Numerical modelling of the M2 tide on the northern Patagonian Shelf

Science.gov (United States)

Glorioso, P. D.; Simpson, J. H.

1994-02-01

The previously reported occurrence of tidal fronts on the Patagonian Shelf ( CARRETOet al., 1986 , Journal of Plankton Research, 8, 15-28; GLORIOSO, 1987 , Continental Shelf Research, 7, 27-34), motivated the application of a numerical model to solve the shallow-water equations with external forcing by the principal-lunar semidiurnal tide (M2) prescribed along the open boundary. The mean width of the Patagonian Shelf is comparable with a quarter wavelength of the semidiurnal tide, giving the conditions for standing wave resonance at that frequency ( WEBB, 1975 , Deep-Sea Research, 23, 1-15). The region is well recognized by its large tidal elevations and by the speed of the tidal wave changing phase very rapidly. Some of the results obtained from the modelling exercise include the mapping of the M2 tidal constants, the Simpson-Hunter stratification parameter, the mean sea surface elevation, and the distribution of tidal energy dissipation by bottom friction. These results agree qualitatively with the ship data available and with satellite infrared imagery.

Taxonomic review of the species of Helina R.-D. (Diptera: Muscidae) from Andean-Patagonian forests.

Science.gov (United States)

Patitucci, Luciano Damián; Mulieri, Pablo Ricardo; Mariluis, Juan Carlos

2016-08-12

Helina Robineau-Desvoidy, 1830 is the second genus of Muscidae in terms of richness. This genus includes several species collected at high altitudes and high latitudes, and is poorly studied in the Neotropical region. Only 12 species of Helina have been recorded in the southern limit of South America in the Andean-Patagonian forests. In the present work, we studied all the species known from the Andean-Patagonian forests, with the exception of H. viola Malloch, 1934, present three new species, H. araucana sp. nov., H. dorada sp. nov., and H. ouina sp. nov., and provide the first description of the females of H. australis Carvalho & Pont, 1993 and H. rufoapicata Malloch, 1934. We also propose four new synonymies: H. nigrimana basilaris (Carvalho & Pont, 1993) and H. nigrimana grisea (Malloch, 1934) as new junior synonyms of H. nigrimana (Macquart, 1851); and H. fulvocalyptrata Malloch, 1934 and H. simplex Malloch, 1934 as new junior synonyms of H. chilensis Malloch, 1934. Finally, we provide a generic diagnosis and a new key for the Helina species of the Andean-Patagonian forests, as well as notes on the biology and distribution maps of each specimen, and discuss a preliminary contruction of groups of species.

How fast is the Patagonian shelf-break acidifying?

Science.gov (United States)

Orselli, Iole B. M.; Kerr, Rodrigo; Ito, Rosane G.; Tavano, Virginia M.; Mendes, Carlos Rafael B.; Garcia, Carlos A. E.

2018-02-01

Anthropogenic carbon (Cant) concentration is determined according to the TrOCA method, from carbonate system data and hydrographic parameters collected during two consecutive spring cruises (2007 and 2008) in the Argentinean Patagonian shelf-break zone between 36°S and 50°S. Cant has intruded the water column until intermediate depths, with no Cant below 1000 m, in the deeper waters (i.e., North Atlantic Deep Water and Antarctic Bottom Water) of the Northern sector of the study area (i.e., North of 38°S). The higher Cant concentration is observed in Subantarctic Shelf Water in the Southern region, whereas in the Northern sector both Tropical Water and South Atlantic Central Water are equally affected by Cant intrusion. The Antarctic Intermediate Water represents the depth-limit achieved by Cant penetration, reinforcing the role that this water mass plays as an important vehicle to transport Cant to the oceans interior. The estimated Cant average (± method precision) is 46.6 ± 5.3 μmol kg- 1, considering the full depth of the water column. The ocean acidification state (ΔpH) shows an average (± standard deviation) of - 0.11 ± 0.05, thus, indicating an annual pH reduction of - 0.0010 yr- 1 since the Industrial Revolution (c.a. 1750). The degree of aragonite saturation is lowered towards undersaturation levels of calcite. The Patagonian shelf and shelf-break zones-a strong CO2 sink region in the global ocean-are likely a key area for Cant intrusion in the southwestern South Atlantic Ocean.

Late cenozoic magmatism in the South Patagonian batholith: SHRIMP U-Pb zircon age evidence

International Nuclear Information System (INIS)

Fanning, C.M; Herve, F; Pankhurst, R.J; Thomson, S; Faundez, V

2001-01-01

The North Patagonian Batholith (NPB) has a zonal age pattern which includes a well defined belt of Miocene and Mio-Pliocene plutons in its central portion (Pankhurst et al., 1999) which are spatially, and probably genetically related to the Liquine-Ofqui Fault Zone. Previous geochronological studies in the Southern Patagonian Batholith (SPB), as summarized by Bruce et al. (1991), have yielded 9 late Cenozoic K-Ar or Ar-Ar ages out of a total of 116 age determinations. None of these young ages correspond to U-Pb determinations on zircons, and some of the young ages correspond to satellite plutons east of the SPB proper, such as the Torres del Paine intrusion. In this paper we present the first late Cenozoic SHRIMP U-Pb zircon ages in the area of the SPB. The morphology of the analysed zircon crystals is described and leads to some inferences on the methodology and on the geological interpretation of the obtained ages (au)

A model-based telecoupling analysis for the Patagonian shelf: a new suggested template on how to study global seabirds-fisheries interactions for sustainability

Science.gov (United States)

Huettmann, F.; Raya Rey, A.

2016-12-01

The Southwest Atlantic Ocean, and the extended Patagonian shelf in particular, presents us with a very complex ecosystem of global relevance for food security and global peace. It is a highly productive area and it maintains a great diversity and abundance of seabird species. Fisheries have been identified as a main stressor for the marine ecosystems and as one of the main causes of seabird population declines. Using the framework of telecoupling - a sophisticated description of natural and socioeconomic interactions over large distances - here we present a fresh holistic look at the dynamic fisheries and (endangered) seabird interactions for the Patagonian shelf. While data are sparse, we employ machine learning-based predictions for a more holistic overview. We found that these waters of the Patagonian Shelf are significantly affected by many nations and outside players. We found that the input, output and spill-over of the Patagonian shelf ecosystem are distributed virtually all over the globe. In addition, we also found `losers' (=nations and their citizens that are left out entirely from this global resource and its governance). Our findings are based on best-available public trade and fish harvest analysis for this region, linked with predictive modeling (machine learning and geographic information systems GIS) to generalize for nine seabird species. We conveniently extend this analysis with a perspective from the financial sector and policy that enables the Patagonian fisheries as international investment and development projects. As increasingly recognized elsewhere, we believe that telecoupling can serve as a new but rather sophisticated study template highlighting wider complexities, bottlenecks and sensitivities for a vastly improved conservation research on oceans and global sustainability questions.

Effects of Patagonian pine forestry on native breeding birds

Directory of Open Access Journals (Sweden)

Moises Pescador

2014-12-01

Full Text Available Aim of the study: The objective is to assess the influences of the tree stand age and other forestry management practices on species richness, composition, and distribution of the Patagonian pine plantation bird assemblages. Area of Study: The work was carried out in forested plots of Ponderosa pine located at the Lanín National Park (Patagonia, Argentina.Material and Methods: Birds were sampled using 25 m fixed radius point counts, at four plots varying in age, management, and forest structure. Main Results: A total of 2090 individuals belonging to 34 bird species were observed, their numbers vary significantly depending on the different modes of plantation management. The population density of the 14 most abundant bird species was compared among the four plantation plots and ten species don’t show statistically significant differences in their population density among the different forest plots. The California Quail, the White-Crested Elaenia and the Southern House Wren showed higher densities in pine plantations with lower tree densities and fewer cutting treatments. The Diuca Finch had high densities in the younger plantations not subjected to any treatment. Research highlights: Most of these bird species are opportunistic and a few are found more regularly in these non-native woods than in other native forested or afforested areas. Our data suggest that a mixed scenario based on a mosaic of plantation with patches of native deciduous forest may help maximize the bird diversity in the management of northwestern Patagonian plantation landscapes.Keywords: Bird population; diversity; exotic plantations; Patagonia; tree-age.

Zoonotic parasites associated with felines from the Patagonian Holocene

Directory of Open Access Journals (Sweden)

Martín Horacio Fugassa

2009-12-01

Full Text Available Feline coprolites were examined for parasites with the aim of studying ancient infections that occurred in the Patagonian region during the Holocene period. Eggs compatible to Trichuris sp., Calodium sp., Eucoleus sp., Nematodirus sp., Oesophagostomum sp. (Nematoda, Monoecocestus sp. (Cestoda and Eimeria macusaniensis (Coccidia were recovered from faecal samples. The results obtained from the analysis provide evidence of consumption by felids of the viscera of both rodents and camelids. This knowledge allows for improved explanations as to the distribution of parasitism and its significance to the health of humans and animals inhabiting the area under study during the Middle Holocene.

Pyroclastic Eruption Boosts Organic Carbon Fluxes Into Patagonian Fjords

Science.gov (United States)

Mohr, Christian H.; Korup, Oliver; Ulloa, Héctor; Iroumé, Andrés.

2017-11-01

Fjords and old-growth forests store large amounts of organic carbon. Yet the role of episodic disturbances, particularly volcanic eruptions, in mobilizing organic carbon in fjord landscapes covered by temperate rainforests remains poorly quantified. To this end, we estimated how much wood and soils were flushed to nearby fjords following the 2008 eruption of Chaitén volcano in south-central Chile, where pyroclastic sediments covered >12 km2 of pristine temperate rainforest. Field-based surveys of forest biomass, soil organic content, and dead wood transport reveal that the reworking of pyroclastic sediments delivered 66,500 + 14,600/-14,500 tC of large wood to two rivers entering the nearby Patagonian fjords in less than a decade. A similar volume of wood remains in dead tree stands and buried beneath pyroclastic deposits ( 79,900 + 21,100/-16,900 tC) or stored in active river channels (5,900-10,600 tC). We estimate that bank erosion mobilized 132,300+21,700/-30,600 tC of floodplain forest soil. Eroded and reworked forest soils have been accreting on coastal river deltas at >5 mm yr-1 since the eruption. While much of the large wood is transported out of the fjord by long-shore drift, the finer fraction from eroded forest soils is likely to be buried in the fjords. We conclude that the organic carbon fluxes boosted by rivers adjusting to high pyroclastic sediment loads may remain elevated for up to a decade and that Patagonian temperate rainforests disturbed by excessive loads of pyroclastic debris can be episodic short-lived carbon sources.

Fire cue effects on seed germination of six species of northwestern Patagonian grasslands

Science.gov (United States)

Gonzalez, S. L.; Ghermandi, L.

2012-09-01

Postfire recruitment of seedlings has been attributed to a stimulation of germination by fire-related cues. The germination response to heat shock (80 °C - 5 min), smoke (60 min), the combination of both factors and no heat no smoke (control) was studied in six native species (two dominant grasses, two dominant shrubs and two annual fugitive herbs) of northwestern Patagonian grasslands. Seeds of the grasses Festuca pallescens and Stipa speciosa and the shrub Senecio bracteolatus (Asteraceae) germinated when they were exposed to heat shock, whereas seeds of the other shrub, Mulinum spinosum (Apiaceae), were killed by this fire cue. In grasses, probably the glume of caryopsis protected embryos from heat. Possibly, the seed size could explain the different responses of the two shrubs. Heat combined with smoke reduced seed germination for S. speciosa and S. bracteolatus. The heat could have scarified seeds and the longer exposure to smoke could have been toxic for embryos. The same treatment increased germination of the annual fugitive herb Boopis gracilis (Calyceraceae). We concluded that fire differentially affects the seedling recruitment of the studied species in the northwestern Patagonian grasslands.

Mohorovicic discontinuity depth analysis beneath North Patagonian Massif

Science.gov (United States)

Gómez Dacal, M. L.; Tocho, C.; Aragón, E.

2013-05-01

The North Patagonian Massif is a 100000 km2, sub-rectangular plateau that stands out 500 to 700 m higher in altitude than the surrounding topography. The creation of this plateau took place during the Oligocene through a sudden uplift without noticeable internal deformation. This quite different mechanical response between the massif and the surrounding back arc, the short time in which this process took place and a regional negative Bouguer anomaly in the massif area, raise the question about the isostatic compensation state of the previously mentioned massif. In the present work, a comparison between different results about the depth of the Mohorovicic discontinuity beneath the North Patagonian Massif and a later analysis is made. It has the objective to analyze the crustal thickness in the area to contribute in the determination of the isostatic balance and the better understanding of the Cenozoic evolution of the mentioned area. The comparison is made between four models; two of these were created with seismic information (Feng et al., 2006 and Bassin et al., 2000), another model with gravity information (Barzaghi et al., 2011) and the last one with a combination of both techniques (Tassara y Etchaurren, 2011). The latter was the result of the adaptation to the work area of a three-dimensional density model made with some additional information, mainly seismic, that constrain the surfaces. The work of restriction and adaptation of this model, the later analysis and comparison with the other three models and the combination of both seismic models to cover the lack of resolution in some areas, is presented here. According the different models, the crustal thickness of the study zone would be between 36 and 45 Km. and thicker than the surrounding areas. These results talk us about a crust thicker than normal and that could behave as a rigid and independent block. Moreover, it can be observed that there are noticeable differences between gravimetric and seismic

Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species

Science.gov (United States)

Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Maria E. Arce

2009-01-01

We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Leaf) hydraulic conductivity, wood density (Pw), rooting depth, and specific leaf...

Dicty_cDB: Contig-U15444-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 3H04SK PhyRootSw1 Citrus sinensis cDNA clone... 52 0.001 2 ( FE207941 ) K052G01 Antarctic fish Dissostichus mawson...E224119 ) O052F03 Antarctic fish Dissostichus mawsoni adult... 38 0.002 3 ( EW770...2 2 ( FE205779 ) K020F10 Antarctic fish Dissostichus mawsoni adult... 38 0.003 3 ( FE205204 ) K010B01 Antarctic fish Dissostichus maw...cDNA clone:whsct13p03, 3' end. 52 0.003 2 ( FE207197 ) K043G11 Antarctic fish Dissostichus mawsoni adult... ... Antarctic fish Dissostichus mawsoni adult... 38 0.003 3 ( FE223392 ) O043F12 Ant

Dicty_cDB: SLD739 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available Antarctic fish Dissostichus mawsoni adult... 42 6.5 1 ( FE221128 ) O019B05 Antarctic fish Dissostichus mawson...i adult... 42 6.5 1 ( FE203112 ) B385G09 Antarctic fish Dissostichus mawsoni ad...ult... 42 6.5 1 ( FE196180 ) B197B12 Antarctic fish Dissostichus mawsoni adult... 42 6.5 1 ( FE195928 ) B193...H07 Antarctic fish Dissostichus mawsoni adult... 42 6.5 1 dna update 2009. 3.21 Homology vs Protein Score E

Occurrence of arbuscular mycorrhizal fungi in high altitude sites of the Patagonian Altoandina region in Nahuel Huapi National Park (Argentina

Directory of Open Access Journals (Sweden)

María Silvana Velázquez

Full Text Available ABSTRACT Knowledge of the occurrence and diversity of arbuscular mycorrhizal fungi (AMF in National Parks is essential for the establishment of policies for conservation. The aim of this study was to characterize the AMF communities in the Patagonian Altoandina region in Nahuel Huapi National Park, Argentina. We surveyed AMF spores associated with the rhizospheres of 9 plant species in the Patagonian Steppe (PS, Challhuaco Hill (ChH, Catedral Hill (CH, and Tronador Hill (TH regions and detected a total of 27 Glomeromycota species. Acaulospora laevis was dominant at all sites. The AMF community was dominated by Acaulosporaceae, as regards the number of species and contribution of each one to the total number of spores. Three Glomeromycota families were detected at PS, the site with the lowest elevation; whereas five to six families were detected at ChH, CH, and TH. Cluster analysis indicated that the AMF communities were grouped according to habitat. We concluded that certain patterns of the AMFcommunity structure detected were equivalent to those of high-altitude environments from other studies, while others were unique to the Patagonian region; thus suggesting that historical influences like dispersion and speciation played a critical role in shaping AMF community composition in such high-altitude environments.

Links between Patagonian Ice Sheet fluctuations and Antarctic dust variability during the last glacial period (MIS 4-2)

Science.gov (United States)

Kaiser, Jérôme; Lamy, Frank

2010-06-01

Antarctic and Greenland ice-core records reveal large fluctuations of dust input on both orbital and millennial time-scales with potential global climate implications. At least during glacial periods, the Antarctic dust fluctuations appear to be largely controlled by environmental changes in southern South America. We compare dust flux records from two Antarctic ice-cores to variations in the composition of the terrigenous supply at ODP Site 1233 located off southern Chile and known to record fluctuations in the extent of the northern part of the Patagonian ice-sheet (NPIS) during the last glacial period (Marine Isotope Stage, MIS, 4 to 2). Within age uncertainties, millennial-scale glacial advances (retreats) of the NPIS correlate to Antarctic dust maxima (minima). In turn, NPIS fluctuations were closely related to offshore sea surface temperature (SST) changes. This pattern suggests a causal link involving changes in temperature, in rock flour availability, in latitudinal extensions of the westerly winds and in foehn winds in the southern Pampas and Patagonia. We further suggest that the long-term trend of dust accumulation is partly linked to the sea-level related changes in the size if the Patagonian source area due to the particular morphology of the Argentine shelf. We suggest that sea-level drops at the beginning of MIS 4 and MIS 2 were important for long-term dust increases, while changes in the Patagonian dust source regions primarily control the early dust decrease during the MIS 4/3 transition and Termination 1.

Understanding the Transport of Patagonian Dust and Its Influence on Marine Biological Activity in the South Atlantic Ocean

Science.gov (United States)

Johnson, Matthew; Meskhidze, Nicholas; Kiliyanpilakkil, Praju; Gasso, Santiago

2010-01-01

Modeling and remote sensing techniques were applied to examine the horizontal and vertical transport pathways of Patagonian dust and quantify the effect of soluble-iron- laden mineral dust deposition on marine primary productivity in the South Atlantic Ocean (SAO) surface waters. The global chemistry transport model GEOS-Chem, implemented with an iron dissolution scheme, was applied to evaluate the atmospheric transport and deposition of mineral dust and bioavailable iron during two dust outbreaks originating in the source regions of Patagonia. In addition to this "rapidly released" iron, offline calculations were also carried out to estimate the amount of bioavailable iron leached during the residence time of dust in the ocean mixed layer. Model simulations showed that the horizontal and vertical transport pathways of Patagonian dust plumes were largely influenced by the synoptic meteorological patterns of high and low pressure systems. Model-predicted horizontal and vertical transport pathways of Patagonian dust over the SAO were in reasonable agreement with remotely-sensed data. Comparison between remotely-sensed and offline calculated ocean surface chlorophyll-a concentrations indicated that, for the two dust outbreaks examined in this study, the deposition of bioavailable iron in the SAO through atmospheric pathways was insignificant. As the two dust transport episodes examined here represent typical outflows of mineral dust from South American sources, our study suggests that the atmospheric deposition of mineral dust is unlikely to induce large scale marine primary productivity and carbon sequestration in the South Atlantic sector of the Southern Ocean.

K-Ar ages of rocks from Lago Alumine, Rucachoroi and Quillen, North Patagonian Andes, Neuquen, Republica Argentina

International Nuclear Information System (INIS)

Latorre, Carlos O.; Vattuone, M.E; Linares, Enrique; Leal, Pablo R

2001-01-01

This study presents new K-Ar ages of granitic rocks from the Patagonian Batholit in the North Patagonian Andes (38 o 00'- 39 o 30' SL), from localities near Alumine lake and from Norquinco lake to Quillen valley, in the Neuquen Province, Argentine. The granitic rocks of Patagonia had been recognized as Upper Paleozoic to Middle Jurassic batholits and as Late Jurassic to Tertiary batholiths (Rapela and Pankhurst, 1992). Geochronologically, Rapela and Kay (1988) had distinguished Early Cretaceous (140 to 120 Ma) and Late Cretaceous (110 to 75 Ma ) magmatic episodes based in potassium-argon data. For the granitic rocks of the area of Paso Icalma, Moquehue and the Rahue granodiorites, Cingolani et al. (1991) presented Rb-Sr whole rock isochron ages of 70±10 Ma, 209±13 Ma and 237±37 Ma, respectively, and Varela et al. (1994), with the same method, cited an age of 285±5 Ma for the Rahue granodiorites and diorites (au)

Impact of glaciations on the long-term erosion in Southern Patagonian Andes

Science.gov (United States)

Simon-Labric, Thibaud; Herman, Frederic; Baumgartner, Lukas; Shuster, David L.; Braun, Jean; Reiners, Pete W.; Valla, Pierre G.; Leuthold, Julien

2014-05-01

The Southern Patagonian Andes are an ideal setting to study the impact of Late-Cenozoic climate cooling and onset of glaciations impact on the erosional history of mountain belts. The lack of tectonic activity during the last ~12 Myr makes the denudation history mainly controlled by surface processes, not by tectonics. Moreover, the glaciations history of Patagonia shows the best-preserved records within the southern hemisphere (with the exception of Antarctica). Indeed, the dry climate on the leeward side of Patagonia and the presence of lava flows interbedded with glacial deposits has allowed an exceptional preservation of late Cenozoic moraines with precise dating using K-Ar analyses on lava flow. The chronology of moraines reveals a long history covering all the Quaternary, Pliocene, and up to the Upper Miocene. The early growth of large glaciers flowing on eastern foothills started at ~7-6 Myr, while the maximum ice-sheet extent dates from approximately 1.1 Myr. In order to quantify the erosion history of the Southern Patagonian Andes and compare it to the glaciations sediment record, we collected samples along an age-elevation profile for low-temperature thermochronology in the eastern side of the mountain belt (Torres del Paine massif). The (U-Th)/He age-elevation relationship shows a clear convex shape providing an apparent long-term exhumation rate of ~0.2 km/Myr followed by an exhumation rate increase at ~6 Myr. Preliminary results of 4He/3He thermochronometry for a subset of samples complete the erosion history for the Plio-Pleistocene epoch. We used inverse procedure predicting 4He distributions within an apatite grain using a radiation-damage and annealing model to quantify He-diffusion kinetics in apatite. The model also allows quantifying the impact of potential U-Th zonation throughout each apatite crystal. Inversion results reveal a denudation history composed by a pulse of denudation at ~6 Ma, as suggested by the age-elevation relationship

Dicty_cDB: Contig-U15259-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 0006742 rw_mgpallid Polysphondylium pallidum ... 50 4e-10 2 ( FE218415 ) L110G07 Antarctic fish Dissostichus mawson...i adult... 56 0.001 1 ( FE208600 ) K060D09 Antarctic fish Dissostichus mawsoni adult... 56 0.001 1 ( ...FE205438 ) K012C10 Antarctic fish Dissostichus mawsoni adult... 56 0.001 1 ( FE20...5424 ) K012A12 Antarctic fish Dissostichus mawsoni adult... 56 0.001 1 ( CT754403 ) Paramecium tetraurelia 5...A01 Antarctic fish Dissostichus mawsoni adult... 48 0.28 1 ( ES894727 ) LET081_2007-02-10/LET081_G11_042_1 S

Pogonophryne neyelovi, a new species of Antarctic short-barbeled plunderfish (Perciformes, Notothenioidei, Artedidraconidae from the deep Ross Sea

Directory of Open Access Journals (Sweden)

Gennadiy Shandikov

2013-04-01

Full Text Available This paper continues descriptions of new deep-water Antarctic barbeled plunderfishes of the poorly known and the most speciose notothenioid genus Pogonophryne. It is based on a comprehensive collection obtained by the authors in 2009–2010 during an Antarctic toothfish (Dissostichus mawsoni fishing trip. A new species, the hopbeard plunderfish P. neyelovi, the twenty-second species of the genus, is described. The new species belongs to dorsally-spotted short-barbeled species forming the “P. mentella” group. Pogonophryne neyelovi sp.n. is characterized by the following combination of characters: a very short and small mental barbel with an ovaloid and short terminal expansion covered by flattened scale-like processes that are mostly bluntly palmate; a moderately protruding lower jaw; a high second dorsal fin almost uniformly black and lacking a sharply elevated anterior lobe; pectoral fins striped anteriorly and uniformly light posteriorly; the anal and pelvic fins light; the dorsal surface of the head and the area anterior to the first dorsal fin covered with large, irregular dark brown blotches and spots; the ventral surface of the head, breast and belly without sharp dark markings. The new species is compared to the closest species P. brevibarbata, P. tronio, and P. ventrimaculata. English vernacular names are proposed for all species of the genus.

Complex brittle deformation pattern along the Southern Patagonian Andes (Argentina)

Science.gov (United States)

Barberón, Vanesa; Sue, Christian; Ronda, Gonzalo; Ghiglione, Matías

2016-04-01

The Southern Patagonian Andes is located in the southern extreme of the Pacific subduction zone, where the Antartic oceanic plate sinks underneath South America. The history of the area begins with compression during Paleozoic, Jurassic extension associated to the rift and opening of the South Atlantic Ocean, then a sag stage in the Lower Cretaceous followed by a foreland phase as a result of plate tectonics (Ghiglione et al., 2016). The kinematic study is concentrated in the Argentinean foothills, between 46°40' and 48° SL. We measured around 800 fault planes and their striaes with the sense of movement in order to characterize the stress field. The software used to make the stress inversion were Tensor (Delvaux, 2011) and Multiple Inverse Method MIM (Yamaji et al., 2011). The stress field map was built with the results of the MIM. We present new data from 48 sites located in the northern sector of the Southern Patagonian Andes. The measurements were made in several rocks from Paleozoic to Lower Cretaceous, even though most were taken in pyroclastic jurassic rocks from El Quemado Complex. Paleostress tensors obtained are mostly strike-slip, although a 25% is normal and there are a few compresional. The pattern of faults found is complex. In some sites the tensor can be locally linked to satellite images and observations from the field or be related to a major thrust front. There is no clear correlation between the age and/or lithology with the tensor since the youngest rocks measured are Lower Cretaceous. Probably there are several generations of family faults connected to different and recent tectonic phases then the paleostress tensors might correspond to the latest tectonic events.

Rb/Sr and U/Pb isotopic ages in basement rocks of Mina Gonzalito and Arroyo Salado, Atlantic North-Patagonian Massif, Rio Negro, Argentina

International Nuclear Information System (INIS)

Varela, Ricardo; Sato, Ana M.; Cingolani, Carlos A.; Basei, Miguel A.S.; Siga, Oswaldo; Sato, Kei

1998-01-01

Isotopic ages from metamorphic and plutonic rocks of the Atlantic area of North Patagonian basement indicate that the main crustal tectonic events occurred during the late Proterozoic to early Paleozoic times. Rb/Sr and U/Pb data in the 550-470 Ma interval suggest an old tecto-thermal activity during the upper Brazilian Cycle (Rio Doce Orogeny). At regional scale, the comparable Neo proterozoic basement of Ventania and sedimentary for eland cover of Tandilia continues to the Northeast, in the Dom Feliciano Belt. A possible correlation of the North Patagonian basement with igneous-metamorphic relics of Central Argentina (Pampean Ranges of San Luis-Cordoba and at La Pampa province) is also indicated. (author)

The Patagonian Orocline: Paleomagnetic evidence of a large counter-clockwise rotation during the closure of the Rocas Verdes basin.

Science.gov (United States)

Poblete, Fernando; Roperch, Pierrick; Herve, Francisco; Ramirez, Cristobal; Arriagada, Cesar

2014-05-01

The southernmost Andes of Patagonia and Tierra del Fuego present a prominent arc-shaped structure, the Patagonian Orocline. Despite the fact that this major structure was already described by Alfred Wegener in his famous textbook in 1929, few paleomagnetic studies have been attempted to describe the rotations associated with the formation of the Patagonian Orocline. In this study we present a paleomagnetic and anisotropy of magnetic susceptibility (AMS) study from more than 130 sites obtained from the Ultima Esperanza region (NS structures at ~51°S) to Península Hardy, south of the Beagle Channel at ~55°S. 45 sites were sampled in early-cretaceous gabbros (gabbro complex), mid-cretaceous tonalites and granodiorites (Canal Beagle group) and Paleocene intrusive rocks (Seno Año Nuevo group) from the South Patagonian batholith, 4 sites from the late Jurassic Hardy formation, a volcanic succession outcropping in Hardy Peninsula and Stewart Island, 9 sites were drilled in the lower cretaceous sedimentary infill of the Rocas Verdes Basin, 3 sites from the Tortuga ophiolite, a quasi-oceanic crust related to the opening of the Rocas Verdes basin. 80 sites were sampled in Cretaceous to Miocene sedimentary rocks from the Magallanes fold and thrust belt and Magallanes Basin. Characteristic Remanent Magnetizations (ChRMs) obtained from the Rocas Verdes Basin tectonic province correspond to secondary magnetizations postdating the early phase of folding. Pyrrhotite is the main magnetic carrier in some of these sites. ChRMs from the South Patagonian Batholith correspond to a primary magnetization. These rocks record about 90° counterclockwise rotations south of the Beagle channel. Few sites from sediments of the Magallanes fold and thrust belt have stable ChRM. The available paleomagnetic results show that no rotation has occurred in the Provincia of Ultima Esperanza (51.5°S), at least, for the last 60 Ma. In the southern part of Provincia de Magallanes and Tierra del Fuego

Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

Science.gov (United States)

Signorini, Sergio R.; Garcia, Virginia M.T.; Piola, Alberto R.; Evangelista, Heitor; McClain, Charles R.; Garcia, Carlos A.E.; Mata, Mauricio M.

2009-01-01

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed.

Dicty_cDB: Contig-U04369-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 3 1 ( FG083940 ) CMRC-FF-IH0-abv-c-22-0-CMRC.r1 Ceratitis capitata... 44 6.3 1 ( FE199855 ) B322G01 Antarctic fish Dissostichus mawso...ni adult... 44 6.3 1 ( FE194211 ) B169G05 Antarctic fish Dissostichus mawsoni adult...... 44 6.3 1 ( FE194209 ) B169G03 Antarctic fish Dissostichus mawsoni adult... 44... 6.3 1 ( FE194180 ) B169D07 Antarctic fish Dissostichus mawsoni adult... 44 6.3 1 ( EW982994 ) EST_sras_evg_

Infection with Toxoplasma gondii in a red kangaroo (Macropus rufus and a Patagonian mara (Dolichotis patagonum in captivity

Directory of Open Access Journals (Sweden)

Nataly Díaz-Ayala

Full Text Available Abstract Toxoplasmosis is an infectious, zoonotic and parasitic disease, caused by Toxoplasma gondii. In this manucript, two cases of infection with T. gondii in captive animals from a zoological park in the central region of Chile are described. One case was a red kangaroo (Macropus rufus, which is highly susceptible to the infection, and the other was a Patagonian mara (Dolichotis patagonum, a rodent in which there is no previous report of the infection. Both animals had myocarditis, with the presence of intralesional tachizoites and cysts suggestive of infection with T. gondii. This infection was confirmed by immunohistochemistry in both animals. The origin of the infection is unknown, but it is likely that free ranging domestic felines were associated with the dissemination of the parasites. This highlights the importance of controlling the domestic animal populations in zoological parks. To the best of our knowledge, this is the first time that T. gondii infection is described in a Patagonian mara, adding a new host for this infectious agent.

Traveling around Cape Horn: Otolith chemistry reveals a mixed stock of Patagonian hoki with separate Atlantic and Pacific spawning grounds

Science.gov (United States)

Schuchert, P.C.; Arkhipkin, A.I.; Koenig, A.E.

2010-01-01

Trace element fingerprints of edge and core regions in otoliths from 260 specimens of Patagonian hoki, Macruronus magellanicus L??nnberg, 1907, were analyzed by LA-ICPMS to reveal whether this species forms one or more population units (stocks) in the Southern Oceans. Fish were caught on their spawning grounds in Chile and feeding grounds in Chile and the Falkland Islands. Univariate and multivariate analyses of trace element concentrations in the otolith edges, which relate to the adult life of fish, could not distinguish between Atlantic (Falkland) and Pacific (Chile) hoki. Cluster analyses of element concentrations in the otolith edges produced three different clusters in all sample areas indicating high mixture of the stocks. Cluster analysis of trace element concentrations in the otolith cores, relating to juvenile and larval life stages, produced two separate clusters mainly distinguished by 137Ba concentrations. The results suggest that Patagonian hoki is a highly mixed fish stock with at least two spawning grounds around South America. ?? 2009 Elsevier B.V.

Conflicting evolutionary patterns due to mitochondrial introgression and multilocus phylogeography of the Patagonian freshwater crab Aegla neuquensis.

Directory of Open Access Journals (Sweden)

Brian R Barber

Full Text Available BACKGROUND: Multiple loci and population genetic methods were employed to study the phylogeographic history of the Patagonian freshwater crab Aegla neuquensis (Aeglidae: Decopoda. This taxon occurs in two large river systems in the Patagonian Steppe, from the foothills of the Andes Mountains east to the Atlantic Ocean. METHODOLOGY/PRINCIPAL FINDINGS: A nuclear phylogeny and multilocus nested clade phylogeographic analysis detected a fragmentation event between the Negro and Chico-Chubut river systems. This event occurred approximately 137 thousand years ago. An isolation-with-migration analysis and maximum-likelihood estimates of gene flow showed asymmetrical exchange of genetic material between these two river systems exclusively in their headwaters. We used information theory to determine the best-fit demographic history between these two river systems under an isolation-with-migration model. The best-fit model suggests that the Negro and the ancestral populations have the same effective population sizes; whereas the Chico-Chubut population is smaller and shows that gene flow from the Chico-Chubut into the Negro is four times higher than in the reverse direction. Much of the Chico-Chubut system appears to have only been recently colonized while the Negro populations appear to have been in place for most of the evolutionary history of this taxon. CONCLUSIONS/SIGNIFICANCE: Due to mitochondrial introgression, three nuclear loci provided different phylogeographic resolution than the three mitochondrial genes for an ancient fragmentation event observed in the nuclear phylogeny. However, the mitochondrial locus provided greater resolution on more recent evolutionary events. Our study, therefore, demonstrates the need to include both nuclear and mitochondrial loci for a more complete understanding of evolutionary histories and associated phylogeographic events. Our results suggest that gene flow between these systems, before and after fragmentation

Migratory timing, rate, routes and wintering areas of White-crested Elaenia (Elaenia albiceps chilensis, a key seed disperser for Patagonian forest regeneration.

