Background:Massively parallel sequencing of environmental DNA allows microbiological studies to be performed in greater detail than was possible with first-generation sequencing.For example,it facilitates the use of a...Background:Massively parallel sequencing of environmental DNA allows microbiological studies to be performed in greater detail than was possible with first-generation sequencing.For example,it facilitates the use of approaches hitherto largely applied to flora and fauna,such as rank abundance distribution(RAD)analyses.Methods:Here,we set out to advance the knowledge on Ca.Pelagibacterales(SAR11)communities from southern South America using environmental sequences from the open ocean in the Argentine sea,the uncharted Engaño Bay,as well as a river and an oligohaline shallow lake from the Patagonian Steppe ecoregion.The structures of the SAR11 assemblages present in these ecosystems were dissected by direct and rarefaction-based estimates of species richness,and evaluations of the corresponding abundance distributions(ADs),which was addressed by RAD analyses.Results:Microbial community composition analyses revealed that the studied SAR11 assemblages coexist with 27 bacterial phyla.SAR11 richness was in general very high,but ADs turned out to be highly uneven.The results were compatible with prior knowledge,and similar to that derived from point estimates of diversity.However,our comprehensive dissection allowed for more detailed quantitative comparisons to be made between the environments surveyed,and revealed differences regarding both richness and the underlying ADs.Conclusions:Despite SAR11 assemblages being extremely rich,their ADs are very uneven.Richness and ADs can vary,not only between fresh and salt water,but also between oceanic and coastal marine environments.The obtained results provide insights on general topics such as adaptation and the contrast between marine and freshwater radiations.展开更多
This pilot study documented the occurrence and levels of brominated flame retardants in the tissues of farmed and wild salmon in southern Chile.Samples of Coho salmon and rainbow trout were obtained from fish farms,ri...This pilot study documented the occurrence and levels of brominated flame retardants in the tissues of farmed and wild salmon in southern Chile.Samples of Coho salmon and rainbow trout were obtained from fish farms,rivers and lakes in the Patagonia in Aysen Region,Chile.The samples were analyzed by Gas Chromatography Negative Chemical Ionization Mass Spectrometry for the different polybrominated diphenyl ether（PBDE） congeners.Contaminants were observed in all the samples,and the congeners BDE 17,28,47 and 66 were observed in all both farmed and wild samples.The concentrations were higher in the farmed Coho salmon,presenting significant differences with wild salmon.The levels reached 182 pg/g wet weight（ww） vs.120 ww.In the case of the rainbow trout,the concentrations were lower,although the congener profile was quite similar.The levels reached an average of 100 pg/g ww in the farmed fish versus 110 pg/g ww in wild fish,and no significant difference was observed between the species.In both species,the congener with the highest concentration was BDE 47.Based on this information,the BDE ？ow was estimated for commerce,which is a form of pollutant transport not usually considered in POP pollution studies.A preliminary estimation indicated that the quantity of PBDEs mobilized by commerce was in the order of kg,and in the case of Chile might reach almost 1 kg.展开更多
The deep, ultraoligotrophic piedmont lakes of Northern Patagonia （Argentina） are located in pristine and barely impacted areas, along a wide latitudinal range. Several studies have reported moderate to high total me...The deep, ultraoligotrophic piedmont lakes of Northern Patagonia （Argentina） are located in pristine and barely impacted areas, along a wide latitudinal range. Several studies have reported moderate to high total mercury （Hg） concentrations and contrasting methylmercury （CH3Hg＋） production in different lake compartments. Sources of Hg for western Patagonian terrestrial and aquatic ecosystems are still not clear; while point sources can be ruled out and atmospheric deposition is a plausible source, along with contribution from active volcanic areas of the Andes. In this investigation, we reported a noticeably seasonal, spatial （between lake branches）, and vertical （between water column strata） heterogeneity in the total Hg concentrations found in the pelagic zone of Lake Moreno. Sterile water samples taken in a depth profile of the lake showed moderate to high concentrations of CH3Hg＋ in autumn with a decreasing trend with depth. Our results indicated that Hg is largely allocated in the plankton fraction between 10–53 μm; which dominated within the euphotic （epilimnetic） zone of the lake due to the high densities attained by two species of the dinoflagellate Gymnodinium. The 53–200 μm planktonic size fraction （comprising rotifers, ciliates and immature stages of crustaceans） and the 200 μm fraction （calanoid copepods and cladocerans） were found to bear strikingly lower total Hg concentrations, suggesting that the magnification of Hg at the planktonic consumer level is negligible.展开更多
Structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Co granite and in La Sefia and Pangare mylonites, indicate that the pluton was intruded as a sheet-like body into an openin...Structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Co granite and in La Sefia and Pangare mylonites, indicate that the pluton was intruded as a sheet-like body into an opening pull-apart structure during the Gondwana Orogeny. Geochronological studies in the massif indicate a first, lower to middle Permian stage of regional deformation, related to movements during indentation tectonics, with emplacement of foliated granites in the western and central areas of the North Patagonian Massif. Between the upper Permian and lower Triassic, evidence indicates emplacement of undeformed granitic bodies in the central part of the North Patagonian Massif. A second pulse of deformation between the middle and upper Triassic is related to the emplacement of the Caita CO granite, the development of mylonitic belts, and the opening of the Los Menucos Basin. During this pulse of deformation, compression direction was from the eastern quadrant.展开更多
