The Antarctic Paleogene marine fossil record has been the key to reconstructing the evolution of the Weddellian Sea and final dismemberment of Southern Gondwana.In this context,Eocene marine vertebrates from Seymour(M...The Antarctic Paleogene marine fossil record has been the key to reconstructing the evolution of the Weddellian Sea and final dismemberment of Southern Gondwana.In this context,Eocene marine vertebrates from Seymour(Marambio)Island have provided valuable information.We present the first Eocene record of marine reptiles from the southern Atlantic Coast of South America.This corresponds to several postcranial turtle remains represented by a proximal end of the right humerus,three caudal and one thoracic vertebrae,a fragment of the left pubis,and ten ossicles of the dorsal carapace,coming from the Leticia Formation(late-mid Eocene)at Cabo Tiburones,Tierra del Fuego,Argentina.These materials show severalfeatures such as the size and general morphology of the humerus and vertebrae,and the presence of relatively small,irregular,smooth,and unkeeled ossicles,which allow us to assign them to Dermochelyidae indet.Dermochelyids are a cosmopolitan group ofcryptodiran turtles,registered from the late Cretaceous up to the recent,with some physiological-biological peculiarities(e.g.,endothermy and an exclusive jellyfish-based diet)and characterized by the presence of an osseous carapace formed by ossicles.The new finding from the Leticia Formation is an addition to the scarce and extremely fragmentary record of Eocene dermochelyids from the southern seas like those from the La Meseta and Submeseta formations(Antarctica)and the Waihao and Burnside formations(New Zealand).This new information allows us to discuss the presence of these turtles in such high latitudes in the past and its implication in the evolution of the Weddellian fauna.展开更多
The worldwide record of Cretaceous Neornithes and Neornithine-like birds is both controversial and poorly understood.However,in recent years,the Antarctic continent has yielded a substantial number of Maastrichtian av...The worldwide record of Cretaceous Neornithes and Neornithine-like birds is both controversial and poorly understood.However,in recent years,the Antarctic continent has yielded a substantial number of Maastrichtian avian specimens,contributing significantly to our understanding of the early evolution of this group.Simultaneously,the keen interest and collaborative efforts of various paleornithologists have resulted in a wealth of knowledge,which we have thoroughly reviewed,updated,and discussed in the context of recent discoveries.展开更多
In this work,we report long-term trends in the abundance and breeding performance of Adélie penguins(Pygoscelis adeliae)nesting in three Antarctic colonies(i.e.,at Martin Point,South Orkneys Islands;Stranger Poin...In this work,we report long-term trends in the abundance and breeding performance of Adélie penguins(Pygoscelis adeliae)nesting in three Antarctic colonies(i.e.,at Martin Point,South Orkneys Islands;Stranger Point/Cabo Funes,South Shetland Islands;and Esperanza/Hope Bay in the Antarctic Peninsula)from 1995/96 to 2022/23.Using yearly count data of breeding groups selected,we observed a decline in the number of breeding pairs and chicks in crèche at all colonies studied.However,the magnitude of change was higher at Stranger Point than that in the remaining colonies.Moreover,the index of breeding success,which was calculated as the ratio of chicks in crèche to breeding pairs,exhibited no apparent trend throughout the study period.However,it displayed greater variability at Martin Point compared to the other two colonies under investigation.Although the number of chicks in crèche of Adélie penguins showed a declining pattern,the average breeding performance was similar to that reported in gentoo penguin colonies,specifically,those undergoing a population increase(even in sympatric colonies facing similar local conditions).Consequently,it is plausible to assume a reduction of the over-winter survival as a likely cause of the declining trend observed,at least in the Stranger Point and Esperanza colonies.However,we cannot rule out local effects during the breeding season affecting the Adélie population of Martin Point.展开更多
The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to invest...The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.展开更多
In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in ...In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in a complete revision of the Antarctic Eocene ichthyofauna housed in the Vertebrate Paleontology collection of the Museo de La Plata,Argentina.This collection constitutes one of the largest and taxonomically most diverse in the world,with approximately 20000 specimens,which provides a solid database used for the analysis of qualitative and quantitative chondrichthyan taxonomic composition.The information provided herein might be useful to understand the sudden decline in chondrichthyan taxonomic diversity towards the top of La Meseta Formation as well as its potential relationship with environmental changes during the Eocene.展开更多
The Astrapotheria constitutes one of the five orders of extinct South American native ungulates,with a fossil record that also extends to the Eocene of the Antarctic Peninsula.In contrast to the abundant specimens kno...The Astrapotheria constitutes one of the five orders of extinct South American native ungulates,with a fossil record that also extends to the Eocene of the Antarctic Peninsula.In contrast to the abundant specimens known for litoptern Sparnotheriodontidae and metatherians,astrapotheres are represented by scant remains assigned to the endemic Antarctodon sobrali and indeterminate astrapotheres,restricted to levels 35C_(u0)and 35n of the Cucullaea I Allomember of the La Meseta Formation.The discovery of alower molar assignable to this species in the Eocene levels of Seymour(Marambio)Island,enables a revision of the diagnosis and the homologies of the dental characters used to describe this taxon.A reanalysis of its phylogenetic relationships reveals the nearly simultaneous presence of basal astrapotheres in the early Eocene of Itaboraí(Brazil),Patagonia,and West Antarctica.These taxa are characterized by lacking dental specializations usually associated with more abrasive diets like terminal forms of Uruguaytheriinae and Astrapotheriinae.Antarctodon appears to have thrived on the Antarctic continent during the Early Eocene Climatic Optimum within the paleoclimatic context of a hot-house world.Unlike present conditions in Antarctica where no terrestrial mammals inhabit,the early Eocene climate was characterized by warmer temperatures and a biologically diverse environment rich in primary producers,dominated by Nothofagus forests,encompassing both deciduous and evergreen forests,which supported a diverse assemblage of continental vertebrates.展开更多