Directory of Open Access Journals (Sweden)

Susana Patricia Bravo

Full Text Available Migratory animals often play key ecological roles within the communities they visit throughout their annual journeys. As a consequence of the links between biomes mediated by migrants, changes in one biome could affect remote areas in unpredictable ways. Migratory routes and timing of most Neotropical austral migrants, which breed at south temperate latitudes of South America and overwinter closer to or within tropical latitudes of South America, have yet to be described in detail. As a result, our understanding about how these birds provide links between South American biomes is almost non-existent. White-crested Elaenia (Elaenia albiceps chilensis is a long-distance austral migrant that breeds in the Patagonian Forest biome and overwinters in tropical South America. Because this small flycatcher plays a key role in the regeneration of this ecosystem, our objective was to describe the annual cycle of White-crested elaenias to evaluate the degree of migratory connectivity between breeding and wintering areas and therefore to determine if there are specific biomes of northern South America linked by elaenias to Patagonian forests. Fifteen individuals were successfully tracked throughout a complete migration cycle using miniature light-level geolocators. All individuals resided and moved through the same general regions. During fall (March-April-May, elaenias were located in the Caatinga and the Atlantic Forest biomes, from Rio de Janeiro to the region near Salvador da Bahia, Brazil. During winter (June-July-Aug., birds were located further inland, within the Cerrado biome. Birds used three different routes during fall migration. Our results indicate that some individuals use a direct route, flying between 500-600 km/day, crossing desert and grasslands, while others took a detour, flying 100-200 km/day through forested areas with refueling opportunities. All birds used the Yunga forest during spring migration, with ten out of 15 individuals

Patagonian red wines: selection of Lactobacillus plantarum isolates as potential starter cultures for malolactic fermentation.

Science.gov (United States)

Bravo-Ferrada, Bárbara Mercedes; Hollmann, Axel; Delfederico, Lucrecia; Valdés La Hens, Danay; Caballero, Adriana; Semorile, Liliana

2013-09-01

The aim of this study was to evaluate fifty-three Lactobacillus plantarum isolates obtained from a Patagonian red wine, molecularly identified and typified using RAPD analysis, in order to select starter cultures for malolactic fermentation (MLF). The results obtained suggest a considerable genetic diversity, taking into account that all L. plantarum isolates were obtained from one cellar and one vintage. Based on the capacity to tolerate a concentration of 14 % ethanol in MRS broth for 2 days, eight isolates were selected for the subsequent analysis. The incidence of various wine stress factors (ethanol, acid pH, lysozyme and sulfur dioxide) on isolates growth was studied. Besides, glucosidase and tannase activities were evaluated, and the presence of genes involved in the synthesis of biogenic amines was examined by PCR. A previously characterized indigenous Oenococcus oeni strain was included with comparative purposes. Differences in technologically relevant characteristics were observed among the eight L. plantarum selected isolates, revealing an isolate-dependent behavior. Detectable glucosidase and tannase activities were found in all isolates. The presence of genes encoding histidine and tyrosine descarboxylases and putrescine carbamoyltransferase was not detected. The ability of L. plantarum isolates to grow and consume L-malic acid in simulated laboratory-scale vinifications revealed that two of them could be considered as possible MLF starter cultures for Patagonian red wines. These isolates will be subjected to further analysis, for a final winery technological characterization.

Dicty_cDB: Contig-U11323-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available AF134321 |pid:none) Dissostichus mawsoni clone Dm7m ch... 84 3e-14 AM747721_702( ...S101... 81 2e-13 U58944_1( U58944 |pid:none) Dissostichus mawsoni AFGP antifreeze g... 81 2e-13 AM182501_1( ...017194_2467( AE017194 |pid:none) Bacillus cereus ATCC 10987, com... 75 1e-11 U43149_1( U43149 |pid:none) Dissostichus mawson

Phenolic compounds as indicators of drought resistance in shrubs from Patagonian shrublands (Argentina).

Science.gov (United States)

Varela, M Celeste; Arslan, Idris; Reginato, Mariana A; Cenzano, Ana M; Luna, M Virginia

2016-07-01

Plants exposed to drought stress, as usually occurs in Patagonian shrublands, have developed different strategies to avoid or tolerate the lack of water during their development. Production of phenolic compounds (or polyphenols) is one of the strategies used by some native species of adverse environments to avoid the oxidative damage caused by drought. In the present study the relationship between phenolic compounds content, water availability and oxidative damage were evaluated in two native shrubs: Larrea divaricata (evergreen) and Lycium chilense (deciduous) of Patagonian shrublands by their means and/or by multivariate analysis. Samples of both species were collected during the 4 seasons for the term of 1 year. Soil water content, relative water content, total phenols, flavonoids, flavonols, tartaric acid esters, flavan-3-ols, proanthocyanidins, antioxidant capacity and lipid peroxidation were measured. According to statistical univariate analysis, L. divaricata showed high production of polyphenols along the year, with a phenolic compound synthesis enhanced during autumn (season of greatest drought), while L. chilense has lower production of these compounds without variation between seasons. The variation in total phenols along the seasons is proportional to the antioxidant capacity and inversely proportional to lipid peroxidation. Multivariate analysis showed that, regardless their mechanism to face drought (avoidance or tolerance), both shrubs are well adapted to semi-arid regions and the phenolic compounds production is a strategy used by these species living in extreme environments. The identification of polyphenol compounds showed that L. divaricata produces different types of flavonoids, particularly bond with sugars, while L. chilense produces high amount of non-flavonoids compounds. These results suggest that flavonoid production and accumulation could be a useful indicator of drought tolerance in native species. Copyright © 2016 Elsevier Masson

Native and exotic fishes in a Patagonian reservoir with rainbow trout cage culture: spatial and trophic resource use

Directory of Open Access Journals (Sweden)

Nabaes Jodar Diego N.

2017-01-01

Full Text Available Although the interactions of exotic salmonids with native Patagonian fishes are well known, little is known about the ecology and impact of farmed fish escapees. Salmonid production in Argentina is largely concentrated in the Alicurá reservoir in north Patagonia, where fish community studies have been scarce. Here, we assess and compare the spatial distribution, body size–condition and diet of the different fish species in this reservoir. Strong vertical segregation was observed between exotic rainbow trout Oncorhynchus mykiss (both escapees and wild, dominating the littoral zone, and native Percichthys trucha which dominate the medium and deep strata. Low piscivory–benthivory and high zooplanktivory were observed for rainbow trout, both traits being uncommon at a regional scale. Escaped farmed rainbow trout (ERT diet included abundant indigestible items along with wild prey. Higher body condition of P. trucha close to farms, as well as the regionally unprecedented high incidence of Daphnia sp. in the guts of all the species suggest that farm nutrient discharges have had significant impacts. Finally, the high body condition of ERT, together with their wild food diet and the long dispersal distance observed, demonstrate post-escape success, drawing our attention to potential upstream dispersion affecting the biodiversity and fisheries of Patagonian rivers and lakes.

The Gondwana Orogeny in northern North Patagonian Massif: Evidences from the Caita Có granite, La Seña and Pangaré mylonites, Argentina

Directory of Open Access Journals (Sweden)

Daniel A. Gregori

2016-07-01

Full Text Available Structural analyses in the northern part of the North Patagonia Massif, in the foliated Caita Có granite and in La Seña and Pangaré 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 Có 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.

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation

Science.gov (United States)

Metcalf, Jessica L.; Turney, Chris; Barnett, Ross; Martin, Fabiana; Bray, Sarah C.; Vilstrup, Julia T.; Orlando, Ludovic; Salas-Gismondi, Rodolfo; Loponte, Daniel; Medina, Matías; De Nigris, Mariana; Civalero, Teresa; Fernández, Pablo Marcelo; Gasco, Alejandra; Duran, Victor; Seymour, Kevin L.; Otaola, Clara; Gil, Adolfo; Paunero, Rafael; Prevosti, Francisco J.; Bradshaw, Corey J. A.; Wheeler, Jane C.; Borrero, Luis; Austin, Jeremy J.; Cooper, Alan

2016-01-01

The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.6 ka) but during contrasting temperature trends across each continent. Unfortunately, limited data sets in South America have so far precluded detailed comparison. We analyze genetic and radiocarbon data from 89 and 71 Patagonian megafaunal bones, respectively, more than doubling the high-quality Pleistocene megafaunal radiocarbon data sets from the region. We identify a narrow megafaunal extinction phase 12,280 ± 110 years ago, some 1 to 3 thousand years after initial human presence in the area. Although humans arrived immediately prior to a cold phase, the Antarctic Cold Reversal stadial, megafaunal extinctions did not occur until the stadial finished and the subsequent warming phase commenced some 1 to 3 thousand years later. The increased resolution provided by the Patagonian material reveals that the sequence of climate and extinction events in North and South America were temporally inverted, but in both cases, megafaunal extinctions did not occur until human presence and climate warming coincided. Overall, metapopulation processes involving subpopulation connectivity on a continental scale appear to have been critical for megafaunal species survival of both climate change and human impacts. PMID:27386563

Wing pattern variation in the Patagonian biting midge, Forcipomyia (Forcipomyia multipicta Ingram & Macfie (Diptera, Ceratopogonidae

Directory of Open Access Journals (Sweden)

Gustavo R. SPINELLI

2012-01-01

Full Text Available Examination of the type-series and non-type specimens of the Patagonian biting midge, Forcipomyia (Forcipomyia multipicta Ingram & Macfie (Diptera: Ceratopogonidae, revealed considerable variation in wing patterns of both sexes. One pattern includes several distinct light spot areas, whereas another pattern (e.g, in the holotype only features marginal light spots in cell r3, while other light spots are barely perceptible or absent. The cause(s of the differential lack of dark macrotrichia in certain areas of the wing membrane in specimens of some series could not be attributed either to their age, sex, or method of preservation.

New insights into the morphology, reproduction and distribution of the large-tuberculate octopus Graneledone macrotyla from the Patagonian slope

Directory of Open Access Journals (Sweden)

Ángel Guerra

2012-05-01

Full Text Available The new information reported in this paper is based on 11 specimens of the large-tuberculate octopus Graneledone macrotyla. These specimens were caught in bottom trawl surveys ATLANTIS 2009 and 2010 carried out on the Patagonian slope off the Argentinean Economic Exclusive Zone between 24 February and 1 April 2009 and from 9 March to 5 April 2010 respectively. A new diagnosis and a complete description of the species are provided. This is the first time that stylets, beaks and spermatophores are described. This is also the first time in which mature females have been studied and the female genitalia described. Like other eledonid octopods, G. macrotyla does not have spermathecae in the oviducal glands. The presence of fertilized eggs inside the ovary suggests that fertilization takes place within the ovary. The simultaneous occurrence of oocyte cohorts at different oogenic stages suggests that the species is a multiple spawner. G. macrotyla inhabits shallower waters on the Patagonian slope (475-921 m than in the subantartic area (1647-2044 m. From a biogeographical point of view, our data show that G. macrotyla inhabits the plume of cold subantarctic waters, which is pushed far north into the southwestern Atlantic by the Falkland (Malvinas Current.

A winter dinoflagellate bloom drives high rates of primary production in a Patagonian fjord ecosystem

Science.gov (United States)

Montero, P.; Pérez-Santos, I.; Daneri, G.; Gutiérrez, M. H.; Igor, G.; Seguel, R.; Purdie, D.; Crawford, D. W.

2017-12-01

A dense winter bloom of the dinoflagellate Heterocapsa triquetra was observed at a fixed station (44°35.3‧S; 72°43.6‧W) in the Puyuhuapi Fjord in Chilean Patagonia during July 2015. H. triquetra dominated the phytoplankton community in the surface waters between 2 and 15 m (13-58 × 109 cell m-2), with abundances some 3 to 15 times higher than the total abundance of the diatom assemblage, which was dominated by Skeletonema spp. The high abundance of dinoflagellates was reflected in high rates of gross primary production (GPP; 0.6-1.6 g C m-2 d-1) and chlorophyll-a concentration (Chl-a; 70-199.2 mg m-2) that are comparable to levels reported in spring diatom blooms in similar Patagonian fjords. We identify the main forcing factors behind a pulse of organic matter production during the non-productive winter season, and test the hypothesis that low irradiance levels are a key factor limiting phytoplankton blooms and subsequent productivity during winter. Principal Component Analysis (PCA) indicated that GPP rates were significantly correlated (r = -0.8, p bloom. The bloom occurred under low surface irradiance levels characteristic of austral winter and was accompanied by strong northern winds, associated with the passage of a low-pressure system, and a water column dominated by double diffusive layering. To our knowledge, this is the first report of a dense dinoflagellate bloom during deep austral winter in a Patagonian fjord, and our data challenge the paradigm of light limitation as a factor controlling phytoplankton blooms in this region in winter.

Pluton emplacement and magmatic arc construction: A model from the Patagonian batholith

Science.gov (United States)

Bruce, Robert; Nelson, Eric; Weaver, Stephen

1988-01-01

A model of batholithic construction in Andean arcs and its applicability to possibly similar environments in the past is described. Age and compositional data from the Patagonian batholith of southern Chile show a long history of magmatism in any given area (total age range is 15 to 157 Ma), but different regions appear to have different magmatic starting ages. Furthermore, mafic rocks seem to be the oldest components of any given region. An assembly line model involving semicontinuous magmatism and uplift was outlined, which has implications for other terranes: uplift rates will be proportional to observed ranges in age, and total uplift will be proportional to the age of the oldest pluton in any given area. It is suggested that misleading results would be obtained if only small areas of similar terranes in the Archean were available for study.

Ignition probability of fine dead surface fuels of native Patagonian forests or Argentina

Directory of Open Access Journals (Sweden)

Lucas O. Bianchi

2014-04-01

Full Text Available Aim of study: The Canadian Forest Fire Weather Index (FWI is being implemented all over the world. This index is being adapted to the Argentinean ecosystems since the year 2000. With the objective of calibrating the Fine Fuel Moisture Code (FFMC of the FWI system to Patagonian forests, we studied the relationship between ignition probability and fine dead surface fuel moisture content (MC as an indicator of potential fire ignition.Area of study: The study area is located in northwestern Patagonia, Argentina, and comprised two main forest types (cypress and ñire grown under a Mediterranean climate, with a dry summer and precipitations during winter and autumn (~500-800 mm per year.Material and Methods: We conducted lab ignition tests fires to determine the threshold of fine dead fuel ignition at different MC levels. Moisture content of dead fine surface fuels in the field was measured every 10-15 days from November to March for three seasons. We calculated the FFMC during these seasons and correlated it with the measured MC by applying a logistic regression model. We combined the results of the ignition tests and of the regressions to suggest FFMC categories for estimating fire danger in Patagonian forests.Main results: The ignition threshold occurred at MC values of 21.5 and 25.0% for cypress and ñire sites, respectively. The MC measured varied from 7.3 to 129.6%, and the calculated FFMC varied between 13.4 and 92.6. Highly significant regressions resulted when FFMC was related to MC. The ignition threshold corresponded to a FFMC=85. We proposed to divide the FFMC scale in three fire danger categories: Low (FFMC≤85, High (8589.Research highlights: Our results provide a useful tool for predicting fire danger in these ecosystems, and are a contribution to the development of the Argentinean Fire Danger Rating and a reference for similar studies in other countries where the FWI is being implemented

Alkaline lavas from southern Mendoza, Argentina, extend the Patagonian DUPAL mantle field to the north

Science.gov (United States)

Soager, N.; Holm, P. M.; Llambias, E.

2010-12-01

The lavas sampled around Río Colorado ~37°S at the border of Mendoza and Neuquén provinces, Argentina, define an OIB-like end-member composition for the Pleistocene and Holocene activity in the Payún Matrú volcanic field. Although positioned in the far back-arc of the Andes, only a few lavas show signs of involvement of slab fluids or crustal contamination such as relatively high LILEs relative to Nb. The very low La/Nb (~0.66) and Zr/Nb (~5) and high U/Pb (0.3-0.4) of the end-member composition clearly distinguish the source from normal MORB mantle, while high Ba/Nb (~10) and K/Nb (370-400) compared to FOZO and HIMU type OIBs suggest an EM type of mantle. Overall, the trace element patterns of the Río Colorado lavas are similar to the central and north Patagonian intraplate basalts and to South Atlantic E-MORB affected by the Discovery plume and the LOMU component (le Roux et al., 2002, EPSL 203). The isotopic composition of the Río Colorado component has a 206Pb/204Pb = 18.4, 207Pb/204Pb = 15.58, 208Pb/204Pb = 38.3, 87Sr/86Sr = 0.70353 and 143Nd/144Nd = 0.51285. This composition overlaps the central and north Patagonian intraplate basalts in Pb-isotopic space but is slightly less enriched in Sr and Nd-isotopes. It is distinctly different from the FOZO like composition of the south Patagonian intraplate basalts and the nearby Juan Fernandéz plume but similar to the South Atlantic N-MORB and MORB from the southern Chile Ridge segment 4 (Sturm et al., 1999, JGR 104) described as DUPAL type. The DUPAL-MORB type isotopic composition and the plume-like trace element patterns of the Río Colorado lavas suggest the presence of a weak plume beneath the area. The eruption of the large Payún Matrú volcano and the gigantic Pleistocene flood basalts also calls for a thermal anomaly to produce these melts during a weakly compressive tectonic regime with no significant addition of slab fluids. This was supported by Burd et al. (2008, Abstr., 7th Int. Sym. And. Geo

Dicty_cDB: Contig-U15057-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available ( U58944 |pid:none) Dissostichus mawsoni AFGP antifreeze g... 44 0.012 C81265( C81265 )probable lipoprotein ...U43149_1( U43149 |pid:none) Dissostichus mawsoni antifreeze glycop... 36 3.2 ( P24856 ) RecName: Full=Ice-st

Marine effect of introduced salmonids: Prey consumption by exotic steelhead and anadromous brown trout in the Patagonian Continental Shelf

Science.gov (United States)

Ciancio, J.; Beauchamp, D.A.; Pascual, M.

2010-01-01

On the basis of stable isotope analysis, we estimated the marine diet of the most abundant anadromous salmonid species in Patagonian Atlantic basins. The results were coupled with bioenergetic and population models to estimate the consumption of food by salmonids and was compared with that by seabirds, the most abundant top predators in the area. Amphipods were the main salmonid prey, followed by sprat, silversides, squid, and euphausiids. The total consumption, even assuming large anadromous salmonid populations, represented Limnology and Oceanography, Inc.

Freezing resistance in Patagonian woody shrubs: the role of cell wall elasticity and stem vessel size.

Science.gov (United States)

Zhang, Yong-Jiang; Bucci, Sandra J; Arias, Nadia S; Scholz, Fabian G; Hao, Guang-You; Cao, Kun-Fang; Goldstein, Guillermo

2016-08-01

Freezing resistance through avoidance or tolerance of extracellular ice nucleation is important for plant survival in habitats with frequent subzero temperatures. However, the role of cell walls in leaf freezing resistance and the coordination between leaf and stem physiological processes under subzero temperatures are not well understood. We studied leaf and stem responses to freezing temperatures, leaf and stem supercooling, leaf bulk elastic modulus and stem xylem vessel size of six Patagonian shrub species from two sites (plateau and low elevation sites) with different elevation and minimum temperatures. Ice seeding was initiated in the stem and quickly spread to leaves, but two species from the plateau site had barriers against rapid spread of ice. Shrubs with xylem vessels smaller in diameter had greater stem supercooling capacity, i.e., ice nucleated at lower subzero temperatures. Only one species with the lowest ice nucleation temperature among all species studied exhibited freezing avoidance by substantial supercooling, while the rest were able to tolerate extracellular freezing from -11.3 to -20 °C. Leaves of species with more rigid cell walls (higher bulk elastic modulus) could survive freezing to lower subzero temperatures, suggesting that rigid cell walls potentially reduce the degree of physical injury to cell membranes during the extracellular freezing and/or thaw processes. In conclusion, our results reveal the temporal-spatial ice spreading pattern (from stem to leaves) in Patagonian shrubs, and indicate the role of xylem vessel size in determining supercooling capacity and the role of cell wall elasticity in determining leaf tolerance of extracellular ice formation. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Dicty_cDB: Contig-U15728-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 054-501 Normalized CNS library (juven... 34 0.99 2 ( FE200246 ) B328E04 Antarctic fish Dissostichus mawsoni ...adult... 38 0.99 2 ( FE225391 ) O067F02 Antarctic fish Dissostichus mawsoni adult... 38 0.99 2 ( FI095335 )

Structural control on arc volcanism: The Caviahue Copahue complex, Central to Patagonian Andes transition (38°S)

Science.gov (United States)

Melnick, Daniel; Folguera, Andrés; Ramos, Victor A.

2006-11-01

This paper describes the volcanostratigraphy, structure, and tectonic implications of an arc volcanic complex in an oblique subduction setting: the Caviahue caldera Copahue volcano (CAC) of the Andean margin. The CAC is located in a first-order morphotectonic transitional zone, between the low and narrow Patagonian and the high and broad Central Andes. The evolution of the CAC started at approximately 4-3 Ma with the opening of the 20 × 15 km Caviahue pull-apart caldera; Las Mellizas volcano formed inside the caldera and collapsed at approximately 2.6 Ma; and the Copahue volcano evolved in three stages: (1) 1.2-0.7 Ma formed the approximately 1 km thick andesitic edifice, (2) 0.7-0.01 Ma erupted andesitic-dacitic subglacial pillow lavas, and (3) 0.01-0 Ma erupted basaltic-andesites and pyroclastic flows from fissures, aligned cones, and summit craters. Magma ascent has occurred along planes perpendicular to the least principal horizontal stress, whereas hydrothermal activity and hot springs also occur along parallel planes. At a regional scale, Quaternary volcanism concentrates along the NE-trending, 90 km long Callaqui-Copahue-Mandolegüe lineament, the longest of the southern volcanic zone, which is here interpreted as an inherited crustal-scale transfer zone from a Miocene rift basin. At a local scale within the CAC, effusions are controlled by local structures that formed at the intersection of regional fault systems. The Central to Patagonian Andes transition occurs at the Callaqui-Copahue-Mandolegüe lineament, which decouples active deformation from the intra-arc strike-slip Liquiñe-Ofqui fault zone to the south and the backarc Copahue-Antiñir thrust system.

Analysis of Production and Delivery Center Hydrogen Applied to the Southern Patagonian Circuit

Directory of Open Access Journals (Sweden)

Maximiliano Fernando Medina

2016-08-01

Full Text Available The Desire department of the province of Santa Cruz, Argentina, presents the greatest potential electrolytic Hydrogen Production Country, From Three primary sources of sustainable energy: wind, solar, biomass. There, the Hydrogen Plant of Pico Truncado has capacity central production of hydrogen 100m3 of H2 / day, enough to supply 353 vehicles with hybrid fuel called HGNC, made by cutting 12% V / V of hydrogen in CNG (in situ at each station. Puerto Deseado, Fitz Roy, Caleta Olivia, Las Heras, Comodoro Rivadavia, Sarmiento and the Ancients: From the production cost, the cost of delivering hydrogen to the Southern Patagonian circuit comprised analyzed. Considering various local parameters are determined as a way of delivering more profitable virtual pipeline, with total cost of hydrogen estimated 6.5 USD / kg H2 and HGNC shipped in the station at 0.50 USD / Nm3.

Whole-community facilitation regulates biodiversity on Patagonian rocky shores.

Directory of Open Access Journals (Sweden)

Brian R Silliman

Full Text Available Understanding the factors that generate and maintain biodiversity is a central goal in ecology. While positive species interactions (i.e., facilitation have historically been underemphasized in ecological research, they are increasingly recognized as playing important roles in the evolution and maintenance of biodiversity. Dominant habitat-forming species (foundation species buffer environmental conditions and can therefore facilitate myriad associated species. Theory predicts that facilitation will be the dominant community-structuring force under harsh environmental conditions, where organisms depend on shelter for survival and predation is diminished. Wind-swept, arid Patagonian rocky shores are one of the most desiccating intertidal rocky shores ever studied, providing an opportunity to test this theory and elucidate the context-dependency of facilitation.Surveys across 2100 km of southern Argentinean coastline and experimental manipulations both supported theoretical predictions, with 43 out of 46 species in the animal assemblage obligated to living within the matrices of mussels for protection from potentially lethal desiccation stress and predators having no detectable impact on diversity.These results provide the first experimental support of long-standing theoretical predictions and reveal that in extreme climates, maintenance of whole-community diversity can be maintained by positive interactions that ameliorate physical stress. These findings have important conservation implications and emphasize that preserving foundation species should be a priority in remediating the biodiversity consequences of global climate change.

Natural Environmental Hazards Reflected in High-Altitude Patagonian Lake Sediments (lake Caviahue, Argentina)

Science.gov (United States)

Müller, Anne; Scharf, Burkhard; von Tümpling, Wolf; Pirrung, Michael

2009-03-01

Two 6-m long sediment cores drilled in the two basins of Lake Caviahue give new evidence of the impact of natural hazards such as ash fallouts linked to nearby volcanic eruptions in the ecologically sensitive environment of the high-altitude region of the Argentinan Patagonian Andes. The two cores show distinct signals of changes in autochthonous productivity and terrigenous input into the lake from ash fallout as well as from river load and shore erosion. Multiproxy records of the sediments indicate whether these changes can be related to volcanic activity. High values of magnetic susceptibility in the cores reflect periods of basaltic ash fallouts during eruptions of the nearby Copahue Volcano. The southern basin is located in the prevalent direction of ash fallouts and has been affected by these volcanic inputs more intensely than the northern basin of the lake. In contrast, sedimentation and authochthonous productivity in the northern basin are strongly affected by fluvial inputs such as suspended river load and acidic stream waters.

Use of AFLP and RAPD molecular genetic markers and cytogenetic analysis to explore relationships among taxa of the Patagonian Bromus setifolius complex

Directory of Open Access Journals (Sweden)

Ana M. García

2009-01-01

Full Text Available Bromus setifolius var. pictus (Hook Skottsb., B. setifolius var. setifolius Presl. and B. setifolius var. brevifolius Ness are three native Patagonian taxa in the section Pnigma Dumort of the genus Bromus L. AFLP and RAPD analysis, in conjunction with genetic distance measurements and statistical techniques, revealed variation within this group and indicated that B. setifolius var. brevifolius was closely related to B. setifolius var. pictus, with both taxa being more distantly related to B. setifolius var. setifolius. Cytogenetic analysis confirmed the chromosomal number of B. setifolius var. pictus (2n = 70 and B. setifolius var. setifolius (2n = 28 and showed for the first time that B. setifolius var. brevifolius had 2n = 70. The combination of molecular genetic and cytogenetic evidence supported a species status for two of the three taxa and suggested hypotheses for the evolutionary origin of these complex taxa. Species status was also indicated for B. setifolius var. setifolius. Based on these findings, we suggest that B. setifolius var. pictus be referred to as B. pictus Hook var. pictus, and B. setifolius var brevifolius as B. pictus Hook var brevifolius. The correlation between AFLP diversity and variation in ecological parameters suggested that this marker system could be used to assess breeding progress and to monitor the domestication of Patagonian Bromus species for agronomic use.

Didymosphenia geminata invasion in South America: Ecosystem impacts and potential biogeochemical state change in Patagonian rivers

Science.gov (United States)

Reid, Brian; Torres, Rodrigo

2014-01-01

The diatom Didymosphenia geminata has emerged as a major global concern, as both an aggressive invader of rivers and streams in the southern hemisphere, and for its ability to form nuisance blooms in oligotrophic systems in its native range. South American D. geminata blooms were first documented in Chilean Patagonia in May 2010, and have spread to over five regions and three provinces, in Chile and Argentina respectively. The Patagonian invasion represents a distinct challenge compared to other regions; not only are affected systems poorly characterized, but also a general synthesis of the nature and magnitude of ecosystem impacts is still lacking. The latter is essential in evaluating impacts to ecosystem services, forms the basis for a management response that is proportional to the potentially valid threats, or aids in the determination of whether action is warranted or feasible. Based on a revision of the recent literature, some of the most significant impacts may be mediated through physical changes: substantially increased algal biomass, trapping of fine sediment, altered hydrodynamics, and consequent effects on biogeochemical states and processes such as redox condition, pH and nutrient cycling in the benthic zone. Surveys conducted during the early invasion in Chile show a strong correlation between benthic biomass and associated fine sediments, both of which were one-two orders of magnitude higher within D. geminata blooms. Experimental phosphorous amendments showed significant abiotic uptake, while interstitial water in D. geminata mats had nearly 10-20 fold higher soluble reactive phosphorous and a pronounced pH cycle compared to the water column. A dominant and aggressive stalk-forming diatom with this combination of characteristics is in sharp contrast to the colonial cyanobacteria and bare gravel substrate that characterize many Patagonian streams. The potential displacement of native benthic algal communities with contrasting functional groups

Preandean geological configuration of the eastern North Patagonian Massif, Argentina

Directory of Open Access Journals (Sweden)

Daniel A. Gregori

2013-11-01

Full Text Available 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 by an ∼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 Cañadón Asfalto basin interbedded in the Marifil Complex. These volcaniclastic sequences show mild deformation of accommodation zones in a pre-Jurassic paleorelief.

Late cenozoic tectonic and geomorphic evolution of the Patagonian Andes between 42oS and 52oS, southern Chile assessed using fission-track thermochronology

International Nuclear Information System (INIS)

Thomson, S.N; Herve, F; Stockhert, B.; Brix, M.R.; Adriasola, A

2001-01-01

Fission-track (FT) analysis has been applied in the Patagonian Andes of southern Chile to assess the late Cenozoic geomorphic and tectonic response of the overriding plate to subduction of the Chile rise active oceanic spreading centre (Thomson et al., 2001). The timing and nature of tectonic uplift and denudation along the southern parts of the major transpression intra-arc Liquine-Ofqui fault (LOF) system have also been investigated (Thomson, 2001, submitted). Results from 130 FT ages (72 zircon and 58 apatite ages) and 39 apatite track length measurements reveal initiation of rapid cooling and denudation at ca. 30 Ma at the western margin of southern continental South America. This was followed by a ca. 200km eastward migration of the locus of maximum denudation to the position of the present day topographic divide between ca. 30 Ma and ca. 12 to 10 Ma. East of the Andean divide less than 3 km of denudation has occurred since the Late Cretaceous. Enhanced denudation is interpreted to be the result of increased tectonic uplift driven by a large increase in convergence rates at ca. 28 to 26 Ma that triggered orographically enhanced precipitation on the west-side of the Patagonian Andes allowing increased erosion by fluvial incision and mass transport processes. The eastward migration of the locus of maximum denudation can be related to either coeval eastward migration of the retro-arc deformation front, the effects of subduction erosion in the overriding plate at the Peru-Chile trench or shallowing of the angle of subduction. Away from the influence of the LOF the process of spreading centre subduction and collision itself coincides with an overall slow-down in denudation rates in the overriding plate most likely caused by a major reduction in the main tectonic force driving tectonic uplift in the upper plate to subduction. In contrast to the Andes south of ca. 46 o S, increased cooling and denudation related to transpression induced rock uplift and erosion along

Dicty_cDB: Contig-U15936-1 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available s Petromyzon m... 38 7.2 2 ( FE200565 ) B332G05 Antarctic fish Dissostichus mawsoni adult... 40 7.2 2 ( EF71...rctic fish Dissostichus mawsoni adult... 40 5.5 2 ( CQ311760 ) Sequence 22865 fro...tivus var. oleiformi... 46 5.5 1 ( Y10744 ) L.meyeri metY and metX genes. 46 5.5 1 ( FE196946 ) B206A08 Anta

Egg masses of the Patagonian squid Doryteuthis (Amerigo gahi attached to giant kelp (Macrocystis pyrifera in the sub-Antarctic ecoregion

Directory of Open Access Journals (Sweden)

Sebastián Rosenfeld

2014-11-01

Full Text Available Egg masses of the Patagonian squid Doryteuthis (Amerigo gahi attached to giant kelp (Macrocystis pyrifera in the Magellanic channels of the sub-Antarctic ecoregion in southern South America is documented for the first time. Of seven egg masses observed between 2008 and 2011, one was taken to the laboratory to be analysed and photographed. Comprising long transparent capsules containing eggs, the masses were strongly attached to the stipes of M. pyrifera. This macroalgae is a potentially important economic resource due to its multiple industrial uses; this study shows that it also serves an important ecological role as a spawning substrate for D. gahi.

Trends in the Breeding Population of Adélie Penguins in the Ross Sea, 1981–2012: A Coincidence of Climate and Resource Extraction Effects

Science.gov (United States)

Lyver, Phil O’B.; Barron, Mandy; Barton, Kerry J.; Ainley, David G.; Pollard, Annie; Gordon, Shulamit; McNeill, Stephen; Ballard, Grant; Wilson, Peter R.