Using more than 14 years of GRACE(Gravity Recovery and Climate Experiment) satellite gravimetry observations, we estimate the ice loss rate for the Patagonia Ice Field(PIF) of South America. After correcting the effec...Using more than 14 years of GRACE(Gravity Recovery and Climate Experiment) satellite gravimetry observations, we estimate the ice loss rate for the Patagonia Ice Field(PIF) of South America. After correcting the effects of glacier isostatic adjustment(GIA) and hydrological variations, the ice loss rate is -23.5 ± 8.1 Giga ton per year(Gt/yr) during the period April 2002 through December 2016, equivalent to an average ice thickness change of-1.3 m/yr if evenly distributed over PIF. The PIF ice mass change series also show obvious inter-annual variations during the entire period. For the time spans April 2002 to December 2007, January 2008 to December 2012 and January 2013 to December 2016, the ice loss rates are -26.4,-9.0 and -25.0 Gt/yr, respectively, indicating that the ice melting experienced significant slowing down and accelerating again in the past decade. Comparison with time series from temperature and precipitation data over PIF suggests that the inter-annual ice losses might not be directly correlated with the temperature changes and precipitation anomalies, and thus their interrelation is intricate. However, the dramatic ice loss acceleration in 2016(with more than 100 Gt within the first half of the year) appears closely related with the evident temperature increase and severe precipitation shortage over 2016, which are likely correlated with the strong E1 Nino event around 2016. Moreover, we compare the GRACE spherical harmonic(SH) and mass concentration(Mascon) solutions in estimating the PIF ice loss rate, and find that the Mascon result has larger uncertainty in leakage error correction,while the SH solutions can better correct leakage errors based on a constrained forward modeling iterative method. Thus the GRACE SH solutions with constrained forward modeling recovery are recommended to evaluating the ice mass change of PIF or other glacier regions with relatively smaller spatial scales.展开更多
The regional Weather and Research Forecast (WRF) Model was run for the 2000-2010 period over the Northern Patagonia Icefield (NPI) with an horizontal resolution of 5 km. The regional model was initialized using the NC...The regional Weather and Research Forecast (WRF) Model was run for the 2000-2010 period over the Northern Patagonia Icefield (NPI) with an horizontal resolution of 5 km. The regional model was initialized using the NCEP/NCAR atmospheric Reanalysis database. The simulation results, centered over the NPI, were validated against the observed data from the local surface stations in order to evaluate the improvement of the model results due to its increased horizontal resolution with respect to the lower resolution from Global Climate Model simulations. Interest in the NPI is due to 1) the large body of frozen water exposed to the impact of the warming planet, 2) the scarce availability of observed meteorological and glaciological information in this large and remote icefield, and 3) the need to validate the model behavior in simulating the current climate and its variability in complex terrain. The results will shed light on the degree of confidence in simulating future climate scenarios in the region and also in similar geographical settings. Based on this study subsequent model runs will allow to model future climate changes in Patagonia, which is basic information for estimating glacier variations to be expected during this century.展开更多
The information about ecological topics of mosquitoes at the southernmost tip of South America is fragmentary and scarce. The present study evaluates lentic freshwater habitat located in the surroundings of main roads...The information about ecological topics of mosquitoes at the southernmost tip of South America is fragmentary and scarce. The present study evaluates lentic freshwater habitat located in the surroundings of main roads of the Argentine sector of Tierra del Fuego as larval habitat of Ochlerotatus albifasciatus, also analyzes the relationships between their presence and several environmental variables: water turbidity, percentage of gramineans, percentage of macrophytes, presence of crustaceous cyanobacteria, and filamentous chlorophyceans. Mosquito inmatures were collected with dip nets. A generalized linear model (GLM) with negative binomial error distribution was used to determine the effects of different variables of the water bodies on abundance of Oc. albifasciatus in the larval habitats. Collections were made in 45 lentic freshwater bodies. Preimaginal stages were found in 17.70% of the studied habitats. Oc. albifasciatus was the only culicid registered. The GLM explained 93.17% of the variability, and showed a negative relationship between the abundances of Oc. albifasciatus and water turbidity, and a positive relationship with percent-age of gramineans. The gramineans would improve food supply, because the plants are providing suitable substrate for different types of microbiota, a layer of leaves would protect eggs from extreme temperatures, and could help the larvae to hide from potential predators. The negative association between abundance of this species with water turbidity could be related to the presence of vegetation that favors retaining the substrate, reducing water turbidity.展开更多
The Preandean geological configuration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis.The positive gravity anomalies located near the Atlantic coast are du...The Preandean geological configuration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis.The positive gravity anomalies located near the Atlantic coast are due to 535 and 540 Ma old rocks belonging to the Pampean Orogeny （Precambrian-middle Cambrian）,which are widely recognized in central and northern Argentina.The Famatinian Cycle （Ordovician-Devonian） is represented by a Silurian-Devonian marine basin equivalent to those of eastern-central Argentina and South Africa,and which was deformed at the end of the Devonian byan～E-W to WNW-ESE compressional event,part of the Famatinian Orogeny.Containing strong gravity gradients,the NW-SE belt is coincident with fault zones which were originated during the Gondwanide Orogeny.This event also produced NW-SE overthrusting of the Silurian-Devonian sequences and strike-slip faults that displaced blocks in the same direction.This deformation event belongs to the Gondwanide Orogeny that includes movements related to a counterclockwise rotation of blocks in northern Patagonia.The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Ca（n）adón Asfalto basin interbedded in the Marifil Complex.These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief.展开更多
