reconstruction of climate history and glaciation in the Venezuelan Andes using lake sediments. Four glacial advances occurred between anno Domini (A.D.) 1250 and 1810, coincident with solar-activity minima. Temperature declines of -3.2 +/- 1.4 degrees C and precipitation increases of approximately 20% are required to produce the observed glacial responses. These results highlight the sensitivity of high-altitude tropical regions to relatively small changes in radiative forcing, implying even greater probable responses to future anthropogenic forcing.

Climate↗
PubMed2006

A northern glacial refugium for bank voles (Clethrionomys glareolus).

There is controversy and uncertainty on how far north there were glacial refugia for temperate species during the Pleistocene glaciations and in the extent of the contribution of such refugia to present-day populations. We examined these issues using phylogeographic analysis of a European woodland mammal, the bank vole (Clethrionomys glareolus). A Bayesian coalescence analysis indicates that a bank vole population survived the height of the last glaciation (approximately 25,000-10,000 years B.P.) in the vicinity of the Carpathians, a major central European mountain chain well north of the Mediterranean areas typically regarded as glacial refugia for temperate species. Parameter estimates from the fitted isolation with migration model show that the divergence of the Carpathian population started at least 22,000 years ago, and it was likely followed by only negligible immigration from adjacent regions, suggesting the persistence of bank voles in the Carpathians through the height of the last glaciation. On the contrary, there is clear evidence for gene flow out of the Carpathians, demonstrating the contribution of the Carpathian population to the colonization of Europe after the Pleistocene. These findings are consistent with data from animal and plant fossils recovered in the Carpathians and provide the clearest phylogeographic evidence to date of a northern glacial refugium for temperate species in Europe.

Animals↗
PubMed2006

Production of hydrogen peroxide in the atmosphere of a Snowball Earth and the origin of oxygenic photosynthesis.

During Proterozoic time, Earth experienced two intervals with one or more episodes of low-latitude glaciation, which are probable "Snowball Earth" events. Although the severity of the historical glaciations is debated, theoretical "hard Snowball" conditions are associated with the nearly complete shutdown of the hydrological cycle. We show here that, during such long and severe glacial intervals, a weak hydrological cycle coupled with photochemical reactions involving water vapor would give rise to the sustained production of hydrogen peroxide. The photochemical production of hydrogen peroxide has been proposed previously as the primary mechanism for oxidizing the surface of Mars. During a Snowball, hydrogen peroxide could be stored in the ice; it would then be released directly into the ocean and the atmosphere upon melting and could mediate global oxidation events in the aftermath of the Snowball, such as that recorded in the Fe and Mn oxides of the Kalahari Manganese Field, deposited after the Paleoproterozoic low-latitude Makganyene glaciation. Low levels of peroxides and molecular oxygen generated during Archean and earliest Proterozoic non-Snowball glacial intervals could have driven the evolution of oxygen-mediating and -using enzymes and thereby paved the way for the eventual appearance of oxygenic photosynthesis.

Earth, Planet↗
PubMed2004

The effectiveness of ESP (Electronic Stability Program) in reducing real life accidents.

ESP (Electronic Stability Program) has recently been introduced onto the market in an effort to reduce the number and severity of loss-of-control automobile accidents. This reduction is expected to be particularly evident for accidents on roads with low friction (e.g., wet or icy conditions). This study aimed to evaluate the statistical effectiveness of ESP using data from accidents that occurred in Sweden during 2000 to 2002. To control for exposure, induced exposure methods were used, where ESP-sensitive to ESP-insensitive accidents and road conditions were matched in relation to cars equipped with and without ESP. Cars of similar, or in some cases identical, make and model were used to isolate the role of ESP. As predicted, the study showed a positive effect of ESP in circumstances where road surfaces have low friction. The overall effectiveness was 22.1 (+/-21) percent, while for accidents on wet roads, the effectiveness increased to 31.5 (+/-23.4) percent. On roads covered with ice and snow, the corresponding effectiveness was 38.2 (+/-26.1) percent. In addition, ESP was found to be effective for three different types of cars: small front-wheel drive; large front-wheel drive; and large rear-wheel drive.