2014-01-01

Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981–2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of −0.019 during 1981–2000, followed by a positive per capita growth rate of 0.067 for 2001–2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then. PMID:24621601

Trends in the breeding population of Adelie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

Directory of Open Access Journals (Sweden)

Phil O'B Lyver

Full Text Available Measurements of the size of Adélie penguin (Pygoscelis adeliae colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28% of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island. The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni, may explain the sharp increasing trend evident since then.

Tolerance to winemaking stress conditions of Patagonian strains of Saccharomyces eubayanus and Saccharomyces uvarum.

Science.gov (United States)

Origone, A C; Del Mónaco, S M; Ávila, J R; González Flores, M; Rodríguez, M E; Lopes, C A

2017-08-01

Evaluating the winemaking stress tolerance of a set of both Saccharomyces eubayanus and Saccharomyces uvarum strains from diverse Patagonian habitats. Yeast strains growth was analysed under increasing ethanol concentrations; all of them were able to grow until 8% v/v ethanol. The effect of different temperature and pH conditions as well as at SO 2 and hexose concentrations was evaluated by means of a central composite experimental design. Only two S. uvarum strains (NPCC 1289 and 1321) were able to grow in most stress conditions. Kinetic parameters analysed (μ max and λ) were statistically affected by temperature, pH and SO 2 , but not influenced by sugar concentration. The obtained growth model was used for predicting optimal growth conditions for both strains: 20°C, 0% w/v SO 2 and pH 4·5. Strains from human-associated environments (chichas) presented the highest diversity in the response to different stress factors. Two S. uvarum strains from chichas demonstrated to be the most tolerant to winemaking conditions. This work evidenced the potential use of two S. uvarum yeast strains as starter cultures in wines fermented at low temperatures. Saccharomyces eubayanus was significantly affected by winemaking stress conditions, limiting its use in this industry. © 2017 The Society for Applied Microbiology.

Melting of the Patagonian Ice Sheet and deglacial perturbations of the nitrogen cycle in the eastern South Pacific

Science.gov (United States)

De Pol-Holz, Ricardo; Ulloa, Osvaldo; Dezileau, Laurent; Kaiser, Jérôme; Lamy, Frank; Hebbeln, Dierk

2006-02-01

We report the last glacial-interglacial transition of marine denitrification off northern Chile based on sedimentary nitrogen isotopes. Our results show a relatively early, large and abrupt transition from low to high denitrification regimes consistent with recently-reported data from off Peru. The deglaciation is characterized by millennial-scale adjustments of the oxygen minimum zone that mimic the atmospheric temperature record from Antarctica. We also show that the sharp denitrification onset was not caused by an increase in local primary productivity, nor by ventilation changes occurring in the Southern Ocean, as previously proposed. We found that the magnitude and timing of the deglacial denitrification changes are in close agreement with the fresh-water pulses that resulted from the melting of the Patagonian Ice Sheet. We consequently attribute the deglacial onset of marine denitrification in the area to a collapse of the thermocline ventilation occurred at the mid-latitude subduction region of the eastern South Pacific.

A fuzzy multi-objective linear programming approach for integrated sheep farming and wildlife in land management decisions: a case study in the Patagonian rangelands

Science.gov (United States)

Metternicht, Graciela; Blanco, Paula; del Valle, Hector; Laterra, Pedro; Hardtke, Leonardo; Bouza, Pablo

2015-04-01

Wildlife is part of the Patagonian rangelands sheep farming environment, with the potential of providing extra revenue to livestock owners. As sheep farming became less profitable, farmers and ranchers could focus on sustainable wildlife harvesting. It has been argued that sustainable wildlife harvesting is ecologically one of the most rational forms of land use because of its potential to provide multiple products of high value, while reducing pressure on ecosystems. The guanaco (Lama guanicoe) is the most conspicuous wild ungulate of Patagonia. Guanaco ?bre, meat, pelts and hides are economically valuable and have the potential to be used within the present Patagonian context of production systems. Guanaco populations in South America, including Patagonia, have experienced a sustained decline. Causes for this decline are related to habitat alteration, competition for forage with sheep, and lack of reasonable management plans to develop livelihoods for ranchers. In this study we propose an approach to explicitly determinate optimal stocking rates based on trade-offs between guanaco density and livestock grazing intensity on rangelands. The focus of our research is on finding optimal sheep stocking rates at paddock level, to ensure the highest production outputs while: a) meeting requirements of sustainable conservation of guanacos over their minimum viable population; b) maximizing soil carbon sequestration, and c) minimizing soil erosion. In this way, determination of optimal stocking rate in rangelands becomes a multi-objective optimization problem that can be addressed using a Fuzzy Multi-Objective Linear Programming (MOLP) approach. Basically, this approach converts multi-objective problems into single-objective optimizations, by introducing a set of objective weights. Objectives are represented using fuzzy set theory and fuzzy memberships, enabling each objective function to adopt a value between 0 and 1. Each objective function indicates the satisfaction of

Interannual variability in the skate assemblage on the South Patagonian shelf and slope.

Science.gov (United States)

Winter, A; Pompert, J; Arkhipkin, A; Brewin, P E

2015-12-01

Observer data from the commercial fishery on the Patagonian shelf and slope around the Falkland Islands (home to an assemblage of >16 skate species (Rajiformes), for which commercial catches have been recorded since 1987), as well as survey data from an area closed to skate target fishing after exploitation, were summarized by species to examine changes in the population status of individual skate species. Total skate catch per unit effort increased significantly in the target fishery since 1994, and four species have made up >85% of all skate catch. Bathyraja brachyurops and Zearaja chilensis increased significantly in catch proportions and abundance from 1994 to 2013. Bathyraja albomaculata and Bathyraja griseocauda decreased significantly before rebounding with trends of increasing abundance. Concurrently, B. brachyurops and Z. chilensis showed decreasing trends in size at 50% maturity in areas where skates continue to be targeted commercially. The increasing abundances and concomitant reductions in size at maturity of B. brachyurops and Z. chilensis suggest either plasticity in life-history traits or a density-dependent growth response to fishing pressure. Bathyraja griseocauda decreased in size at 50% maturity in the area that was closed to skate target fishing, where it was initially larger, but only decreased to the same average size as in the commercially targeted areas. Bathyraja albomaculata and Z. chilensis are IUCN-listed as vulnerable and B. griseocauda is listed as endangered, but their abundance trends since 1994 indicate that these populations are not declining in Falkland waters. © 2015 The Fisheries Society of the British Isles.

Do soil organisms affect aboveground litter decomposition in the semiarid Patagonian steppe, Argentina?

Science.gov (United States)

Araujo, Patricia I; Yahdjian, Laura; Austin, Amy T

2012-01-01

Surface litter decomposition in arid and semiarid ecosystems is often faster than predicted by climatic parameters such as annual precipitation or evapotranspiration, or based on standard indices of litter quality such as lignin or nitrogen concentrations. Abiotic photodegradation has been demonstrated to be an important factor controlling aboveground litter decomposition in aridland ecosystems, but soil fauna, particularly macrofauna such as termites and ants, have also been identified as key players affecting litter mass loss in warm deserts. Our objective was to quantify the importance of soil organisms on surface litter decomposition in the Patagonian steppe in the absence of photodegradative effects, to establish the relative importance of soil organisms on rates of mass loss and nitrogen release. We estimated the relative contribution of soil fauna and microbes to litter decomposition of a dominant grass using litterboxes with variable mesh sizes that excluded groups of soil fauna based on size class (10, 2, and 0.01 mm), which were placed beneath shrub canopies. We also employed chemical repellents (naphthalene and fungicide). The exclusion of macro- and mesofauna had no effect on litter mass loss over 3 years (P = 0.36), as litter decomposition was similar in all soil fauna exclusions and naphthalene-treated litter. In contrast, reduction of fungal activity significantly inhibited litter decomposition (P soil fauna have been mentioned as a key control of litter decomposition in warm deserts, biogeographic legacies and temperature limitation may constrain the importance of these organisms in temperate aridlands, particularly in the southern hemisphere.

Spatial Models of Abundance and Habitat Preferences of Commerson's and Peale's Dolphin in Southern Patagonian Waters.

Science.gov (United States)

Dellabianca, Natalia A; Pierce, Graham J; Raya Rey, Andrea; Scioscia, Gabriela; Miller, David L; Torres, Mónica A; Paso Viola, M Natalia; Goodall, R Natalie P; Schiavini, Adrián C M

2016-01-01

Commerson's dolphins (Cephalorhynchus c. commersonii) and Peale's dolphins (Lagenorhynchus australis) are two of the most common species of cetaceans in the coastal waters of southwest South Atlantic Ocean. Both species are listed as Data Deficient by the IUCN, mainly due to the lack of information about population sizes and trends. The goal of this study was to build spatially explicit models for the abundance of both species in relation to environmental variables using data collected during eight scientific cruises along the Patagonian shelf. Spatial models were constructed using generalized additive models. In total, 88 schools (212 individuals) of Commerson's dolphin and 134 schools (465 individuals) of Peale's dolphin were recorded in 8,535 km surveyed. Commerson's dolphin was found less than 60 km from shore; whereas Peale's dolphins occurred over a wider range of distances from the coast, the number of animals sighted usually being larger near or far from the coast. Fitted models indicate overall abundances of approximately 22,000 Commerson's dolphins and 20,000 Peale's dolphins in the total area studied. This work provides the first large-scale abundance estimate for Peale's dolphin in the Atlantic Ocean and an update of population size for Commerson's dolphin. Additionally, our results contribute to baseline data on suitable habitat conditions for both species in southern Patagonia, which is essential for the implementation of adequate conservation measures.

Spatial Models of Abundance and Habitat Preferences of Commerson's and Peale's Dolphin in Southern Patagonian Waters.

Directory of Open Access Journals (Sweden)

Natalia A Dellabianca

Full Text Available Commerson's dolphins (Cephalorhynchus c. commersonii and Peale's dolphins (Lagenorhynchus australis are two of the most common species of cetaceans in the coastal waters of southwest South Atlantic Ocean. Both species are listed as Data Deficient by the IUCN, mainly due to the lack of information about population sizes and trends. The goal of this study was to build spatially explicit models for the abundance of both species in relation to environmental variables using data collected during eight scientific cruises along the Patagonian shelf. Spatial models were constructed using generalized additive models. In total, 88 schools (212 individuals of Commerson's dolphin and 134 schools (465 individuals of Peale's dolphin were recorded in 8,535 km surveyed. Commerson's dolphin was found less than 60 km from shore; whereas Peale's dolphins occurred over a wider range of distances from the coast, the number of animals sighted usually being larger near or far from the coast. Fitted models indicate overall abundances of approximately 22,000 Commerson's dolphins and 20,000 Peale's dolphins in the total area studied. This work provides the first large-scale abundance estimate for Peale's dolphin in the Atlantic Ocean and an update of population size for Commerson's dolphin. Additionally, our results contribute to baseline data on suitable habitat conditions for both species in southern Patagonia, which is essential for the implementation of adequate conservation measures.

Pine Plantations and Invasion Alter Fuel Structure and Potential Fire Behavior in a Patagonian Forest-Steppe Ecotone

Directory of Open Access Journals (Sweden)

Juan Paritsis

2018-03-01

Full Text Available Planted and invading non-native plant species can alter fire regimes through changes in fuel loads and in the structure and continuity of fuels, potentially modifying the flammability of native plant communities. Such changes are not easily predicted and deserve system-specific studies. In several regions of the southern hemisphere, exotic pines have been extensively planted in native treeless areas for forestry purposes and have subsequently invaded the native environments. However, studies evaluating alterations in flammability caused by pines in Patagonia are scarce. In the forest-steppe ecotone of northwestern Patagonia, we evaluated fine fuels structure and simulated fire behavior in the native shrubby steppe, pine plantations, pine invasions, and mechanically removed invasions to establish the relative ecological vulnerability of these forestry and invasion scenarios to fire. We found that pine plantations and their subsequent invasion in the Patagonian shrubby steppe produced sharp changes in fine fuel amount and its vertical and horizontal continuity. These changes in fuel properties have the potential to affect fire behavior, increasing fire intensity by almost 30 times. Pruning of basal branches in plantations may substantially reduce fire hazard by lowering the probability of fire crowning, and mechanical removal of invasion seems effective in restoring original fuel structure in the native community. The current expansion of pine plantations and subsequent invasions acting synergistically with climate warming and increased human ignitions warrant a highly vulnerable landscape in the near future for northwestern Patagonia if no management actions are undertaken.

Silicic acid enrichment of subantarctic surface water from continental inputs along the Patagonian archipelago interior sea (41-56°S)

Science.gov (United States)

Torres, Rodrigo; Silva, Nelson; Reid, Brian; Frangopulos, Máximo

2014-12-01

We estimated Si∗, the surplus or deficit of orthosilicic acid (DSi) relative to nitrate available for diatom growth, in the Chilean Patagonian Archipelago Interior Sea (PAIS). Si∗ and salinity were negatively correlated in the PAIS because of the mixing of high nitrate, low DSi subantarctic surface water and high DSi, low nitrate continental freshwater runoff. Both the slope and the intercept of this relationship decreased from northern to southern Patagonia, which was likely a consequence of reduced DSi inputs from several overlapping hydrological, biological and geological drivers along this gradient. In general, lower freshwater DSi concentrations were expected below 46°S, and a lower total DSi load was expected from reduced runoff below 51°S. The north-south decreasing DSi concentration trend may be linked to dilutions from a higher proportion of runoff in latitudes with higher precipitation rates (45-53°S), the transition to more resistant granitic rocks and glacial melt-water from the Northern and Southern Patagonia Ice Fields (46-51°S) and a reduced density of volcanoes active during the Holocene (48-56°S). The intensification of a southward DSi deficit may be a forcing factor involved in the reported southward reductions in plankton biomass and a more frequent occurrence of non-diatom blooms in southern PAIS.

Dicty_cDB: SLI124 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available 35 1 ( DU862057 ) 70626 Tomato HindIII BAC Library Solanum lycopers... 48 0.35 1 ( FE211390 ) L018C10 Antarctic fish Dissostichus maw...soni adult... 48 0.35 1 ( AC067869 ) Homo sapiens chromo

Residential energy use in one-family households with natural gas provision in a city of the Patagonian Andean region

International Nuclear Information System (INIS)

Gonzalez, A.D.; Carlsson-Kanyama, A.; Crivelli, E.S.; Gortari, S.

2007-01-01

Residential energy use was studied in one-family houses in the city of Bariloche, in the Patagonian Andean region of Argentina. A survey was conducted of households connected to the natural gas network to correlate use of gas, living area and number of inhabitants per house. The annual average consumption of gas was found to be 169 GJ, and consumption of electricity 8 GJ. This total energy use per household per year is almost double the average value reported for Stockholm, Sweden, although both locations have similar heating requirements. The difference was mainly due to heating energy consumption per unit living space, which in Bariloche was 1530 MJ/m 2 per year, while in Stockholm the average is around 570 MJ/m 2 per year. The high energy consumption in Bariloche is explained primarily by the construction characteristics of the buildings, and secondarily by the efficiency of the heating devices used. We were able to conclude that subsidies on natural gas tariffs given to the residential sector do not promote a rational use of the resource. Furthermore, almost 40% of the population (mostly households in poverty) are not connected to the subsidised gas resource, but pay prices for alternative fuels that are between 10- and 15 times higher. Policies to improve buildings and appliances would reduce emissions and make access to energy more equitable

How much is too much? Assessment of prey consumption by Magellanic penguins in Patagonian colonies.

Directory of Open Access Journals (Sweden)

Juan E Sala

Full Text Available Penguins are major consumers in the southern oceans although quantification of this has been problematic. One suggestion proposes the use of points of inflection in diving profiles ('wiggles' for this, a method that has been validated for the estimation of prey consumption by Magellanic penguins (Spheniscus magellanicus by Simeone and Wilson (2003. Following them, we used wiggles from 31 depth logger-equipped Magellanic penguins foraging from four Patagonian colonies; Punta Norte (PN, Bahía Bustamente (BB, Puerto Deseado (PD and Puerto San Julián (PSJ, all located in Argentina between 42-49° S, to estimate the prey captured and calculate the catch per unit time (CPUT for birds foraging during the early chick-rearing period. Numbers of prey caught and CPUT were significantly different between colonies. Birds from PD caught the highest number of prey per foraging trip, with CPUT values of 68±19 prey per hour underwater (almost two times greater than for the three remaining colonies. We modeled consumption from these data and calculate that the world Magellanic penguin population consumes about 2 million tons of prey per year. Possible errors in this calculation are discussed. Despite this, the analysis of wiggles seems a powerful and simple tool to begin to quantify prey consumption by Magellanic penguins, allowing comparison between different breeding sites. The total number of wiggles and/or CPUT do not reflect, by themselves, the availability of food for each colony, as the number of prey consumed by foraging trip is strongly associated with the energy content and wet mass of each colony-specific 'prey type'. Individuals consuming more profitable prey could be optimizing the time spent underwater, thereby optimizing the energy expenditure associated with the dives.

Spatial Models of Abundance and Habitat Preferences of Commerson’s and Peale’s Dolphin in Southern Patagonian Waters

Science.gov (United States)

Dellabianca, Natalia A.; Pierce, Graham J.; Raya Rey, Andrea; Scioscia, Gabriela; Miller, David L.; Torres, Mónica A.; Paso Viola, M. Natalia; Schiavini, Adrián C. M.

2016-01-01

Commerson’s dolphins (Cephalorhynchus c. commersonii) and Peale’s dolphins (Lagenorhynchus australis) are two of the most common species of cetaceans in the coastal waters of southwest South Atlantic Ocean. Both species are listed as Data Deficient by the IUCN, mainly due to the lack of information about population sizes and trends. The goal of this study was to build spatially explicit models for the abundance of both species in relation to environmental variables using data collected during eight scientific cruises along the Patagonian shelf. Spatial models were constructed using generalized additive models. In total, 88 schools (212 individuals) of Commerson’s dolphin and 134 schools (465 individuals) of Peale’s dolphin were recorded in 8,535 km surveyed. Commerson’s dolphin was found less than 60 km from shore; whereas Peale’s dolphins occurred over a wider range of distances from the coast, the number of animals sighted usually being larger near or far from the coast. Fitted models indicate overall abundances of approximately 22,000 Commerson’s dolphins and 20,000 Peale’s dolphins in the total area studied. This work provides the first large-scale abundance estimate for Peale’s dolphin in the Atlantic Ocean and an update of population size for Commerson’s dolphin. Additionally, our results contribute to baseline data on suitable habitat conditions for both species in southern Patagonia, which is essential for the implementation of adequate conservation measures. PMID:27783627

Genetic evidence and new morphometric data as essential tools to identify the Patagonian seahorse Hippocampus patagonicus (Pisces, Syngnathidae).

Science.gov (United States)

González, R; Dinghi, P; Corio, C; Medina, A; Maggioni, M; Storero, L; Gosztonyi, A

2014-02-01

A genetic study to support morphometric analyses was used to improve the description and validate the Patagonian seahorse Hippocampus patagonicus (Syngnathidae) on the basis of a large number of specimens collected in the type locality (San Antonio Bay, Patagonia, Argentina). DNA sequence data (from the cytochrome b region of the mitochondrial genome) were used to differentiate this species from its relatives cited for the west Atlantic Ocean. Both phylogenetic and genetic distance analyses supported the hypothesis that H. patagonicus is a species clearly differentiated from others, in agreement with morphometric studies. Hippocampus patagonicus can be distinguished from Hippocampus erectus by the combination of the following morphometric characteristics: (1) in both sexes and all sizes of H. patagonicus, the snout length is always less than the postorbital length, whereas the snout length of H. erectus is not shorter than the postorbital length in the largest specimens; (2) in both sexes of H. patagonicus, the trunk length:total length (LTr :LT ) is lower than in H. erectus (in female H. patagonicus: 0·27-0·39, H. erectus: 0·36-0·40 and in male H. patagonicus: 0·24-0·34, H. erectus: 0·33-0·43) and (3) in both sexes, tail length:total length (LTa :LT ) in H. patagonicus is larger than in H. erectus (0·61-0·78 v. 0·54-0·64). © 2014 The Fisheries Society of the British Isles.

Transcriptome survey of Patagonian southern beech Nothofagus nervosa (= N. Alpina: assembly, annotation and molecular marker discovery

Directory of Open Access Journals (Sweden)

Torales Susana L

2012-07-01

Full Text Available Abstract Background Nothofagus nervosa is one of the most emblematic native tree species of Patagonian temperate forests. Here, the shotgun RNA-sequencing (RNA-Seq of the transcriptome of N. nervosa, including de novo assembly, functional annotation, and in silico discovery of potential molecular markers to support population and associations genetic studies, are described. Results Pyrosequencing of a young leaf cDNA library generated a total of 111,814 high quality reads, with an average length of 447 bp. De novo assembly using Newbler resulted into 3,005 tentative isotigs (including alternative transcripts. The non-assembled sequences (singletons were clustered with CD-HIT-454 to identify natural and artificial duplicates from pyrosequencing reads, leading to 21,881 unique singletons. 15,497 out of 24,886 non-redundant sequences or unigenes, were successfully annotated against a plant protein database. A substantial number of simple sequence repeat markers (SSRs were discovered in the assembled and annotated sequences. More than 40% of the SSR sequences were inside ORF sequences. To confirm the validity of these predicted markers, a subset of 73 SSRs selected through functional annotation evidences were successfully amplified from six seedlings DNA samples, being 14 polymorphic. Conclusions This paper is the first report that shows a highly precise representation of the mRNAs diversity present in young leaves of a native South American tree, N. nervosa, as well as its in silico deduced putative functionality. The reported Nothofagus transcriptome sequences represent a unique resource for genetic studies and provide a tool to discover genes of interest and genetic markers that will greatly aid questions involving evolution, ecology, and conservation using genetic and genomic approaches in the genus.

Estado del conocimiento de humedales del norte patagónico (Argentina: aspectos relevantes e importancia para la conservación de la biodiversidad regional State of the knowledge of north Patagonian wetlands (Argentina: major aspects and importance for regional biodiversity conservation

Directory of Open Access Journals (Sweden)

MARÍA G PEROTTI

2005-12-01

Full Text Available Las áreas de humedal ocupan casi el 5 % del territorio de la Patagonia argentina. En la zona extrandina y el desierto patagónico estos ecosistemas son esenciales para sostener numerosas especies de fauna y flora silvestre. Además, los humedales del norte patagónico permiten el desarrollo de comunidades acuáticas complejas y constituyen el hábitat crítico de grupos de organismos como los peces y los anfibios incluidos en listados de conservación prioritaria. Estos ecosistemas tienen un funcionamiento complejo que depende estrechamente de las fluctuaciones de las variables meteorológicas y son por lo tanto muy sensibles a los efectos del cambio climático. En la actualidad el uso de la tierra, la introducción de especies y la interacción de estos aspectos con el cambio climático constituyen las variables de mayor impacto sobre estos ambientes patagónicos. En este trabajo se presenta información geográfica, geomorfológica y climática de un número de humedales del norte de la Patagonia argentina. Por otra parte, se sintetiza información sobre la flora y la distribución de peces y anfibios con el propósito de enfatizar la importancia de estos ambientes en el mantenimiento de la biodiversidad regional. Por último, se señalan los procesos que actualmente afectan a estos sistemas poniendo en evidencia la necesidad de obtención de conocimientos básicos para el diseño de planes de manejo y conservación de sus comunidades biológicasAlmost 5 % of the lansdscape of Patagonia is occupied by wetlands. In the extra-andean region and the patagonian desert, wetlands are essential for sustaining biodiversity and wildlife. Besides, North patagonian wetlands present complex aquatic communities and provide habitat for threatened species of fishes and amphibians. These ecosystems have complex dynamics mostly driven by climatic fluctuations which make them vulnerable to the effect of climate change. Nowadays, the main impact on patagonian

Geodetic Mass Balance of the Northern Patagonian Icefield from 2000 to 2012 Using Two Independent Methods

Directory of Open Access Journals (Sweden)

Inés Dussaillant

2018-02-01

Full Text Available We compare two independent estimates of the rate of elevation change and geodetic mass balance of the Northern Patagonian Icefield (NPI between 2000 (3,856 km2 and 2012 (3,740 km2 from space-borne data. The first is obtained by differencing the Shuttle Radar Topography Mission (SRTM digital elevation model (DEM from February 2000 and a Satellite pour l'Observation de la Terre 5 (SPOT5 DEM from March 2012. The second is deduced by fitting pixel-based linear elevation trends over 118 DEMs calculated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER stereo images acquired between 2000 and 2012. Both methods lead to similar and strongly negative icefield-wide mass balance rates of −1.02 ± 0.21 and −1.06 ± 0.14 m w.e. yr−1 respectively, which is in agreement with earlier studies. Contrasting glacier responses are observed, with individual glacier mass balance rates ranging from −0.15 to −2.30 m w.e. yr−1 (standard deviation = 0.49 m w.e. yr−1; N = 38. For individual glaciers, the two methods agree within error bars, except for small glaciers poorly sampled in the SPOT5 DEM due to clouds. Importantly, our study confirms the lack of penetration of the C-band SRTM radar signal into the NPI snow and firn except for a region above 2,900 m a.s.l. covering <1% of the total area. Ignoring penetration would bias the mass balance by only 0.005 m w.e. yr−1. A strong advantage of the ASTER method is that it relies only on freely available data and can thus be extended to other glacierized areas.

Phylogeography of the Patagonian otter Lontra provocax: adaptive divergence to marine habitat or signature of southern glacial refugia?

Directory of Open Access Journals (Sweden)

Chehébar Claudio

2011-02-01

Full Text Available Abstract Background A number of studies have described the extension of ice cover in western Patagonia during the Last Glacial Maximum, providing evidence of a complete cover of terrestrial habitat from 41°S to 56°S and two main refugia, one in south-eastern Tierra del Fuego and the other north of the Chiloé Island. However, recent evidence of high genetic diversity in Patagonian river species suggests the existence of aquatic refugia in this region. Here, we further test this hypothesis based on phylogeographic inferences from a semi-aquatic species that is a top predator of river and marine fauna, the huillín or Southern river otter (Lontra provocax. Results We examined mtDNA sequences of the control region, ND5 and Cytochrome-b (2151 bp in total in 75 samples of L. provocax from 21 locations in river and marine habitats. Phylogenetic analysis illustrates two main divergent clades for L. provocax in continental freshwater habitat. A highly diverse clade was represented by haplotypes from the marine habitat of the Southern Fjords and Channels (SFC region (43°38' to 53°08'S, whereas only one of these haplotypes was paraphyletic and associated with northern river haplotypes. Conclusions Our data support the hypothesis of the persistence of L. provocax in western Patagonia, south of the ice sheet limit, during last glacial maximum (41°S latitude. This limit also corresponds to a strong environmental change, which might have spurred L. provocax differentiation between the two environments.

First report on the contribution of small-sized species to the copepod community structure of the southern Patagonian shelf (Argentina, 47-55°S

Directory of Open Access Journals (Sweden)

Julieta Carolina Antacli

2014-03-01

Full Text Available The copepod community structure, with special emphasis on small-sized species, was studied over the southern Patagonian shelf in late summer 2004, applying the first plankton sampling in the region with a fine-mesh (66 μm net. The key role of the copepods Drepanopus forcipatus and Calanus australis was confirmed, but also the high abundance and frequency of occurrence of the microcopepods Oithona helgolandica and Microsetella norvegica and of the medium-sized copepod Ctenocalanus vanus were revealed. Copepod community structure was nearly homogenous over the entire study area. Drepanopus forcipatus, O. helgolandica and M. norvegica were identified as the typical species of the region, although secondarily C. australis and Oithona atlantica also contributed significantly to community similarity across the area. The study of interspecific relationships of dominant copepods indicated that D. forcipatus and C. australis were associated positively with O. helgolandica, while C. vanus, and M. norvegica constituted a separate assemblage with Clausocalanus brevipes and O. atlantica. The importance of fine-mesh-size nets for collecting the smaller size fractions of mesozooplankton and for accurately portraying the mesozooplankton assemblage structure in the area is stressed by this study.

Short-term variations in mesozooplankton, ichthyoplankton, and nutrients associated with semi-diurnal tides in a patagonian Gulf

Science.gov (United States)

Castro, L. R.; Cáceres, M. A.; Silva, N.; Muñoz, M. I.; León, R.; Landaeta, M. F.; Soto-Mendoza, S.

2011-03-01

The relationships between the distribution of different zooplankton and ichthyoplankton stages and physical and chemical variables were studied using samples and data (CTD profiles, ADCP and current meter measurements, nutrients, mesozooplankton, ichthyoplankton) obtained from different strata during two 24-h cycles at two oceanographic stations in a Chilean Patagonian gulf during the CIMAR 10-Fiordos cruise (November, 2004). A station located at the Chacao Channel was dominated by tidal mixing and small increments in surface stratification during high tides, leading to decreased nutrient availability. This agreed with short periods of increased phytoplankton abundance during slack waters at the end of flood currents. Increases in larval density for all zooplankton and ichthyoplankton taxa corresponded to the flooding phases of the tidal cycle. When the larval density data were fit to a sinusoidal model, the regression coefficients were high, suggesting that tides are important features that modulate short-term variations in plankton abundance. All larvae did not vary synchronously with the tidal phase; rather, time lags were observed among species. The abundances of older individuals of the copepodite Rhincalanus nasutus and all zoea stages of the squat lobster Munida gregaria increased during night flood tides, whereas younger stages increased during daytime flood tides. At a station located at the Queullin Pass, which was dominated by vertical stratification patterns, the variations in peak larval density were better fitted to the semi-diurnal sea level fluctuations. Other evidence indicated internal tides below the pycnocline, which could promote larval transport in deeper layers. In the overall picture that emerges from this study, planktonic organisms from different habitats and phylogenetic origins seem to respond to the local tidal regimes. In some cases, this response might be beneficial, transporting these individuals inshore to areas that are rich in

Tectonic evolution of the North Patagonian Andes (41°-44° S) through recognition of syntectonic strata

Science.gov (United States)

Echaurren, A.; Folguera, A.; Gianni, G.; Orts, D.; Tassara, A.; Encinas, A.; Giménez, M.; Valencia, V.

2016-05-01

The North Patagonian fold-thrust belt (41°-44° S) is characterized by a low topography, reduced crustal thickness and a broad lateral development determined by a broken foreland system in the retroarc zone. This particular structural system has not been fully addressed in terms of the age and mechanisms that built this orogenic segment. Here, new field and seismic evidence of syntectonic strata constrain the timing of the main deformational stages, evaluating the prevailing crustal regime for the different mountain domains through time. Growth strata and progressive unconformities, controlled by extensional or compressive structures, were recognized in volcanic and sedimentary rocks from the cordilleran to the extra-Andean domain. These data were used to construct a balanced cross section, whose deep structure was investigated through a thermomechanical model that characterizes the upper plate rheology. Our results indicate two main compressive stages, interrupted by an extensional relaxation period. The first contractional stage in the mid-Cretaceous inverted Jurassic-Lower Cretaceous half graben systems, reactivating the western Cañadón Asfalto rift border ~ 500 km away from the trench, at a time of arc foreland expansion. For this stage, available thermochronological data reveal forearc cooling episodes, and global tectonic reconstructions indicate mid-ocean ridge collisions against the western edge of an upper plate with rapid trenchward displacement. Widespread synextensional volcanism is recognized throughout the Paleogene during plate reorganization; retroarc Paleocene--Eocene flare up activity is interpreted as product of a slab rollback, and fore-to-retroarc Oligocene slab/asthenospheric derived products as an expression of enhanced extension. The second stage of mountain growth occurred in Miocene time associated with Nazca Plate subduction, reaching nearly the same amplitude than the first compressive stage. Extensional weakening of the upper plate

Tides and lake-level variations in the great Patagonian lakes: Observations, modelling and geophysical implications.

Science.gov (United States)

Marderwald, Eric; Richter, Andreas; Horwath, Martin; Hormaechea, Jose Luis; Groh, Andreas

2016-04-01

-level time series from Lagos Argentino and Viedma yields the amplitudes and phases of the lake tides for the four major tidal constituents M2, S2, O1 and K1. The maximum amplitude, corresponding to the semi-diurnal moon tide M2 in Lago Argentino, amounts to 3 mm. For the four lakes under investigation the theoretical amplitudes and phases of seven constituents (Q1, O1, P1, K1, N2, M2 and S2) are modelled accounting for the contributions of both the solid earth's body tides and the ocean tidal loading (Marderwald 2014). Both contributions involve a deformation of the earth surface and of the equipotential surfaces of the gravity field. For the load tide computation the global ocean tide model EOT11a (Savcenko and Bosch, 2012) and the Gutenberg-Bullen A earth model (Farrell, 1972) was applied and the conservation of water volume is taken into account. The comparison of the tidal signal extracted from the lake-level observations in Lagos Argentino and Viedma with the lake tide models indicates a phase shift which is most likely explained by an 1 hour phase lag of the employed global ocean tide model in the region of the highly fragmented Pacific coast. REFERENCES: Farrell, W. E., (1972). Deformation of the Earth by Surface Loads. Rev. Geophy. Space Phy., 10(3):761-797. Ivins, E., James, T., 2004. Bedrock response to Llanquihue Holocene and present-day glaciation in southernmost South America. Geophys. Res. Lett. 31 (L24613). Doi:10.1029/2004GL021500. Klemann, V., E. R. Ivins, Z. Martinec, and D. Wolf (2007), Models of active glacial isostasy roofing warm subduction: Case of the South Patagonian Ice Field, J. Geophys. Res., 112, B09405, doi: 10.1029/2006JB004818. Lange, H., Casassa, G., Ivins, E. R., Schröder, L., Fritsche, M., Richter, A., Groh, A., Dietrich, R., (2014). Observed crustal uplift near the Southern Patagonian Icefield constrains improved viscoelastic Earth models. Geophysical Research Letters, DOI: 10.1002/2013GL058419. Marderwald ER, 2014. Modelado de las mareas

Genetic variation in seedling water-use efficiency of Patagonian Cypress populations from contrasting precipitation regimes assessed through carbon isotope discrimination

Energy Technology Data Exchange (ETDEWEB)

Pastorino, M. J.; Aparicio, A. G.; Marchelli, P.; Gallo, L. A.