We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^...We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^2 Island is one of the very rare exposures of the Mesozoic accretionary subduction complex along the Chilean margin. Unstable weather, strong winds, steep topography, and very dense vegetation make an on-land mission difficult. Careful preparation based on high-resolution satellite images is advised to optimize shore access and minimize risks of injury. Despite a relatively important degree of regional reequilibration of metamorphic assemblages due to sluggish exhumation through the forearc crust, our results have shown that the island is composed of a nappe stack of ocean-floor derived slivers of metasedimentary units that exhibit very different pressure-temperature-time paths during burial by subduction under the Chilean margin and subsequent exhumation. These rocks are witness to a complex thermal evolution of the subduction zone between Jurassic and Cretaceous times from granulite facies to blueschist facies conditions as well as multiple episodes of accretion at ca. 35 -40 km in depth for almost100 Ma over the Mesozoic era.展开更多
This short report communicates the finding of a Deep-bodied pipefish, Leptonotus blainvilleanus, (Eydoux & Gervais, 1837) [Syngnathiformes, Syngnathidae] in shallow waters of the San Jorge Gulf, Patagonia Argentin...This short report communicates the finding of a Deep-bodied pipefish, Leptonotus blainvilleanus, (Eydoux & Gervais, 1837) [Syngnathiformes, Syngnathidae] in shallow waters of the San Jorge Gulf, Patagonia Argentina, in August 2010. It’s a new record for its known distribution range in the coast of South America. Photos and videos are available.展开更多
The Patagonian Icefield has the largest temperate ice mass in the southern hemisphere. Using remote sensing techniques, this study analyzed multi-decadal glacial retreat and expansion of glacier lakes in Northern Pata...The Patagonian Icefield has the largest temperate ice mass in the southern hemisphere. Using remote sensing techniques, this study analyzed multi-decadal glacial retreat and expansion of glacier lakes in Northern Patagonia. Glacial boundaries and glacier lake boundaries for 1979, 1985, 2000, and 2013 were delineated from Chilean topographic maps and Landsat satellite images. Aster stereo images were used to measure mass balance from 2007 to 2012. The highest retreat was observed in San Quintin glacier. The area of glacier lakes increased from 13.49 km2 in 1979 to 65.06 km2 in 2013. Four new glacier lakes formed between 1979 and 2013. Between 2007 and 2012, significant glacial thinning was observed in major glaciers, including HPN1, Pared Norte, Strindberg, Acodado, Nef, San Quintin, Colonia, HPN4, and Benito glaciers. Generally, ablation zones lost more mass than accumulation zones.展开更多
Climate data of mean monthly temperature and total monthly precipitation compiled from different sources in northern Patagonia were interpolated to 20-km resolution grids over the period 1997-2010. This northern Patag...Climate data of mean monthly temperature and total monthly precipitation compiled from different sources in northern Patagonia were interpolated to 20-km resolution grids over the period 1997-2010. This northern Patagonian climate grid （NPCG） improves upon previous gridded products in terms of its spatial resolution and number of contributing stations, since it incorporates 218 and 114 precipitation and temper- ature records, respectively. A geostatistical method using surface elevation from a Digital Elevation Model （DEM） as the ancillary variable was used to interpolate station data into even spaced points. The maps provided by NPCG are consistent with the broad spatial and temporal patterns of the northern Patagonian climate, showing a comprehensive representation of the latitudinal and altitudinal gradients in temperature and precipitation, as well as their related patterns of seasonality and continentality. We compared the per- formance of NPCG and various other datasets available to the climate community for northern Patagonia. The grids used for the comparison included those of the Global Precipitation Climatology Project, ERA- Interim, Climate Research Unit （University of East Anglia）, and University of Delaware. Based on three statistics that quantitatively assess the spatial coherence of gridded data against available observations （bias, MAE, and RMSE）, NPCG outperforms other global grids. NPCG represents a useful tool for understand- ing climate variability in northern Patagonia and a valuable input for regional models of hydrological and ecological processes. Its resolution is optimal for validating data from the general circulation models and working with raster data derived from remote sensing, such as vegetation indices.展开更多
Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature.In particular,niche-specialist lizards are dependent on their physiological plasticity to adjust ...Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature.In particular,niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions.Lizards of the genus Phymaturus are viviparous,mainly herbivorous,and inhabit only rock promontories in the steppe environments of Patagonia and the Andes.Herein,we examine the vulnerability of the southernmost Phymaturus species to global warming:the endemic Phymaturus calcogaster,which lives in a mesic environment in eastern Patagonia.We studied body temperatures in the field(T_(b)),preferred body temperatures in a thermogradient(T_(pref)),the operative(T_(e))and environmental temperatures,and the dependence of running performance on body temperature.P.calcogaster had a mean T_(b)(27.04℃)and a mean Te(31.15℃)both lower than their preferred temperature(T_(pref)=36.61℃)and the optimal temperature for running performance(T_(o)=37.13℃).Lizard activity seems to be restraint during the early afternoon due high environmental temperatures.However,both,the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming(IPCC report in 2018)would not threaten,but indeed enhance locomotor performance in this population.展开更多