Antarctic Peninsula is experiencing one of the largest global warming events worldwide.Shallow water bodies generated by the melting of snow in summer are numerous,and they might act as sentinels of climate change due...Antarctic Peninsula is experiencing one of the largest global warming events worldwide.Shallow water bodies generated by the melting of snow in summer are numerous,and they might act as sentinels of climate change due to their rapid response and ability to integrate catchment information.Shifts in climate can influence the structure of microbial communities which dominate these freshwaters ecosystems.Here,we characterize three ponds at Cierva Point(Antarctic Peninsula)by examining their physico-chemical and morphological characteristics and we explored how different factors modify the structure of the microbial community.We studied the abundance and biomass of heterotrophic bacteria,picocyanobacteria and picoeukaryote algae during January and February of two consecutive summers(2017 and 2018).We found that ponds had different limnological characteristics,due to their location,geomorphological features and presence of the surrounding flora and fauna.Physico-chemical parameters as well as microbial community differed between ponds,months and years.In 2017,most ponds were oligo to mesotrophic states.The larger accumulated rainfall(as a result of environmental changes on the Antarctic Peninsula)during 2018,particularly in February,causes nutrient runoff into water bodies.This affects those ponds with the highest seabird circulation,such as gentoo penguin,increasing eutrophication.As a result,picoplanktonic abundances were higher,and the community structure shifts to a largely heterotrophic bacteria dominated one.These results suggest that these communities could act as sentinels to environmental changes,anticipating a future with mostly hypertrophic ponds.展开更多
The first dinosaur discovered in the Antarctic continent was the ankylosaur Antarctopelta oliveroi in the 1980s.Nevertheless,since then several hypotheses of phylogenetical relationships have been proposed because the...The first dinosaur discovered in the Antarctic continent was the ankylosaur Antarctopelta oliveroi in the 1980s.Nevertheless,since then several hypotheses of phylogenetical relationships have been proposed because these have been depended on how the skeletal remains have been interpreted.The main obstacle for clarifying its phylogenetic position is that many portions of the skeleton remain unknown,in addition to the presence of unknown characters in typical ankylosaurs.Considered an ankylosaurid,nodosaurid,or even a chimaera,a recent proposal based on mostly complete material of a new ankylosaur from Chilean Patagonia provided support for a novel phylogenetic hypothesis:Antarctopelta and other southern ankylosaurs are an early branching clade,the Parankylosauria,whose origin probably dates to the Late Jurassic.In the light of this new view,a redescription of the available skeletal remains is provided together with a new reconstruction of the first Antarctic dinosaur known to the science community.展开更多
We are pleased to announce that“The 11th SCAR Open Science Conference”will take place in Pucón,Chile from 19-23 August 2024,hosted by the Chilean Antarctic Institute.Detailed information at https://www.scar2024...We are pleased to announce that“The 11th SCAR Open Science Conference”will take place in Pucón,Chile from 19-23 August 2024,hosted by the Chilean Antarctic Institute.Detailed information at https://www.scar2024.org/.The 11th SCAR Open Science Conference theme“Antarctic Science:Crossroads for a New Hope”,recognizes the importance of Antarctica as a unique and fragile ecosystem.With increasing concerns about climate change and its impact on the polar regions,this theme aims to highlight the significance of Antarctic research in shaping our understanding of global environmental challenges.By fostering collaboration and knowledge exchange,the SCAR Open Science conference hopes to inspire new solutions and a renewed sense of hope for the future of our planet.展开更多
Motivated by the spirit ignited during the I Provincial Scientific Congress on Antarctica in the city of Ushuaia,in Tierra del Fuego,Antártida e Islas del Atlántico Sur Province,Argentina,convened in October...Motivated by the spirit ignited during the I Provincial Scientific Congress on Antarctica in the city of Ushuaia,in Tierra del Fuego,Antártida e Islas del Atlántico Sur Province,Argentina,convened in October 2022,we proudly introduce this special volume entitled“Past and present climatic change in Antarctica:geological proxies and biological processes”.What began as a collaborative effort emerging from that landmark event has blossomed into a collection of diverse works,each offering unique perspectives and analytical scales on climate change and the Antarctic environment.展开更多
Acknowledgement to reviewers for Vol.35 No.1 issue The editors of this special volume,along with the Editorial Board and Editorial Office of Advance in Polar Science,wish to express deep gratitude for the time investe...Acknowledgement to reviewers for Vol.35 No.1 issue The editors of this special volume,along with the Editorial Board and Editorial Office of Advance in Polar Science,wish to express deep gratitude for the time invested and the meticulous revisions carried out by Enrique Bostelmann(Chile),Michael Burns(USA),Rodolfo Coria(Argentina),Jun Ebersole(USA),Jürgen Kriwet(Austria),Guillermo M.López(Argentina),James Parham(USA),Juan Saad(Argentina),Leonardo Salgado(Argentina),Sergio Soto Acuña(Chile),Washington Jones(Uruguay)and seven anonymous reviewers from Argentina,China,Germany,Poland,and USA.展开更多
On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global affairs.This strategy emphasizes traditio...On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global affairs.This strategy emphasizes traditional security issues in the Arctic,attaches great importance to climate governance in the region,and advocates for restoring American leadership through international cooperation.In view of the strong influence of the United States(U.S.)in the Arctic region,the changes of the U.S.Arctic strategy will inevitably have an impact on China’s scientific researchrights,economic interests,and governance rights in the Arctic region.To respond to the new situation brought about by the changes in the U.S.Arctic strategy,China should take the initiative to maintain positive relationships with all Arctic countries,and continue its active participation in Arctic affairs.展开更多