Accidents, Traffic↗
PubMed2006

The effectiveness of electronic stability control (ESC) in reducing real life crashes and injuries.

UNLABELLED: Electronic Stability Control (ESC) was introduced on the mass market in 1998. Since then, several studies showing the positive effects of ESC have been presented. OBJECTIVE: In this study, data from crashes occurring in Sweden during 1998 to 2004 were used to evaluate the effectiveness of ESC on real life crashes. The effectiveness was analyzed for different road conditions, and some accident types and injury levels. METHODS: The study used statistical analysis. To control for exposure, induced exposure methods were used, where ESC-sensitive to ESC-insensitive crashes and road conditions were matched in relation to cars equipped with and without ESC. Cars of similar or, in some cases, identical make and model were used to isolate the role of ESC. RESULTS: The study shows a positive and consistent effect of ESC overall and in circumstances where the road has low friction. The overall effectiveness on all injury crash types, except rear end crashes, was 16.7 +/- 9.3%, while for serious and fatal crashes; the effectiveness was 21.6 +/- 12.8%. The corresponding estimates for crashes with injured car occupants were 23.0 +/- 9.2% and 26.9 +/- 13.9%. For serious and fatal loss-of-control type crashes on wet roads the effectiveness was 56.2 +/- 23.5% and for roads covered with ice or snow the effectiveness was 49.2 +/- 30.2%. It was estimated that for Sweden, with a total of 500 vehicle related deaths annually, that 80-100 fatalities could be saved annually if all cars had ESC. CONCLUSIONS: ESC was found to reduce crashes with personal injuries, especially serious and fatal injuries. The effectiveness ranged from at least 13% for car occupants in all types of crashes with serious or fatal outcome to a minimum of 35% effectiveness for single/oncoming/overtaking serious and fatal crashes on wet or icy road surface. No difference in deformation pattern was found for cars with or without ESC.

Accidents, Traffic↗
PubMed2006

Impact craters as biospheric microenvironments, Lawn Hill Structure, Northern Australia.

Impact craters on Mars act as traps for eolian sediment and in the past may have provided suitable microenvironments that could have supported and preserved a stressed biosphere. If this is so, terrestrial impact structures such as the 18-km-diameter Lawn Hill Structure, in northern Australia, may prove useful as martian analogs. We sampled outcrop and drill core from the carbonate fill of the Lawn Hill Structure and recorded its gamma-log signature. Facies data along with whole rock geochemistry and stable isotope signatures show that the crater fill is an outlier of the Georgina Basin and was formed by impact at, or shortly before, approximately 509-506 million years ago. Subsequently, it was rapidly engulfed by the Middle Cambrian marine transgression, which filled it with shallow marine carbonates and evaporites. The crater formed a protected but restricted microenvironment in which sediments four times the thickness of the nearby basinal succession accumulated. Similar structures, common on the martian surface, may well have acted as biospheric refuges as the planet's water resources declined. Low-pH aqueous environments on Earth similar to those on Mars, while extreme, support diverse ecologies. The architecture of the eolian crater fill would have been defined by long-term ground water cycles resulting from intermittent precipitation in an extremely arid climate. Nutrient recycling, critical to a closed lacustrine sub-ice biosphere, could be provided by eolian transport onto the frozen water surface.

Ecosystem↗
PubMed2004

Four kingdoms on glacier ice: convergent energetic processes boost energy levels as temperatures fall.

A diverse group of glacially obligate organisms coexist on temperate glaciers between Washington State and Alaska. A fundamental challenge for these and other cold-adapted species is the necessity to maintain an energy flux capable of sustaining life at low physiological temperatures. We show here that ice-adapted psychrophiles from four kingdoms (Animalia, Eubacteria, Fungi, Protista) respond to temperature fluctuations in a similar manner; namely, ATP levels and the total adenylate pool increase as temperatures fall (within their viable temperature limits, respectively), yet growth rate increases with temperature. By contrast, mesophilic representatives of each kingdom respond in an opposite manner (i.e. adenylates increase with temperature). These observations suggest that elevated adenylate levels in psychrophiles may offset inherent reductions in molecular diffusion at low physiological temperatures.