The quantification of carbon storage in vegetation biomass is a crucial factor in the estimation and mitigation of CO2 emissions.Globally,arid and semi-arid regions are considered an important carbon sink.However,they...The quantification of carbon storage in vegetation biomass is a crucial factor in the estimation and mitigation of CO2 emissions.Globally,arid and semi-arid regions are considered an important carbon sink.However,they have received limited attention and,therefore,it should be a priority to develop tools to quantify biomass at the local and regional scales.Individual plant variables,such as stem diameter and crown area,were reported to be good predictors of individual plant weight.Stand-level variables,such as plant cover and mean height,are also easy-to-measure estimators of above-ground biomass(AGB)in dry regions.In this study,we estimated the AGB in semi-arid woody vegetation in Northeast Patagonia,Argentina.We evaluated whether the AGB at the stand level can be estimated based on plant cover and to what extent the estimation accuracy can be improved by the inclusion of other field-measured structure variables.We also evaluated whether remote sensing technologies can be used to reliably estimate and map the regional mean biomass.For this purpose,we analyzed the relationships between field-measured woody vegetation structure variables and AGB as well as LANDSAT TM-derived variables.We obtained a model-based ratio estimate of regional mean AGB and its standard error.Total plant cover allowed us to obtain a reliable estimation of local AGB,and no better fit was attained by the inclusion of other structure variables.The stand-level plant cover ranged between 18.7%and 95.2%and AGB between about 2.0 and 70.8 Mg/hm^(2).AGB based on total plant cover was well estimated from LANDSAT TM bands 2 and 3,which facilitated a model-based ratio estimate of the regional mean AGB(approximately 12.0 Mg/hm^(2))and its sampling error(about 30.0%).The mean AGB of woody vegetation can greatly contribute to carbon storage in semi-arid lands.Thus,plant cover estimation by remote sensing images could be used to obtain regional estimates and map biomass,as well as to assess and monitor the impact of land-use change on the carbon balance,f展开更多
Vespertilionidae is the most diverse chiropteran family, and its diversity is concentrated in warmregions of the World; however, due to physiological and behavioral adaptations, these bats alsodominate bat faunas in t...Vespertilionidae is the most diverse chiropteran family, and its diversity is concentrated in warmregions of the World; however, due to physiological and behavioral adaptations, these bats alsodominate bat faunas in temperate regions. Here we performed a comparative study of vespertili-onid assemblages from two broad regions of the New World, the cold and harsh Patagonia, versusthe remaining temperate-to-subtropical, extra-Patagonian eco-regions of the South AmericanSouthern Cone. We took an ecomorphological approach and analyzed the craniodental morpho-logical structure of these assemblages within a phylogenetic framework. We measured 17 cranio-dental linear variables from 447 specimens of 22 currently recognized vespertilionid species of thestudy regions. We performed a multivariate analysis to define the morphofunctional space, andcalculated the pattern and degree of species packing for each assemblage. We assessed the im-portance of phylogeny and biogeography, and their impact on depauperate （Patagonian） versusrich （extra-Patagonian） vespertilionid assemblages as determinants of morphospace structuring.We implemented a sensitivity analysis associated to small samples of rare species. The morpho-logical patterns were determined chiefly by the evolutionary history of the family. The Patagonianassemblage can be described as a structurally similar but comparatively depauperate ecomorpho-logical version of those assemblages from neighboring extra-Patagonian eco-regions. ThePatagonian assemblage seems to have formed by successively adding populations from Northernregions that eventually speciated in the region, leaving corresponding sisters （vicariants） in extra-Patagonian eco-regions that continued to be characteristically richer. Despite being structurallyakin, degree of species packing in Patagonia was comparatively very low, which may reflect the ef-fect of limited dispersal success into a harsh region for bat survival.展开更多
Our study investigated the diet of the southernmost gecko in the world, Homonota darwini. Fifty-three specimens were captured during spring and summer in four locations in Patagonia, Argentina. The stomach contents of...Our study investigated the diet of the southernmost gecko in the world, Homonota darwini. Fifty-three specimens were captured during spring and summer in four locations in Patagonia, Argentina. The stomach contents of the specimens were identified, and we tbund that prey consisted of six main groups： Coleoptera, Hymenoptera, Homoptera and Araneae, and the adults and larvae of moth Lepidoptera. Lepidoptera was the major dietary component. The presence of ants and moths as common prey suggests an ambush feeding strategy. In spring, females consumed more ants than males although no other dietary differences between males and females were evident. We tbund nine geckos with empty stomachs and six parasitized by nematodes. Presence of empty stomachs corroborates previous observations of other nocturnal geckos and non-gecko lizards. Reduced foraging success of nocturnal lizards could be due to difficulty in prey detection due to dim light, reduced or erratic activity of insect prey at night, or shorter activity times of geckos relative to diurnal success. Sex and season were not associated with the incidence of empty stomachs. Principal component analysis showed that four food alternatives correlated with season. The constraint of nocturnality, coupled with low night-time temperatures restricting feeding to only a few hours after sunset, appear to have caused a generality of diet which may limit energy acquisition. We conclude that H. darwini is an arthropod generalist and likely an ambush forager, as are many other nocturnal gekkonids展开更多
基金supported by grants PIP 2021-202311220200102657CO(CONICET)PICT 2020 series A-03643(FONCyT)PI 1657(UNPSJB).