In recent decades,environmental changes in the Arctic have aroused widespread concern around the world.To better understand ecology issues such as ecosystem dynamics,the Arctic and the subarctic regions were integrate...In recent decades,environmental changes in the Arctic have aroused widespread concern around the world.To better understand ecology issues such as ecosystem dynamics,the Arctic and the subarctic regions were integrated as the“pan-Arctic”region.In this study,mesozooplankton were sampled from the Bering Sea shelf to the northern Chukchi Sea during the 10th Chinese National Arctic Research Expedition in 2019.Based on the species composition and abundance,three geographical communities were identified:the Bering Sea shelf community(BSS),the Bering Strait transitional community(BST),and the Chukchi Sea shelf community(CSS).The BSS was characterized by Bering Sea oceanic species such as Eucalanus bungii;the BST was mainly composed of the pan-Arctic distributed Calanus glacialis,meroplankton of benthos,and neritic species such as Centropages abdominalis;copepods,especially the copepodite of C.glacialis,were predominant in the CSS community.The BSS community structure was strongly affected by the inflow of Bering Shelf Water,while those of BST and CSS were determined by the recruitment of local species.The zooplankton community structure is influenced by both advection and environmental changes such as warming and a prolonged productivity period.Here,it was difficult to distinguish the changes induced by climate change from the effects of the Bering Sea Water.The key to solving this problem is the accumulation of comparable data,which requires continuous monitoring of key species such as C.glacialis and Calanus hyperboreus.展开更多
Radiation is the direct energy source of the surface natural environment and the main driving force of climate change.It has increasingly become an important meteorological factor affecting the surface heat exchange a...Radiation is the direct energy source of the surface natural environment and the main driving force of climate change.It has increasingly become an important meteorological factor affecting the surface heat exchange and glacier mass balance,especially in the glacier changes of the Greenland Ice Sheet(Gr IS).Due to the harsh climatic conditions of Gr IS and sparse observed data,it has become an important way to obtain radiation data from reanalysis datasets.However,the applicability of these radiation data on Gr IS is uncertain and worth exploring.In this work,we evaluate five reanalysis datasets(the fifth generation of European Centre for Medium-Range Weather Forecasts(ERA5),European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim),Japanese 55-year Reanalysis(JRA55),National Centers for Environmental Prediction Reanalysis II(NCEP2)and Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA-2))during 1997-2022 using observations from 26 Program for Monitoring the Greenland Ice Sheet(PROMICE)automatic weather stations(AWSs)and 3 K-transect AWSs on Gr IS.The conclusions are as follows:ERA5 has the best performances in downward shortwave radiation(SWD)as well as downward and upward longwave radiation(LWD and LWU),but the performance is not the best in upward shortwave radiation(SWU).Based on the radiation budget analysis with ERA5 during 1979-2022,the fluctuation of longwave radiation is greater than that of shortwave radiation.The seasonal variation of shortwave radiation is obvious,while that of longwave radiation is small.The increasing trend of longwave radiation may result from global warming,in which ice sheets absorb more solar radiation and the surface heats up significantly,emitting more LWU.展开更多
Recent research has shown that winter warmings are phenomenally high compared to summer warmings over the poles,especially over the Arctic.Taking the current scenario into account,this paper attempts to understand the...Recent research has shown that winter warmings are phenomenally high compared to summer warmings over the poles,especially over the Arctic.Taking the current scenario into account,this paper attempts to understand the atmospheric variables causing sea ice variability over and around the region of Svalbard for seasons;winter,spring,summer and autumn for the span of 42 years(1979-2021).The variability in atmospheric and oceanic parameters namely temperature,precipitation,wind speed,and sea surface salinity are analysed over inter-spatial,inter-seasonal and inter-annual domains.Winters are characterized by inter-annual increasing trend in temperature.During 1981-1990 the rise from the decadal mean is found to be 0.39 K·a^(-1),during 1991-2000 it is 0.20 K·a^(-1),during 2001-2010 it is 0.04 K·a^(-1) and during 2011-2020 it is 0.23 K·a^(-1).Interestingly while considering inter-spatial domains,the region southwest to Svalbard seems to be wetter(0.05 mm·(10 a)-1)compared to its northeast(-0.03 mm·(10 a)-1).Across all the three domains,wind speeds are highest during autumn and then decrease subsequently through summer,spring and are least during winter.Wind is predominantly from the south,and hence it is suspected to carry hot Atlantic air.Additionally,the significant role of salinity in the ocean also plays a key role in governing the fate of sea ice conditions.The long-term forecasts of temperature over seaice of Svalbard are alarming especially for the winter ice(r=-0.84).Correlation matrices between atmospheric and sea ice parameters are shown to gain a better understanding on their inter relation.展开更多
Microplastics,plastic particles smaller than 5 mm in size,are a growing source of environmental pollution.Microplastic pollution has been observed in situ in the remote Arctic,where it has been found in the land,sea,c...Microplastics,plastic particles smaller than 5 mm in size,are a growing source of environmental pollution.Microplastic pollution has been observed in situ in the remote Arctic,where it has been found in the land,sea,cryosphere,and atmosphere.This review summarizes the sample pretreatment techniques and analytical methods commonly used in microplastic research,as well as the pollution status of microplastics in the Arctic,their sources,and their effects on the environment.In the Arctic,the size distribution of microplastics is more inclined to small-scale aggregation,the shape of microplastics is mostly fibrous,with the proportion of fibers often accounting for more than 70%.There are marked differences among studies in terms of abundance and polymer composition,but polyester is generally dominant in seawater.Many microplastic particles are transported to the Arctic by ocean currents and rivers,but atmospheric transport and deposition are slowly being recognized as an important transport route.Sea ice is particularly important for the temporary storage,transport,and release of Arctic microplastics.The average storage of microplastics in sea ice was estimated to be approximately 6.1×108 items.Given their properties,microplastics can affect glacier melting,sea surface temperature changes,and even the carbon cycle.Urgent measures must be taken to improve research standards and overcome sampling difficulties in the Arctic region to achieve time continuity and large-scale distribution patterns of Arctic microplastics.展开更多