Adaptation, Physiological↗
PubMed2006

On the rate and causes of twentieth century sea-level rise.

Both the rate and causes of twentieth century global sea-level rise (GSLR) have been controversial. Estimates from tide-gauges range from less than one, to more than two millimetre yr(-1). In contrast, values based on the processes mostly responsible for GSLR-mass increase (from mountain glaciers and the great high latitude ice masses) and volume increase (expansion due to ocean warming)-fall below this range. Either the gauge estimates are too high, or one (or both) of the component estimates is too low. Gauge estimates of GSLR have been in dispute for several decades because of vertical land movements, especially due to glacial isostatic adjustment (GIA). More recently, the possibility has been raised that coastal tide-gauges measure exaggerated rates of sea-level rise because of localized ocean warming. Presented here are two approaches to a resolution of these problems. The first is morphological, based on the limiting values of observed trends of twentieth century relative sea-level rise as a function of distance from the centres of the ice loads at last glacial maximum. This observational approach, which does not depend on a geophysical model of GIA, supports values of GSLR near 2 mm yr(-1). The second approach involves an analysis of long records of tide-gauge and hydrographic (in situ temperature and salinity) observations in the Pacific and Atlantic Oceans. It was found that sea-level trends from tide-gauges, which reflect both mass and volume change, are 2-3 times higher than rates based on hydrographic data which reveal only volume change. These results support those studies that put the twentieth century rate near 2 mm yr(-1), thereby indicating that mass increase plays a much larger role than ocean warming in twentieth century GSLR.

Climate↗
PubMed2006

Modelling the glacial isostatic adjustment of the UK region.

The glacial isostatic adjustment of the UK region has been considered in a number of recent studies. We have revisited this problem in order to: (i) highlight some key issues with regard to limitations in the ice modelling approach adopted in these studies and (ii) consider the constraints provided from observations of crustal motion available via continuous global positioning system monitoring. With regard to the first aim, we have found that: (i) previous studies have significantly overestimated ice thicknesses in regions where trim line field constraints were adopted and (ii) the duration of the glaciation phase of the UK ice sheet is a critical aspect of the model and that discrepancies in this model component have led to inconsistent inferences of Earth model parameters. With regard to the second aim, we have found that predictions of horizontal velocities (relative to a chosen site) based on a UK ice model calibrated to fit the regional sea-level database capture the geometry of the signal well but only account for 10% of the magnitude (for a range of Earth models).

Computer Simulation↗
PubMed2006

Towards improved empirical isobase models of Holocene land uplift for mainland Scotland, UK.

A new approach to modelling patterns of glacio-isostatic land uplift during the Holocene in mainland Scotland, UK, is described. The approach is based upon altitude measurements at the inner margin or locally highest point of raised estuarine surfaces dated by radiocarbon assay supported by microfossil analyses. 2,241 altitudes have been analysed by a technique new to studies of former sea-levels, Gaussian Trend Surface Analysis, and isobase models for four Holocene shorelines: the Holocene Storegga Slide tsunami shoreline, abandoned rapidly circa 7,900 sidereal years BP; the Main Postglacial shoreline, abandoned during circa 6,400-7,700 sidereal years BP; the Blairdrummond shoreline, abandoned during circa 4,500-5,800 sidereal years BP, and a speculative fourth shoreline, the Wigtown shoreline, abandoned during circa 1,520-3,700 sidereal years BP, are shown in a series of maps. The implications of the shoreline patterns for glaicio-isostasy in the area are discussed. It is maintained that the statistical technique used enables broad estimates to be made of near shore sea surface change.

Age Factors↗
PubMed2006

Atmospheric composition and climate on the early Earth.