文摘Background:Massively parallel sequencing of environmental DNA allows microbiological studies to be performed in greater detail than was possible with first-generation sequencing.For example,it facilitates the use of approaches hitherto largely applied to flora and fauna,such as rank abundance distribution(RAD)analyses.Methods:Here,we set out to advance the knowledge on Ca.Pelagibacterales(SAR11)communities from southern South America using environmental sequences from the open ocean in the Argentine sea,the uncharted Engaño Bay,as well as a river and an oligohaline shallow lake from the Patagonian Steppe ecoregion.The structures of the SAR11 assemblages present in these ecosystems were dissected by direct and rarefaction-based estimates of species richness,and evaluations of the corresponding abundance distributions(ADs),which was addressed by RAD analyses.Results:Microbial community composition analyses revealed that the studied SAR11 assemblages coexist with 27 bacterial phyla.SAR11 richness was in general very high,but ADs turned out to be highly uneven.The results were compatible with prior knowledge,and similar to that derived from point estimates of diversity.However,our comprehensive dissection allowed for more detailed quantitative comparisons to be made between the environments surveyed,and revealed differences regarding both richness and the underlying ADs.Conclusions:Despite SAR11 assemblages being extremely rich,their ADs are very uneven.Richness and ADs can vary,not only between fresh and salt water,but also between oceanic and coastal marine environments.The obtained results provide insights on general topics such as adaptation and the contrast between marine and freshwater radiations.
基金supported by Fondecyt No. 1080294 and Fondecyt 1110719 (R Barra)
文摘This pilot study documented the occurrence and levels of brominated flame retardants in the tissues of farmed and wild salmon in southern Chile.Samples of Coho salmon and rainbow trout were obtained from fish farms,rivers and lakes in the Patagonia in Aysen Region,Chile.The samples were analyzed by Gas Chromatography Negative Chemical Ionization Mass Spectrometry for the different polybrominated diphenyl ether（PBDE） congeners.Contaminants were observed in all the samples,and the congeners BDE 17,28,47 and 66 were observed in all both farmed and wild samples.The concentrations were higher in the farmed Coho salmon,presenting significant differences with wild salmon.The levels reached 182 pg/g wet weight（ww） vs.120 ww.In the case of the rainbow trout,the concentrations were lower,although the congener profile was quite similar.The levels reached an average of 100 pg/g ww in the farmed fish versus 110 pg/g ww in wild fish,and no significant difference was observed between the species.In both species,the congener with the highest concentration was BDE 47.Based on this information,the BDE ？ow was estimated for commerce,which is a form of pollutant transport not usually considered in POP pollution studies.A preliminary estimation indicated that the quantity of PBDEs mobilized by commerce was in the order of kg,and in the case of Chile might reach almost 1 kg.
基金funded by the projects PICT 2005-33838 and PICT 2007-00393, Agencia Nacional de Promoción Científica y Tecnológica (Argentina), and by IAEA TCPARG7007
文摘The deep, ultraoligotrophic piedmont lakes of Northern Patagonia （Argentina） are located in pristine and barely impacted areas, along a wide latitudinal range. Several studies have reported moderate to high total mercury （Hg） concentrations and contrasting methylmercury （CH3Hg＋） production in different lake compartments. Sources of Hg for western Patagonian terrestrial and aquatic ecosystems are still not clear; while point sources can be ruled out and atmospheric deposition is a plausible source, along with contribution from active volcanic areas of the Andes. In this investigation, we reported a noticeably seasonal, spatial （between lake branches）, and vertical （between water column strata） heterogeneity in the total Hg concentrations found in the pelagic zone of Lake Moreno. Sterile water samples taken in a depth profile of the lake showed moderate to high concentrations of CH3Hg＋ in autumn with a decreasing trend with depth. Our results indicated that Hg is largely allocated in the plankton fraction between 10–53 μm; which dominated within the euphotic （epilimnetic） zone of the lake due to the high densities attained by two species of the dinoflagellate Gymnodinium. The 53–200 μm planktonic size fraction （comprising rotifers, ciliates and immature stages of crustaceans） and the 200 μm fraction （calanoid copepods and cladocerans） were found to bear strikingly lower total Hg concentrations, suggesting that the magnification of Hg at the planktonic consumer level is negligible.
基金part of the research project"Configuración Geológica y Geodinámica del sector central de la Comarca Nordpatagónica,Argentina"(24/H100)granted by the Universidad Nacional del Sur"La Orogenia Gondwánica en el sector central de la Comarca Nordpatagónica"(11420090100108)granted by CONICET
文摘Structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Co granite and in La Sefia and Pangare mylonites, indicate that the pluton was intruded as a sheet-like body into an opening pull-apart structure during the Gondwana Orogeny. Geochronological studies in the massif indicate a first, lower to middle Permian stage of regional deformation, related to movements during indentation tectonics, with emplacement of foliated granites in the western and central areas of the North Patagonian Massif. Between the upper Permian and lower Triassic, evidence indicates emplacement of undeformed granitic bodies in the central part of the North Patagonian Massif. A second pulse of deformation between the middle and upper Triassic is related to the emplacement of the Caita CO granite, the development of mylonitic belts, and the opening of the Los Menucos Basin. During this pulse of deformation, compression direction was from the eastern quadrant.