2012-11-01

Water-use efficiency (WUE) is a physiological parameter that plays a significant role in the evolutionary dynamics of many forest tree species. It can be estimated indirectly through carbon isotope discrimination (A). In general, plants of more arid origins have lower values of A. In order to study the degree of genetic control of this parameter and the genetic variation in A of Patagonian Cypress seedlings, three Argentinean natural populations chosen to represent two contrasting precipitation regimes were sampled in a common garden trial. The dry situation was represented by two neighboring marginal forest patches from the steppe, while the humid condition was represented by a population with 1,200 mm higher mean annual precipitation. Height (H) and A were measured in 246 five-year-old seedlings from 41 open-pollinated families. The factor family had a significant effect on both variables; however heritability for A was found not to be significant in two out of the three populations. This could be explained by low sample size in one of them and by a real evolutionary effect in the other. An inverse association between H and A was verified, which is interpreted as evidence of an adaptation process at the intra-population level. The studied populations were not shown to discriminate carbon isotopes differently; hence evidence of adaptation to current environmental conditions could not be obtained. On the other hand, the arid populations proved to be quite different in terms of genetic variation, which seems to be the consequence of genetic drift and isolation. (Author) 49 refs.

Genetic Structure in a Small Pelagic Fish Coincides with a Marine Protected Area: Seascape Genetics in Patagonian Fjords.

Directory of Open Access Journals (Sweden)

Cristian B Canales-Aguirre

Full Text Available Marine environmental variables can play an important role in promoting population genetic differentiation in marine organisms. Although fjord ecosystems have attracted much attention due to the great oscillation of environmental variables that produce heterogeneous habitats, species inhabiting this kind of ecosystem have received less attention. In this study, we used Sprattus fuegensis, a small pelagic species that populates the inner waters of the continental shelf, channels and fjords of Chilean Patagonia and Argentina, as a model species to test whether environmental variables of fjords relate to population genetic structure. A total of 282 individuals were analyzed from Chilean Patagonia with eight microsatellite loci. Bayesian and non-Bayesian analyses were conducted to describe the genetic variability of S. fuegensis and whether it shows spatial genetic structure. Results showed two well-differentiated genetic clusters along the Chilean Patagonia distribution (i.e. inside the embayment area called TicToc, and the rest of the fjords, but no spatial isolation by distance (IBD pattern was found with a Mantel test analysis. Temperature and nitrate were correlated to the expected heterozygosities and explained the allelic frequency variation of data in the redundancy analyses. These results suggest that the singular genetic differences found in S. fuegensis from inside TicToc Bay (East of the Corcovado Gulf are the result of larvae retention bya combination of oceanographic mesoscale processes (i.e. the west wind drift current reaches the continental shelf exactly in this zone, and the local geographical configuration (i.e. embayment area, islands, archipelagos. We propose that these features generated an isolated area in the Patagonian fjords that promoted genetic differentiation by drift and a singular biodiversity, adding support to the existence of the largest marine protected area (MPA of continental Chile, which is the Tic-Toc MPA.

Genetic Structure in a Small Pelagic Fish Coincides with a Marine Protected Area: Seascape Genetics in Patagonian Fjords.

Science.gov (United States)

Canales-Aguirre, Cristian B; Ferrada-Fuentes, Sandra; Galleguillos, Ricardo; Hernández, Cristián E

2016-01-01

Marine environmental variables can play an important role in promoting population genetic differentiation in marine organisms. Although fjord ecosystems have attracted much attention due to the great oscillation of environmental variables that produce heterogeneous habitats, species inhabiting this kind of ecosystem have received less attention. In this study, we used Sprattus fuegensis, a small pelagic species that populates the inner waters of the continental shelf, channels and fjords of Chilean Patagonia and Argentina, as a model species to test whether environmental variables of fjords relate to population genetic structure. A total of 282 individuals were analyzed from Chilean Patagonia with eight microsatellite loci. Bayesian and non-Bayesian analyses were conducted to describe the genetic variability of S. fuegensis and whether it shows spatial genetic structure. Results showed two well-differentiated genetic clusters along the Chilean Patagonia distribution (i.e. inside the embayment area called TicToc, and the rest of the fjords), but no spatial isolation by distance (IBD) pattern was found with a Mantel test analysis. Temperature and nitrate were correlated to the expected heterozygosities and explained the allelic frequency variation of data in the redundancy analyses. These results suggest that the singular genetic differences found in S. fuegensis from inside TicToc Bay (East of the Corcovado Gulf) are the result of larvae retention bya combination of oceanographic mesoscale processes (i.e. the west wind drift current reaches the continental shelf exactly in this zone), and the local geographical configuration (i.e. embayment area, islands, archipelagos). We propose that these features generated an isolated area in the Patagonian fjords that promoted genetic differentiation by drift and a singular biodiversity, adding support to the existence of the largest marine protected area (MPA) of continental Chile, which is the Tic-Toc MPA.

Occurrence and levels of glyphosate and AMPA in shallow lakes from the Pampean and Patagonian regions of Argentina.

Science.gov (United States)

Castro Berman, M; Marino, D J G; Quiroga, María Victoria; Zagarese, Horacio

2018-06-01

Glyphosate (N-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide used to kill weeds that compete with commercial crops. In Argentina, the use of glyphosate-based herbicides increased dramatically (up to ∼200,000 tons on 2012) since the introduction of glyphosate-resistant crops, such as transgenic soy and resistant corn, and the adoption of non-till practices in the 1990's. Sallow lakes within the Pampa region may be potentially impacted by continuous herbicide usage. We surveyed 52 shallow lakes from the Pampa region (Buenos Aires Province, Argentina) to assess the occurrence and concentrations of glyphosate and its main degradation product (AMPA). For comparison, we also sampled 24 shallow lakes from an area with no agricultural use of glyphosate (Northern Patagonia). Glyphosate and AMPA were analyzed by UPLC-MS/MS ESI (±) in lake water, suspended particulate matter (SPM), and sediment samples. Within the Pampa region, glyphosate residues were detected in >40% of samples. Glyphosate residues were detected more frequently in sediment and surface water than in SPM samples. The mean (maximum) concentrations of glyphosate were 2.11 (4.52) μg l -1 for surface water; 0.10 (0.13) μg l -1 for SPM and 10.47 (20.34) μg kg -1 for sediment samples, respectively. Whereas, mean (maximum) concentrations of AMPA were 0.84 and (0.90) μg l -1 for surface water; 0.07 (0.07) μg l -1 for SPM; and 22.53 (32.89) μg kg -1 for sediment samples. The herbicide was not detected in samples from the Patagonian region. To our knowledge, this is the first study reporting the occurrence and concentrations of the herbicide in freshwater lakes of Argentina. Copyright © 2018 Elsevier Ltd. All rights reserved.

Three-dimensional temperature fields of the North Patagonian Sea recorded by Magellanic penguins as biological sampling platforms

Science.gov (United States)

Sala, Juan E.; Pisoni, Juan P.; Quintana, Flavio

2017-04-01

Temperature is a primary determinant of biogeographic patterns and ecosystem processes. Standard techniques to study the ocean temperature in situ are, however, particularly limited by their time and spatial coverage, problems which might be partially mitigated by using marine top predators as biological platforms for oceanographic sampling. We used small archival tags deployed on 33 Magellanic penguins (Spheniscus magellanicus), and obtained 21,070 geo-localized profiles of water temperature, during late spring of 2008, 2011, 2012 and 2013; in a region of the North Patagonian Sea with limited oceanographic records in situ. We compared our in situ data of sea surface temperature (SST) with those available from satellite remote sensing; to describe the three-dimensional temperature fields around the area of influence of two important tidal frontal systems; and to study the inter-annual variation in the three-dimensional temperature fields. There was a strong positive relationship between satellite- and animal-derived SST data although there was an overestimation by remote-sensing by a maximum difference of +2 °C. Little inter-annual variability in the 3-dimensional temperature fields was found, with the exception of 2012 (and to a lesser extent in 2013) where the SST was significantly higher. In 2013, we found weak stratification in a region which was unexpected. In addition, during the same year, a warm small-scale vortex is indicated by the animal-derived temperature data. This allowed us to describe and better understand the dynamics of the water masses, which, so far, have been mainly studied by remote sensors and numerical models. Our results highlight again the potential of using marine top predators as biological platforms to collect oceanographic data, which will enhance and accelerate studies on the Southwest Atlantic Ocean. In a changing world, threatened by climate change, it is urgent to fill information gaps on the coupled ocean-atmosphere system

Synoptic oceanography of San Jorge Gulf (Argentina): A template for Patagonian red shrimp (Pleoticus muelleri) spatial dynamics

Science.gov (United States)

Glembocki, Nora Gabriela; Williams, Gabriela Noemí; Góngora, María Eva; Gagliardini, Domingo Antonio; Orensanz, José María (Lobo)

2015-01-01

An extensive series of high-resolution satellite images from the advanced very high-resolution radiometer (AVHRR) and the sea-viewing wide field-of-view sensor (SeaWIFS) was used in a synoptic oceanographic characterization of San Jorge Gulf (SJG, Argentine Patagonia), an area of great significance for marine conservation and commercial fishing. Remotely sensed information was combined with on-board observer's data and published information to investigate the role of distinctive oceanographic features in relation to the life cycle of the Patagonian red shrimp (Pleoticus muelleri), main target of the industrial fleet in SJG. Three frontal systems-North, South and Outer SJG-are characterized. The North and South SJG fronts are associated with shrimp reproductive aggregations during late spring and summer. While both function as spawning/nursery grounds, they differ from each other in many respects. The thermohaline South SJG front has its maximum expression during the winter, reflecting the influence of the low-salinity Magellanic Plume, while the thermal North SJG front develops during spring and summer as the water column becomes stratified in the central basin of the gulf. Wind-related down-welling inshore of the front prevails in the North SJG, and upwelling in the South SJG frontal area. Chlorophyll a is concentrated near the thermocline on the stratified side of the North SJG, and for that reason, it is not detected by remote sensors during the spring bloom and the summer but becomes apparent offshore from the location of the front when the thermocline deepens during the fall (May). In the South SJG front, Chl-a concentration is apparent inshore from the front all year-round, related in part to upwelling-mediated resuspension. The northern end of the outer front coincides in time and space with a recurrent non-reproductive aggregation of red shrimp between November and January and is presumably related to foraging. It is argued that keeping the North and South

By-catch composition of the Patagonian scallop fishery: the fishes Composición de la captura incidental en la pesquería de vieira patagónica: los peces

Directory of Open Access Journals (Sweden)

Laura Schejter

2012-11-01

Full Text Available An inventory of 24 fish species incidentally caught by the Patagonian scallop fleet in the SW Atlantic Ocean is provided for the first time. The most frequent species were Psammobatis spp. (81.4%, Bathyraja brachyurops (75.1%, B. macloviana (73.5%, Patagonotothen ramsayi (66.1%, Merluccius hubbsi (53.7% and B. albomaculata (50.3%. Many of the recorded chondrichthyes are considered vulnerable or endangered species. The number of taxa (fishes + invertebrates that conforms the by-catch of the fishery was increased and updated to nearly 200 species.Este estudio presenta por primera vez un inventario con 24 especies de peces registradas en la captura incidental de la pesca de la vieira patagónica en el Océano Atlántico sudoccidental por la flota pesquera comercial. Las especies más frecuentes fueron Psammobatis spp. (81,4%, Bathyraja brachyurops (75,1%, B. macloviana (73,5%, Patagonotothen ramsayi (66,1%, Merluccius hubbsi (53,7% y B. albomaculata (50,3%. Muchos de los condrictios registrados se encuentran actualmente considerados como especies vulnerables o en peligro. El número de taxa (peces + invertebrados que conforman la captura incidental de esta pesquería se incrementó y actualizó con estos resultados a aproximadamente 200 especies.

The Patagonian scallop fishing grounds in shelf break frontal areas: the non assessed benthic fraction Bancos de pesca de vieira patagónica en áreas del frente de talud: fracción bentónica no evaluada

Directory of Open Access Journals (Sweden)

María de los Ángeles Sánchez

2011-01-01

Full Text Available In this study, a Picard dredge was used to sample the benthic community in shelf break frontal areas off Argentina in order to detect species that could be sensitive to fishing activities but are not usually caught during the annual monitoring of Patagonian scallop and associated fauna. The present results show at least 62 taxa not reported previously as components of the benthos in the scallop grounds that are potentially subjected to trawling disturbance.En este trabajo se utilizó una rastra Picard para muestrear la comunidad bentónica en áreas del frente de talud, Argentina, para detectar especies que serían sensibles a la actividad pesquera pero no son capturadas usualmente durante los monitoreos anuales de vieira patagónica y fauna asociada. Los resultados muestran que al menos 62 taxa, no reportados previamente como componentes del bentos en los bancos de vieira, están potencialmente sujetos a perturbaciones por el arrastre.

Trace-element and Sr, Nd, Pb, and O isotopic composition of Pliocene and Quaternary alkali basalts of the Patagonian Plateau lavas of southernmost South America

Science.gov (United States)

Stern, C.R.; Frey, F.A.; Futa, K.; Zartman, R.E.; Peng, Z.; Kurtis, Kyser T.

1990-01-01

The Pliocene and Quaternary Patagonian alkali basalts of southernmost South America can be divided into two groups. The "cratonic" basalts erupted in areas of Cenozoic plateau volcanism and continental sedimentation and show considerable variation in 87Sr/86Sr (0.70316 to 0.70512), 143Nd/144Nd (e{open}Nd) and 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios (18.26 to 19.38, 15.53 to 15.68, and 38.30 to 39.23, respectively). These isotopic values are within the range of oceanic island basalts, as are the Ba/La, Ba/Nb, La/Nb, K/Rb, and Cs/Rb ratios of the "cratonic" basalts. In contrast, the "transitional" basalts, erupted along the western edge of the outcrop belt of the Pliocene and Quaternary plateau lavas in areas that were the locus of earlier Cenozoic Andean orogenic arc colcanism, have a much more restricted range of isotopic composition which can be approximated by 87Sr/86Sr=0.7039??0.0004, e{open}Nd, 206Pb/204Pb=18.60??0.08, 207Pb/204Pb=15.60??0.01, and 208Pb/204Pb=38.50??0.10. These isotopic values are similar to those of Andean orogenic are basalts and, compared to the "cratonic" basalts, are displaced to higher 87Sr/86Sr at a given 143Nd/144Nd and to higher 207Pb/204Pb at a given 208Pb/204Pb. The "transitional" basalts also have Ba/La, Ba/Nb, La/Nb, and Cs/Rb ratios higher than the "cratonic" and oceanic island basalts, although not as high as Andean orogenic are basalts. In contrast to the radiogenic isotopes, ??18O values for both groups of the Patagonian alkali basalts are indistinguishable and are more restricted than the range reported for Andean orogenic are basalts. Whole rock ??18O values calculated from mineral separates for both groups range from 5.3 to 6.5, while measured whole rock ??18O values range from 5.1 to 7.8. The trace element and isotopic data suggest that decreasing degrees of partial melting in association with lessened significance of subducted slabderived components are fundamental factors in the west to east transition from arc

Environmental conditions, early life stages distributions and larval feeding of patagonian sprat Sprattusfuegensis and common sardine Strangomerabentincki in fjords and channels of the northern Chilean patagonia

Science.gov (United States)

Contreras, Tabit; Castro, Leonardo R.; Montecinos, Sandra; Gonzalez, Humberto E.; Soto, Samuel; Muñoz, Maria I.; Palma, Sergio

2014-12-01

We assessed ontogenetic changes in distribution and feeding of the Patagonian sprat Sprattus fuegensis and common sardine Strangomera bentincki, and their association with environmental characteristics (hydrography, larval food, gelatinous zooplankton predators), and actual feeding from inshore to offshore areas of the Chilean Patagonia. During the springs of 2007 and 2008, S. bentincki egg and larvae were present north of the Taitao Peninsula (47°S) and S. fuegensis was found to the south of the peninsula. Along the inshore-offshore axis, distributions also differed: while eggs and early larval stages of S. bentincki occurred inshore and seawards, larger larvae occurred mostly seawards. The opposite was observed in S. fuegensis. However, distributions of both species followed the same rule, determined by the size of their prey: eggs and early larval stages occurred in areas of higher abundance of small prey sizes, and larger larvae coincided with the highest abundances of larger prey sizes. No relationship was detected between potential gelatinous predators and the egg and larval distributions of both fish species. Mean ingested prey sizes in both species increased as larvae grew, while maintaining the capacity to feed on small sized items. This ontogenetic feeding pattern and the distributions linked to prey seem to be beneficial in order to take advantage of short term food pulses and to overcome the strong changes in environmental conditions east to west from fjords to open waters.

Influence of oceanographic features on the spatial and seasonal patterns of mesozooplankton in the southern Patagonian shelf (Argentina, SW Atlantic)

Science.gov (United States)

Sabatini, M. E.; Reta, R.; Lutz, V. A.; Segura, V.; Daponte, C.

2016-05-01

Surveys conducted during spring, summer and late winter in 2005-2006 over the southern Patagonian shelf have allowed the seasonal distribution of mesozooplankton communities in relation to water masses and circulation to be investigated. In this system, most of the shelf is dominated by a distinct low salinity plume that is related to the runoff from the Magellan Strait (MSW), while the outer shelf is highly influenced by the cold and salty Subantarctic water (SAW) of the boundary Malvinas Current. Separating these two, the Subantarctic Shelf water mass (SASW) extends over the middle shelf. Correspondingly, the structure of the MSW and SAW mesozooplankton communities was found to be clearly different, while the former and the SASW assemblages were barely separable. This relatively fresh water mass is actually a variant of Subantarctic water that enters into the region from the south and the shelf-break, and hence its mesozooplankton community was not significantly different from that of the SAW water mass. Dissimilar species abundance, in turn associated with different life histories and population development, was more important than species composition in defining the assemblages. Total mesozooplankton abundance increased about 2.5-fold from the beginning of spring to late summer, and then decreased at least two orders of magnitude in winter. Across all seasons copepods represented > 70-80% of total mesozooplankton over most of the shelf. Copepod species best represented through all seasons, in terms of both relative abundance and occurrence, were Drepanopus forcipatus and Oithona helgolandica. Although seasonal differences in abundance were striking, the spatial distribution of mesozooplankton was largely similar across seasons, with relatively higher concentrations occurring mainly in Grande Bay and surroundings. The well defined spatial patterns of mesozooplankton that appear from our results in conjunction with the southward wide extension of the shelf and

Cambios latitudinales en la pesquería pelágica de merluza de cola (Macruronus magellanicus de la zona centro-sur (1986-2003 Latitudinal changes in the Patagonian grenadier (Macruronus magellanicus pelagic fishery off central-southern Chile (1986-2003

Directory of Open Access Journals (Sweden)

Luis A Cubillos

2009-01-01

Full Text Available Se analizaron los cambios espacio-temporales de las capturas de merluza de cola obtenidas por la flota industrial de cerco en la zona centro-sur de Chile (34°-41°30'S, para revisar la hipótesis de migración hacia el norte de la fracción juvenil de merluza de cola en primavera. Se utilizaron datos de bitácoras de pesca del periodo 1986-2003, y a partir de éstos se calcularon centros de gravedad de las capturas y su varianza. Se postula que si la flota sigue el comportamiento migratorio de la fracción juvenil, se esperaría que los centros de gravedad de las capturas migren latitudinalmente de sur a norte conforme la estación de pesca avanza. No obstante, sólo se encontró cuatro casos en que ocurrió una migración hacia el norte de los centroides. Más bien, los centros de gravedad se presentan estacionarios, al interior de cada temporada de pesca. Se postula que existe una fracción juvenil residente que sólo incrementa su accesibilidad y vulnerabilidad en aguas superficiales en primavera debido al régimen ambiental, que se caracteriza por la dominancia de eventos de surgencia y no a una migración de sur a norte.We analyzed spatio-temporal changes in Patagonian grenadier catches by the purse-seine fleet off central-southern Chile (34°-41°30'S in order to check the hypothesis that the juvenile fraction of the population migrates northward in spring. Log-book data from 1986 to 2003 were used to calculate the center of gravity of and variance of each catch. We proposed that, if the fleet follows the migratory behavior of the juvenile fraction, the centers of gravity of the catches will migrate from south to north as the fishing season progresses. Nevertheless, the centers of gravity migrated northward in only four cases. Unexpectedly, the centers of gravity remained stationary within each fishing season. Now we propose that, in spring, a resident juvenile fraction of Patagonian grenadier increases its accessibility and vulnerability

Xanthophyllomyces dendrorhous (Phaffia rhodozyma on stromata of Cyttaria hariotii in northwestern Patagonian Nothofagus forests

Directory of Open Access Journals (Sweden)

Diego Libkind

2011-09-01

Full Text Available The occurrence and distribution of Xanthophyllomyces dendrorhous associated with Cyttaria hariotii parasitizing three Nothofagus species (N. dombeyi, N. antarctica and N. pumilio in northwestern Patagonia (Argentina, as well as the factors that may affect this distribution were herein studied. Between 2000 and 2007, samples were obtained from 18 different locations. Based on physiological tests and morphological characteristics of sexual structures, 72 isolates were identified as X. dendrorhous. Representative strains were studied by MSP-PCR fingerprinting and sequence analysis of the ITS region. MSP-PCR fingerprints were similar for the newly isolated strains, and were also identical to the profiles of the strains previously found in this region. Patagonian strains appear to be a genetically uniform and distinct population, supporting the hypothesis that the association with different host species has determined genetically distinct X. dendrorhous populations worldwide. X. dendrorhous was recovered from N. dombeyi and N. antarctica. Approximately half the sampling sites and samples were positive for X. dendrorhous, but the isolation recovery rate was low. X. dendrorhous was absent in the early stages of ascostromata maturation, becoming more abundant in later stages. The present work represents a step forward in the understanding of the natural distribution and ecology of this biotechnologically relevant yeast.Xanthophyllomyces dendrorhous (Phaffia rhodozyma asociado a estromas de Cyttaria hariotii en bosques de Nothofagus en el noroeste de la Patagonia. Se estudió la ocurrencia y la distribución de Xanthophyllomyces dendrorhous asociado a Cyttaria hariotii en tres especies de Nothofagus (N. dombeyi, N. antarctica y N. pumilio del noroeste de la Patagonia (Argentina, y los factores que podrían afectar esta distribución. El muestreo se realizó entre 2000 y 2007 en 18 sitios diferentes. Según las pruebas fisiológicas y las caracter

Combined impact of ultraviolet radiation and increased nutrients supply: A test of the potential anthropogenic impacts on the benthic amphipod Amphitoe valida from Patagonian waters (Argentina

Directory of Open Access Journals (Sweden)

Macarena S. Valiñas

2014-08-01

Full Text Available Experiments were conducted during the Austral Summer of 2014 to determine the effects of increased nutrient input and ultraviolet radiation (UVR on the food consumption rate (FCR and food preference in the amphipod Amphitoe valida. We collected specimens from the Patagonian coast (Argentina, from beaches close (Barrancas Blancas; BB and further away (Cangrejales; C from the Chubut River, which constitutes the potential source of eutrophication. Organisms were exposed to different radiation regimes (full radiation vs. PAR only and fed with different macroalgae diets (i.e., from different geographical location and with different quality in terms on nutrient content. Males collected from C showed food compensation, consuming more food under low-nutrient diets, while no compensation was observed in males from BB. Regardless of their origin, UVR decreased the FCR when males where fed on ambient nutrient diets, but not when males fed on high-quality diets indicating that in the former case, individuals were in worse physiological conditions to cope with UVR; food quality, however, significantly counteracted the deleterious effects of UVR on FCR. Females collected from the two beaches showed similar FCR under high-nutrient diet and had no food compensation when fed in low-nutrient diets. Females were more vulnerable to UVR, since their FCR were lower when exposed to UV radiation independent of the diet. Our results show that under anthropogenic eutrophication and high solar UVR levels an increase in the nutrient input could favor only males of A. valida, by reducing the negative effects of UVR on their FCR. Nevertheless, these nutrient inputs might cause additional problems like anoxia, as a result of an unusual macroalgal growth, thus affecting amphipod’s survival.

Occurrences of ikaite and pseudomorphs after ikaite in Patagonian lakes - crystal morphologies and stable isotope composition

Science.gov (United States)

Oehlerich, Markus; Mayr, Christoph; Griesshaber, Erika; Ohlendorf, Christian; Zolitschka, Bernd; Sánchez-Pastor, Nuria; Kremer, Barbara; Lücke, Andreas; Oeckler, Oliver; Schmahl, Wolfgang

2010-05-01

Ikaite (CaCO3•6H2O), a hydrated calcium carbonate mineral occasionally found in marine sediments, has so far rarely been reported from non-marine sites. Modern ikaite and calcitic pseudomorphs after ikaite were recently discovered in Patagonian Argentina at the polymictic lakes of Laguna Potrok Aike (51°57´S, 70°23´W) and Laguna Cháltel (49°57´S, 71°07´W), respectively. Both lakes are of volcanic origin and have phosphorous-rich, alkaline waters, but differ in altitude (790 m asl and 110 m asl for Laguna Cháltel and Laguna Potrok Aike, respectively) and water temperature. The aim of this study is (1) to investigate conditions for the formation of ikaite and its transformation to more stable, water-free carbonate pseudomorphs after ikaite and (2) to assess the potential of ikaite and calcite pseudomorphs after ikaite as a paleoenvironmental tool in freshwater lakes. Crystallographic, morphological and isotopic characteristics of the pseudomorphs were investigated. Ikaite crystals were found (in September 2008) primarily on aquatic macrophytes and cyanobacteria colonies at Laguna Potrok Aike. Ikaite crystals transformed quickly to calcite pseudomorphs after ikaite after recovery from the cool lake water (4°C). The crystal structure of ikaite was investigated with single crystal X-ray diffraction on samples that were permanently kept cold (in the lake water). At Laguna Cháltel calcite pseudomorphs after ikaite were discovered in littoral sediment cores from 25 m water depth. The mm-sized, porous, polycrystalline calcium carbonate aggregates from the 104 cm long sediment core of Laguna Cháltel are morphologically pseudomorphs after ikaite. SEM and XRD analyses highlight that these pseudomorphs consist of several µm-small calcite crystals in a calcitic matrix. The shape of these micro-crystals changes from rounded to fibrous with increasing sediment depth. Some specimens show casts of cyanobacteria trichomes. The oxygen isotopic composition of calcite

Efectos del pastoreo sobre el suelo y la vegetación en la Estepa Patagónica Grazing effects on soil and vegetation in the Patagonian Steppe

Directory of Open Access Journals (Sweden)

Juan José Gaitán

2009-12-01

Full Text Available La ganadería ovina durante más de 100 años produjo grandes cambios en los ecosistemas y es una de las principales causas de la desertificación en la estepa patagónica. Este trabajo tiene por objetivo evaluar los efectos del pastoreo sobre el suelo y la vegetación mediante la aplicación de una versión modificada de la metodología «Landscape Function Analysis» desarrollada en Australia. El estudio se realizó en siete sitios con distintos niveles de degradación por pastoreo en Pilcaniyeu (noroeste de Río Negro: tres clausurados al pastoreo (CLA, tres bajo pastoreo moderado (PM y uno bajo pastoreo intenso (PI. Se evaluaron indicadores de la composición florística y estructura espacial de la vegetación, del estado de la superficie del suelo en los interparches, los cuales fueron integrados en tres Índices de Función (Estabilidad -EST-, Infiltración -INFy Reciclaje de nutrientes -NUT- y el stock de carbono orgánico (CO. Al incrementarse la intensidad de pastoreo se observó una disminución en la cobertura basal de la vegetación (47,4; 23,2 y 17,4% en CLA, PM y PI, respectivamente, parches vegetados más distanciados entre sí (61,9; 117,9 y 181,7 cm, menor cobertura de gramíneas palatables (26,3; 3,4 y 2,1% y mayor de no palatables (4,4; 15,8 y 17,6%. También se observó una tendencia a disminuir en los Índices de Función del suelo (EST: 43,0; 42,3 y 36,2; INF: 48,3; 41,7 y 36,2; NUT: 33,1; 23,5 y 18,1 y del CO (33,8; 26,5 y 7,9 t/ha al incrementarse la intensidad de pastoreo. Se requieren más estudios para adaptar esta metodología a las condiciones de Patagonia y testear con datos experimentales de que manera los índices reflejan adecuadamente los procesos y funciones de estos ecosistemas.More than 100 years of sheep breeding has caused profound changes to ecosystems and is one of the main causes of desertification in the Patagonian steppe. The aim of this study was to evaluate sheep grazing effects on soils and

Land-ocean gradient in haline stratification and its effects on plankton dynamics and trophic carbon fluxes in Chilean Patagonian fjords (47-50°S)

Science.gov (United States)

González, H. E.; Castro, L. R.; Daneri, G.; Iriarte, J. L.; Silva, N.; Tapia, F.; Teca, E.; Vargas, C. A.

2013-12-01

Patagonian fjord systems, and in particular the fjords and channels associated with the Baker/Pascua Rivers, are currently under conspicuous natural and anthropogenic perturbations. These systems display very high variability, where limnetic and oceanic features overlap generating strong vertical and horizontal physicochemical gradients. The CIMAR 14-Fiordos cruise was conducted in the Chilean fjords located between 47° and 50°S during the spring (October-November) of 2008. The main objectives were to study vertical and horizontal gradients in physical, chemical and biological characteristics of the water column, and to assess plankton dynamics and trophic carbon fluxes in the fjords and channels of central-south Patagonia. The water column was strongly stratified, with a pycnocline at ca. 20 m depth separating a surface layer of silicic acid-rich freshwater discharged by rivers, from the underlying nitrate- and orthophosphate-rich Subantarctic waters. The outflows from the Baker and Pascua Rivers, which range annually between 500 and 1500 m3 s-1, generate the strong land-ocean gradient in salinity (1-32 psu) and inorganic nutrient concentrations (2-8 and 2-24 μM in nitrate and silicic-acid, respectively) we observed along the Baker Fjord. The POC:chl-a ratio fluctuated from 1087 near the fjord’s head to 175 at its oceanic end in the Penas Gulf. This change was mainly due to an increase in diatom dominance and a concurrent decrease in allochthonous POC towards the ocean. Depth-integrated net primary production (NPP) and bacterial secondary production (BSP) fluctuated between 49 and 1215 and 36 and 150 mg C m-2 d-1, respectively, with higher rates in oceanic waters. At a time series station located close to the Baker River mouth, the average NPP was lower (average 360 mg C m-2 d-1) than at more oceanic stations (average 1063 mg C m-2 d-1), and numerically dominated (45%) by the picoplankton (food web is the main trophic pathway in these environments.

New Patagonian Cretaceous theropod sheds light about the early radiation of Coelurosauria

Directory of Open Access Journals (Sweden)

Fernando E Novas

2012-06-01

Full Text Available Here we describe a new theropod, Bicentenaria argentina nov. gen. et nov. sp., from the early Late Cretaceous of Patagonia. It is represented by more than a hundred bones belonging to different sized individuals, which were buried together in disarticulation after little transportation. The available association of skeletal elements suggests a gregarious behaviour for Bicentenaria, an ethological trait also recorded among other theropod clades. Increasing documentation of monospecific assemblages of different groups of theropods suggests that a gregarious behaviour may have constituted the ancestral condition for Theropoda, at least. Bicentenaria characterizes for the surangular bone with a high dorsal margin and a prominent lateral shelf, a retroarticular process that is low, wide and spoon-shaped, and quadrate bone with its lateral condyle larger than the medial one. Phylogenetic analysis found the Chinese Tugulusaurus and the Patagonian Bicentenaria as successive sister taxa of all other coelurosaurs, thus revealing the importance of the new taxon in the understanding of the early diversification of Coelurosauria. In particular, Bicentenaria amplifies the array of basal coelurosaurs that inhabited Gondwana during the Cretaceous, also including compsognathids, Aniksosaurus and Santanaraptor. Although still restricted to a handful of forms, available information indicates that Gondwana was a cradle for the evolution of different lineages of basal coelurosaurs, different from those documented in Upper Cretaceous beds in the northern landmasses. Analysis of body size distribution in averostran theropods results in the identification of two main episodes of drastic size reduction in the evolutionary history of Coelurosauria: one occurred at the initial radiation of the group (as represented by Bicentenaria, Zuolong, Tugulusaurus, compsognathids, and Aniksosaurus, and a second episode occurred at the early diverification of Paraves or avialans

Influence of precipitation, landscape and hydrogeomorphic lake features on pelagic allochthonous indicators in two connected ultraoligotrophic lakes of North Patagonia

International Nuclear Information System (INIS)

Queimaliños, Claudia; Reissig, Mariana; Diéguez, María del Carmen; Arcagni, Marina; Ribeiro Guevara, Sergio; Campbell, Linda; Soto Cárdenas, Carolina; Rapacioli, Raúl

2012-01-01

We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Patagonia (Argentina) through the seasonal analysis of two pelagic allochthonous indicators: i) water color, as a proxy of allochthonous dissolved organic matter in lakes; and ii) the color to chlorophyll a ratio (Color:Chla), as an indicator of the relationship between allochthonous and autochthonous carbon pools. We also evaluated the potential transfer pathways of the allochthonous dissolved organic matter into the pelagic food webs of these deep lakes, including the natural zooplankton δ 13 C in the analysis. The dynamics of the allochthonous indicators were related to the precipitation regime, water level fluctuations, and hydrogeomorphic and catchment features of lakes Moreno East and Moreno West. The water color (absorbance at 440 nm) was extremely low ( −1 ) in both lakes regardless of the season. However, precipitation and snowmelt regimes drove the increase and decrease of water color, respectively. A significant positive relationship between the zooplankton bulk δ 13 C with the water color would suggest an input of allochthonous organic carbon into the pelagic consumers. The incorporation of the dissolved allochthonous material into higher trophic levels is likely favored by the bacterivorous behavior of planktonic organisms, mixotrophic flagellates and ciliates, which dominate the pelagic food webs of these Patagonian lakes. Morphometric aspects, mainly the higher water residence time, led to lower values of allochthony in Moreno East compared to Moreno West, probably accentuated by its upper position in the lake chain. Overall, our results suggest that these allochthonous signals can bring insight into the magnitude of the interaction between terrestrial environments and lake ecosystems, even in extremely clear and ultraoligotrophic systems, such as the Andean Patagonian lakes. - Highlights: ► Pelagic allochthonous indicators were detected in two

Glaciation effects on the phylogeographic structure of Oligoryzomys longicaudatus (Rodentia: Sigmodontinae in the southern Andes.