The article contributes to the study of the content of major and trace elements in various types of natural waters of the Broknes Peninsula,Larsemann Hills,Antarctica collected in January–February 2014 and 2020 durin...The article contributes to the study of the content of major and trace elements in various types of natural waters of the Broknes Peninsula,Larsemann Hills,Antarctica collected in January–February 2014 and 2020 during the 7th and 12th Belarusian Antarctic Expeditions.Samples of old(13 samples)and newly fallen snow(5),lakes(23)and groundwater(8)were analyzed.The content of 25 major and trace elements was determined using ICP-MS method,main anions was determined by titrimetric and turbidimetric methods.Good similarity chemical composition of snow,groundwater and lake waters in spite of differences in the content of major ions and trace elements has been obtained.The influence of marine salts on natural waters are analyzed,and their accumulation in lake waters especially in the endorheic small and shallow lakes in spite of ultra-oligotrophic atmospheric precipitates are shown.The spatial heterogeneity of groundwater and temporal and spatial heterogeneity of lake waters have been demonstrated.The results are important for understanding the variabilities of major and trace elements content in snow,groundwater and lake waters,and their relationship,as well as for identifying trends in their change,taking into account anthropogenic loads in the region and climate change.展开更多
Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transec...Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transect to investigate spatial variability in key nitrogen transformation processes,functional gene abundances,ammonia-oxidizing archaea(AOA)community structures,and key nitrogen transformation regulators.The potential denitrification rates were higher than the nitrification rates in the soil samples,although nitrification may still regulate N2O emissions from tundra soil.The nutrient(total carbon,total organic carbon,total nitrogen,and NH_(4)^(+)-N)contents were important determinants of spatial variability in the potential denitrification rates of soil along the tundra transect.The total sulfurcontent was the main variable controlling potential nitrification processes,probably in association with sulfate-reducing bacteria.The nitrate content was the main variable affecting potential dissimilatory nitrate reduction to ammonium.AOA and ammonia-oxidizing bacteria amoA,nirS,and anammox 16S rRNA genes were found in all of the soil samples.AOA play more important roles than ammonia-oxidizing bacteria in soilnitrification.Anammox bacteria may utilize NO_(2)^(-)produced through nitrification.Phylogenetic analysis indicated that the AOA amoA sequences could be grouped into eight unique operational taxonomic units(OTUs)with a 97%sequence similarity and were affiliated with three group 1.1b Nitrososphaeraclusters.The results indicated that heterogeneous environmental factors(e.g.,the carbon and nitrogen contents of soil)along the High Arctic tundra transect strongly affected the nitrogen transformation rate and relevant functional gene abundances in soil.展开更多
With the present day rise of interest in acquiring sustainability in the pharmaceutical industry,there has been an emphasis on finding natural resources to replace the use of synthetic compounds used in products.Micro...With the present day rise of interest in acquiring sustainability in the pharmaceutical industry,there has been an emphasis on finding natural resources to replace the use of synthetic compounds used in products.Microalgae have garnered significant attention owing to their natural and sustainable capability to produce a diverse array of bioactive compounds.Therefore,this study aims to evaluate the biochemical composition and antioxidant properties of Chlorella strains from a tropical region(Chlorella UMACC 051 and Chlorella UMACC 038)and a polar region(Chlorella UMACC 250 and Chlorella UMACC 234).The cultures were grown for 10 d.At the end of the experiment,the specific growth rate,chlorophyll-a content,carotenoid content,biomass,and biochemical composition such as carbohydrate,protein and lipid content were determined.In addition,the phytochemical properties were determined using a total phenolic assay while the antioxidant activities were determined using 2,2-diphenyl-1-picrylhydrazyl(DPPH).Of all Chlorella strains tested,the tropical Chlorella UMACC 051 showed the fastest growth rate and biomass while the polar Chlorella UMACC 234 contained the highest pigment content and tropical Chlorella UMACC 038 has the highest total phenolic content.The biochemical composition analysis showed all strains have a high lipid content ranging from 45.36%to 60.30%dry weight.All Chlorella strains exhibited a small amount of antioxidant activity(15.42%to 30.15%)and total phenolic content ranging from 1.91±0.04 to 4.43±0.10 mg GAE·g–1 dry weight.The results indicated that polar Chlorella UMACC 234 has the most potential in containing significant amounts of bioactive compounds.展开更多
One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being ele...One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being elevation of inorganic phosphate concentrations around feces depositions.The complex soil biochemistry in the region makes it difficult to define the causal factors of these changes using common research approaches.Here,we addressed the effects of phosphate alone on microbiome structure and dynamics over time by adding external phosphate to selected soils in the Antarctic region.We then analyzed the soil bacterial community composition and diversity using 16S rRNA amplicon sequencing and compared these data with phosphate levels.Parallel geochemical analysis revealed changes in nine soil geochemical factors upon phosphate addition,all of which were relevant to microbiome structure,with soil pH showing the highest correlation.Links between geochemical factors and composition were identified,as were interactions between bacterial taxa.Additionally,Sphingobacteriia,Sphingobacteriales and Chitinophagaceae were found to be more abundant in phosphate-treated soils.Co-occurrence network analysis revealed significantly increased levels of associations in all major network properties over time after phosphate supplementation.Therefore,we conclude phosphate addition has diverse effects on Antarctic soil microbiomes.展开更多
基金funded by the Agencia Nacional de Promoción Científica y Tecnológica-Proyectos de Investigación Científica y Tecnológica-PICT 2017-0607(to M.Reguero)and PICT 2019-00327(to M.Buono).