基金supported by the Natural Science Foundation of Shanghai (17ZR1435600)the Open Fund of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan University (16-01-05)the National Key Research and Development Program of China (2016YFB0501405)
文摘Using more than 14 years of GRACE(Gravity Recovery and Climate Experiment) satellite gravimetry observations, we estimate the ice loss rate for the Patagonia Ice Field(PIF) of South America. After correcting the effects of glacier isostatic adjustment(GIA) and hydrological variations, the ice loss rate is -23.5 ± 8.1 Giga ton per year(Gt/yr) during the period April 2002 through December 2016, equivalent to an average ice thickness change of-1.3 m/yr if evenly distributed over PIF. The PIF ice mass change series also show obvious inter-annual variations during the entire period. For the time spans April 2002 to December 2007, January 2008 to December 2012 and January 2013 to December 2016, the ice loss rates are -26.4,-9.0 and -25.0 Gt/yr, respectively, indicating that the ice melting experienced significant slowing down and accelerating again in the past decade. Comparison with time series from temperature and precipitation data over PIF suggests that the inter-annual ice losses might not be directly correlated with the temperature changes and precipitation anomalies, and thus their interrelation is intricate. However, the dramatic ice loss acceleration in 2016(with more than 100 Gt within the first half of the year) appears closely related with the evident temperature increase and severe precipitation shortage over 2016, which are likely correlated with the strong E1 Nino event around 2016. Moreover, we compare the GRACE spherical harmonic(SH) and mass concentration(Mascon) solutions in estimating the PIF ice loss rate, and find that the Mascon result has larger uncertainty in leakage error correction,while the SH solutions can better correct leakage errors based on a constrained forward modeling iterative method. Thus the GRACE SH solutions with constrained forward modeling recovery are recommended to evaluating the ice mass change of PIF or other glacier regions with relatively smaller spatial scales.
文摘The regional Weather and Research Forecast (WRF) Model was run for the 2000-2010 period over the Northern Patagonia Icefield (NPI) with an horizontal resolution of 5 km. The regional model was initialized using the NCEP/NCAR atmospheric Reanalysis database. The simulation results, centered over the NPI, were validated against the observed data from the local surface stations in order to evaluate the improvement of the model results due to its increased horizontal resolution with respect to the lower resolution from Global Climate Model simulations. Interest in the NPI is due to 1) the large body of frozen water exposed to the impact of the warming planet, 2) the scarce availability of observed meteorological and glaciological information in this large and remote icefield, and 3) the need to validate the model behavior in simulating the current climate and its variability in complex terrain. The results will shed light on the degree of confidence in simulating future climate scenarios in the region and also in similar geographical settings. Based on this study subsequent model runs will allow to model future climate changes in Patagonia, which is basic information for estimating glacier variations to be expected during this century.
文摘The information about ecological topics of mosquitoes at the southernmost tip of South America is fragmentary and scarce. The present study evaluates lentic freshwater habitat located in the surroundings of main roads of the Argentine sector of Tierra del Fuego as larval habitat of Ochlerotatus albifasciatus, also analyzes the relationships between their presence and several environmental variables: water turbidity, percentage of gramineans, percentage of macrophytes, presence of crustaceous cyanobacteria, and filamentous chlorophyceans. Mosquito inmatures were collected with dip nets. A generalized linear model (GLM) with negative binomial error distribution was used to determine the effects of different variables of the water bodies on abundance of Oc. albifasciatus in the larval habitats. Collections were made in 45 lentic freshwater bodies. Preimaginal stages were found in 17.70% of the studied habitats. Oc. albifasciatus was the only culicid registered. The GLM explained 93.17% of the variability, and showed a negative relationship between the abundances of Oc. albifasciatus and water turbidity, and a positive relationship with percent-age of gramineans. The gramineans would improve food supply, because the plants are providing suitable substrate for different types of microbiota, a layer of leaves would protect eggs from extreme temperatures, and could help the larvae to hide from potential predators. The negative association between abundance of this species with water turbidity could be related to the presence of vegetation that favors retaining the substrate, reducing water turbidity.
基金funded by ANPCYT-UNS (Agencia Nacional de Promoción Científca y Tecnológica of Argentina)
文摘The Preandean geological configuration of the eastern North Patagonian Massif is established through the use of geological and geophysical analysis.The positive gravity anomalies located near the Atlantic coast are due to 535 and 540 Ma old rocks belonging to the Pampean Orogeny （Precambrian-middle Cambrian）,which are widely recognized in central and northern Argentina.The Famatinian Cycle （Ordovician-Devonian） is represented by a Silurian-Devonian marine basin equivalent to those of eastern-central Argentina and South Africa,and which was deformed at the end of the Devonian byan～E-W to WNW-ESE compressional event,part of the Famatinian Orogeny.Containing strong gravity gradients,the NW-SE belt is coincident with fault zones which were originated during the Gondwanide Orogeny.This event also produced NW-SE overthrusting of the Silurian-Devonian sequences and strike-slip faults that displaced blocks in the same direction.This deformation event belongs to the Gondwanide Orogeny that includes movements related to a counterclockwise rotation of blocks in northern Patagonia.The strong negative anomalies located in the western part of the area stem from the presence of rocks of the Jurassic Ca（n）adón Asfalto basin interbedded in the Marifil Complex.These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief.