Directory of Open Access Journals (Sweden)

R Eduardo Palma

Full Text Available The long-tailed pygmy rice rat Oligoryzomys longicaudatus (Sigmodontinae, the major reservoir of Hantavirus in Chile and Patagonian Argentina, is widely distributed in the Mediterranean, Temperate and Patagonian Forests of Chile, as well as in adjacent areas in southern Argentina. We used molecular data to evaluate the effects of the last glacial event on the phylogeographic structure of this species. We examined if historical Pleistocene events had affected genetic variation and spatial distribution of this species along its distributional range. We sampled 223 individuals representing 47 localities along the species range, and sequenced the hypervariable domain I of the mtDNA control region. Aligned sequences were analyzed using haplotype network, bayesian population structure and demographic analyses. Analysis of population structure and the haplotype network inferred three genetic clusters along the distribution of O. longicaudatus that mostly agreed with the three major ecogeographic regions in Chile: Mediterranean, Temperate Forests and Patagonian Forests. Bayesian Skyline Plots showed constant population sizes through time in all three clusters followed by an increase after and during the Last Glacial Maximum (LGM; between 26,000-13,000 years ago. Neutrality tests and the "g" parameter also suggest that populations of O. longicaudatus experienced demographic expansion across the species entire range. Past climate shifts have influenced population structure and lineage variation of O. longicaudatus. This species remained in refugia areas during Pleistocene times in southern Temperate Forests (and adjacent areas in Patagonia. From these refugia, O. longicaudatus experienced demographic expansions into Patagonian Forests and central Mediterranean Chile using glacial retreats.

Influence of precipitation, landscape and hydrogeomorphic lake features on pelagic allochthonous indicators in two connected ultraoligotrophic lakes of North Patagonia

Energy Technology Data Exchange (ETDEWEB)

Queimalinos, Claudia, E-mail: queimalinosc@comahue-conicet.gob.ar [Laboratorio de Fotobiologia, Instituto de Investigaciones en Biodiversidad y Medio Ambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, R8400FRF Bariloche, Rio Negro (Argentina); Reissig, Mariana; Dieguez, Maria del Carmen [Laboratorio de Fotobiologia, Instituto de Investigaciones en Biodiversidad y Medio Ambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, R8400FRF Bariloche, Rio Negro (Argentina); Arcagni, Marina; Ribeiro Guevara, Sergio [Laboratorio de Analisis por Activacion Neutronica (LAAN), Centro Atomico Bariloche, Comision Nacional de Energia Atomica, Av. Bustillo 9500, R8402AGP Bariloche, Rio Negro (Argentina); Campbell, Linda [School of Environmental Studies, Saint Mary' s University, 923 Robie Street, Halifax, Nova Scotia, Canada B3H-3C3 (Canada); Soto Cardenas, Carolina [Laboratorio de Fotobiologia, Instituto de Investigaciones en Biodiversidad y Medio Ambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, R8400FRF Bariloche, Rio Negro (Argentina); Rapacioli, Raul [Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires1400, Q8300IBX Neuquen (Argentina); and others

2012-06-15

We investigated the terrestrial influence on two chained deep ultraoligotrophic lakes of North Patagonia (Argentina) through the seasonal analysis of two pelagic allochthonous indicators: i) water color, as a proxy of allochthonous dissolved organic matter in lakes; and ii) the color to chlorophyll a ratio (Color:Chla), as an indicator of the relationship between allochthonous and autochthonous carbon pools. We also evaluated the potential transfer pathways of the allochthonous dissolved organic matter into the pelagic food webs of these deep lakes, including the natural zooplankton {delta}{sup 13}C in the analysis. The dynamics of the allochthonous indicators were related to the precipitation regime, water level fluctuations, and hydrogeomorphic and catchment features of lakes Moreno East and Moreno West. The water color (absorbance at 440 nm) was extremely low (< 0.28 m{sup -1}) in both lakes regardless of the season. However, precipitation and snowmelt regimes drove the increase and decrease of water color, respectively. A significant positive relationship between the zooplankton bulk {delta}{sup 13}C with the water color would suggest an input of allochthonous organic carbon into the pelagic consumers. The incorporation of the dissolved allochthonous material into higher trophic levels is likely favored by the bacterivorous behavior of planktonic organisms, mixotrophic flagellates and ciliates, which dominate the pelagic food webs of these Patagonian lakes. Morphometric aspects, mainly the higher water residence time, led to lower values of allochthony in Moreno East compared to Moreno West, probably accentuated by its upper position in the lake chain. Overall, our results suggest that these allochthonous signals can bring insight into the magnitude of the interaction between terrestrial environments and lake ecosystems, even in extremely clear and ultraoligotrophic systems, such as the Andean Patagonian lakes. - Highlights: Black-Right-Pointing-Pointer Pelagic

Morphometric variation of extant platyrrhine molars: taxonomic implications for fossil platyrrhines

Directory of Open Access Journals (Sweden)

Mónica Nova Delgado

2016-05-01

Full Text Available The phylogenetic position of many fossil platyrrhines with respect to extant ones is not yet clear. Two main hypotheses have been proposed: the layered or successive radiations hypothesis suggests that Patagonian fossils are Middle Miocene stem platyrrhines lacking modern descendants, whereas the long lineage hypothesis argues for an evolutionary continuity of all fossil platyrrhines with the extant ones. Our geometric morphometric analysis of a 15 landmark-based configuration of platyrrhines’ first and second lower molars suggest that morphological stasis may explain the reduced molar shape variation observed. Platyrrhine lower molar shape might be a primitive retention of the ancestral state affected by strong ecological constraints throughout the radiation of the main platyrrhine families. The Patagonian fossil specimens showed two distinct morphological patterns of lower molars, Callicebus—like and Saguinus—like, which might be the precursors of the extant forms, whereas the Middle Miocene specimens, though showing morphological resemblances with the Patagonian fossils, also displayed new, derived molar patterns, Alouatta—like and Pitheciinae—like, thereby suggesting that despite the overall morphological stasis of molars, phenotypic diversification of molar shape was already settled during the Middle Miocene.

Eocene relatives of cod icefishes (Perciformes: Notothenioidei) from Seymour Island, Antarctica

DEFF Research Database (Denmark)

Bieńkowska-Wasiluk, Małgorzata; Bonde, Niels Christensøn; Møller, Peter Rask

2013-01-01

Fragmentary skull bones and vertebra from the Upper Eocene La Meseta Formation on Seymour (Marambio) Island, Antarctic Peninsula have been described as gadiform fishes, informally named “Mesetaichthys”. Here we describe jaws as Mesetaichthys jerzmanskae n. g. and n. sp., and refer this taxon...... to the perciform suborder Notothenioidei. This group is almost unknown as fossils. Similarities to the living, ‘primitive’ nototheniid Dissostichus eleginoides are indicated in the dentition. Gadiform evolution in the Paleocene-Eocene, and the possibility of a correlation between the origin and evolution...... of notothenioids in connection with the deterioration of the climate in Antarctica during the Late Eocene-Oligocene is discussed....

Reductions of plant cover induced by sheep grazing change the above-belowground partition and chemistry of organic C stocks in arid rangelands of Patagonian Monte, Argentina.

Science.gov (United States)

Larreguy, C; Carrera, A L; Bertiller, M B

2017-09-01

The objective of this study was to estimate the size and chemical quality of the total organic C stock and its partition between above-belowground plant parts and soil at sites with different plant cover induced by sheep grazing in the arid Patagonian Monte. This study was conducted at six representative sites with increasing signs of canopy disturbance attributed to grazing pressure. We used faeces density as a proxy of grazing pressure at each site. We assessed the total plant cover, shrub and perennial grass cover, total standing aboveground biomass (AGB), litter mass and belowground biomass (BGB) at each site. We further estimated the content of organic C, lignin and soluble phenols in plant compartments and the content of organic C, organic C in humic substances (recalcitrant C) and water soluble C (labile C) in soil at each site. Total plant cover was significantly related to grazing pressure. Standing AGB and litter mass decreased with increasing canopy disturbance while BGB did not vary across sites. Total organic C stock and the organic C stock in standing AGB increased with increasing total plant, shrub, and perennial grass cover. The organic C stock in litter mass increased with increasing total plant and shrub cover, while the organic C stock in BGB did not vary across sites. Lignin content in plant compartments increased with increasing total and shrub cover, while soluble phenols content did not change across sites. The organic C stock and the water soluble C content in soil were positively associated with perennial grass cover. Changes in total plant cover induced by grazing pressure negatively affected the size of the total organic C stock, having minor impact on the size of belowground than aboveground components. The reduction of perennial grass cover was reflected in decreasing chemical quality of the organic C stock in soil. Accordingly, plant managerial strategies should not only be focused on the amount of organic C sequestered but also on the

The Quaternary calc-alkaline volcanism of the Patagonian Andes close to the Chile triple junction: geochemistry and petrogenesis of volcanic rocks from the Cay and Maca volcanoes (˜45°S, Chile)

Science.gov (United States)

D'Orazio, M.; Innocenti, F.; Manetti, P.; Tamponi, M.; Tonarini, S.; González-Ferrán, O.; Lahsen, A.; Omarini, R.

2003-08-01

Major- and trace-element, Sr-Nd isotopes, and mineral chemistry data were obtained for a collection of volcanic rock samples erupted by the Cay and Maca Quaternary volcanoes, Patagonian Andes (˜45°S, Chile). Cay and Maca are two large, adjacent stratovolcanoes that rise from the Chiloe block at the southern end of the southern volcanic zone (SVZ) of the Andes. Samples from the two volcanoes are typical medium-K, calc-alkaline rocks that form two roughly continuous, largely overlapping series from subalkaline basalt to dacite. The overall geochemistry of the samples studied is very similar to that observed for most volcanoes from the southern SVZ. The narrow range of Sr-Nd isotope compositions ( 87Sr/ 86Sr=0.70389-0.70431 and 143Nd/ 144Nd=0.51277-0.51284) and the major- and trace-element distributions indicate that the Cay and Maca magmas differentiated by crystal fractionation without significant contribution by crustal contamination. This is in accordance with the thin (Maca magmas is investigated by means of the relative concentration of fluid mobile (e.g. Ba) and fluid immobile (e.g. Nb, Ta, Zr, Y) elements and other relevant trace-element ratios (e.g. Sr/Y). The results indicate that small amounts (Maca volcanoes and that, despite the very young age (Maca magma sources to the northern edge of the slab window generated by the subduction of the Chile ridge under the South American plate, we did not find any geochemical evidence for a contribution of a subslab asthenospheric mantle. However, this mantle has been used to explain the peculiar geochemical features (e.g. the mild alkalinity and relatively low ratios between large ion lithophile and high field strength elements) of the Hudson volcano, which is located even closer to the slab window than the Cay and Maca volcanoes are.

An evaluation of methods for modelling distribution of Patagonian insects Una evaluación de los métodos para modelizar la distribución de insectos patagónicos

Directory of Open Access Journals (Sweden)

MARCELO F TOGNELLI

2009-01-01

Full Text Available Various studies have shown that model performance may vary depending on the species being modelled, the study área, or the number of sampled localities, and suggest that it is necessary to assess which model is better for a particular situation. Thus, in this study we evalúate the performance of different techniques for modelling the distribution of Patagonian insects. We applied eight of the most widely used modelling methods (artificial neural networks, BIOCLIM, classification and regression trees, DOMAIN, generalized additive models, GARP, generalized linear models, and Maxent to the distribution of ten Patagonian insect species. We compared model performance with five accuracy measures. To overeóme the problem of not having reliable absence data with which to evalúate model performance, we used randomly selected pseudo-absences located outside of the polygon área defined by taxonomic experts. Our analyses show significant differences among modelling methods depending on the chosen accuracy measure. Maxent performed the best according to four out of the five accuracy measures, although its accuracy did not differ significantly from that obtained with artificial neural networks. When assessed on per species basis, Maxent was also one of the strongest performing methods, particularly for species sampled from a relatively low number of localities. Overall, our study identified four groups of modelling techniques based on model performance. The top-performing group is composed of Maxent and artificial neural networks, followed closely by the DOMAIN technique. The third group includes GARP, GAM, GLM, and CART, and the fourth best performer is the BIOCLIM technique. Although these results may allow obtaining better distributional predictions for reserve selection, it is necessary to be cautious in their use due to the provisional nature of these simulations.Varios estudios han mostrado que el desempeño de los modelos de distribución puede

Helminth communities of two populations of Myotis chiloensis (Chiroptera: Vespertilionidae from Argentinean Patagonia

Directory of Open Access Journals (Sweden)

Antonella C. Falconaro

2018-04-01

Full Text Available Most of the studies on chiropteran endoparasites in Argentina come from the Central and Northeast regions of the country, and there is only one parasitological study of bats from the Argentinean Patagonia. The aim of this study is to describe the helminth fauna of 42 Myotis chiloensis, comparing the composition and the structure of the endoparasite communities between two populations, inhabiting different environments in Andean humid forest and the ecotone between forest and Patagonian steppe. A total of 697 helminths were recovered from 33 bats: five species of trematodes, Ochoterenatrema sp., Paralecithodendrium sp., Parabascus limatulus, Parabascus sp., and Postorchigenes cf. joannae, two species of cestodes, Vampirolepis sp. 1 and Vampirolepis sp. 2, and three species of nematodes, Allintoshius baudi, Physaloptera sp., and Physocephalus sp. All the helminths, but Physocephalus sp., were recovered from the small and large intestine. This is the first survey of M. chiloensis’ helminth fauna. All the species, but A. baudi, represent new records of helminths in Patagonian bats. There were differences of parasite species richness between localities and both bat populations share almost half of the endoparasite species. Different preferences for intestinal regions were found for three species of trematodes in the bats from the site in the humid forest. Myotis chiloensis serves as both a definitive and intermediate host for endoparasites in the Patagonian ecosystem. Keywords: Bats, Parasites, South America

Population structure and reticulate evolution of Saccharomyces eubayanus and its lager-brewing hybrids.

Science.gov (United States)

Peris, David; Sylvester, Kayla; Libkind, Diego; Gonçalves, Paula; Sampaio, José Paulo; Alexander, William G; Hittinger, Chris Todd

2014-04-01

Reticulate evolution can be a major driver of diversification into new niches, especially in disturbed habitats and at the edges of ranges. Industrial fermentation strains of yeast provide a window into these processes, but progress has been hampered by a limited understanding of the natural diversity and distribution of Saccharomyces species and populations. For example, lager beer is brewed with Saccharomyces pastorianus, an alloploid hybrid of S. cerevisiae and S. eubayanus, a species only recently discovered in Patagonia, Argentina. Here, we report that genetically diverse strains of S. eubayanus are readily isolated from Patagonia, demonstrating that the species is well established there. Analyses of multilocus sequence data strongly suggest that there are two diverse and highly differentiated Patagonian populations. The low nucleotide diversity found in the S. eubayanus moiety of hybrid European brewing strains suggests that their alleles were drawn from a small subpopulation that is closely related to one of the Patagonian populations. For the first time, we also report the rare isolation of S. eubayanus outside Patagonia, in Wisconsin, USA. In contrast to the clear population differentiation in Patagonia, the North American strains represent a recent and possibly transient admixture of the two Patagonian populations. These complex and varied reticulation events are not adequately captured by conventional phylogenetic methods and required analyses of Bayesian concordance factors and phylogenetic networks to accurately summarize and interpret. These findings show how genetically diverse eukaryotic microbes can produce rare but economically important hybrids with low genetic diversity when they migrate from their natural ecological context. © 2014 John Wiley & Sons Ltd.

Petrogenesis of volcanic rocks that host the world-class Agsbnd Pb Navidad District, North Patagonian Massif: Comparison with the Jurassic Chon Aike Volcanic Province of Patagonia, Argentina

Science.gov (United States)

Bouhier, Verónica E.; Franchini, Marta B.; Caffe, Pablo J.; Maydagán, Laura; Rapela, Carlos W.; Paolini, Marcelo

2017-05-01

We present the first study of the volcanic rocks of the Cañadón Asfalto Formation that host the Navidad world-class Ag + Pb epithermal district located in the North Patagonian Massif, Patagonia, Argentina. These volcanic and sedimentary rocks were deposited in a lacustrine environment during an extensional tectonic regime associated with the breakup of Gondwana and represent the mafic to intermediate counterparts of the mainly silicic Jurassic Chon Aike Volcanic Province. Lava flows surrounded by autobrecciated carapace were extruded in subaerial conditions, whereas hyaloclastite and peperite facies suggest contemporaneous subaqueous volcanism and sedimentation. LA-ICPMS Usbnd Pb ages of zircon crystals from the volcanic units yielded Middle Jurassic ages of 173.9 ± 1.9 Ma and 170.8 ± 3 Ma. In the Navidad district, volcanic rocks of the Cañadón Asfalto Formation show arc-like signatures including high-K basaltic-andesite to high-K dacite compositions, Rb, Ba and Th enrichment relative to the less mobile HFS elements (Nb, Ta), enrichment in light rare earth elements (LREE), Ysbnd Ti depletion, and high Zr contents. These characteristics could be explained by assimilation of crustal rocks in the Jurassic magmas, which is also supported by the presence of zircon xenocrysts with Permian and Middle-Upper Triassic ages (281.3 Ma, 246.5, 218.1, and 201.3 Ma) and quartz xenocrysts recognized in these volcanic units. Furthermore, Sr and Nd isotope compositions suggest a contribution of crustal components in these Middle Jurassic magmas. High-K basaltic andesite has initial 87Sr/86Sr ratios of 0.70416-0.70658 and ξNd(t) values of -5.3 and -4. High-K dacite and andesite have initial 87Sr/86Sr compositions of 0.70584-0.70601 and ξNd(t) values of -4,1 and -3,2. The range of Pb isotope values (206Pb/204Pb = 18.28-18.37, 207Pb/204Pb = 15.61-15.62, and 208Pb/204Pb = 38.26-38.43) of Navidad volcanic rocks and ore minerals suggest mixing Pb sources with contributions of

Multiple territories in dispute : water policies, participation and Mapuce indigenous rights in Patagonia, Argentina

NARCIS (Netherlands)

Moreyra, A.

2009-01-01

This thesis is about the multiple territories which dispute the shape and control of
the development of the Trahunco-Quitrahue watershed, at Cerro Chapelko,
Neuquén province in Argentinean Patagonian. Built into these disputes are the
struggles of Mapuce peoples -indigenous peoples

Freshwater fishes of Patagonia: conservation and fisheries.

Science.gov (United States)

Cussac, V E; Habit, E; Ciancio, J; Battini, M A; Riva Rossi, C; Barriga, J P; Baigún, C; Crichigno, S

2016-07-01

The absence of much literature on the Patagonian fish fauna in comparison with that of the neotropics, has previously been blamed on its poor species diversity. Knowledge of the fishes of Patagonia, however, rose sharply at the beginning of the present century, allowing for an understanding of the complex biogeographical history that has led to the present diversity and distribution patterns. There are several new and potential threats to biodiversity and conservation of Patagonian fishes, such as the introduction of exotic species, damming, climate change and changes geared to safeguard economic interests, often acting synergistically. A great amount of new information is now available and the aim of the present review is to articulate this knowledge in a comprehensive way in order to aid in the development of tools to face the increasing challenges posed by environmental change and human activity. Knowledge about fishes of Patagonia has grown at the same time as human actions, and presence. © 2016 The Fisheries Society of the British Isles.

Spatial patterns of copepod biodiversity in relation to a tidal front system in the main spawning and nursery area of the Argentine hake Merluccius hubbsi

Science.gov (United States)

Temperoni, B.; Viñas, M. D.; Martos, P.; Marrari, M.

2014-11-01

Copepods play an important role in marine ecosystems as a direct link of energy transfer between primary producers and higher trophic level consumers, such as fish. In the Argentine Sea, the Patagonian stock of Argentine hake Merluccius hubbsi spawns from late austral spring (December) to early autumn (April) in the northern Patagonian shelf region (43°-45°30‧S), in association with a highly productive tidal front system. Since hake larvae prey mainly upon copepods, the objective of this study was to assess the spatial variability in the abundance and diversity of these potential food items in different sectors of the front, as one of the possible factors affecting hake recruitment success. Two complementary mesh sizes (67 and 300 μm) were used to accurately target the entire copepod size spectrum. The copepod community was dominated by developmental stages sustain M. hubbsi larval growth resulting from high availability of adequate prey, the suitable thermal ranges, and the existence of retention mechanisms.

A non-diatom plankton bloom controlled by copepod grazing and amphipod predation: Preliminary results from the LOHAFEX iron-fertilisation experiment

Digital Repository Service at National Institute of Oceanography (India)

Mazzocchi, M.G.; Gonzalez, H.E.; Vandromme, P.; Borrione, I.; deAlcala, M.R.; Gauns, M.; Assmy, P.; Fuchs, B.; Klaas, C.; Martin, P.; Montresor, M.; Ramaiah, N.; Naqvi, S.W.A.; Smetacek, V.

” and is reported to be the main food of the squid Ilex argentinus which is the target of the intense squid fishery along the Patagonian shelf break, prominent in satellite images of the world by night, because lights are used to attract squid. So why does only...

Biological activity of some Patagonian plants.

Science.gov (United States)

Cuadra, Pedro; Furrianca, María; Oyarzún, Alejandra; Yáñez, Erwin; Gallardo, Amalia; Fajardo, Víctor

2005-12-01

Citotoxicity (inhibition of cell division in fertilized eggs of Loxechinus albus) and general toxicity (using embryos of Artemia salina) of plants belonging to the genera Senecio, Deschampsia, Alstroemeria, Anarthrophyllum, Chloraea and Geranium were investigated.

Cenozoic intraplate tectonics in Central Patagonia: Record of main Andean phases in a weak upper plate

Science.gov (United States)

Gianni, G. M.; Echaurren, A.; Folguera, A.; Likerman, J.; Encinas, A.; García, H. P. A.; Dal Molin, C.; Valencia, V. A.

2017-11-01

Contraction in intraplate areas is still poorly understood relative to similar deformation at plate margins. In order to contribute to its comprehension, we study the Patagonian broken foreland (PBF) in South America whose evolution remains controversial. Time constraints of tectonic events and structural characterization of this belt are limited. Also, major causes of strain location in this orogen far from the plate margin are enigmatic. To unravel tectonic events, we studied the Cenozoic sedimentary record of the central sector of the Patagonian broken foreland (San Bernardo fold and thrust belt, 44°30‧S-46°S) and the Andes (Meseta de Chalia, 46°S) following an approach involving growth-strata detection, U-Pb geochronology and structural modeling. Additionally, we elaborate a high resolution analysis of the effective elastic thickness (Te) to examine the relation between intraplate contraction location and variations in lithospheric strength. The occurrence of Eocene growth-strata ( 44-40 Ma) suggests that contraction in the Andes and the Patagonian broken foreland was linked to the Incaic phase. Detection of synextensional deposits suggests that the broken foreland collapsed partially during Oligocene to early Miocene. During middle Miocene times, the Quechua contractional phase produced folding of Neogene volcanic rocks and olistostrome deposition at 17 Ma. Finally, the presented Te map shows that intraplate contraction related to Andean phases localized preferentially along weak lithospheric zones (Te < 15 km). Hence, the observed strain distribution in the PBF appears to be controlled by lateral variations in the lithospheric strength. Variations in this parameter could be related to thermo-mechanical weakening produced by intraplate rifting in Paleozoic-Mesozoic times.

Temperature-dependent enthalpy of oxygenation in Antarctic fish hemoglobins

DEFF Research Database (Denmark)

Fago, A.; Wells, R.M.G.; Weber, Roy E.

1997-01-01

The effect of temperature on the oxygen-binding properties of the hemoglobins of three cold-adapted Antarctic fish species, Dissostichus mawsoni, Pagothenia borchgrevinki and Trematomus, sp., has been investigated under different pH values and buffer conditions. A clear non linear van't Hoff plot...... (logP(50) vs 1/T) of D. mawsoni hemoglobin indicates that the enthalpy of oxygenation (slope of the plot) is temperature dependent and that at high temperatures oxygen-binding becomes less exothermic. Nearly linear relationships were found in the hemoglobins of the other two species. The data were...... oxygen binding. The degree of the temperature dependence of the heat of oxygenation observed in these hemoglobins seems to reflect the differences in their allosteric effects rather than a specific molecular adaptation to low temperatures. Moreover, this study indicates that the disagreement between...

Argentinean Students' and Teachers' Conceptions of Day and Night: An Analysis in Relation to Astronomical Reference Systems

Science.gov (United States)

Galperin, D.; Raviolo, A.

2015-01-01

This work analysed the evolution of day/night cycle conceptions held by students of different ages and teachers in the Patagonian region of Argentina. The research was based on drawings, written explanations and semi-structured individual interviews. The results showed that both teachers and students had significant comprehension problems. These…

Pine invasions in treeless environments: dispersal overruns microsite heterogeneity.

Science.gov (United States)

Pauchard, Aníbal; Escudero, Adrián; García, Rafael A; de la Cruz, Marcelino; Langdon, Bárbara; Cavieres, Lohengrin A; Esquivel, Jocelyn

2016-01-01

Understanding biological invasions patterns and mechanisms is highly needed for forecasting and managing these processes and their negative impacts. At small scales, ecological processes driving plant invasions are expected to produce a spatially explicit pattern driven by propagule pressure and local ground heterogeneity. Our aim was to determine the interplay between the intensity of seed rain, using distance to a mature plantation as a proxy, and microsite heterogeneity in the spreading of Pinus contorta in the treeless Patagonian steppe. Three one-hectare plots were located under different degrees of P. contorta invasion (Coyhaique Alto, 45° 30'S and 71° 42'W). We fitted three types of inhomogeneous Poisson models to each pine plot in an attempt for describing the observed pattern as accurately as possible: the "dispersal" models, "local ground heterogeneity" models, and "combined" models, using both types of covariates. To include the temporal axis in the invasion process, we analyzed both the pattern of young and old recruits and also of all recruits together. As hypothesized, the spatial patterns of recruited pines showed coarse scale heterogeneity. Early pine invasion spatial patterns in our Patagonian steppe site is not different from expectations of inhomogeneous Poisson processes taking into consideration a linear and negative dependency of pine recruit intensity on the distance to afforestations. Models including ground-cover predictors were able to describe the point pattern process only in a couple of cases but never better than dispersal models. This finding concurs with the idea that early invasions depend more on seed pressure than on the biotic and abiotic relationships seed and seedlings establish at the microsite scale. Our results show that without a timely and active management, P. contorta will invade the Patagonian steppe independently of the local ground-cover conditions.

Biotic diversity of benthic macroinvertebrates at contrasting glacier-fed systems in Patagonia Mountains: The role of environmental heterogeneity facing global warming.

Science.gov (United States)

Miserendino, María Laura; Brand, Cecilia; Epele, Luis B; Di Prinzio, Cecilia Y; Omad, Guillermo H; Archangelsky, Miguel; Martínez, Oscar; Kutschker, Adriana M

2018-05-01

Patagonia is by far the largest glacierized area in South America. However, little is known about ecology, functioning and biodiversity of glacier-fed streams facing global warming. We investigated changes in environmental features and macroinvertebrate communities along a longitudinal gradient of glacier influence of two Patagonian systems that differ in glacier cover magnitude and the spatial sequence of lotic and lentic phases. Both glaciers, Torrecillas (~5.5km 2 , Torrecillas system) and Cónico (~0.44km 2 , Baggilt system), are retreating. Longitudinal distribution of benthic invertebrates partially fitted to predictions for glacierized temperate systems, with Diamesinae spp. dominating at closest sites to the Cónico, and Orthocladiinae increasing downstream, but patterns were unclear at Torrecillas. Generalized Linear Model identified chlorophyll a and conductivity as having significant effect on richness and density respectively at Torrecillas; detritus biomass and gravel influenced species richness, and boulder percentage and water temperature affected density, at Baggilt. Canonical Correspondence Analyses integrating benthic biota and environmental variables revealed that a higher environmental heterogeneity at Baggilt, related with spatial dimension (unshaded/shaded reaches, wetland reaches), local resources (detritus, bryophytes) and temperature, probably explained the unexpected high richness in benthic assemblages (67 taxa). Environmental conditions imposed by the lake outlet (proglacial) at Torrecillas resulted in a less diverse community (31 taxa). Finally our results suggest that these isolated, small glacier-fed streams typical of the Patagonian landscape appear highly vulnerable to global warming. Endemic elements could disappear at upper segments being replaced by other species common at rhithral environments, which might increase local diversity (alfa diversity) but decrease regional diversity (gamma diversity). From an ecosystem perspective

Modulation of Fire Regimes by Vegetation and Site Type in Southwestern Patagonia Since 13 ka

Directory of Open Access Journals (Sweden)

Patricio I. Moreno

2018-04-01

Full Text Available The degree to which vegetation and site type have influenced fire regimes through the Holocene has not been investigated in detail in the temperate ecosystems of southern Patagonia. Here we present a first attempt using a paired-basin approach to study the evolution of fire regimes in sectors dominated by humid Nothofagus forests and the xeric Patagonian steppe in the Magallanes region of Chilean Patagonia (51°S. We analyzed sediment cores from two small lakes and a bog located within the same climate zone on opposite sides of the forest-steppe ecotone, ~28 km apart. The position of this biological boundary east of the Andes is controlled by the strength and position of the southern westerly winds, which constitute the sole source of precipitation throughout western Patagonia. Our results indicate that fires have occurred in the study region repeated times over the last ~13,000 years at bi- and tridecadal timescales. Sectors currently dominated by Patagonian steppe feature high frequency and low magnitude of local fires, and vice versa in humid forests. Climate-driven expansion of Nothofagus scrubland/woodland into steppe environments over the last ~4,200 years increased the magnitude and lowered the frequency of fire events, culminating with peak Nothofagus abundance, fire magnitude and frequency during the last millennium. We also detect divergences between lake-based vs. bog-based paleofire histories among paired sites located within the Patagonian steppe, ~12 km apart, which we attribute to local burning of the bog at times of lowered water table. This divergence suggests to us that bog-based vegetation and fire histories exacerbate a local, azonal, signal blurring extra-local or regional regimes, thus accounting for some discrepancies in the Quaternary paleovegetation/paleoclimate literature of southern Patagonia.

The Japanese alga Polysiphonia morrowii (Rhodomelaceae, Rhodophyta) on the South Atlantic Ocean: first report of an invasive macroalga inhabiting oyster reefs

Science.gov (United States)

Croce, M. Emilia; Parodi, Elisa R.

2014-06-01

Conspicuous tufts of the filamentous algae Polysiphonia Greville inhabit the reefs of Crassostrea gigas on the Atlantic Patagonian coast. The population was recorded for the first time in 1994 and identified as P. argentinica. This study exhaustively investigated the morphology and reproduction of specimens and the seasonality of the population. The results revealed the identity of the specimens as the invasive Japanese macroalga Polysiphonia morrowii Harvey, on the basis of several striking features: the setaceous and tufted thalli, the corymbose growing apices, the endogenous axillary branches, the urceolate cystocarps and the sharply pointed branches. Sexual reproduction was evidenced; however, fertile male gametophytes were absent in the samples. The population was found almost all year round, but its abundance became higher in autumn and winter. The present study constitutes the first record of this invasive macroalga on the South Atlantic Ocean; the fourth record of an exotic macroalgal species on the Atlantic Patagonian coast; and the first record of an invasive species related to the establishment of C. gigas in Atlantic Patagonia.

Constraints on deformation of the Southern Andes since the Cretaceous from anisotropy of magnetic susceptibility

Science.gov (United States)

Maffione, Marco; Hernandez-Moreno, Catalina; Ghiglione, Matias C.; Speranza, Fabio; van Hinsbergen, Douwe J. J.; Lodolo, Emanuele

2015-12-01

The southernmost segment of the Andean Cordillera underwent a complex deformation history characterized by alternation of contractional, extensional, and strike-slip tectonics. Key elements of southern Andean deformation that remain poorly constrained, include the origin of the orogenic bend known as the Patagonian Orocline (here renamed as Patagonian Arc), and the exhumation mechanism of an upper amphibolite facies metamorphic complex currently exposed in Cordillera Darwin. Here, we present results of anisotropy of magnetic susceptibility (AMS) from 22 sites in Upper Cretaceous to upper Eocene sedimentary rocks within the internal structural domain of the Magallanes fold-and-thrust belt in Tierra del Fuego (Argentina). AMS parameters from most sites reveal a weak tectonic overprint of the original magnetic fabric, which was likely acquired upon layer-parallel shortening soon after sedimentation. Magnetic lineation from 17 sites is interpreted to have formed during compressive tectonic phases associated to a continuous N-S contraction. Our data, combined with the existing AMS database from adjacent areas, show that the Early Cretaceous-late Oligocene tectonic phases in the Southern Andes yielded continuous contraction, variable from E-W in the Patagonian Andes to N-S in the Fuegian Andes, which defined a radial strain field. A direct implication is that the exhumation of the Cordillera Darwin metamorphic complex occurred under compressive, rather than extensional or strike-slip tectonics, as alternatively proposed. If we agree with recent works considering the curved Magallanes fold-and-thrust belt as a primary arc (i.e., no relative vertical-axis rotation of the limbs occurs during its formation), then other mechanisms different from oroclinal bending should be invoked to explain the documented radial strain field. We tentatively propose a kinematic model in which reactivation of variably oriented Jurassic faults at the South American continental margin controlled

Construction and first atmospheric observations of a high spectral resolution lidar system in Argentina in the frame of a trinational Japanese-Argentinean-Chilean collaboration

Science.gov (United States)

Papandrea, S.; Jin, Y.; Ristori, P.; Otero, L.; Nishizawa, T.; Mizuno, A.; Sugimoto, N.; Quel, E.