文摘The Antarctic Paleogene marine fossil record has been the key to reconstructing the evolution of the Weddellian Sea and final dismemberment of Southern Gondwana.In this context,Eocene marine vertebrates from Seymour(Marambio)Island have provided valuable information.We present the first Eocene record of marine reptiles from the southern Atlantic Coast of South America.This corresponds to several postcranial turtle remains represented by a proximal end of the right humerus,three caudal and one thoracic vertebrae,a fragment of the left pubis,and ten ossicles of the dorsal carapace,coming from the Leticia Formation(late-mid Eocene)at Cabo Tiburones,Tierra del Fuego,Argentina.These materials show severalfeatures such as the size and general morphology of the humerus and vertebrae,and the presence of relatively small,irregular,smooth,and unkeeled ossicles,which allow us to assign them to Dermochelyidae indet.Dermochelyids are a cosmopolitan group ofcryptodiran turtles,registered from the late Cretaceous up to the recent,with some physiological-biological peculiarities(e.g.,endothermy and an exclusive jellyfish-based diet)and characterized by the presence of an osseous carapace formed by ossicles.The new finding from the Leticia Formation is an addition to the scarce and extremely fragmentary record of Eocene dermochelyids from the southern seas like those from the La Meseta and Submeseta formations(Antarctica)and the Waihao and Burnside formations(New Zealand).This new information allows us to discuss the presence of these turtles in such high latitudes in the past and its implication in the evolution of the Weddellian fauna.
基金To the Universidad Nacional de La Plata PID N955,ANPCyT PICT 20170607,and CONICET PIP 0096 for partial support.
文摘The worldwide record of Cretaceous Neornithes and Neornithine-like birds is both controversial and poorly understood.However,in recent years,the Antarctic continent has yielded a substantial number of Maastrichtian avian specimens,contributing significantly to our understanding of the early evolution of this group.Simultaneously,the keen interest and collaborative efforts of various paleornithologists have resulted in a wealth of knowledge,which we have thoroughly reviewed,updated,and discussed in the context of recent discoveries.
基金Nacional de Promoción Científica y Tecnológica(Grant:PICTO 2010-0111)the Instituto Antártico Argentino-Dirección Nacional del Antártico(PINST-05)provided financial and logistical support.
文摘In this work,we report long-term trends in the abundance and breeding performance of Adélie penguins(Pygoscelis adeliae)nesting in three Antarctic colonies(i.e.,at Martin Point,South Orkneys Islands;Stranger Point/Cabo Funes,South Shetland Islands;and Esperanza/Hope Bay in the Antarctic Peninsula)from 1995/96 to 2022/23.Using yearly count data of breeding groups selected,we observed a decline in the number of breeding pairs and chicks in crèche at all colonies studied.However,the magnitude of change was higher at Stranger Point than that in the remaining colonies.Moreover,the index of breeding success,which was calculated as the ratio of chicks in crèche to breeding pairs,exhibited no apparent trend throughout the study period.However,it displayed greater variability at Martin Point compared to the other two colonies under investigation.Although the number of chicks in crèche of Adélie penguins showed a declining pattern,the average breeding performance was similar to that reported in gentoo penguin colonies,specifically,those undergoing a population increase(even in sympatric colonies facing similar local conditions).Consequently,it is plausible to assume a reduction of the over-winter survival as a likely cause of the declining trend observed,at least in the Stranger Point and Esperanza colonies.However,we cannot rule out local effects during the breeding season affecting the Adélie population of Martin Point.
基金funded by the National Natural Science Foundation of China(Grant nos.42276255 and 41976227)project“Impact and Response of Antarctic Seas to Climate Change,IRASCC 2020-2022”(Grant nos.01-01-02A and 02-02-05).
文摘The Southern Ocean is an important carbon sink pool and plays a critical role in the global carbon cycling.The Amundsen Sea was reported to be highly productive in inshore area in the Southern Ocean.In order to investigate the influence of transparent exopolymer particles(TEP)on the behavior of dissolved organic carbon(DOC)in this region,a comprehensive study was conducted,encompassing both open water areas and highly productive polynyas.It was found that microbial heterotrophic metabolism is the primary process responsible for the production of humic-like fluorescent components in the open ocean.The relationship between apparent oxygen utilization and the two humic-like components can be accurately described by a power-law function,with a conversion rate consistent with that observed globally.The presence of TEP was found to have little impact on this process.Additionally,the study revealed the accumulation of DOC at the sea surface in the Amundsen Sea Polynya,suggesting that TEP may play a critical role in this phenomenon.These findings contribute to a deeper understanding of the dynamics and surface accumulation of DOC in the Amundsen Sea Polynya,and provide valuable insights into the carbon cycle in this region.
基金Thanks to the Agencia Nacional de Promoción Científica y Tecnológica for financial support trough PICT 2017-0607(to MR),PICT 2019-02419(to SGC).
文摘In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in a complete revision of the Antarctic Eocene ichthyofauna housed in the Vertebrate Paleontology collection of the Museo de La Plata,Argentina.This collection constitutes one of the largest and taxonomically most diverse in the world,with approximately 20000 specimens,which provides a solid database used for the analysis of qualitative and quantitative chondrichthyan taxonomic composition.The information provided herein might be useful to understand the sudden decline in chondrichthyan taxonomic diversity towards the top of La Meseta Formation as well as its potential relationship with environmental changes during the Eocene.
基金Marcelo Reguero for the opportunities provided within the framework of the Antarctic projects PICT 0607-2018 and UNLP 11N812.
文摘The Astrapotheria constitutes one of the five orders of extinct South American native ungulates,with a fossil record that also extends to the Eocene of the Antarctic Peninsula.In contrast to the abundant specimens known for litoptern Sparnotheriodontidae and metatherians,astrapotheres are represented by scant remains assigned to the endemic Antarctodon sobrali and indeterminate astrapotheres,restricted to levels 35C_(u0)and 35n of the Cucullaea I Allomember of the La Meseta Formation.The discovery of alower molar assignable to this species in the Eocene levels of Seymour(Marambio)Island,enables a revision of the diagnosis and the homologies of the dental characters used to describe this taxon.A reanalysis of its phylogenetic relationships reveals the nearly simultaneous presence of basal astrapotheres in the early Eocene of Itaboraí(Brazil),Patagonia,and West Antarctica.These taxa are characterized by lacking dental specializations usually associated with more abrasive diets like terminal forms of Uruguaytheriinae and Astrapotheriinae.Antarctodon appears to have thrived on the Antarctic continent during the Early Eocene Climatic Optimum within the paleoclimatic context of a hot-house world.Unlike present conditions in Antarctica where no terrestrial mammals inhabit,the early Eocene climate was characterized by warmer temperatures and a biologically diverse environment rich in primary producers,dominated by Nothofagus forests,encompassing both deciduous and evergreen forests,which supported a diverse assemblage of continental vertebrates.