Oxygen isotope data from ancient sedimentary rocks appear to suggest that the early Earth was significantly warmer than today, with estimates of surface temperatures between 45 and 85 degrees C. We argue, following others, that this interpretation is incorrect-the same data can be explained via a change in isotopic composition of seawater with time. These changes in the isotopic composition could result from an increase in mean depth of the mid-ocean ridges caused by a decrease in geothermal heat flow with time. All this implies that the early Earth was warm, not hot.A more temperate early Earth is also easier to reconcile with the long-term glacial record. However, what triggered these early glaciations is still under debate. The Paleoproterozoic glaciations at approximately 2.4Ga were probably caused by the rise of atmospheric O2 and a concomitant decrease in greenhouse warming by CH4. Glaciation might have occurred in the Mid-Archaean as well, at approximately 2.9Ga, perhaps as a consequence of anti-greenhouse cooling by hydrocarbon haze. Both glaciations are linked to decreases in the magnitude of mass-independent sulphur isotope fractionation in ancient rocks. Studying both the oxygen and sulphur isotopic records has thus proved useful in probing the composition of the early atmosphere.

Atmosphere↗
PubMed2005

Novel members of the family Flavobacteriaceae from Antarctic maritime habitats including Subsaximicrobium wynnwilliamsii gen. nov., sp. nov., Subsaximicrobium saxinquilinus sp. nov., Subsaxibacter broadyi gen. nov., sp. nov., Lacinutrix copepodicola gen. nov., sp. nov., and novel species of the genera Bizionia, Gelidibacter and Gillisia.

Several orange- and yellow-pigmented, halophilic, strictly aerobic, chemoheterotrophic, Gram-negative strains were isolated during investigations of maritime Antarctic habitats, including coastal fast sea-ice brine and algae, crustaceans and quartz stone sublithic cyanobacterial biofilms. Isolates investigated in this study belonged to the marine clade of the family Flavobacteriaceae and represented lineages that were either distinct from species with validly published names or appeared to be distinct species within existing genera. A polyphasic taxonomic analysis demonstrated the novelty of these strains, and several new taxa are proposed. Strains from quartz stone sublithic communities were grouped into two new genera designated Subsaximicrobium gen. nov. and Subsaxibacter gen. nov. The genus Subsaximicrobium included the species Subsaximicrobium wynnwilliamsii sp. nov. (type species; type strain G#7(T)=ACAM 1070(T)=CIP 108525(T)) and Subsaximicrobium saxinquilinus sp. nov. (type strain Y4-5(T)=ACAM 1063(T)=CIP 108526(T)). The genus Subsaxibacter contained a single species designated Subsaxibacter broadyi sp. nov. (type strain P7(T)=ACAM 1064(T)=CIP 108527(T)). A novel bacterial strain isolated from the lake-dwelling, calanoid copepod Paralabidocera antarctica was given the name Lacinutrix copepodicola gen. nov., sp. nov. (type strain DJ3(T)=ACAM 1055(T)=CIP 108538(T)). Four novel species of the genus Bizionia were discovered, Bizionia algoritergicola sp. nov. (type strain APA-1(T)=ACAM 1056(T)=CIP 108533(T)) and Bizionia myxarmorum sp. nov. (type strain ADA-4(T)=ACAM 1058(T)=CIP 108535(T)), which were isolated from the carapace surfaces of sea-ice algae-feeding amphipods, and Bizionia gelidisalsuginis sp. nov. (type strain IC164(T)=ACAM 1057(T)=CIP 108536(T)) and Bizionia saleffrena sp. nov. (type strain HFD(T)=ACAM 1059(T)=CIP 108534(T)), which were isolated from sea-ice brines. Several other novel species were also isolated from sea-ice samples, including two novel species of the genus Gelidibacter, Gelidibacter gilvus sp. nov. (type strain IC158(T)=ACAM 1054(T)=CIP 108531(T)) and Gelidibacter salicanalis sp. nov. (type strain IC162(T)=ACAM 1053(T)=CIP 108532(T)), as well as three novel species of the genus Gillisia, Gillisia illustrilutea sp. nov. (type strain IC157(T)=ACAM 1062(T)=CIP 108530(T)), Gillisia sandarakina sp. nov. (type strain IC148(T)=ACAM 1060(T)=CIP 108529(T)) and Gillisia hiemivivida sp. nov. (type strain IC154(T)=ACAM 1061(T)=CIP 108528(T)).