2016-05-01

Atmospheric monitoring stations are being developed in Argentina. The most important targets are volcanic ashes, desert aerosols in particular Patagonian dust and biomass burning aerosols. Six stations deployed in the Patagonian Region and Buenos Aires have lidar systems, sun photometers integrated to the AERONET/NASA monitoring network, in situ optical particle analyzers, four solar radiation sensors (pyranometer, UVA, UVB and GUV), and meteorological equipment. The stations are in the main international airports of the Regions (San Carlos de Bariloche, Comodoro Rivadavia, Neuquén, Rio Gallegos) and in Buenos Aires (Aeroparque Jorge Newbery and at CEILAP/CITEDEF). CEILAP and the National Institute of Environmental Studies (NIES) at Tsukuba, Japan developed the first iodine cell-based high spectral resolution lidar (HSRL) in Argentina to add in the lidar network. We upgraded the standard CEILAP multi-wavelength Raman lidar adding the laser frequency tuning system and the 532 iodine-filtered channel at the reception to built the HSRL. HSRL will provide daytime and nighttime direct observation of the aerosol and cloud optical properties (backscatter and extinction) without the pre-assumption of the lidar ratio. This work shows the design and construction of the first Argentinean HSRL. We also show the first lidar observations done in the country with this kind of lidar.

Soft-bottom macrobenthic faunal associations in the southern Chilean glacial fjord complex

Directory of Open Access Journals (Sweden)

Carlos Ríos

2005-12-01

Full Text Available Macrobenthic associations were investigated at 29 sampling stations with a semi-quantitative Agassiz trawl, ranging from the South Patagonian Icefield to the Straits of Magellan in the South Chilean fjord system. A total of 1,895 individuals belonging to 131 species were collected. 19 species belong to colonial organisms, mainly Bryozoa (17 species and Octocorallia (2 species. The phylum Echinodermata was the most diverse in species number (47 species, with asteroids (25 species and ophiuroids (13 species being the best represented within this taxon. Polychaeta was the second dominant group in terms of species richness (46 species. Multidimensional scaling ordination (MDS separated two station groups, one related to fjords and channels off the South Patagonian Icefield and the second one to stations surrounding the Straits of Magellan. 45 species account for 90% of the dissimilarity between these two groups. These differences can mainly be explained by the influence of local environmental conditions determined by processes closely related to the presence/absence of glaciers. Abiotic parameters such as water depth, type of sediment and chemical features of the superficial sediment were not correlated with the numbers of individuals caught by the Agassiz trawl in each group of sampling stations.

Reproductive strategy of the Patagonian catfish Hatcheria macraei.

Science.gov (United States)

Chiarello-Sosa, J M; Battini, M A; Barriga, J P

2016-09-01

This study describes the reproductive strategy of the stream-dwelling catfish Hatcheria macraei in the Pichileufu River, Argentina. Gonad maturity phases, classified on the basis of histological analysis, stages of gamete development and the frequency distribution of oocyte size, were correlated with macroscopic features of the gonads. Hatcheria macraei has a cystovarian ovary, asynchronous oocyte development and lobular testes. Five oocyte and four spermatogenic stages were identified and related to macroscopic gonad characteristics, making it possible to divide gonad development into five phases for females and males. Mature oocyte diameter ranged from 922 to 1935 µm. Absolute fecundity in mature females varied from 115 to 480 oocytes. Hatcheria macraei has multiple spawning during a protracted reproductive season that extends from December to April. This, together with its small size, is characteristic of an opportunistic reproductive strategy, commonly found in species that inhabit adverse and unpredictable environments, such as the low-order rivers of Patagonia. © 2016 The Fisheries Society of the British Isles.

Glacial lakes of the Central and Patagonian Andes

Science.gov (United States)

Wilson, Ryan; Glasser, Neil F.; Reynolds, John M.; Harrison, Stephan; Anacona, Pablo Iribarren; Schaefer, Marius; Shannon, Sarah

2018-03-01

The prevalence and increased frequency of high-magnitude Glacial Lake Outburst Floods (GLOFs) in the Chilean and Argentinean Andes suggests this region will be prone to similar events in the future as glaciers continue to retreat and thin under a warming climate. Despite this situation, monitoring of glacial lake development in this region has been limited, with past investigations only covering relatively small regions of Patagonia. This study presents new glacial lake inventories for 1986, 2000 and 2016, covering the Central Andes, Northern Patagonia and Southern Patagonia. Our aim was to characterise the physical attributes, spatial distribution and temporal development of glacial lakes in these three sub-regions using Landsat satellite imagery and image datasets available in Google Earth and Bing Maps. Glacial lake water volume was also estimated using an empirical area-volume scaling approach. Results reveal that glacial lakes across the study area have increased in number (43%) and areal extent (7%) between 1986 and 2016. Such changes equate to a glacial lake water volume increase of 65 km3 during the 30-year observation period. However, glacial lake growth and emergence was shown to vary sub-regionally according to localised topography, meteorology, climate change, rate of glacier change and the availability of low gradient ice areas. These and other factors are likely to influence the occurrence of GLOFs in the future. This analysis represents the first large-scale census of glacial lakes in Chile and Argentina and will allow for a better understanding of lake development in this region, as well as, providing a basis for future GLOF risk assessments.

Checklist of helminths found in Patagonian wild mammals.

Science.gov (United States)

Fugassa, Martin H

2015-09-03

Using available reports, a checklist of the recorded helminth parasites of wild mammals from Patagonia was generated. Records of parasites found in Patagonia were included, together with records from mammals in áreas outside of Patagonia but whose range extends into Patagonia. Information about the host, localities, and references were also included. A total of 1323 records (224 Cestoda, 167 Trematoda, 894 Nematoda, 34 Acanthocephala, and 4 Pentastomida) belonging to 452 helminth species (77 Cestoda, 76 Trematoda, 277 Nematoda, 21 Acanthocephala, and 1 Pentastomida) found in 57 native mammals (22 Rodentia, 4 Didelphimorphia 1 Microbiotheria, 7 Chiroptera, 5 Cingulata, and 13 Carnivora) were listed. However, only 10.6 % of the reports were conducted on samples from Patagonia and corresponded to 25% of mammals in the region. In addition, many studies were made on a few species and, for example, 52% corresponded to studies made on Lama guanicoe. This suggests the need to increase efforts to know the parasitic fauna in a peculiar region as is the Patagonia. This is the first compilation of the helminth parasites of mammals in Argentine Patagonia and is important for parasitological and paleoparasitological studies.

Combined U-Pb SHRIMP and Hf isotope study of the Late Paleozoic Yaminué Complex, Rio Negro Province, Argentina: Implications for the origin and evolution of the Patagonia composite terrane

Directory of Open Access Journals (Sweden)

Carlos J. Chernicoff

2013-01-01

Combining geological and isotope data, as well as geophysical models, we identify the Yaminué Complex within the La Esperanza-Yaminué crustal block flanked by two other, distinct crustal blocks: the Eastern block which forms part of the Patagonia terrane sensu stricto, located in the eastern Patagonian region, and the Western block forming part of the Southern Patagonia terrane. Their origins and timing of amalgamation to form the Patagonia composite terrane are also discussed.

Respuesta barotrópica de los golfos norpatagónicos argentinos forzados por mareas y vientos Barotropic response of north Patagonian gulfs in Argentina to tidal and wind forcing

Directory of Open Access Journals (Sweden)

Mariano H Tonini

2011-11-01

Full Text Available En este trabajo se presentan los resultados de un modelo hidrodinámico barotrópico de alta resolución no-lineal tridimensional para examinar la respuesta de los golfos norpatagónicos argentinos, San Matías (GSM, Nuevo (GN y San José (GSJ, ante forzante de marea y patrones idealizados de viento superficial. La estructura de la circulación inducida por el viento predominante (Oeste en los tres golfos consiste en dos giros independientes: uno anticiclónico en el Oeste con una corriente costera más intensa que fluye hacia el sur y un retorno más débil por el centro de los golfos y otro giro ciclónico en el Este, que establece la conexión con la Plataforma en el caso del GSM. El GN y GSJ tienen la comunicación con el exterior muy restringida. La inclusión de efectos disipativos producidos por la marea reduce la intensidad de los giros, pero la estructura espacial de la circulación permanece. Si se incrementa la magnitud del viento se intensifican principalmente los giros anticiclónicos y el transporte de intercambio en la boca del GSM y se profundiza la capa superficial de Ekman. En los experimentos forzados con vientos meridionales la circulación media se divide en dos giros cuyo sentido de circulación depende de la dirección del viento: un giro Norte ciclónico (anticiclónico y un giro Sur anticiclónico (ciclónico para vientos del Sur (Norte. Cuando los golfos son forzados simultáneamente por marea y vientos, las corrientes residuales de marea dominan la circulación media y contribuyen a un mayor aislamiento dinámico de los mismos con la plataforma exterior.This work presents the results of a high resolution three dimensional non-linear barotropic hydrodynamic model used to examine the response of three north Patagonian gulfs in Argentina (San Matías, SMG; Nuevo, NG; and San José, SJG forced by tides and idealized patterns of surface winds. The structure of the circulation induced by the dominant winds (Westerly in all

An Assessment of Oil Pollution in the Coastal Zone of Patagonia, Argentina

Science.gov (United States)

Commendatore, Marta Graciela; Esteves, José Luis

2007-11-01

The Patagonian coast is considered a relatively pristine environment. However, studies conducted along coastal Patagonia have showed hydrocarbon pollution mostly concentrated at ports that have fishing, oil loading, general merchant, and/or tourist activities. A high value of total aliphatic hydrocarbons (TAH) was found at the Rawson fishing port (741 μg/g dw). In other ports with and without petroleum-related activities, hydrocarbon values were approximately 100 μg/g dw. The highest values for TAH and total aromatic hydrocarbons (TArH) were found in Faro Aristizábal, north of San Jorge gulf (1304 and 737 μg/g dw, respectively). This is very likely the result of petroleum-related activities at the Comodoro Rivadavia, Caleta Cordova, and Caleta Olivia ports located within this gulf. In other coastal areas away from potential anthropogenic sources, hydrocarbon values were less than 2 and 3 μg/g dw for TAH and TArH, respectively. This review of published and unpublished information suggests that ports are important oil pollution sources in the Patagonian coast. More detailed studies are needed to evaluate the area affected by port activities, to understand the mechanisms of hydrocarbon distribution in surrounding environments, and to assess bioaccumulation in marine organisms. Despite that some regulations exist to control oil pollution derived from port and docked vessel activities, new and stricter management guidelines should be implemented.

Assessing the performance of macroinvertebrate metrics in the Challhuaco-Ñireco System (Northern Patagonia, Argentina

Directory of Open Access Journals (Sweden)

Melina Mauad

2015-09-01

Full Text Available ABSTRACT Seven sites were examined in the Challhuaco-Ñireco system, located in the reserve of the Nahuel Huapi National Park, however part of the catchment is urbanized, being San Carlos de Bariloche (150,000 inhabitants placed in the lower part of the basin. Physico-chemical variables were measured and benthic macroinvertebrates were collected during three consecutive years at seven sites from the headwater to the river outlet. Sites near the source of the river were characterised by Plecoptera, Ephemeroptera, Trichoptera and Diptera, whereas sites close to the river mouth were dominated by Diptera, Oligochaeta and Mollusca. Regarding functional feeding groups, collector-gatherers were dominant at all sites and this pattern was consistent among years. Ordination Analysis (RDA revealed that species assemblages distribution responded to the climatic and topographic gradient (temperature and elevation, but also were associated with variables related to human impact (conductivity, nitrate and phosphate contents. Species assemblages at headwaters were mostly represented by sensitive insects, whereas tolerant taxa such as Tubificidae, Lumbriculidae, Chironomidae and crustacean Aegla sp. were dominant at urbanised sites. Regarding macroinvertebrate metrics employed, total richness, EPT taxa, Shannon diversity index and Biotic Monitoring Patagonian Stream index resulted fairly consistent and evidenced different levels of disturbances at the stream, meaning that this measures are suitable for evaluation of the status of Patagonian mountain streams.

Forest Typification to Characterize the Structure and Composition of Old-growth Evergreen Forests on Chiloe Island, North Patagonia (Chile

Directory of Open Access Journals (Sweden)

Jan R. Bannister

2013-11-01

Full Text Available The Evergreen forest type develops along the Valdivian and North-Patagonian phytogeographical regions of the south-central part of Chile (38° S–46° S. These evergreen forests have been scarcely studied south of 43° S, where there is still a large area made up of old-growth forests. Silvicultural proposals for the Evergreen forest type have been based on northern Evergreen forests, so that the characterization of the structure and composition of southern Evergreen forests, e.g., their typification, would aid in the development of appropriate silvicultural proposals for these forests. Based on the tree composition of 46 sampled plots in old-growth forests in an area of >1000 ha in southern Chiloé Island (43° S, we used multivariate analyses to define forest groups and to compare these forests with other evergreen forests throughout the Archipelago of North-Patagonia. We determined that evergreen forests of southern Chiloé correspond to the North-Patagonian temperate rainforests that are characterized by few tree species of different shade tolerance growing on fragile soils. We discuss the convenience of developing continuous cover forest management for these forests, rather than selective cuts or even-aged management that is proposed in the current legislation. This study is a contribution to forest classification for both ecologically- and forestry-oriented purposes.

Morphological variability, spatial distribution and abundance of Helicostomella species (Ciliophora: Tintinnina in relation to environmental factors (Argentine shelf; 40-55°S

Directory of Open Access Journals (Sweden)

Luciana F. Santoferrara

2009-12-01

Full Text Available For the first time a taxonomic and ecological study of species belonging to Helicostomella was performed over a mesoscale spatial distribution by examining ca. 3000 loricae collected in Argentine shelf waters during the austral autumn. Microscopic and statistical analysis revealed that the general shape and the oral diameter remained practically constant in the whole area surveyed, despite a continuous length fluctuation of ca. 300 µm, which includes the entire range present in eight previously reported species. Consequently, we consider that the genus may be represented only by H. subulata, whose strong fluctuations in length (mostly attributed to an increase in the collar length, density and biomass seem to respond to temperature, food availability and front-related processes. In Buenos Aires coastal waters associated with a quasi permanent estuarine front (40-40.5°S, mixed conditions would favour moderate abundances of long loricae, whereas in northern (42.5-45.5°S and southern (46-54.5°S Patagonian waters, high (103 ind. L-1 and low (< 5 ind. L-1 densities of short loricae seem to be a consequence of stratification and encystment, respectively. The non-occurrence of the species at 41-42°S, together with a three-fold reduction in length-related parameters between specimens from Buenos Aires and Patagonian waters, suggests a disjunct distribution.

Spatial and temporal uplift history of South America from calibrated drainage analysis

Science.gov (United States)

Rodríguez Tribaldos, V.; White, N. J.; Roberts, G. G.; Hoggard, M. J.

2017-06-01

A multidisciplinary approach is used to analyze the Cenozoic uplift history of South America. Residual depth anomalies of oceanic crust abutting this continent help to determine the pattern of present-day dynamic topography. Admittance analysis and crustal thickness measurements indicate that the elastic thickness of the Borborema and Altiplano regions is ≤10 km with evidence for sub-plate support at longer wavelengths. A drainage inventory of 1827 river profiles is assembled and used to investigate landscape development. Linear inverse modeling enables river profiles to be fitted as a function of the spatial and temporal history of regional uplift. Erosional parameters are calibrated using observations from the Borborema Plateau and tested against continent-wide stratigraphic and thermochronologic constraints. Our results predict that two phases of regional uplift of the Altiplano plateau occurred in Neogene times. Regional uplift of the southern Patagonian Andes also appears to have occurred in Early Miocene times. The consistency between observed and predicted histories for the Borborema, Altiplano, and Patagonian plateaux implies that drainage networks record coherent signals that are amenable to simple modeling strategies. Finally, the predicted pattern of incision across the Amazon catchment constrains solid sedimentary flux at the Foz do Amazonas. Observed and calculated flux estimates match, suggesting that erosion and deposition were triggered by regional Andean uplift during Miocene times.

Reproductive traits of the small Patagonian octopus Octopus tehuelchus

Science.gov (United States)

Storero, Lorena P.; Narvarte, Maite A.; González, Raúl A.

2012-12-01

This study evaluated the reproductive features of Octopus tehuelchus in three coastal environments of San Matías Gulf (Patagonia). Monthly samples of O. tehuelchus were used to estimate size at maturity, compare seasonal changes in oocyte size frequency distributions between sites as well as oocyte number and size between female maturity stage and sites. Females in Islote Lobos had a smaller size at maturity than females in San Antonio Bay and El Fuerte, probably as a consequence of a generally smaller body size. Males in San Antonio Bay were smaller at maturity than females. O. tehuelchus is a simultaneous terminal spawner. Fecundity (expressed as number of vitellogenic oocytes in ovary) was lower in Islote Lobos, and an increase in oocyte number in relation to female total weight was found. Females in San Antonio Bay had the largest oocytes, which may indicate higher energy reserves for the embryo and therefore higher juvenile survival. There was a close relationship between reproduction, growth and condition, represented as size at maturity, number and size of vitellogenic oocytes and period of maturity and spawning. Given the local variation in some reproductive features of O. tehuelchus, studies should focus on the environmental factors, which bring about this variation, and on how it affects the dynamics of local populations.

Genomic evidence for the Pleistocene and recent population history of Native Americans

DEFF Research Database (Denmark)

Raghavan, Maanasa; Steinruecken, Matthias; Harris, Kelley

2015-01-01

Howand when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand....... Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericues and South American Fuego-Patagonians, are not directly...

Spoilage yeasts in Patagonian winemaking: molecular and physiological features of Pichia guilliermondii indigenous isolates Levaduras contaminantes en vinos patagónicos: características moleculares y fisiológicas de los aislamientos indígenas de Picchia guilliermondii

Directory of Open Access Journals (Sweden)

C. A. Lopes

2009-09-01

Full Text Available Yeasts belonging to the genus Dekkera/Brettanomyces, especially the species Dekkera bruxellensis, have long been associated with the production of volatile phenols responsible for off-flavour in wines. According to recent reports, the species Pichia guilliermondii could also produce these compounds at the initial stages of fermentation. Based on the abundance of P. guilliermondii in Patagonian winemaking, we decided to study the relevance of indigenous isolates belonging to this species as wine spoilage yeast. Twenty-three indigenous isolates obtained from grape surfaces and red wine musts were analyzed in their capacity to produce volatile phenols on grape must. The relationship between molecular Random Amplified Polymorphic DNA (RAPD and physiological (killer biotype patterns detected in indigenous populations of P. guilliermondii and volatile phenol production was also evaluated. Different production levels of 4-ethylphenol, 4-vinylguaiacol and 4-ethylguaiacol were detected among the isolates; however, the values were always lower than those produced by the D. bruxellensis reference strain in the same conditions. High levels of 4-vinylphenol were detected among P. guilliermondii indigenous isolates. The combined use of RAPD and killer biotype allowed us to identify the isolates producing the highest volatile phenol levels.Las levaduras del género Dekkera/Brettanomyces, sobre todo la especie Dekkera bruxellensis, siempre han sido asociadas con la producción de fenoles volátiles responsables de aromas desagradables en los vinos. Recientemente, se ha demostrado que la especie Pichia guilliermondii también es capaz de producir estos compuestos, particularmente durante las etapas iniciales de la fermentación. Dada la abundancia de P. guilliermondii en las bodegas de la Patagonia, se decidió evaluar la importancia de algunos aislamientos indígenas de esta especie como levaduras alterantes de vinos regionales. Se evaluó la capacidad de

Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

Science.gov (United States)

Yusseppone, Maria S.; Rocchetta, Iara; Sabatini, Sebastian E.; Luquet, Carlos M.; Ríos de Molina, Maria del Carmen; Held, Christoph; Abele, Doris

2018-01-01

Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L), hypoxia (2 mg O2/L), and normoxia (9 mg O2/L). Specifically, we investigated the expression of an alternative oxidase (AOX) pathway assumed to shortcut the regular mitochondrial electron transport system (ETS) during metabolic rate depression (MRD) in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP) and succinate dehydrogenase (SDH) in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH) activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx) expression] and apoptotic intensity (caspase 3/7 activity) decreased, whereas an unfolded protein response (HSP90) was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks. PMID:29527172

Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

Directory of Open Access Journals (Sweden)

Maria S. Yusseppone

2018-02-01

Full Text Available Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L, hypoxia (2 mg O2/L, and normoxia (9 mg O2/L. Specifically, we investigated the expression of an alternative oxidase (AOX pathway assumed to shortcut the regular mitochondrial electron transport system (ETS during metabolic rate depression (MRD in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP and succinate dehydrogenase (SDH in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx expression] and apoptotic intensity (caspase 3/7 activity decreased, whereas an unfolded protein response (HSP90 was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks.

First South American Agathis (Araucariaceae), Eocene of Patagonia.

Science.gov (United States)

Wilf, Peter; Escapa, Ignacio H; Cúneo, N Rubén; Kooyman, Robert M; Johnson, Kirk R; Iglesias, Ari

2014-01-01

Agathis is an iconic genus of large, ecologically important, and economically valuable conifers that range over lowland to upper montane rainforests from New Zealand to Sumatra. Exploitation of its timber and copal has greatly reduced the genus's numbers. The early fossil record of Agathis comes entirely from Australia, often presumed to be its area of origin. Agathis has no previous record from South America. We describe abundant macrofossils of Agathis vegetative and reproductive organs, from early and middle Eocene rainforest paleofloras of Patagonia, Argentina. The leaves were formerly assigned to the New World cycad genus Zamia. Agathis zamunerae sp. nov. is the first South American occurrence and the most complete representation of Agathis in the fossil record. Its morphological features are fully consistent with the living genus. The most similar living species is A. lenticula, endemic to lower montane rainforests of northern Borneo. Agathis zamunerae sp. nov. demonstrates the presence of modern-aspect Agathis by 52.2 mya and vastly increases the early range and possible areas of origin of the genus. The revision from Zamia breaks another link between the Eocene and living floras of South America. Agathis was a dominant, keystone element of the Patagonian Eocene floras, alongside numerous other plant taxa that still associate with it in Australasia and Southeast Asia. Agathis extinction in South America was an integral part of the transformation of Patagonian biomes over millions of years, but the living species are disappearing from their ranges at a far greater rate.

HLA-DRB1 alleles in four Amerindian populations from Argentina and Paraguay

Science.gov (United States)

2009-01-01

The major histocompatibility complex (MHC) is one of the biological systems of major polymorphisms. The study of HLA class II variability has allowed the identification of several alleles that are characteristic to Amerindian populations, and it is an excellent tool to define the relations and biological affinities among them. In this work, we analyzed the allelic distribution of the HLA-DRB1 class II locus in four Amerindian populations: Mapuche (n = 34) and Tehuelche (n = 23) from the Patagonian region of Argentina, and Wichi SV (n = 24) and Lengua (n = 17) from the Argentinean and Paraguayan Chaco regions, respectively. In all of these groups, relatively high frequencies of Amerindian HLA-DRB1 alleles were observed (DRB1*0403, DRB1*0407, DRB1*0411, DRB1*0417, DRB1*0802, DRB1*0901, DRB1*1402, DRB1*1406 and DRB1*1602). However, we also detected the presence of non-Amerindian variants in Mapuche (35%) and Tehuelche (22%). We compared our data with those obtained in six indigenous groups of the Argentinean Chaco region and in a sample from Buenos Aires City. The genetic distance dendrogram showed a clear-cut division between the Patagonian and Chaco populations, which formed two different clusters. In spite of their linguistic differences, it can be inferred that the biological affinities observed are in concordance with the geographic distributions and interethnic relations established among the groups studied. PMID:21637670

Potential and Limitations of Photometric Reconstruction Through a Flock of Dove Cubesats

Science.gov (United States)

Altena, B.; Mousivand, A.; Mascaro, J.; Kääb, A.

2017-10-01

When Earth observation satellite systems are designed, one typically prefers a sun-synchronous orbit. However, the first generations of cubesats from Planet were deployed out of the International Space Station (ISS) and therefore do not obey such an orbit. Their configuration samples at different local times within the mid-latitudes. Consequently, it is in theory possible to exploit photometric techniques and extract highly detailed topographic information. In this study we demonstrate and explore photometry based on Planet cubesat images for Tyndall glacier at the Southern Patagonian icefield, and Zhadang glacier situated on the Tibetan plateau.

Regional Extinctions and Quaternary Shifts in the Geographic Range of Lestodelphys halli, the Southernmost Living Marsupial: Clues for Its Conservation.

Directory of Open Access Journals (Sweden)

Anahí E Formoso

Full Text Available The Patagonian opossum (Lestodelphys halli, the southernmost living marsupial, inhabits dry and open environments, mainly in the Patagonian steppe (between ~32 °S and ~49 °S. Its rich fossil record shows its occurrence further north in Central Argentina during the Quaternary. The paleoenvironmental meaning of the past distribution of L. halli has been mostly addressed in a subjective framework without an explicit connection with the climatic "space" currently occupied by this animal. Here, we assessed the potential distribution of this species and the changes occurred in its geographic range during late Pleistocene-Holocene times and linked the results obtained with conservation issues. To this end, we generated three potential distribution models with fossil records and three with current ones, using MaxEnt software. These models showed a decrease in the suitable habitat conditions for the species, highlighting a range shift from Central-Eastern to South-Western Argentina. Our results support that the presence of L. halli in the Pampean region during the Pleistocene-Holocene can be related to precipitation and temperature variables and that its current presence in Patagonia is more related to temperature and dominant soils. The models obtained suggest that the species has been experiencing a reduction in its geographic range since the middle Holocene, a process that is in accordance with a general increase in moisture and temperature in Central Argentina. Considering the findings of our work and the future scenario of global warming projected for Patagonia, we might expect a harsh impact on the distribution range of this opossum in the near future.

Regional Extinctions and Quaternary Shifts in the Geographic Range of Lestodelphys halli, the Southernmost Living Marsupial: Clues for Its Conservation

Science.gov (United States)

Formoso, Anahí E.; Martin, Gabriel M.; Teta, Pablo; Carbajo, Aníbal E.; Sauthier, Daniel E. Udrizar; Pardiñas, Ulyses F. J.

2015-01-01

The Patagonian opossum (Lestodelphys halli), the southernmost living marsupial, inhabits dry and open environments, mainly in the Patagonian steppe (between ~32°S and ~49°S). Its rich fossil record shows its occurrence further north in Central Argentina during the Quaternary. The paleoenvironmental meaning of the past distribution of L. halli has been mostly addressed in a subjective framework without an explicit connection with the climatic “space” currently occupied by this animal. Here, we assessed the potential distribution of this species and the changes occurred in its geographic range during late Pleistocene-Holocene times and linked the results obtained with conservation issues. To this end, we generated three potential distribution models with fossil records and three with current ones, using MaxEnt software. These models showed a decrease in the suitable habitat conditions for the species, highlighting a range shift from Central-Eastern to South-Western Argentina. Our results support that the presence of L. halli in the Pampean region during the Pleistocene-Holocene can be related to precipitation and temperature variables and that its current presence in Patagonia is more related to temperature and dominant soils. The models obtained suggest that the species has been experiencing a reduction in its geographic range since the middle Holocene, a process that is in accordance with a general increase in moisture and temperature in Central Argentina. Considering the findings of our work and the future scenario of global warming projected for Patagonia, we might expect a harsh impact on the distribution range of this opossum in the near future. PMID:26203650

Are owl pellets good estimators of prey abundance?

Directory of Open Access Journals (Sweden)

Analia Andrade

2016-07-01

Full Text Available Some ecologists have been skeptics about the use of owl pellets to estimate small mammal’s fauna. This is due to the assumptions required by this method: (a that owls hunt at random, and (b that pellets represent a random sample from the environment. We performed statistical analysis to test these assumptions and to assess the effectiveness of Barn owl pellets as a useful estimator of field abundances of its preys. We used samples collected in the arid Extra-Andean Patagonia along an altitudinal environmental gradient from lower Monte ecoregion to upper Patagonian steppe ecoregion, with a mid-elevation ecotone. To test if owls hunt at random, we estimated expected pellet frequency by creating a distribution of random pellets, which we compared with data using a simulated chi-square. To test if pellets represent a random sample from the environment, differences between ecoregions were evaluated by PERMANOVAs with Bray–Curtis dissimilarities. We did not find evidence that owls foraged non-randomly. Therefore, we can assume that the proportions of the small mammal’s species in the diet are representative of the proportions of the species in their communities. Only Monte is different from other ecoregions. The ecotone samples are grouped with those of Patagonian steppes. There are no real differences between localities in the small mammal’s abundances in each of these ecoregions and/or Barn owl pellets cannot detect patterns at a smaller spatial scale. Therefore, we have no evidence to invalidate the use of owl pellets at an ecoregional scale.

Impact of ice melting on distribution of particulate sterols in glacial fjords of Chilean Patagonia

Science.gov (United States)

Gutiérrez, Marcelo H.; Riquelme, Pablo; Pantoja, Silvio

2016-04-01

We analyzed variability in abundance and composition of sterols in waters of the fjord adjacent to glacier Jorge Montt, one of the fastest retreated glaciers in Patagonian Icefields. The study was carried out between August 2012 and November 2013 under different meltwater scenarios. Distribution of sterols in surface and bottom waters was determined by Gas Chromatography coupled to Mass Spectrometry. Sterol concentration ranged from 18 to 1726 ng/L in surface and bottom waters and was positive correlated with chlorophyll-a concentration. Under high melting conditions in austral summer, surface meltwaters showed high concentrations of sterols and were dominated by methylene-cholesterol, a representative sterol of centric diatoms. In the area near open ocean and in austral autumn, winter and spring in proglacial fjord, lower sterol concentrations in surface waters were accompanied by other microalgae sterols and an increase in relative abundance of plant sterols, evidencing a different source of organic matter. In autumn, when high meltwater flux was also evidenced, presence of stanols and an uncommon tri-unsaturated sterol suggests influence of meltwaters in composition of sterols in the downstream fjord. We conclude that ice melting can modify sterol composition by setting conditions for development of a singular phytoplankton population able to thrive in surface meltwater and by carrying glacier organic matter into Patagonian glacial fjords. In projected ice melting scenario, these changes in organic matter quantity and quality can potentially affect availability of organic substrates for heterotrophic activity and trophic status of glacial fjords. This research was funded by COPAS Sur-Austral (PFB-31)

Descripción de una nueva especie del género Agrotis (Lepidoptera: Noctuidae Description of a new species of the genus Agrotis (Lepidoptera: Noctuidae

Directory of Open Access Journals (Sweden)

Germán San Blas

2011-06-01

Full Text Available Se describe e ilustra una nueva especie de Noctuidae: Agrotis leucovenata sp. nov. Esta se distribuye en la estepa patagónica de la provincia de Neuquén, en Argentina. Se discuten los caracteres propios de la nueva especie, que la diferencian de otras especies similares del género.Agrotis leucovenata sp. nov., a new species of Noctuidae, is described and illustrated. This species is distributed in the Patagonian steppe of Neuquén province, Argentina. Characteristic traits of the new species which differentiate it from similar species of the genus are discussed.

Structure and dynamics of Antarctic fish neuroglobin assessed by computer simulations.

Science.gov (United States)

Boron, Ignacio; Russo, Roberta; Boechi, Leonardo; Cheng, C-H Christina; di Prisco, Guido; Estrin, Darío A; Verde, Cinzia; Nadra, Alejandro D

2011-03-01

Neuroglobin (Ngb) is a heme protein, highly conserved along evolution, predominantly found in the nervous system. It is upregulated by hypoxia and ischemia and may have a neuroprotective role under hypoxic stress. Although many other roles have been proposed, the physiological function is still unclear. Antarctic icefishes lack hemoglobin and some species also lack myoglobin, but all have Ngb and thus may help the elucidation of Ngb function. We present the first theoretically derived structure of fish Ngb and describe its behavior using molecular dynamics simulations. Specifically, we sequenced and analyzed Ngbs from a colorless-blooded Antarctic icefish species Chaenocephalus aceratus and a related red-blooded species (Dissostichus mawsoni). Both fish Ngbs are 6-coordinated but have some peculiarities that differentiate them from mammalian counterparts: they have extensions in the N and C termini that can interact with the EF loop, and a gap in the alignment that changes the CD-region structure/dynamics that has been found to play a key role in human neuroglobin. Our results suggest that a single mutation between both fish Ngbs is responsible for significant difference in the behavior of the proteins. The functional role of these characteristics is discussed. Copyright © 2011 Wiley Periodicals, Inc.

The MIS 3 maximum of the Torres del Paine and Última Esperanza ice lobes in Patagonia and the pacing of southern mountain glaciation

Science.gov (United States)

García, Juan-Luis; Hein, Andrew S.; Binnie, Steven A.; Gómez, Gabriel A.; González, Mauricio A.; Dunai, Tibor J.