基金supported by ANPCy T (Grant PICT-2016-2517) directed by Dr. G. Matalonithe National Scientific and Technical Research Council-Argentina (CONICET)
文摘Antarctic Peninsula is experiencing one of the largest global warming events worldwide.Shallow water bodies generated by the melting of snow in summer are numerous,and they might act as sentinels of climate change due to their rapid response and ability to integrate catchment information.Shifts in climate can influence the structure of microbial communities which dominate these freshwaters ecosystems.Here,we characterize three ponds at Cierva Point(Antarctic Peninsula)by examining their physico-chemical and morphological characteristics and we explored how different factors modify the structure of the microbial community.We studied the abundance and biomass of heterotrophic bacteria,picocyanobacteria and picoeukaryote algae during January and February of two consecutive summers(2017 and 2018).We found that ponds had different limnological characteristics,due to their location,geomorphological features and presence of the surrounding flora and fauna.Physico-chemical parameters as well as microbial community differed between ponds,months and years.In 2017,most ponds were oligo to mesotrophic states.The larger accumulated rainfall(as a result of environmental changes on the Antarctic Peninsula)during 2018,particularly in February,causes nutrient runoff into water bodies.This affects those ponds with the highest seabird circulation,such as gentoo penguin,increasing eutrophication.As a result,picoplanktonic abundances were higher,and the community structure shifts to a largely heterotrophic bacteria dominated one.These results suggest that these communities could act as sentinels to environmental changes,anticipating a future with mostly hypertrophic ponds.
基金supported by Núcleo Milenio EVOTEM from ANIDGobierno de Chile
文摘The first dinosaur discovered in the Antarctic continent was the ankylosaur Antarctopelta oliveroi in the 1980s.Nevertheless,since then several hypotheses of phylogenetical relationships have been proposed because these have been depended on how the skeletal remains have been interpreted.The main obstacle for clarifying its phylogenetic position is that many portions of the skeleton remain unknown,in addition to the presence of unknown characters in typical ankylosaurs.Considered an ankylosaurid,nodosaurid,or even a chimaera,a recent proposal based on mostly complete material of a new ankylosaur from Chilean Patagonia provided support for a novel phylogenetic hypothesis:Antarctopelta and other southern ankylosaurs are an early branching clade,the Parankylosauria,whose origin probably dates to the Late Jurassic.In the light of this new view,a redescription of the available skeletal remains is provided together with a new reconstruction of the first Antarctic dinosaur known to the science community.
文摘We are pleased to announce that“The 11th SCAR Open Science Conference”will take place in Pucón,Chile from 19-23 August 2024,hosted by the Chilean Antarctic Institute.Detailed information at https://www.scar2024.org/.The 11th SCAR Open Science Conference theme“Antarctic Science:Crossroads for a New Hope”,recognizes the importance of Antarctica as a unique and fragile ecosystem.With increasing concerns about climate change and its impact on the polar regions,this theme aims to highlight the significance of Antarctic research in shaping our understanding of global environmental challenges.By fostering collaboration and knowledge exchange,the SCAR Open Science conference hopes to inspire new solutions and a renewed sense of hope for the future of our planet.
文摘Motivated by the spirit ignited during the I Provincial Scientific Congress on Antarctica in the city of Ushuaia,in Tierra del Fuego,Antártida e Islas del Atlántico Sur Province,Argentina,convened in October 2022,we proudly introduce this special volume entitled“Past and present climatic change in Antarctica:geological proxies and biological processes”.What began as a collaborative effort emerging from that landmark event has blossomed into a collection of diverse works,each offering unique perspectives and analytical scales on climate change and the Antarctic environment.
文摘Acknowledgement to reviewers for Vol.35 No.1 issue The editors of this special volume,along with the Editorial Board and Editorial Office of Advance in Polar Science,wish to express deep gratitude for the time invested and the meticulous revisions carried out by Enrique Bostelmann(Chile),Michael Burns(USA),Rodolfo Coria(Argentina),Jun Ebersole(USA),Jürgen Kriwet(Austria),Guillermo M.López(Argentina),James Parham(USA),Juan Saad(Argentina),Leonardo Salgado(Argentina),Sergio Soto Acuña(Chile),Washington Jones(Uruguay)and seven anonymous reviewers from Argentina,China,Germany,Poland,and USA.
基金This study was supported the National Social Science Foundation Major Research Project(Grant no.20VHQ011)Chinese Arctic and Antarctic Administration program“New Developments in the Arctic Strategy of Major Countries”in 2022.
文摘On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global affairs.This strategy emphasizes traditional security issues in the Arctic,attaches great importance to climate governance in the region,and advocates for restoring American leadership through international cooperation.In view of the strong influence of the United States(U.S.)in the Arctic region,the changes of the U.S.Arctic strategy will inevitably have an impact on China’s scientific researchrights,economic interests,and governance rights in the Arctic region.To respond to the new situation brought about by the changes in the U.S.Arctic strategy,China should take the initiative to maintain positive relationships with all Arctic countries,and continue its active participation in Arctic affairs.
基金This study was financially supported by the National Natural Science Foundation of China(Grant nos.41706217,42166228).