Amphipoda↗
PubMed2005

Pedobacter himalayensis sp. nov., from the Hamta glacier located in the Himalayan mountain ranges of India.

Strain HHS 22(T) was isolated from a glacial water sample from the snout of the Hamta glacier located in the Himalayan mountain ranges of India. Phenotypic, chemotaxonomic and phylogenetic analyses established the affiliation of the isolate to the genus Pedobacter. HHS 22(T) exhibits high 16S rRNA gene sequence similarity with Pedobacter cryoconitis (98 %). However, the level of DNA-DNA relatedness between HHS 22(T) and P. cryoconitis is only 42 %. Furthermore, HHS 22(T) differs from P. cryoconitis and the four other recognized species of Pedobacter in a number of phenotypic characteristics. These data suggest that HHS 22(T) represents a novel species of the genus Pedobacter, for which the name Pedobacter himalayensis sp. nov. is proposed. The type strain is HHS 22(T) (= JCM 12171(T) = MTCC 6384(T)).

Bacterial Typing Techniques↗
PubMed2005

Dyadobacter hamtensis sp. nov., from Hamta glacier, located in the Himalayas, India.

Strain HHS 11(T) was isolated from a water sample collected from the snout of Hamta glacier located in the Himalayan mountain ranges of India. Phenotypic, chemotaxonomic and phylogenetic analyses established the affiliation of the isolate to the genus Dyadobacter. HHS 11(T) possessed 96 and 95% 16S rRNA gene sequence similarity with respect to Dyadobacter crusticola and Dyadobacter fermentans, respectively. Furthermore, strain HHS 11(T) differs from D. crusticola and D. fermentans in a number of phenotypic characteristics. These data suggest that strain HHS 11(T) represents a novel species of the genus Dyadobacter, for which the name Dyadobacter hamtensis sp. nov. is proposed. The type strain is HHS 11(T) (=JCM 12919(T)=MTCC 7023(T)).

Bacterial Typing Techniques↗
PubMed2006

Psychromonas ingrahamii sp. nov., a novel gas vacuolate, psychrophilic bacterium isolated from Arctic polar sea ice.

A gas vacuolate bacterium, designated strain 37T, was isolated from a sea ice core collected from Point Barrow, Alaska, USA. Cells of strain 37T were large (6-14 microm in length), rod-shaped, contained gas vacuoles of two distinct morphologies, and grew well at NaCl concentrations of 1-10 % and at temperatures of -12 to 10 degrees C. The DNA G+C content was 40 mol%. Whole-cell fatty acid analysis showed that 16 : 1omega7c comprised 67 % of the total fatty acid content. Phylogenetic analysis of 16S rRNA gene sequences indicated that this bacterium was closely related to members of the genus Psychromonas, with highest sequence similarity (96.8 %) to Psychromonas antarctica. Phenotypic analysis differentiated strain 37T from P. antarctica on the basis of several characteristics, including cell morphology, growth temperature range and the ability to hydrolyse polymers. DNA-DNA hybridization experiments revealed a level of relatedness of 37 % between strain 37T and P. antarctica, providing further support that it represents a distinct species. The name Psychromonas ingrahamii sp. nov. is proposed for this novel species. The type strain is 37T (=CCUG 51855T=CIP 108865T).

Alaska↗
PubMed2006

Exiguobacterium indicum sp. nov., a psychrophilic bacterium from the Hamta glacier of the Himalayan mountain ranges of India.