文摘We undertook a boat expedition to explore the geological framework of a very remote, lesser-known island, in the Chilean Patagonia: the Diego de Almagro Island(latitude S51°330'). This uninhabited, ca.400 km^2 Island is one of the very rare exposures of the Mesozoic accretionary subduction complex along the Chilean margin. Unstable weather, strong winds, steep topography, and very dense vegetation make an on-land mission difficult. Careful preparation based on high-resolution satellite images is advised to optimize shore access and minimize risks of injury. Despite a relatively important degree of regional reequilibration of metamorphic assemblages due to sluggish exhumation through the forearc crust, our results have shown that the island is composed of a nappe stack of ocean-floor derived slivers of metasedimentary units that exhibit very different pressure-temperature-time paths during burial by subduction under the Chilean margin and subsequent exhumation. These rocks are witness to a complex thermal evolution of the subduction zone between Jurassic and Cretaceous times from granulite facies to blueschist facies conditions as well as multiple episodes of accretion at ca. 35 -40 km in depth for almost100 Ma over the Mesozoic era.
文摘This short report communicates the finding of a Deep-bodied pipefish, Leptonotus blainvilleanus, (Eydoux & Gervais, 1837) [Syngnathiformes, Syngnathidae] in shallow waters of the San Jorge Gulf, Patagonia Argentina, in August 2010. It’s a new record for its known distribution range in the coast of South America. Photos and videos are available.
文摘The Patagonian Icefield has the largest temperate ice mass in the southern hemisphere. Using remote sensing techniques, this study analyzed multi-decadal glacial retreat and expansion of glacier lakes in Northern Patagonia. Glacial boundaries and glacier lake boundaries for 1979, 1985, 2000, and 2013 were delineated from Chilean topographic maps and Landsat satellite images. Aster stereo images were used to measure mass balance from 2007 to 2012. The highest retreat was observed in San Quintin glacier. The area of glacier lakes increased from 13.49 km2 in 1979 to 65.06 km2 in 2013. Four new glacier lakes formed between 1979 and 2013. Between 2007 and 2012, significant glacial thinning was observed in major glaciers, including HPN1, Pared Norte, Strindberg, Acodado, Nef, San Quintin, Colonia, HPN4, and Benito glaciers. Generally, ablation zones lost more mass than accumulation zones.
基金Supported by the Instituto Nacional de Tecnología Agropecuaria,Consejo Nacional de Investigaciones Científicas y TcnicasAustralian Research Council(ARC DP120104320)+1 种基金Inter-American Institute for Global Change Research(IAICRN02-47)
文摘Climate data of mean monthly temperature and total monthly precipitation compiled from different sources in northern Patagonia were interpolated to 20-km resolution grids over the period 1997-2010. This northern Patagonian climate grid （NPCG） improves upon previous gridded products in terms of its spatial resolution and number of contributing stations, since it incorporates 218 and 114 precipitation and temper- ature records, respectively. A geostatistical method using surface elevation from a Digital Elevation Model （DEM） as the ancillary variable was used to interpolate station data into even spaced points. The maps provided by NPCG are consistent with the broad spatial and temporal patterns of the northern Patagonian climate, showing a comprehensive representation of the latitudinal and altitudinal gradients in temperature and precipitation, as well as their related patterns of seasonality and continentality. We compared the per- formance of NPCG and various other datasets available to the climate community for northern Patagonia. The grids used for the comparison included those of the Global Precipitation Climatology Project, ERA- Interim, Climate Research Unit （University of East Anglia）, and University of Delaware. Based on three statistics that quantitatively assess the spatial coherence of gridded data against available observations （bias, MAE, and RMSE）, NPCG outperforms other global grids. NPCG represents a useful tool for understand- ing climate variability in northern Patagonia and a valuable input for regional models of hydrological and ecological processes. Its resolution is optimal for validating data from the general circulation models and working with raster data derived from remote sensing, such as vegetation indices.
基金supported by Universidad Nacional de la Patagonia San Juan Bosco PI 1123,Universidad Nacional del Comahue(CRUB UNComahue 04/B196)the Argentinean Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET,PIP 100271)Fondo para la Investigación Científica y Tecnológica(FONCyT)PICT-2014-3100.
文摘Behavioral and physiological traits of ectotherms are especially sensitive to fluctuations of environmental temperature.In particular,niche-specialist lizards are dependent on their physiological plasticity to adjust to changing environmental conditions.Lizards of the genus Phymaturus are viviparous,mainly herbivorous,and inhabit only rock promontories in the steppe environments of Patagonia and the Andes.Herein,we examine the vulnerability of the southernmost Phymaturus species to global warming:the endemic Phymaturus calcogaster,which lives in a mesic environment in eastern Patagonia.We studied body temperatures in the field(T_(b)),preferred body temperatures in a thermogradient(T_(pref)),the operative(T_(e))and environmental temperatures,and the dependence of running performance on body temperature.P.calcogaster had a mean T_(b)(27.04℃)and a mean Te(31.15℃)both lower than their preferred temperature(T_(pref)=36.61℃)and the optimal temperature for running performance(T_(o)=37.13℃).Lizard activity seems to be restraint during the early afternoon due high environmental temperatures.However,both,the high safety margin and warming tolerance suggest that the expected increase in environmental temperatures due to global warming(IPCC report in 2018)would not threaten,but indeed enhance locomotor performance in this population.