文摘In recent decades,environmental changes in the Arctic have aroused widespread concern around the world.To better understand ecology issues such as ecosystem dynamics,the Arctic and the subarctic regions were integrated as the“pan-Arctic”region.In this study,mesozooplankton were sampled from the Bering Sea shelf to the northern Chukchi Sea during the 10th Chinese National Arctic Research Expedition in 2019.Based on the species composition and abundance,three geographical communities were identified:the Bering Sea shelf community(BSS),the Bering Strait transitional community(BST),and the Chukchi Sea shelf community(CSS).The BSS was characterized by Bering Sea oceanic species such as Eucalanus bungii;the BST was mainly composed of the pan-Arctic distributed Calanus glacialis,meroplankton of benthos,and neritic species such as Centropages abdominalis;copepods,especially the copepodite of C.glacialis,were predominant in the CSS community.The BSS community structure was strongly affected by the inflow of Bering Shelf Water,while those of BST and CSS were determined by the recruitment of local species.The zooplankton community structure is influenced by both advection and environmental changes such as warming and a prolonged productivity period.Here,it was difficult to distinguish the changes induced by climate change from the effects of the Bering Sea Water.The key to solving this problem is the accumulation of comparable data,which requires continuous monitoring of key species such as C.glacialis and Calanus hyperboreus.
基金funded by the Natural Science Foundation of China (Grant no.42171121)the open fund of Key Laboratory of Oceanic Atmospheric Chemistry and Global Change,Ministry of Natural Resources,China (Grant no.GCMAC2206)support from data availability from PROMICE and ERA5,ERA-Interim,JRA55,MERRA-2,NCEP2。
文摘Radiation is the direct energy source of the surface natural environment and the main driving force of climate change.It has increasingly become an important meteorological factor affecting the surface heat exchange and glacier mass balance,especially in the glacier changes of the Greenland Ice Sheet(Gr IS).Due to the harsh climatic conditions of Gr IS and sparse observed data,it has become an important way to obtain radiation data from reanalysis datasets.However,the applicability of these radiation data on Gr IS is uncertain and worth exploring.In this work,we evaluate five reanalysis datasets(the fifth generation of European Centre for Medium-Range Weather Forecasts(ERA5),European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim),Japanese 55-year Reanalysis(JRA55),National Centers for Environmental Prediction Reanalysis II(NCEP2)and Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA-2))during 1997-2022 using observations from 26 Program for Monitoring the Greenland Ice Sheet(PROMICE)automatic weather stations(AWSs)and 3 K-transect AWSs on Gr IS.The conclusions are as follows:ERA5 has the best performances in downward shortwave radiation(SWD)as well as downward and upward longwave radiation(LWD and LWU),but the performance is not the best in upward shortwave radiation(SWU).Based on the radiation budget analysis with ERA5 during 1979-2022,the fluctuation of longwave radiation is greater than that of shortwave radiation.The seasonal variation of shortwave radiation is obvious,while that of longwave radiation is small.The increasing trend of longwave radiation may result from global warming,in which ice sheets absorb more solar radiation and the surface heats up significantly,emitting more LWU.
文摘Recent research has shown that winter warmings are phenomenally high compared to summer warmings over the poles,especially over the Arctic.Taking the current scenario into account,this paper attempts to understand the atmospheric variables causing sea ice variability over and around the region of Svalbard for seasons;winter,spring,summer and autumn for the span of 42 years(1979-2021).The variability in atmospheric and oceanic parameters namely temperature,precipitation,wind speed,and sea surface salinity are analysed over inter-spatial,inter-seasonal and inter-annual domains.Winters are characterized by inter-annual increasing trend in temperature.During 1981-1990 the rise from the decadal mean is found to be 0.39 K·a^(-1),during 1991-2000 it is 0.20 K·a^(-1),during 2001-2010 it is 0.04 K·a^(-1) and during 2011-2020 it is 0.23 K·a^(-1).Interestingly while considering inter-spatial domains,the region southwest to Svalbard seems to be wetter(0.05 mm·(10 a)-1)compared to its northeast(-0.03 mm·(10 a)-1).Across all the three domains,wind speeds are highest during autumn and then decrease subsequently through summer,spring and are least during winter.Wind is predominantly from the south,and hence it is suspected to carry hot Atlantic air.Additionally,the significant role of salinity in the ocean also plays a key role in governing the fate of sea ice conditions.The long-term forecasts of temperature over seaice of Svalbard are alarming especially for the winter ice(r=-0.84).Correlation matrices between atmospheric and sea ice parameters are shown to gain a better understanding on their inter relation.
基金supported by the National Natural Science Foundation of China (Grant no. 42006190)the Chinese Polar Environmental Comprehensive Investigation and Assessment Programs (Grant no. CHINARE2010-2020)+2 种基金the Chinese International Cooperation Projects (Grant no. 2009DFA22920) from the Ministry of Science and Technologythe Chinese Arctic and Antarctic Administrationthe Third Institute of Oceanography of MNR for their support
文摘Microplastics,plastic particles smaller than 5 mm in size,are a growing source of environmental pollution.Microplastic pollution has been observed in situ in the remote Arctic,where it has been found in the land,sea,cryosphere,and atmosphere.This review summarizes the sample pretreatment techniques and analytical methods commonly used in microplastic research,as well as the pollution status of microplastics in the Arctic,their sources,and their effects on the environment.In the Arctic,the size distribution of microplastics is more inclined to small-scale aggregation,the shape of microplastics is mostly fibrous,with the proportion of fibers often accounting for more than 70%.There are marked differences among studies in terms of abundance and polymer composition,but polyester is generally dominant in seawater.Many microplastic particles are transported to the Arctic by ocean currents and rivers,but atmospheric transport and deposition are slowly being recognized as an important transport route.Sea ice is particularly important for the temporary storage,transport,and release of Arctic microplastics.The average storage of microplastics in sea ice was estimated to be approximately 6.1×108 items.Given their properties,microplastics can affect glacier melting,sea surface temperature changes,and even the carbon cycle.Urgent measures must be taken to improve research standards and overcome sampling difficulties in the Arctic region to achieve time continuity and large-scale distribution patterns of Arctic microplastics.