Strain HHS 31(T), a Gram-positive, motile, rod-shaped, non-spore-forming, alkaliphilic bacterium, was isolated from the melt water of a glacier. Phenotypic and chemotaxonomic characteristics indicate that strain HHS 31(T) is related to species of the genus Exiguobacterium. The 16S rRNA gene sequence similarities between HHS 31(T) and strains of known species confirm that it is closely related to members of the genus Exiguobacterium (93-99 %) and that it exhibits >97 % similarity with Exiguobacterium acetylicum DSM 20416(T) (98.9 %), Exiguobacterium antarcticum DSM 14480(T) (98.0 %), Exiguobacterium oxidotolerans JCM 12280(T) (97.9 %) and Exiguobacterium undae DSM 14481(T) (97.4 %). Phylogenetic analysis based on the 16S rRNA gene sequence further confirms the affiliation of HHS 31(T) with the genus Exiguobacterium. However, the levels of DNA-DNA relatedness between HHS 31(T) and E. oxidotolerans JCM 12280(T), E. acetylicum DSM 20416(T), E. undae DSM 14481(T) and E. antarcticum DSM 14480(T) are 50, 63, 67 and 28 %, respectively. Strain HHS 31(T) also differs from these four closely related species in terms of a number of phenotypic traits. The phenotypic, chemotaxonomic and phylogenetic data suggest that HHS 31(T) merits the status of a novel species, for which the name Exiguobacterium indicum sp. nov. is proposed. The type strain is HHS 31(T) (=LMG 23471(T)=IAM 15368(T)).

Bacillaceae↗
PubMed2006

Flavobacterium glaciei sp. nov., a novel psychrophilic bacterium isolated from the China No.1 glacier.

A novel psychrophilic, yellow-pigmented and obligate aerobic bacterium, strain 0499(T), was isolated from the China No.1 glacier. Strain 0499(T) displayed the common phenotypic and chemotaxonomic features of the genus Flavobacterium, containing menaquinone-6 (MK-6) as the major quinone and C(15 : 0), iso-C(15 : 0), C(17 : 1)omega6c and summed feature 3 (C(16 : 1)omega7c/iso-C(15 : 0) 2-OH) as the major fatty acids. Optimal growth occurred at 21 degrees C. The genomic DNA G+C content was 36.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequence similarity showed that strain 0499(T) was related to members of the genus Flavobacterium, sharing the highest sequence similarities with Flavobacterium succinicans (97.9 %), Flavobacterium granuli (97.4 %) and Flavobacterium hydatis (97.2 %). On the basis of phenotypic characteristics, phylogenetic analysis and DNA-DNA relatedness data, a novel species Flavobacterium glaciei is proposed with strain 0499(T) (=CGMCC 1.5380(T)=JCM 13953(T)) as the type strain.

Bacterial Typing Techniques↗
PubMed2006

Glaciecola psychrophila sp. nov., a novel psychrophilic bacterium isolated from the Arctic.

A novel bacterial strain, designated 170(T), was collected from high latitude Arctic locations (77 degrees 30' N to approximately 81 degrees 12' N), including the Canadian Basin and Greenland Sea. Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain 170(T) was related to members of the genus Glaciecola and had the highest 16S rRNA gene sequence similarity to Glaciecola mesophila. Cells were Gram-negative, psychrophilic, motile rods. The temperature range for growth was 4-15 degrees C, with optimum growth at 12 degrees C and at approximately pH 6.0-9.0. Strain 170(T) contained C(16 : 1)omega7c, C(16 : 0), C(12 : 1) 3-OH and C(18 : 1)omega7c as major fatty acids. The genomic DNA G+C content was 42.9 mol%. On the basis of phenotypic characterization, phylogenetic analysis and DNA-DNA relatedness data, strain 170(T) is considered to represent a novel species of the genus Glaciecola, for which the name Glaciecola psychrophila is proposed. The type strain is 170(T) (=CGMCC 1.6130(T)=JCM 13954(T)).

Alteromonadaceae↗