2018-04-01

The timing, structure and termination of the last southern mountain glaciation and its forcing remains unclear. Most studies have focused on the global Last Glacial Maximum (LGM; 26.5-19 ka) time period, which is just part of the extensive time-frame within the last glacial period, including Marine Isotope Stages 3 and 4. Understanding the glacial fluctuations throughout the glacial period is a prerequisite for uncovering the cause and climate mechanism driving southern glaciation and the interhemispheric linkages of climate change. Here, we present an extensive (n = 65) cosmogenic 10Be glacier chronology derived from moraine belts marking the pre-global LGM extent of the former Patagonian Ice Sheet in southernmost South America. Our results show the mountain ice sheet reached its maximum extent at 48.0 ± 1.8 ka during the local LGM, but attained just half this extent at 21.5 ± 1.8 ka during the global LGM. This finding, supported by nearby glacier chronologies, indicates that at orbital time scales, the southern mid-latitude glaciers fluctuated out-of-phase with northern hemisphere ice sheets. At millennial time-scales, our data suggest that Patagonian and New Zealand glaciers advanced in unison with cold Antarctic stadials and reductions in Southern Ocean sea surface temperatures. This implies a southern middle latitudes-wide millennial rhythm of climate change throughout the last glacial period linked to the north Atlantic by the bipolar seesaw. We suggest that winter insolation, acting alongside other drivers such as the strength and/or position of the southern westerlies, controlled the extents of major southern mountain glaciers such as those in southernmost South America.

Ceratopetalum (Cunoniaceae) fruits of Australasian affinity from the early Eocene Laguna del Hunco flora, Patagonia, Argentina.

Science.gov (United States)

Gandolfo, María A; Hermsen, Elizabeth J

2017-03-01

Radially symmetrical, five-winged fossil fruits from the highly diverse early Eocene Laguna del Hunco flora of Chubut Province, Patagonia, Argentina, are named, described and illustrated. The main goals are to assess the affinities of the fossils and to place them in an evolutionary, palaeoecological and biogeographic context. Specimens of fossil fruits were collected from the Tufolitas Laguna del Hunco. They were prepared, photographed and compared with similar extant and fossil fruits using published literature. Their structure was also evaluated by comparing them with that of modern Ceratopetalum (Cunoniaceae) fruits through examination of herbarium specimens. The Laguna del Hunco fossil fruits share the diagnostic features that characterize modern and fossil Ceratopetalum (symmetry, number of fruit wings, presence of a conspicuous floral nectary and overall venation pattern). The pattern of the minor wing (sepal) veins observed in the Patagonian fossil fruits is different from that of modern and previously described fossil Ceratopetalum fruits; therefore, a new fossil species is recognized. An apomorphy (absence of petals) suggests that the fossils belong within crown-group Ceratopetalum . The Patagonian fossil fruits are the oldest known record for Ceratopetalum . Because the affinities, provenance and age of the fossils are so well established, this new Ceratopetalum fossil species is an excellent candidate for use as a calibration point in divergence dating studies of the family Cunoniaceae. It represents the only record of Ceratopetalum outside Australasia, and further corroborates the biogeographic connection between the Laguna del Hunco flora and ancient and modern floras of the Australasian region. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company.

An Analysis of Mass Balance of Chilean Glaciers

Science.gov (United States)

Ambinakudige, S.; Tetteh, L.

2013-12-01

Glaciers in Chile range from very small glacierets found on the isolated volcanoes of northern Chile to the 13,000 sq.km Southern Patagonian Ice Field. Regular monitoring of these glaciers is very important as they are considered as sensitive indicators of climate change. Millions of people's lives are dependent on these glaciers for fresh water and irrigation purpose. In this study, mass balances of several Chilean glaciers were estimated using Aster satellite images between 2007 and 2012. Highly accurate DEMs were created with supplementary information from IceSat data. The result indicated a negative mass balance for many glaciers indicating the need for further monitoring of glaciers in the Andes.

Surviving historical Patagonian landscapes and climate: molecular insights from Galaxias maculatus

Directory of Open Access Journals (Sweden)

Carrea Cecilia

2010-03-01

Full Text Available Abstract Background The dynamic geological and climatic histories of temperate South America have played important roles in shaping the contemporary distributions and genetic diversity of endemic freshwater species. We use mitochondria and nuclear sequence variation to investigate the consequences of mountain barriers and Quaternary glacial cycles for patterns of genetic diversity in the diadromous fish Galaxias maculatus in Patagonia (~300 individuals from 36 locations. Results Contemporary populations of G. maculatus, east and west of the Andes in Patagonia, represent a single monophyletic lineage comprising several well supported groups. Mantel tests using control region data revealed a strong positive relationship when geographic distance was modeled according to a scenario of marine dispersal. (r = 0.69, P = 0.055. By contrast, direct distance between regions was poorly correlated with genetic distance (r = -0.05, P = 0.463. Hierarchical AMOVAs using mtDNA revealed that pooling samples according to historical (pre-LGM oceanic drainage (Pacific vs. Atlantic explained approximately four times more variance than pooling them into present-day drainage (15.6% vs. 3.7%. Further post-hoc AMOVA tests revealed additional genetic structure between populations east and west of the Chilean Coastal Cordillera (coastal vs. interior. Overall female effective population size appears to have remained relatively constant until roughly 0.5 Ma when population size rapidly increased several orders of magnitude [100× (60×-190×] to reach contemporary levels. Maximum likelihood analysis of nuclear alleles revealed a poorly supported gene tree which was paraphyletic with respect to mitochondrial-defined haplogroups. Conclusions First diversifying in the central/north-west region of Patagonia, G. maculatus extended its range into Argentina via the southern coastal regions that join the Pacific and Atlantic oceans. More recent gene flow between northern populations involved the most ancient and most derived lineages, and was likely facilitated by drainage reversal(s during one or more cooling events of the late Pleistocene. Overall female effective population size represents the end result of a widespread and several hundred-fold increase over approximately 0.5 Ma, spanning several climatic fluctuations of the Pleistocene. The minor influence of glacial cycles on the genetic structure and diversity of G. maculatus likely reflects the access to marine refugia during repeated bouts of global cooling. Evidence of genetic structure that was detected on a finer scale between lakes/rivers is most likely the result of both biological attributes (i.e., resident non-migratory behavior and/or landlocking and natal homing in diadromous populations, and the Coastal Cordillera as a dispersal barrier.

Availability of vitamin D photoconversion weighted UV radiation in southern South America.

Science.gov (United States)

Diaz, Susana; Vernet, Maria; Paladini, Alejandro; Fuenzalida, Humberto; Deferrari, Guillermo; Booth, Charles R; Cabrera, Sergio; Casiccia, Claudio; Dieguez, Maria; Lovengreen, Charlotte; Pedroni, Jorge; Rosales, Alejandro; Vrsalovic, Jazmin

2011-12-01

Ultraviolet radiation (UVR) plays a key role in several biological functions, including human health. Skin exposure to UVR is the main factor in vitamin D photoconversion. There is also evidence relating low levels of vitamin D with certain internal cancers, mainly colon, breast and prostate, as well as other diseases. Several epidemiological studies have shown an inverse relationship between the above-mentioned diseases and latitude, in accordance with the ultraviolet radiation latitudinal gradient. The aim of this study is to determine whether UV irradiance levels in the southern South America are sufficient to produce suitable levels of vitamin D year around. For this purpose, vitamin D photoconversion weighted-irradiance was analyzed between S.S. de Jujuy (24.17°S, 65.02°W) and Ushuaia (54° 50'S, 68° 18'W). In addition to irradiance, skin type and area of body exposed to sunlight are critical factors in vitamin D epidemiology. Due to a broad ethnic variability, it was assumed that the skin type in this region varies between II and V (from the most to the less sensitive). All sites except South Patagonia indicate that skin II under any condition of body area exposure and skin V when exposing head, hands, arms and legs, would produce suitable levels of vitamin D year round (except for some days in winter at North Patagonian sites). At South Patagonian sites, minimum healthy levels of vitamin D year round can be reached only by the more sensitive skin II type, if exposing head, hands, arms and legs, which is not a realistic scenario during winter. At these southern latitudes, healthy vitamin D levels would not be obtained between mid May and beginning of August if exposing only the head. Skin V with head exposure is the most critical situation; with the exception of the tropics, sun exposure would not produce suitable levels of vitamin D around winter, during a time period that varies with latitude. Analyzing the best exposure time during the day in order to

Noble gas composition of subcontinental lithospheric mantle: An extensively degassed reservoir beneath Southern Patagonia

Science.gov (United States)

Jalowitzki, Tiago; Sumino, Hirochika; Conceição, Rommulo V.; Orihashi, Yuji; Nagao, Keisuke; Bertotto, Gustavo W.; Balbinot, Eduardo; Schilling, Manuel E.; Gervasoni, Fernanda

2016-09-01

Patagonia, in the Southern Andes, is one of the few locations where interactions between the oceanic and continental lithosphere can be studied due to subduction of an active spreading ridge beneath the continent. In order to characterize the noble gas composition of Patagonian subcontinental lithospheric mantle (SCLM), we present the first noble gas data alongside new lithophile (Sr-Nd-Pb) isotopic data for mantle xenoliths from Pali-Aike Volcanic Field and Gobernador Gregores, Southern Patagonia. Based on noble gas isotopic compositions, Pali-Aike mantle xenoliths represent intrinsic SCLM with higher (U + Th + K)/(3He, 22Ne, 36Ar) ratios than the mid-ocean ridge basalt (MORB) source. This reservoir shows slightly radiogenic helium (3He/4He = 6.84-6.90 RA), coupled with a strongly nucleogenic neon signature (mantle source 21Ne/22Ne = 0.085-0.094). The 40Ar/36Ar ratios vary from a near-atmospheric ratio of 510 up to 17700, with mantle source 40Ar/36Ar between 31100-6800+9400 and 54000-9600+14200. In addition, the 3He/22Ne ratios for the local SCLM endmember, at 12.03 ± 0.15 to 13.66 ± 0.37, are higher than depleted MORBs, at 3He/22Ne = 8.31-9.75. Although asthenospheric mantle upwelling through the Patagonian slab window would result in a MORB-like metasomatism after collision of the South Chile Ridge with the Chile trench ca. 14 Ma, this mantle reservoir could have remained unhomogenized after rapid passage and northward migration of the Chile Triple Junction. The mantle endmember xenon isotopic ratios of Pali-Aike mantle xenoliths, which is first defined for any SCLM-derived samples, show values indistinguishable from the MORB source (129Xe/132Xe =1.0833-0.0053+0.0216 and 136Xe/132Xe =0.3761-0.0034+0.0246). The noble gas component observed in Gobernador Gregores mantle xenoliths is characterized by isotopic compositions in the MORB range in terms of helium (3He/4He = 7.17-7.37 RA), but with slightly nucleogenic neon (mantle source 21Ne/22Ne = 0.065-0.079). We

Marine biodiversity in the Atlantic and Pacific coasts of South America: knowledge and gaps.

Science.gov (United States)

Miloslavich, Patricia; Klein, Eduardo; Díaz, Juan M; Hernández, Cristián E; Bigatti, Gregorio; Campos, Lucia; Artigas, Felipe; Castillo, Julio; Penchaszadeh, Pablo E; Neill, Paula E; Carranza, Alvar; Retana, María V; Díaz de Astarloa, Juan M; Lewis, Mirtha; Yorio, Pablo; Piriz, María L; Rodríguez, Diego; Yoneshigue-Valentin, Yocie; Gamboa, Luiz; Martín, Alberto

2011-01-31

The marine areas of South America (SA) include almost 30,000 km of coastline and encompass three different oceanic domains--the Caribbean, the Pacific, and the Atlantic--ranging in latitude from 12∘N to 55∘S. The 10 countries that border these coasts have different research capabilities and taxonomic traditions that affect taxonomic knowledge. This paper analyzes the status of knowledge of marine biodiversity in five subregions along the Atlantic and Pacific coasts of South America (SA): the Tropical East Pacific, the Humboldt Current,the Patagonian Shelf, the Brazilian Shelves, and the Tropical West Atlantic, and it provides a review of ecosystem threats and regional marine conservation strategies. South American marine biodiversity is least well known in the tropical subregions (with the exception of Costa Rica and Panama). Differences in total biodiversity were observed between the Atlantic and Pacific oceans at the same latitude. In the north of the continent, the Tropical East Pacific is richer in species than the Tropical West Atlantic, however, when standardized by coastal length, there is very little difference among them. In the south, the Humboldt Current system is much richer than the Patagonian Shelf. An analysis of endemism shows that 75% of the species are reported within only one of the SA regions, while about 22% of the species of SA are not reported elsewhere in the world. National and regional initiatives focusing on new exploration, especially to unknown areas and ecosystems, as well as collaboration among countries are fundamental to achieving the goal of completing inventories of species diversity and distribution.These inventories will allow accurate interpretation of the biogeography of its two oceanic coasts and latitudinal trends,and will also provide relevant information for science based policies.

Marine fronts at the continental shelves of austral South America - Physical and ecological processes

Science.gov (United States)

Acha, Eduardo M.; Mianzan, Hermes W.; Guerrero, Raúl A.; Favero, Marco; Bava, José

2004-01-01

Neritic fronts are very abundant in austral South America, covering several scales of space and time. However, this region is poorly studied from a systemic point of view. Our main goal is to develop a holistic view of physical and ecological patterns and processes at austral South America, regarding frontal arrangements. Satellite information (sea surface temperature and chlorophyll concentration), and historical hydrographic data were employed to show fronts. We compiled all existing evidence (physical and biological) about fronts to identify regions defined by similar types of coastal fronts and to characterize them. Fronts in austral South America can be arranged in six zones according to their location, main forcing, key physical variables, seasonality, and enrichment mechanisms. Four zones, the Atlantic upwelling zone; the temperate estuarine zone; the Patagonian tidal zone and the Argentine shelf-break zone, occupy most of the Atlantic side. The Chile-Peru upwelling zone, on the Pacific, is the largest and best-known region. The Patagonian cold estuarine zone encompasses the tip of South America, connecting the Pacific and Atlantic oceans, and remains poorly studied. When observed at a continental scale, the Pacific coast dominated by two large frontal zones appears simplest than the Atlantic coast in terms of frontal richness. The extension of the continental shelf in the Atlantic coast allows for the development of a great diversity of mesoscale fronts. Though frontal zones we defined are extensive areas of the continental shelves, fronts inside the zones are comparatively small areas. Even so, they play a paramount role in ecological processes, allowing for high biological production; offering feeding and/or reproductive habitats for fishes, squids, and birds; acting as retention areas for larvae of benthic species; and promoting establishment of benthic invertebrates that benefit from the organic production in the frontal area.

Pup Vibrissae Stable Isotopes Reveal Geographic Differences in Adult Female Southern Sea Lion Habitat Use during Gestation.

Directory of Open Access Journals (Sweden)

Alastair M M Baylis

Full Text Available Individuals within populations often differ substantially in habitat use, the ecological consequences of which can be far reaching. Stable isotope analysis provides a convenient and often cost effective means of indirectly assessing the habitat use of individuals that can yield valuable insights into the spatiotemporal distribution of foraging specialisations within a population. Here we use the stable isotope ratios of southern sea lion (Otaria flavescens pup vibrissae at the Falkland Islands, in the South Atlantic, as a proxy for adult female habitat use during gestation. A previous study found that adult females from one breeding colony (Big Shag Island foraged in two discrete habitats, inshore (coastal or offshore (outer Patagonian Shelf. However, as this species breeds at over 70 sites around the Falkland Islands, it is unclear if this pattern is representative of the Falkland Islands as a whole. In order to characterize habitat use, we therefore assayed carbon (δ13C and nitrogen (δ15N ratios from 65 southern sea lion pup vibrissae, sampled across 19 breeding colonies at the Falkland Islands. Model-based clustering of pup isotope ratios identified three distinct clusters, representing adult females that foraged inshore, offshore, and a cluster best described as intermediate. A significant difference was found in the use of inshore and offshore habitats between West and East Falkland and between the two colonies with the largest sample sizes, both of which are located in East Falkland. However, habitat use was unrelated to the proximity of breeding colonies to the Patagonian Shelf, a region associated with enhanced biological productivity. Our study thus points towards other factors, such as local oceanography and its influence on resource distribution, playing a prominent role in inshore and offshore habitat use.

An alternative model for the early peopling of southern South America revealed by analyses of three mitochondrial DNA haplogroups.

Science.gov (United States)

de Saint Pierre, Michelle; Bravi, Claudio M; Motti, Josefina M B; Fuku, Noriyuki; Tanaka, Masashi; Llop, Elena; Bonatto, Sandro L; Moraga, Mauricio

2012-01-01

After several years of research, there is now a consensus that America was populated from Asia through Beringia, probably at the end of the Pleistocene. But many details such as the timing, route(s), and origin of the first settlers remain uncertain. In the last decade genetic evidence has taken on a major role in elucidating the peopling of the Americas. To study the early peopling of South America, we sequenced the control region of mitochondrial DNA from 300 individuals belonging to indigenous populations of Chile and Argentina, and also obtained seven complete mitochondrial DNA sequences. We identified two novel mtDNA monophyletic clades, preliminarily designated B2l and C1b13, which together with the recently described D1g sub-haplogroup have locally high frequencies and are basically restricted to populations from the extreme south of South America. The estimated ages of D1g and B2l, about ~15,000 years BP, together with their similar population dynamics and the high haplotype diversity shown by the networks, suggests that they probably appeared soon after the arrival of the first settlers and agrees with the dating of the earliest archaeological sites in South America (Monte Verde, Chile, 14,500 BP). One further sub-haplogroup, D4h3a5, appears to be restricted to Fuegian-Patagonian populations and reinforces our hypothesis of the continuity of the current Patagonian populations with the initial founders. Our results indicate that the extant native populations inhabiting South Chile and Argentina are a group which had a common origin, and suggest a population break between the extreme south of South America and the more northern part of the continent. Thus the early colonization process was not just an expansion from north to south, but also included movements across the Andes.

Permian depositional age of metaturbidites of the Duque de York Complex, southern Chile: U-Pb SHRIMP data and palynology

International Nuclear Information System (INIS)

Sepulveda, Fernando A; Palma-Heldt, Sylvia; Herve, Francisco; Fanning, Mark

2010-01-01

The Duque de York Complex (DYC) is part of the low grade metamorphic accretionary complexes of the pre-Andean Patagonian 'basement'. It is a sedimentary succession exposed along the western margin of southernmost South America. New U-Pb zircon ages and palynological data restrict the maximum depositional age of the DYC to the limit between the early Permian (Kungurian) and the middle Permian (Roadian). The palynological association recorded in the DYC, characterized mainly by Gymnospermopsida pollen, indicates a humid environment of forest with an under-growth of ferns. Regional paleogeographic correlations point out that an interpretation of DYC as an autochthonous terrane cannot be discarded, contrasting with previous hypotheses which suggest an allochthonous character for this complex

Oral microbiota of Patagonian lizards of genus Diplolaemus (Leiosauridae: fable to facts

Directory of Open Access Journals (Sweden)

Ibargüengoytía, Nora R.

2004-11-01

Full Text Available Existe la creencia popular de que los lagartos del género Diplolaemus (Leiosauridae de Patagonia, Argentina, son capaces de conferir mordeduras venenosas que pueden causar inflamación e incluso la muerte de animales de granja o salvajes. No obstante, no existe evidencia de la existencia de glándulas de veneno en estos lagartos. La inflamación y absceso provocado como resultado de las heridas de mordedura podría ser causado por agentes infecciosos. Este es el primer estudio acerca de la microbiota oral de los lagartos del género Diplolaemus de Argentina. Para este trabajo se analizó un espécimen de D. darwini y tres individuos de Diplolaemus "forma alto patagonica". Las muestras de hisopados de boca de los lagartos fueron incubados aeróbica y anaeróbicamente, algunos de ellos fueron subcultivados en agar de sangre ovina al 5% e incubados nuevamente. Todas las colonias representativas observadas fueron subcultivadas para su purificación y sujetas a tests bioquímicos. La bacteria Clostridium perfigrens fue determinada por medio de la técnica de reacción en cadena de la Polimerasa. Se identificaron cuatro especies de bacterias: Staphylococus warneri, Clostridium bifermentans, Clostridium perfringens y Stomatococcus muscilaginosus. Estas especies son conocidas como agentes etiológicos de numerosas infecciones de humanos y animales. Si bien estas bacterias representan sólo un pequeño número de las posibles bacterias aisladas de la cavidad oral de Diplolaemus, están indicando la presencia de patógenos humanos y animales. Lizards of genus Diplolaemus (Leiosauridae from Patagonia, Argentina are believed to have "poisonous" bites that can cause inflammation and death of farm and wild animals. However there is no evidence of poisonous glands in these lizards. It is proposed that the inflammation and abscesses resulting from these bite wounds are caused by infectious agent(s. This is the first study of the oral microbiota of Diplolaemus lizards from Argentina. One specimen of D. darwini and three individuals of Diplolaemus "forma alto patagonica" were used for the present work. Swabs were taken from the mouths of the lizards, subcultured onto 5% sheep blood agar plates, incubated at 37 C for 48 hours aerobically and anaerobically. All representative colonies observed were subcultured for purity and subjected to conventional biochemical tests. Isolates identified as Clostridium perfringens were typed by a polymerase chain reaction technique. Four species of bacteria were identified as Staphylococcus warneri, Clostridium perfringens, Clostridium bifermentans and Stomatococcus muscilaginosus. These species are known etiologic agents of a number of human and animal infections. While these bacteria represent only a small number of possible isolates from the oral cavity of Diplolaemus species nevertheless it indicates that human and animal pathogens are present in their oral cavity.

Loligo gahi, the Patagonian longfin squid, has been the subject of a ...

African Journals Online (AJOL)

spamer

the FIFD by the Renewable Resources Assessment. Group (RRAG) at Imperial College, London (FIFD. 1989). Assessments of Illex argentinus around the. Falkland Islands made using Delury depletion models have proved to be complex but tractable (Beddington et al. 1990, Rosenberg et al. 1990, Basson et al. 1996).

Progress and turning points in legal development of native forests protection at the argentine provincial and uruguayan jurisdictions

Directory of Open Access Journals (Sweden)

Clara María Minaverry

2017-04-01

Full Text Available The general purpose of this paper is to investigate native forests protection regulatory development level, in a selection of argentine provinces in possession of valuable ecosystem forest´s resources, such as the Andean-Patagonian ones. The especial objectives are: To state if provincial regulations have complied with national native forests environmental protection law 26.331 (and if it regulates water resources, and to make a comparative analysis with Uruguay. This is an exploratory research, where analytical comparative method and legal hermeneutics were applied to this study. We could conclude that law 26.331 exceeded some of the selected argentine provincial regulations outlines, and that Uruguay does not have enough regulatory development in order to make an overall comparative analysis.

The oceanic tides in the South Atlantic Ocean

Directory of Open Access Journals (Sweden)

M. L. Genco

Full Text Available The finite element ocean tide model of Le Provost and Vincent (1986 has been applied to the simulation of the M₂ and K₁ components over the South Atlantic Ocean. The discretisation of the domain, of the order of 200 km over the deep ocean, is refined down to 15 km along the coasts, such refinement enables wave propagation and damping over the continental shelves to be correctly solved. The marine boundary conditions, from Dakar to Natal, through the Drake passage and from South Africa to Antarctica, are deduced from in situ data and from Schwiderski's solution and then optimised following a procedure previously developed by the authors. The solutions presented are in very good agreement with in situ data: the root mean square deviations from a standard subset of 13 pelagic stations are 1.4 cm for M₂ and 0.45 cm for K₁, which is significantly better overall than solutions published to date in the literature. Zooms of the M₂ solution are presented for the Falkland Archipelago, the Weddell Sea and the Patagonian Shelf. The first zoom allows detailing of the tidal structure around the Falklands and its interpretation in terms of a stationary trapped Kelvin wave system. The second zoom, over the Weddell Sea, reveals for the first time what must be the tidal signal under the permanent ice shelf and gives a solution over that sea which is generally in agreement with observations. The third zoom is over the complex Patagonian Shelf. This zoom illustrates the ability of the model to simulate the tides, even over this area, with a surprising level of realism, following purely hydrodynamic modelling procedures, within a global ocean tide model. Maps of maximum associated tidal currents are also given, as a first illustration of a by-product of these simulations.

Class 1 integrons in environments with different degrees of urbanization.

Directory of Open Access Journals (Sweden)

Maximiliano Nardelli

Full Text Available BACKGROUND: Class 1 integrons are one of the most successful elements in the acquisition, expression and spread of antimicrobial resistance genes (ARG among clinical isolates. Little is known about the gene flow of the components of the genetic platforms of class 1 integrons within and between bacterial communities. Thus it is important to better understand the interactions among "environmental" intI1, its genetic platforms and its distribution with human activities. METHODOLOGY/PRINCIPAL FINDINGS: An evaluation of two types of genetic determinants, ARG (sul1 and qacE1/qacEΔ1 genes and lateral genetic elements (LGE (intI1, ISCR1 and tniC genes in a model of a culture-based method without antibiotic selection was conducted in a gradient of anthropogenic disturbances in a Patagonian island recognized as being one of the last regions containing wild areas. The intI1, ISCR1 genes and intI1 pseudogenes that were found widespread throughout natural communities were not associated with urbanization (p>0.05. Each ARG that is embedded in the most common genetic platform of clinical class 1 integrons, showed different ecological and molecular behaviours in environmental samples. While the sul1 gene frequency was associated with urbanization, the qacE1/qacEΔ1 gene showed an adaptive role to several habitats. CONCLUSIONS/SIGNIFICANCE: The high frequency of intI1 pseudogenes suggests that, although intI1 has a deleterious impact within several genomes, it can easily be disseminated among natural bacterial communities. The widespread occurrence of ISCR1 and intI1 throughout Patagonian sites with different degree of urbanization, and within different taxa, could be one of the causes of the increasing frequency of multidrug-resistant isolates that have characterized Argentina for decades. The flow of ARG and LGE between natural and clinical communities cannot be explained with a single general process but is a direct consequence of the interaction of multiple

Characterization of landslide dams in the San Juan province (Argentina)

Science.gov (United States)

Penna, Ivanna; Longchamp, Celine; Derron, Marc-Henri; Jaboyedoff, Michel

2013-04-01

River blockages caused by landslide deposition are common phenomena in active mountain chains, influencing erosion-sedimentation patterns and acting as primary and secondary hazards. Regional scale analyses regarding their spatial distribution and morphometry allow establishing boundary conditions for their occurrence and stability, and determine differences among regions with different landscape and climatic conditions. Owing to the combination of endogenous and exogenous factors, landslide dams are frequent phenomena in the Andes. In the Argentinean NW and the Patagonian Andes, previous studies showed that stability of landslide dams determined by morphometric parameters generally matched satisfactorily with dam behavior, with some exceptions in which climatic component played an important role in dam longevity. Aiming to expand the knowledge of landslide dams in the Argentinean Andes, in this work we analyzed the stability of rock avalanche dams in the Pampeam flat slab subduction zone. In the study area, mountain dynamics creates suitable conditions for the occurrence of 34 rock avalanches with volumes up to 0.3 km3. They developed in deeply carved valleys (Cordillera) and Inter-thrust valleys (Precordillera). 22 impoundments of rivers resulted from channelized rock avalanches with long runouts (4-10 km) that blocked tributaries rivers, but most of them by rock avalanches that filled the valley bottom, with run up in the opposite slope and limited movement parallel to the valley axis. Most of the dams breached in unknown times, except for the last event that occurred on November 12th 2005. The quantification of morphometric parameters and contributing areas indicates the existence of dams with dimensionless blockage index above 2.75 (stable domain) and below 3.08 (instable domain). The Los Erizos dam in our study area and the Barrancas dam in the Patagonian Andes show that besides morphometric parameters, climatic conditions are decisive. Stable landslide dams

Organic carbon in glacial fjords of Chilean Patagonia

Science.gov (United States)

Pantoja, Silvio; Gutiérrez, Marcelo; Tapia, Fabián; Abarzúa, Leslie; Daneri, Giovanni; Reid, Brian; Díez, Beatriz

2016-04-01

The Southern Ice Field in Chilean Patagonia is the largest (13,000 km2) temperate ice mass in the Southern hemisphere, yearly transporting ca. 40 km3 of freshwater to fjords. This volume of fresh and cold water likely affects adjacent marine ecosystems by changing circulation, productivity, food web dynamics, and the abundance and distribution of planktonic and benthic organisms. We hypothesize that freshwater-driven availability of inorganic nutrient and transport of organic and inorganic suspended matter, as well as microbes, become a controlling factor for productivity in the fjord associated with the Baker river and Jorge Montt glacier. Both appear to be sources of silicic acid, but not of nitrate and particulate organic carbon, especially during summer, when surface PAR and glacier thawing are maximal. In contrast to Baker River, the Jorge Montt glacier is also a source of dissolved organic carbon towards a proglacial fjord and the Baker Channel, indicating that a thorough chemical description of sources (tidewater glacier and glacial river) is needed. Nitrate in fiord waters reaches ca. 15 μM at 25 m depth with no evidence of mixing up during summer. Stable isotope composition of particulate organic nitrogen reaches values as low as 3 per mil in low-salinity waters near both glacier and river. Nitrogen fixation could be depleting δ15N in organic matter, as suggested by the detection at surface waters of nif H genes belonging to diazotrophs near the Montt glacier. As diazotrophs have also been detected in other cold marine waters (e.g. Baltic Sea, Arctic Ocean) as well as glaciers and polar terrestrial waters, there is certainly a potential for both marine and freshwater microbes to contribute and have a significant impact on the Patagonian N and C budgets. Assessing the impact of freshwater on C and N fluxes and the microbial community structure in Patagonian waters will allow understanding future scenarios of rapid glacier melting. This research was funded

Ignition probability of fine dead surface fuels in native Patagonia forests of Argentina

Energy Technology Data Exchange (ETDEWEB)

Bianchi, L.; Defosse, G. E.

2014-06-01

Aim of study: The Canadian Forest Fire Weather Index (FWI) is being implemented all over the world. This index is being adapted to the Argentinean ecosystems since the year 2000. With the objective of calibrating the Fine Fuel Moisture Code (FFMC) of the FWI system to Patagonian forests, we studied the relationship between ignition probability and fine dead surface fuel moisture content (MC) as an indicator of potential fire ignition. Area of study: The study area is located in northwestern Patagonia, Argentina, and comprised two main forest types (cypress and nire) grown under a Mediterranean climate, with a dry summer and precipitations during winter and autumn ({approx}500-800 mm per year). Material and methods: We conducted lab ignition tests fires to determine the threshold of fine dead fuel ignition at different MC levels. Moisture content of dead fine surface fuels in the field was measured every 10-15 days from November to March for three seasons. We calculated the FFMC during these seasons and correlated it with the measured MC by applying a logistic regression model. We combined the results of the ignition tests and of the regressions to suggest FFMC categories for estimating fire danger in Patagonian forests. Main results: The ignition threshold occurred at MC values of 21.5 and 25.0% for cypress and nire sites, respectively. The MC measured varied from 7.3 to 129.6%, and the calculated FFMC varied between 13.4 and 92.6. Highly significant regressions resulted when FFMC was related to MC. The ignition threshold corresponded to a FFMC = 85. We proposed to divide the FFMC scale in three fire danger categories: Low (FFMC {<=} 85), High (85 < FFMC{<=}89) and Extreme (FFMC > 89). Research highlights: Our results provide a useful tool for predicting fire danger in these ecosystems, and are a contribution to the development of the Argentinean Fire Danger Rating and a reference for similar studies in other countries where the FWI is being implemented. (Author)

Cystobasidiomycetes yeasts from Patagonia (Argentina): description of Rhodotorula meli sp. nov. from glacial meltwater.

Science.gov (United States)

Libkind, Diego; Sampaio, José Paulo; van Broock, Maria

2010-09-01

A basidiomycetous yeast, strain CRUB 1032(T), which formed salmon-pink colonies, was isolated from glacial meltwater in Patagonia, Argentina. Morphological, physiological and biochemical characterization indicated that this strain belonged to the genus Rhodotorula. Molecular taxonomic analysis based on the 26S rDNA D1/D2 domain and internal transcribed spacer region sequences showed that strain CRUB 1032(T) represents an undescribed yeast species, for which the name Rhodotorula meli sp. nov. is proposed (type strain is CRUB 1032(T)=CBS 10797(T)=JCM 15319(T)). Phylogenetic analysis showed that Rhodotorula lamellibrachii was the closest known species, which, together with R. meli, formed a separate cluster related to the Sakaguchia clade within the Cystobasidiomycetes. Additional Patagonian yeast isolates of the class Cystobasidiomycetes are also investigated in the present work.

Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina.