基金This research was funded by the National University of Río Negro Research Project(40-C-658)the Research Project National Institute of Agricultural Technology,University Association of Higher Agricultural Education and National Council of Veterinary Deans(Proyect 940175).
文摘The quantification of carbon storage in vegetation biomass is a crucial factor in the estimation and mitigation of CO2 emissions.Globally,arid and semi-arid regions are considered an important carbon sink.However,they have received limited attention and,therefore,it should be a priority to develop tools to quantify biomass at the local and regional scales.Individual plant variables,such as stem diameter and crown area,were reported to be good predictors of individual plant weight.Stand-level variables,such as plant cover and mean height,are also easy-to-measure estimators of above-ground biomass(AGB)in dry regions.In this study,we estimated the AGB in semi-arid woody vegetation in Northeast Patagonia,Argentina.We evaluated whether the AGB at the stand level can be estimated based on plant cover and to what extent the estimation accuracy can be improved by the inclusion of other field-measured structure variables.We also evaluated whether remote sensing technologies can be used to reliably estimate and map the regional mean biomass.For this purpose,we analyzed the relationships between field-measured woody vegetation structure variables and AGB as well as LANDSAT TM-derived variables.We obtained a model-based ratio estimate of regional mean AGB and its standard error.Total plant cover allowed us to obtain a reliable estimation of local AGB,and no better fit was attained by the inclusion of other structure variables.The stand-level plant cover ranged between 18.7%and 95.2%and AGB between about 2.0 and 70.8 Mg/hm^(2).AGB based on total plant cover was well estimated from LANDSAT TM bands 2 and 3,which facilitated a model-based ratio estimate of the regional mean AGB(approximately 12.0 Mg/hm^(2))and its sampling error(about 30.0%).The mean AGB of woody vegetation can greatly contribute to carbon storage in semi-arid lands.Thus,plant cover estimation by remote sensing images could be used to obtain regional estimates and map biomass,as well as to assess and monitor the impact of land-use change on the carbon balance,f
文摘Vespertilionidae is the most diverse chiropteran family, and its diversity is concentrated in warmregions of the World; however, due to physiological and behavioral adaptations, these bats alsodominate bat faunas in temperate regions. Here we performed a comparative study of vespertili-onid assemblages from two broad regions of the New World, the cold and harsh Patagonia, versusthe remaining temperate-to-subtropical, extra-Patagonian eco-regions of the South AmericanSouthern Cone. We took an ecomorphological approach and analyzed the craniodental morpho-logical structure of these assemblages within a phylogenetic framework. We measured 17 cranio-dental linear variables from 447 specimens of 22 currently recognized vespertilionid species of thestudy regions. We performed a multivariate analysis to define the morphofunctional space, andcalculated the pattern and degree of species packing for each assemblage. We assessed the im-portance of phylogeny and biogeography, and their impact on depauperate （Patagonian） versusrich （extra-Patagonian） vespertilionid assemblages as determinants of morphospace structuring.We implemented a sensitivity analysis associated to small samples of rare species. The morpho-logical patterns were determined chiefly by the evolutionary history of the family. The Patagonianassemblage can be described as a structurally similar but comparatively depauperate ecomorpho-logical version of those assemblages from neighboring extra-Patagonian eco-regions. ThePatagonian assemblage seems to have formed by successively adding populations from Northernregions that eventually speciated in the region, leaving corresponding sisters （vicariants） in extra-Patagonian eco-regions that continued to be characteristically richer. Despite being structurallyakin, degree of species packing in Patagonia was comparatively very low, which may reflect the ef-fect of limited dispersal success into a harsh region for bat survival.
基金supported by funds from UNC04B129CONICET PIP5625PICT 1086
文摘Our study investigated the diet of the southernmost gecko in the world, Homonota darwini. Fifty-three specimens were captured during spring and summer in four locations in Patagonia, Argentina. The stomach contents of the specimens were identified, and we tbund that prey consisted of six main groups： Coleoptera, Hymenoptera, Homoptera and Araneae, and the adults and larvae of moth Lepidoptera. Lepidoptera was the major dietary component. The presence of ants and moths as common prey suggests an ambush feeding strategy. In spring, females consumed more ants than males although no other dietary differences between males and females were evident. We tbund nine geckos with empty stomachs and six parasitized by nematodes. Presence of empty stomachs corroborates previous observations of other nocturnal geckos and non-gecko lizards. Reduced foraging success of nocturnal lizards could be due to difficulty in prey detection due to dim light, reduced or erratic activity of insect prey at night, or shorter activity times of geckos relative to diurnal success. Sex and season were not associated with the incidence of empty stomachs. Principal component analysis showed that four food alternatives correlated with season. The constraint of nocturnality, coupled with low night-time temperatures restricting feeding to only a few hours after sunset, appear to have caused a generality of diet which may limit energy acquisition. We conclude that H. darwini is an arthropod generalist and likely an ambush forager, as are many other nocturnal gekkonids