基金the framework of the State Programs “Monitoring of the polar regions of the Earth and ensuring the activities of the Arctic and Antarctic expeditions for 2011–2015”“Monitoring of the polar regions of the Earth, the creation of the Belarusian Antarctic station and ensuring the activities of polar expeditions for 2016–2020”
文摘The article contributes to the study of the content of major and trace elements in various types of natural waters of the Broknes Peninsula,Larsemann Hills,Antarctica collected in January–February 2014 and 2020 during the 7th and 12th Belarusian Antarctic Expeditions.Samples of old(13 samples)and newly fallen snow(5),lakes(23)and groundwater(8)were analyzed.The content of 25 major and trace elements was determined using ICP-MS method,main anions was determined by titrimetric and turbidimetric methods.Good similarity chemical composition of snow,groundwater and lake waters in spite of differences in the content of major ions and trace elements has been obtained.The influence of marine salts on natural waters are analyzed,and their accumulation in lake waters especially in the endorheic small and shallow lakes in spite of ultra-oligotrophic atmospheric precipitates are shown.The spatial heterogeneity of groundwater and temporal and spatial heterogeneity of lake waters have been demonstrated.The results are important for understanding the variabilities of major and trace elements content in snow,groundwater and lake waters,and their relationship,as well as for identifying trends in their change,taking into account anthropogenic loads in the region and climate change.
基金This study was funded by the National Key Research and Development Program of China(Grant no.2020YFA0608501)the National Natural Science Foundation of China(Grant no.41976220)the State Key Laboratory of NBC Protection of Civilians(Grant no.SKLNBC2020-10).
文摘Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transect to investigate spatial variability in key nitrogen transformation processes,functional gene abundances,ammonia-oxidizing archaea(AOA)community structures,and key nitrogen transformation regulators.The potential denitrification rates were higher than the nitrification rates in the soil samples,although nitrification may still regulate N2O emissions from tundra soil.The nutrient(total carbon,total organic carbon,total nitrogen,and NH_(4)^(+)-N)contents were important determinants of spatial variability in the potential denitrification rates of soil along the tundra transect.The total sulfurcontent was the main variable controlling potential nitrification processes,probably in association with sulfate-reducing bacteria.The nitrate content was the main variable affecting potential dissimilatory nitrate reduction to ammonium.AOA and ammonia-oxidizing bacteria amoA,nirS,and anammox 16S rRNA genes were found in all of the soil samples.AOA play more important roles than ammonia-oxidizing bacteria in soilnitrification.Anammox bacteria may utilize NO_(2)^(-)produced through nitrification.Phylogenetic analysis indicated that the AOA amoA sequences could be grouped into eight unique operational taxonomic units(OTUs)with a 97%sequence similarity and were affiliated with three group 1.1b Nitrososphaeraclusters.The results indicated that heterogeneous environmental factors(e.g.,the carbon and nitrogen contents of soil)along the High Arctic tundra transect strongly affected the nitrogen transformation rate and relevant functional gene abundances in soil.
基金supported by Ministry of Higher Education (MOHE) Malaysia through Fundamental Research Grant Scheme (FRGS/1/2023/STG01/TAYLOR/02/1)Taylor’s University for the support for this project
文摘With the present day rise of interest in acquiring sustainability in the pharmaceutical industry,there has been an emphasis on finding natural resources to replace the use of synthetic compounds used in products.Microalgae have garnered significant attention owing to their natural and sustainable capability to produce a diverse array of bioactive compounds.Therefore,this study aims to evaluate the biochemical composition and antioxidant properties of Chlorella strains from a tropical region(Chlorella UMACC 051 and Chlorella UMACC 038)and a polar region(Chlorella UMACC 250 and Chlorella UMACC 234).The cultures were grown for 10 d.At the end of the experiment,the specific growth rate,chlorophyll-a content,carotenoid content,biomass,and biochemical composition such as carbohydrate,protein and lipid content were determined.In addition,the phytochemical properties were determined using a total phenolic assay while the antioxidant activities were determined using 2,2-diphenyl-1-picrylhydrazyl(DPPH).Of all Chlorella strains tested,the tropical Chlorella UMACC 051 showed the fastest growth rate and biomass while the polar Chlorella UMACC 234 contained the highest pigment content and tropical Chlorella UMACC 038 has the highest total phenolic content.The biochemical composition analysis showed all strains have a high lipid content ranging from 45.36%to 60.30%dry weight.All Chlorella strains exhibited a small amount of antioxidant activity(15.42%to 30.15%)and total phenolic content ranging from 1.91±0.04 to 4.43±0.10 mg GAE·g–1 dry weight.The results indicated that polar Chlorella UMACC 234 has the most potential in containing significant amounts of bioactive compounds.
基金funded by the National Key R&D Program of China(Grant no.2018YFC1406700)the National Natural Science Foundation of China(Grant no.41776198)the Basic Scientific Fund for National Public Research Institutes of China(Grant no.GY0219Q10)。
文摘One major consequence of global warming in the Antarctic region is increased ice-free zones.Subsequent colonization of these ice-free areas by penguins alters their biogeochemistry,with one prominent example being elevation of inorganic phosphate concentrations around feces depositions.The complex soil biochemistry in the region makes it difficult to define the causal factors of these changes using common research approaches.Here,we addressed the effects of phosphate alone on microbiome structure and dynamics over time by adding external phosphate to selected soils in the Antarctic region.We then analyzed the soil bacterial community composition and diversity using 16S rRNA amplicon sequencing and compared these data with phosphate levels.Parallel geochemical analysis revealed changes in nine soil geochemical factors upon phosphate addition,all of which were relevant to microbiome structure,with soil pH showing the highest correlation.Links between geochemical factors and composition were identified,as were interactions between bacterial taxa.Additionally,Sphingobacteriia,Sphingobacteriales and Chitinophagaceae were found to be more abundant in phosphate-treated soils.Co-occurrence network analysis revealed significantly increased levels of associations in all major network properties over time after phosphate supplementation.Therefore,we conclude phosphate addition has diverse effects on Antarctic soil microbiomes.