Directory of Open Access Journals (Sweden)

Claudio A González-Wevar

Full Text Available Glacial episodes of the Quaternary, and particularly the Last Glacial Maximum (LGM drastically altered the distribution of the Southern-Hemisphere biota, principally at higher latitudes. The irregular coastline of Patagonia expanding for more than 84.000 km constitutes a remarkable area to evaluate the effect of Quaternary landscape and seascape shifts over the demography of near-shore marine benthic organisms. Few studies describing the biogeographic responses of marine species to the LGM have been conducted in Patagonia, but existing data from coastal marine species have demonstrated marked genetic signatures of post-LGM recolonization and expansion. The kelp-dweller limpet Nacella mytilina is broadly distributed along the southern tip of South America and at the Falkland/Malvinas Islands. Considering its distribution, abundance, and narrow bathymetry, N. mytilina represents an appropriate model to infer how historical and contemporary processes affected the distribution of intraspecific genetic diversity and structure along the southern tip of South America. At the same time, it will be possible to determine how life history traits and the ecology of the species are responsible for the current pattern of gene flow and connectivity across the study area. We conducted phylogeographic and demographic inference analyses in N. mytilina from 12 localities along Pacific Patagonia (PP and one population from the Falkland/Malvinas Islands (FI. Analyses of the mitochondrial gene COI in 300 individuals of N. mytilina revealed low levels of genetic polymorphism and the absence of genetic differentiation along PP. In contrast, FI showed a strong and significant differentiation from Pacific Patagonian populations. Higher levels of genetic diversity were also recorded in the FI population, together with a more expanded genealogy supporting the hypothesis of glacial persistence of the species in these islands. Haplotype genealogy, and mismatch analyses in

Genetics, Gene Flow, and Glaciation: The Case of the South American Limpet Nacella mytilina

Science.gov (United States)

González-Wevar, Claudio A.; Rosenfeld, Sebastián; Segovia, Nicolás I.; Hüne, Mathias; Gérard, Karin; Ojeda, Jaime; Mansilla, Andrés; Brickle, Paul; Díaz, Angie; Poulin, Elie

2016-01-01

Glacial episodes of the Quaternary, and particularly the Last Glacial Maximum (LGM) drastically altered the distribution of the Southern-Hemisphere biota, principally at higher latitudes. The irregular coastline of Patagonia expanding for more than 84.000 km constitutes a remarkable area to evaluate the effect of Quaternary landscape and seascape shifts over the demography of near-shore marine benthic organisms. Few studies describing the biogeographic responses of marine species to the LGM have been conducted in Patagonia, but existing data from coastal marine species have demonstrated marked genetic signatures of post-LGM recolonization and expansion. The kelp-dweller limpet Nacella mytilina is broadly distributed along the southern tip of South America and at the Falkland/Malvinas Islands. Considering its distribution, abundance, and narrow bathymetry, N. mytilina represents an appropriate model to infer how historical and contemporary processes affected the distribution of intraspecific genetic diversity and structure along the southern tip of South America. At the same time, it will be possible to determine how life history traits and the ecology of the species are responsible for the current pattern of gene flow and connectivity across the study area. We conducted phylogeographic and demographic inference analyses in N. mytilina from 12 localities along Pacific Patagonia (PP) and one population from the Falkland/Malvinas Islands (FI). Analyses of the mitochondrial gene COI in 300 individuals of N. mytilina revealed low levels of genetic polymorphism and the absence of genetic differentiation along PP. In contrast, FI showed a strong and significant differentiation from Pacific Patagonian populations. Higher levels of genetic diversity were also recorded in the FI population, together with a more expanded genealogy supporting the hypothesis of glacial persistence of the species in these islands. Haplotype genealogy, and mismatch analyses in the FI population

Improved postharvest quality in patagonian squash ( Cucurbita moschata) coated with radiation depolymerized chitosan

Science.gov (United States)

Pugliese, Maria Alicia; Goitia, Maria Teresa; Yossen, Mariana; Cifone, Norma; Agulló, Enrique; Andreucetti, Noemi

2011-12-01

Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes ( Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391 kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV-vis analyses. The molecular weight characterization of chitosans was done by size exclusion chromatography with dual light scattering and concentration detection (SEC-MALLS-RI). The coating effectiveness was evaluated on the following parameters: fungal decay incidence, weight loss, firmness, total reducing sugar, soluble solid, flesh color, carotene content, pH and titratable acidity. No sign of fungal decay was observed in squashes coated with 122 and 56 kDa chitosans, which were also the most effective treatments in reducing the weight loss. The chitosan with Mw=122 kDa was also the best treatment considering firmness, internal aspect, sugar and carotene content. Then, radiation degraded chitosan was better in C. moschata preservation than the original chitosan.

First Patagonian Course on 'Diagnosis and Therapy of Injuries Induced by Ionizing Radiation'

International Nuclear Information System (INIS)

Bellotti, Mariela I.

2013-01-01

In Patagonia there are academic centers, health and industrial facilities that use ionizing radiations in its usual practices. However, they do not have protocols that respond to local needs. For this reason was held from October 5 to November 10, 2012 in Bariloche Atomic Center, a training course for health personnel. The range of topics covered ranged from the definition of dosimetry quantities, types of radiation and biological dosimetry, biological effects, radiation acute syndrome, radiation-induced cutaneous syndrome, internal contamination, screening in radiological emergencies, etc.The course provided a theoretical and practical guide about how to recognize and treat people exposed to radiations, guidelines for acting in radiological emergencies and a perception of the psychosocial impact of the radiation accidents.The result was a pocket book for health personnel that will be used in case of having a patient with radiation induced injury

Improved postharvest quality in patagonian squash (Cucurbita moschata) coated with radiation depolymerized chitosan

Energy Technology Data Exchange (ETDEWEB)

Pugliese, Maria Alicia; Goitia, Maria Teresa [Laboratorio de Investigaciones Basicas Aplicadas en Quitina, Departamento de Quimica, Universidad Nacional del Sur. Avenida Alem 1253, B8000CPB Bahia Blanca (Argentina); Yossen, Mariana [Instituto de Desarrollo Tecnologico para la Industria Quimica (INTEC), CONICET-Universidad Nacional del Litoral, Ruta Nacional 168-Paraje ' El Pozo' , 3000 Santa Fe (Argentina); Cifone, Norma; Agullo, Enrique [Laboratorio de Investigaciones Basicas Aplicadas en Quitina, Departamento de Quimica, Universidad Nacional del Sur. Avenida Alem 1253, B8000CPB Bahia Blanca (Argentina); Andreucetti, Noemi, E-mail: andreuce@criba.edu.ar [Laboratorio de Radioisotopos, Departamento de Quimica, Universidad Nacional del Sur, Avenida Alem 1253, B8000CPB Bahia Blanca (Argentina)

2011-12-15

Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes (Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391 kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV-vis analyses. The molecular weight characterization of chitosans was done by size exclusion chromatography with dual light scattering and concentration detection (SEC-MALLS-RI). The coating effectiveness was evaluated on the following parameters: fungal decay incidence, weight loss, firmness, total reducing sugar, soluble solid, flesh color, carotene content, pH and titratable acidity. No sign of fungal decay was observed in squashes coated with 122 and 56 kDa chitosans, which were also the most effective treatments in reducing the weight loss. The chitosan with Mw=122 kDa was also the best treatment considering firmness, internal aspect, sugar and carotene content. Then, radiation degraded chitosan was better in C. moschata preservation than the original chitosan. - Highlights: > Original Chitosan was radiation depolymerized producing chitosans with lower molecular weights. > Gamma-irradiated chitosans only exhibit chain scission. > SEC-MALLS-RI chromatography is a useful tool in molecular weight analysis. > Depolymerized chitosans were the best in maintaining the quality and the storage life of coated squashes.

FRUPAT: A Tool to Quantify Inputs and Outputs of Patagonian Fruit Production Systems

NARCIS (Netherlands)

Cittadini, E.D.; Keulen, van H.; Peri, P.L.

2006-01-01

A software called FRUPAT was developed for calculating input and output coefficients (Technical Coefficients) of fruit production systems in South Patagonia. FRUPAT combined locations (Río Chubut valley; Sarmiento valley; Los Antiguos valley; Río Chico valley), edaphic environment (good quality soil

Improved postharvest quality in patagonian squash (Cucurbita moschata) coated with radiation depolymerized chitosan

International Nuclear Information System (INIS)

Pugliese, Maria Alicia; Goitia, Maria Teresa; Yossen, Mariana; Cifone, Norma; Agullo, Enrique; Andreucetti, Noemi

2011-01-01

Different molecular weight chitosans were evaluated on the decay of coated Anquito squashes (Cucurbita moschata) as well as the maintenance of the fruit quality along five storage months. The original chitosan (Mw=391 kDa, 83% DD), was depolymerized by gamma radiation. Apart from chain scission, other chemical changes were not detected by FTIR or UV-vis analyses. The molecular weight characterization of chitosans was done by size exclusion chromatography with dual light scattering and concentration detection (SEC-MALLS-RI). The coating effectiveness was evaluated on the following parameters: fungal decay incidence, weight loss, firmness, total reducing sugar, soluble solid, flesh color, carotene content, pH and titratable acidity. No sign of fungal decay was observed in squashes coated with 122 and 56 kDa chitosans, which were also the most effective treatments in reducing the weight loss. The chitosan with Mw=122 kDa was also the best treatment considering firmness, internal aspect, sugar and carotene content. Then, radiation degraded chitosan was better in C. moschata preservation than the original chitosan. - Highlights: → Original Chitosan was radiation depolymerized producing chitosans with lower molecular weights. → Gamma-irradiated chitosans only exhibit chain scission. → SEC-MALLS-RI chromatography is a useful tool in molecular weight analysis. → Depolymerized chitosans were the best in maintaining the quality and the storage life of coated squashes.

Tithonian age of dinosaur fossils in central Patagonian, Chile: U-Pb SHRIMP geochronology

Science.gov (United States)

Suárez, Manuel; De La Cruz, Rita; Fanning, Mark; Novas, Fernando; Salgado, Leonardo

2016-11-01

Three Tithonian concordant U-Pb SHRIMP zircon ages of 148.7 ± 1.4, 147.9 ± 1.5 and 147.0 ± 1.0 from tuffs intercalated in a clastic sedimentary succession with exceptional dinosaur bones including the new taxon Chilesaurus diegosuarezi gen. et sp. nov. exposed in central Chilean Patagonia (ca. 46°30'S) are reported herein. The fossiliferous beds accumulated in a synvolcanic fan delta reaching a shallow marine basin as indicated by glauconite present in some of the beds, and coeval with the beginning of the transgression of the Aysén Basin.

Mass movement-induced tsunamis: main effects during the Patagonian Fjordland seismic crisis in Aisén (45°25'S, Chile Tsunamis inducidos por movimientos en masa: principales efectos durante la crisis sísmica de la Patagonia Archipelágica en Aisén (45°25' S, Chile

Directory of Open Access Journals (Sweden)

José Antonio Naranjo

2009-01-01

Full Text Available The epicentre of the long-lasting seismic crisis started on the evening of January 22,2007 and it was located 20 km to the west of Puerto Chacabuco in the Patagonian fjordland, Chile (45°25'S. Approximately 7,000 events were recorded up to early May, four of which reached magnitudes greater than 5 (Richter, with local intensities up to VII in Puerto Chacabuco and Puerto Aisén and VI in Coihaique. The seismic swarm was located within the Liquiñe-Ofqui Fault Zone (LOFZ, which controls the emplacement of several monogenetic volcanic cones and larger stratovolcanoes. The January 23 (Ms 5,2 and April 1 (Ms 5,4 events caused minor damages in salmón industry installations near the epicentral zone, however the earthquake that oceurred at 13:54 hours (local time on April 21 (Mw 6,2 triggered various mass movements on the Fiordo Aisén slopes and generated tsunamis. Debris flows and tsunami waves caused the death of three people and the disappearance of seven, in addition to severe damages to the salmón industry installations. A similar phenomenon had oceurred in 1927, but then fewer people inhabited the área. Initially, confusión dominated the scientific coordination of the emergeney management due to seismic data misinterpretation.En la noche del 22 de enero de 2007 comenzó una crisis sísmica, cuyos epicentros se localizaron principalmente en el fiordo Aisén, a unos 20 km al noroeste de Puerto Chacabuco, en la zona archipelágica de Patagonia, en Chile (45°25'S. Hasta comienzos de mayo, los sismógrafos habían registrado cerca de 7.000 sismos, de los cuales cuatro habían sobrepasado la magnitud 5 (Richter, con intensidades locales de hasta VII en Puerto Chacabuco y Puerto Aisén y VI en Coihaique. El enjambre sísmico está asociado a estructuras geológicas de la Zona de Falla Liquiñe-Ofqui (ZFLO la cual, además, controla el emplazamiento de numerosos conos volcánicos, así como estratovolcanes mayores. Aunque los sismos del 23 de enero

Biodegradation waste of the stations service by Rhodococcus erythropolis ohp-al-gp

International Nuclear Information System (INIS)

Pucci, Oscar Hector; Acuna, Adrian Javier; Pucci, Graciela Natalia

2013-01-01

The strain Rhodococcus erythropolis ohp-al-gp was isolated from turbine oil contaminated soil from northern Santa Cruz province, Argentina. Because of its potential in bioremediation, the aim was to know the abilities for degradation of pure compounds and mixtures of hydrocarbons, as well as degradation in the presence and absence of diesel nitrogen measured by gas chromatography. The strain possesses the ability to use diesel, kerosene, lubricating oil, pristane, hexane, heptane, octane, pentadecane and hexadecane. R. erythropolis ohp-al-gp has excellent potential for bioremediation of hydrocarbons, which are conflictive as lubricating oils, their potential use in removing mud from washing engines or gas stations would be its most important application. The degradation rate in optimal culture conditions, gives it an additional advantage. It also has a low degradation in the absence of nitrogen, a frequent limiting factor in Patagonian soils.

Long term diet differences between morphs in trophically polymorphic Percichthys trucha (Pisces : Percichthyidae) populations from the southern Andes

DEFF Research Database (Denmark)

Logan, M.S.; Iverson, S.J.; Ruzzante, D.E.

2000-01-01

in resource use by two recently described sympatric morphs of Perichthys trucha, a common freshwater fish of the Andean and Patagonian regions of South America. Because dietary fatty acids are often stored in carnivorous animals with little modification after consumption, they can be used to infer information...... that certain fatty acids were correlated with diet as determined by gut content analysis. Consumption of anisopteran larvae was highly correlated with 14:0 in adipose and muscle tissue; and higher levels of longer chain unsaturated fatty acids (i.e. 20 and 22 carbons) were correlated with the presence of fish...... and also amphipods in the diets. Taken together, the results suggest that there are marked differences in the foraging ecology of the two morphs of P. trucha inhabiting southern Andean lakes. (C) 2000 The Linnean Society of London...

Identification and characterization of microsatellites from calafate (Berberis microphylla, Berberidaceae).

Science.gov (United States)

Varas, Benjamín; Castro, María H; Rodriguez, Roberto; von Baer, Dietrich; Mardones, Claudia; Hinrichsen, Patricio

2013-07-01

Southern barberry or calafate (Berberis microphylla) is a shrub species endemic to the Patagonian region of South America that is used for human consumption. The fruit is very rich in vitamin C and anthocyanins and has a very high antioxidant capacity. There have been only a few genetic studies of this and other closely related species. • Here we present the first 18 microsatellite markers of B. microphylla that were characterized using 66 accessions of calafate from Patagonia. On average, they had 7.6 alleles per marker, with an expected heterozygosity of 0.688. The informativeness of these markers was also evaluated in another 15 Berberis species, including most of the native and endemic Chilean species. • The results confirm that these new simple sequence repeat markers are very polymorphic and potentially useful in genetic studies in any species of the genus Berberis.

Glacier shrinkage and water resources in the Andes

Science.gov (United States)

Francou, Bernard; Coudrain, Anne

For more than a century glaciers around the world have been melting as air temperatures rise due to a combination of natural processes and human activity. The disappearance of these glaciers can have wide-ranging effects, such as the creation of new natural hazards or changes in stream flow that could threaten water suppliesSome of the most dramatic melting has occurred in the Andes mountain range in South America. To highlight the climatic and glacial change in the Andes and to encourage the scientific community to strengthen the glacier observation network that stretches from Colombia to the Patagonian ice fields, the Instituto Nacional de Recursos Naturales (INRENA), Perú, and the Institute of Research and Development (IRD), France, recently organized the second Symposium on Mass Balance of Andean Glaciers in Huaráz,Perú.

Assessment of geomorphological and hydrological changes produced by Pleistocene glaciations in a Patagonian basin

Science.gov (United States)

Scordo, Facundo; Seitz, Carina; Melo, Walter D.; Piccolo, M. Cintia; Perillo, Gerardo M. E.

2018-04-01

This work aims to assess how Pleistocene glaciations modeled the landscape in the upper Senguer River basin and its relationship to current watershed features (drainage surface and fluvial hydrological regime). During the Pleistocene six glacial lobes developed in the upper basin of the Senguer River localized east of the Andean range in southern Argentinean Patagonia between 43° 36' - 46° 27‧ S. To describe the topography and hydrology, map the geomorphology, and propose an evolution of the study area during the Pleistocene we employed multitemporal Landsat images, national geological sheets and a mosaic of the digital elevation model (Shuttle Radar Topography Mission) along with fieldwork. The main conclusion is that until the Middle Pleistocene, the drainage divide of the Senguer River basin was located to the west of its current limits and its rivers drained the meltwater of the glaciers during interglacial periods. However, processes of drainage inversion and drainage surface reduction occurred in the headwater of most rivers of the basin during the Late Pleistocene. Those processes were favored by a relative shorter glacial extension during LGM and the dam effect produced by the moraines of the Post GPG I and III glaciations. Thus, since the Late Pleistocene, the headwaters of several rivers in the basin have been reduced, and the moraines corresponding to the Middle Pleistocene glaciations currently divide the watersheds that drain towards the Senguer River from those that flow west towards the Pacific Ocean.

Sea level anomaly on the Patagonian continental shelf: Trends, annual patterns and geostrophic flows

Science.gov (United States)

Saraceno, M.; Piola, A. R.; Strub, P. T.

2016-01-01

Abstract We study the annual patterns and linear trend of satellite sea level anomaly (SLA) over the southwest South Atlantic continental shelf (SWACS) between 54ºS and 36ºS. Results show that south of 42°S the thermal steric effect explains nearly 100% of the annual amplitude of the SLA, while north of 42°S it explains less than 60%. This difference is due to the halosteric contribution. The annual wind variability plays a minor role over the whole continental shelf. The temporal linear trend in SLA ranges between 1 and 5 mm/yr (95% confidence level). The largest linear trends are found north of 39°S, at 42°S and at 50°S. We propose that in the northern region the large positive linear trends are associated with local changes in the density field caused by advective effects in response to a southward displacement of the South Atlantic High. The causes of the relative large SLA trends in two southern coastal regions are discussed as a function meridional wind stress and river discharge. Finally, we combined the annual cycle of SLA with the mean dynamic topography to estimate the absolute geostrophic velocities. This approach provides the first comprehensive description of the seasonal component of SWACS circulation based on satellite observations. The general circulation of the SWACS is northeastward with stronger/weaker geostrophic currents in austral summer/winter. At all latitudes, geostrophic velocities are larger (up to 20 cm/s) close to the shelf‐break and decrease toward the coast. This spatio‐temporal pattern is more intense north of 45°S. PMID:27840784

Tracing dissolved organic matter (DOM) from land-based aquaculture systems in North Patagonian streams

DEFF Research Database (Denmark)

Nimptsch, Jorge; Woelfl, Stefan; Osorio, Sebastian

2015-01-01

Chile is the second largest producer of salmonids worldwide. The first step in the production of salmonids takes place in land-based aquacultures. However, the effects of the discharge from these aquacultures on stream dissolved organic matter (DOM) content, molecular composition and degradabilit...

Age, growth and mortality of Hake larvae (Merluccius hubbsi in the north Patagonian shelf

Directory of Open Access Journals (Sweden)

Daniel Roberto Brown

2004-06-01

Full Text Available Age and growth and mortality rates were estimated in Argentinean hake (Merlucius hubbsi larvae by counting and measuring otolith daily increments. Larvae were captured with a Bongo net in January and February 2001. Length-at-age data were represented by a linear model whose fitted expression was: L(t = 0.156 t + 1.7. Slope represented mean the daily growth rate (0.156 mm/day. This value was quite similar to the values recorded by other authors for larvae of other Merluccius species. Individual growth rates were not significantly different between January and February. This homogeneity in the larval growth was coincident with the great thermal homogeneity recorded between months. Statistical analysis of the larval growth rates from different areas did not show significant differences. Daily mortality coefficients derived from the exponential decline models were 0.27 and 0.12 for January and February respectively. The difference between the two mortality coefficients could be attributable to the patchinnes, or larval recruitment pulses of distinct intensity between the two months.

Occurrence of Hirudinea species in a post urban reach of a Patagonian mountain stream

Directory of Open Access Journals (Sweden)

M. Laura Miserendino

2014-09-01

Full Text Available Temporal (May 2005 to February 2006 and habitat distribution (pools and riffles of Hirudinea species was analyzed at a post urban reach from Esquel stream (Chubut province, Patagonia, Argentina. Site was located 5.7 km downstream a Waste Treatment Plant. Mean values of nutrients: ammonia, nitrates and soluble reactive phosphate, as well water conductivity, turbidity and total suspended solids indicated physical and organic pollution. Leeches assemblage was composed by the glossiphonids: Helobdella scutifera Blanchard, 1900, H. michaelseni (Blanchard, 1900, H. simplex (Moore, 1911, Helobdella sp., H. hyalina Ringuelet, 1942, H. obscura Ringuelet, 1942 and the semiscolecid Patagoniobdella variabilis (Blanchard, 1900. From these H. hyalina and H. obscura are new records for Chubut province. Helobdella hyalina (810 ind.m-2 and H. simplex (465 ind. m-2 clearly dominated the assemblage at the reach. Only H. simplex displayed a spatial preference being significantly more abundant in pools than in riffle habitats (p<0.001. Species recruitment occurred mostly at September, December and March when juveniles were very abundant. Although several species of Helobdella were able to live in the disturbed section of the stream, only H. simplex and H. hyalina sustained large populations at the site and can be considered as tolerant to organic enrichment. This information is valuable to future studies on stream condition assessment in mountainous areas in Patagonia, and in other areas in which these species are present.

Inorganic mercury (Hg2+ uptake by different plankton fractions of Andean Patagonian lakes (Argentina

Directory of Open Access Journals (Sweden)

Diéguez M.C.

2014-07-01

Full Text Available The species composition and the size structure of natural planktonic food webs may provide essential information to understand the fate of mercury and, in particular, the bioaccumulation pattern of Hg2+ in the water column of lake ecosystems. Heterotrophic and autotrophic picoplankton and phytoplankton are the most important entry points for Hg in aquatic ecosystems since they concentrate Hg2+ and MeHg from ambient water, making them available to planktonic consumers at higher trophic levels of lake food webs. In this investigation we studied the uptake of 197Hg2+ in natural plankton assemblages from four Andean lakes (Nahuel Huapi National Park, Patagonia, Argentina, comprised in the size fractions 0.2-2.7 μm (picoplankton, 0.2-20 μm (pico and nanoplankton and 20-50 μm (microplankton through experiments using Hg2+ labeled with 197Hg2+. The experimental results showed that the uptake of Hg2+ was highest in the smallest plankton fractions (0.2-2.7 μm and 0.2-20 μm compared to the larger fraction comprising microplankton (20-50 um. This pattern was consistent in all lakes, reinforcing the idea that among pelagic organisms, heterotrophic and autotrophic bacteria with the contribution of nanoflagellates and dinoflagellates constitute the main entry point of Hg2+ to the pelagic food web. Moreover, a significant direct relationship was found between the Hg2+ uptake and surface index of the planktonic fractions (SIf. Thus, the smaller planktonic fractions which bore the higher SI were the major contributors to the Hg2+ passing from the abiotic to the biotic pelagic compartments of these Andean lakes.

PILOT STUDIES WITH A PHOTOGRAMMETRIC GLACIER LAKE OUTBURST FLOOD EARLY WARNING SYSTEM

Directory of Open Access Journals (Sweden)

H. G. Maas

2012-07-01

Full Text Available Glacier Lake Outburst Floods (GLOFs depict an environmental risk with an increasing damage potential in many regions of the world. GLOFs are often caused by glacier margin lakes, which suddenly find a drainage path underneath the bottom of a glacier, which is destabilized and retreating as a consequence of local or global climate changes. In a typical GLOF event, a glacier margin lake may drain completely in 24 hours, causing a large flood wave in the area downstream the glacier. The paper documents some recent GLOF events in the Northern Patagonian Icefield (Chile and presents a terrestrial photogrammetric glacier margin lake monitoring system. The system is based on a camera taking images at regular time intervals. In these images, variations of the water level can be detected by tracking the water-land interface at pre-defined image spots. Due to the drainage mechanism, which is characterized by progressive erosion and melting at the bottom of the glacier, GLOFs are indicated by a progressive water level drop in the lake. Water level changes may be detected with subpixel accuracy by image sequence processing methods. If a 3D model of the lake bottom topography (or at least one height profile through the lake exists, water level changes in monoscopic image sequences may be transformed into volume loss. The basic idea herein is the intersection of a terrain profile with a water level detected in the image and projected into object space. The camera orientation is determined through a GPS-supported photogrammetric network. Camera orientation changes, which may for instance be induced by wind, can be compensated by tracking some fiducial marks in the image. The system has been used in a pilot study at two glacier margin lakes in the Northern Patagonian Icefield. These lakes have a depth of about 80 - 100 meters. The larger one has a length of 5 km and a maximum volume of about 200,000,000 cubic meters. During the pilot study, several GLOF events

CO2 and CH4 fluxes of contrasting pristine bogs in southern Patagonia (Tierra del Fuego, Argentina)

Science.gov (United States)

Münchberger, Wiebke; Blodau, Christian; Kleinebecker, Till; Pancotto, Veronica

2015-04-01

South Patagonian peatlands cover a wide range of the southern terrestrial area and thus are an important component of the terrestrial global carbon cycle. These extremely southern ecosystems have been accumulating organic material since the last glaciation up to now and are - in contrast to northern hemisphere bogs - virtually unaffected by human activities. So far, little attention has been given to these pristine ecosystems and great carbon reservoirs which will potentially be affected by climate change. We aim to fill the knowledge gap in the quantity of carbon released from these bogs and in what controls their fluxes. We study the temporal and spatial variability of carbon fluxes in two contrasting bog ecosystems in southern Patagonia, Tierra del Fuego. Sphagnum-dominated bog ecosystems in Tierra del Fuego are similar to the ones on the northern hemisphere, while cushion plant-dominated bogs can almost exclusively be found in southern Patagonia. These unique cushion plant-dominated bogs are found close to the coast and their occurrence changes gradually to Sphagnum-dominated bogs with increasing distance from the coast. We conduct closed chamber measurements and record relevant environmental variables for CO2 and CH4 fluxes during two austral vegetation periods from December to April. Chamber measurements are performed on microforms representing the main vegetation units of the studied bogs. Gas concentrations are measured with a fast analyzer (Los Gatos Ultraportable Greenhouse Gas Analyzer) allowing to accurately record CH4 fluxes in the ppm range. We present preliminary results of the carbon flux variability from south Patagonian peat bogs and give insights into their environmental controls. Carbon fluxes of these two bog types appear to be highly different. In contrast to Sphagnum-dominated bogs, cushion plant-dominated bogs release almost no CH4 while their CO2 flux in both, photosynthesis and respiration, can be twice as high as for Sphagnum

Description, microhabitat selection and infection patterns of sealworm larvae (Pseudoterranova decipiens species complex, nematoda: ascaridoidea) in fishes from Patagonia, Argentina

Science.gov (United States)

2013-01-01

Background Third-stage larvae of the Pseudoterranova decipiens species complex (also known as sealworms) have been reported in at least 40 marine fish species belonging to 21 families and 10 orders along the South American coast. Sealworms are a cause for concern because they can infect humans who consume raw or undercooked fish. However, despite their economic and zoonotic importance, morphological and molecular characterization of species of Pseudoterranova in South America is still scarce. Methods A total of 542 individual fish from 20 species from the Patagonian coast of Argentina were examined for sealworms. The body cavity, the muscles, internal organs, and the mesenteries were examined to detect nematodes. Sealworm larvae were removed from their capsules and fixed in 70% ethanol. For molecular identification, partial fragments of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) were amplified for 10 isolates from 4 fish species. Morphological and morphometric data of sealworms were also obtained. Results A total of 635 larvae were collected from 12 fish species. The most infected fish was Prionotus nudigula, followed by Percophis brasiliensis, Acanthistius patachonicus, Paralichthys isosceles, and Pseudopercis semifasciata. Sequences obtained for the cox1 of sealworms from A. patachonicus, P. isosceles, P. brasiliensis and P. nudigula formed a reciprocally monophyletic lineage with published sequences of adult specimens of Pseudoterranova cattani from the South American sea lion Otaria flavescens, and distinct from the remaining 5 species of Pseudoterranova. A morphological description, including drawings and scanning electron microscopy photomicrographs of these larvae is provided. Sealworms collected from Argentinean fishes did not differ in their diagnostic traits from the previously described larvae of P. cattani. However a discriminant analysis suggests that specimens from P. nudigula were significantly larger than those from other fishes

Description, microhabitat selection and infection patterns of sealworm larvae (Pseudoterranova decipiens species complex, nematoda: ascaridoidea) in fishes from Patagonia, Argentina.

Science.gov (United States)

Hernández-Orts, Jesús S; Aznar, Francisco J; Blasco-Costa, Isabel; García, Néstor A; Víllora-Montero, María; Crespo, Enrique A; Raga, Juan A; Montero, Francisco E

2013-08-29

Third-stage larvae of the Pseudoterranova decipiens species complex (also known as sealworms) have been reported in at least 40 marine fish species belonging to 21 families and 10 orders along the South American coast. Sealworms are a cause for concern because they can infect humans who consume raw or undercooked fish. However, despite their economic and zoonotic importance, morphological and molecular characterization of species of Pseudoterranova in South America is still scarce. A total of 542 individual fish from 20 species from the Patagonian coast of Argentina were examined for sealworms. The body cavity, the muscles, internal organs, and the mesenteries were examined to detect nematodes. Sealworm larvae were removed from their capsules and fixed in 70% ethanol. For molecular identification, partial fragments of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1) were amplified for 10 isolates from 4 fish species. Morphological and morphometric data of sealworms were also obtained. A total of 635 larvae were collected from 12 fish species. The most infected fish was Prionotus nudigula, followed by Percophis brasiliensis, Acanthistius patachonicus, Paralichthys isosceles, and Pseudopercis semifasciata. Sequences obtained for the cox1 of sealworms from A. patachonicus, P. isosceles, P. brasiliensis and P. nudigula formed a reciprocally monophyletic lineage with published sequences of adult specimens of Pseudoterranova cattani from the South American sea lion Otaria flavescens, and distinct from the remaining 5 species of Pseudoterranova. A morphological description, including drawings and scanning electron microscopy photomicrographs of these larvae is provided. Sealworms collected from Argentinean fishes did not differ in their diagnostic traits from the previously described larvae of P. cattani. However a discriminant analysis suggests that specimens from P. nudigula were significantly larger than those from other fishes. Most of the sealworms were

Medicinal plants in the cultural landscape of a Mapuche-Tehuelche community in arid Argentine Patagonia: an eco-sensorial approach.

Science.gov (United States)

Molares, Soledad; Ladio, Ana

2014-08-26

The taste and smell of medicinal plants and their relation to the cultural landscape of a Mapuche-Tehuelche community in the Patagonian steppe was investigated. We assume that the landscapes as a source of therapeutic resources is perceived, classified and named according to different symbolic, ecological and utilitarian criteria which are influenced by chemosensorial appearance of medicinal plants which are valued by inhabitants. Information relating to the cultural landscape experienced by 18 inhabitants, all representing 85% of the families, in terms of medicinal plants, knowledge of species and their organoleptic perception was obtained through participant observation, interviews and free listing. The data were examined using cualitative and quantitative approach, including discourse analysis and non-parametric statistics. Informants use 121 medicinal species, obtained from both wild and non-wild environments, most of which (66%) present aroma and/or taste. It was found that the plants with highest use consensus used for digestive, respiratory, cardio-vascular, analgesic-anti-inflammatory, obstetric-gynaecological and genito-unrinary complaints, have the highest frequencies of cites reporting flavor; and those with the highest frequencies relating to digestive, analgesic-anti-inflammatory and cultural syndromes present the highest frequencies of aroma. Flavor and/or aroma are interpreted as strong or soft, and the strongest are associated with treatment of supernatural ailments. Also, taste is a distinctive trait for the most of the species collected in all natural units of the landscape, while aroma is more closely associated with species growing at higher altitudes. The local pharmacopeia is also enriched with plants that come from more distant phytogeographical environments, such as the Andean forest and the Patagonian Monte, which are obtained through barter with neighboring populations. Herbal products are also obtained in regional shop. The practices of

Groundwater and Terrestrial Water Storage

Science.gov (United States)

Rodell, Matthew; Chambers, Don P.; Famiglietti, James S.

2011-01-01

Most people think of groundwater as a resource, but it is also a useful indicator of climate variability and human impacts on the environment. Groundwater storage varies slowly relative to other non-frozen components of the water cycle, encapsulating long period variations and trends in surface meteorology. On seasonal to interannual timescales, groundwater is as dynamic as soil moisture, and it has been shown that groundwater storage changes have contributed to sea level variations. Groundwater monitoring well measurements are too sporadic and poorly assembled outside of the United States and a few other nations to permit direct global assessment of groundwater variability. However, observational estimates of terrestrial water storage (TWS) variations from the GRACE satellites largely represent groundwater storage variations on an interannual basis, save for high latitude/altitude (dominated by snow and ice) and wet tropical (surface water) regions. A figure maps changes in mean annual TWS from 2009 to 2010, based on GRACE, reflecting hydroclimatic conditions in 2010. Severe droughts impacted Russia and the Amazon, and drier than normal weather also affected the Indochinese peninsula, parts of central and southern Africa, and western Australia. Groundwater depletion continued in northern India, while heavy rains in California helped to replenish aquifers that have been depleted by drought and withdrawals for irrigation, though they are still below normal levels. Droughts in northern Argentina and western China similarly abated. Wet weather raised aquifer levels broadly across western Europe. Rains in eastern Australia caused flooding to the north and helped to mitigate a decade long drought in the south. Significant reductions in TWS seen in the coast of Alaska and the Patagonian Andes represent ongoing glacier melt, not groundwater depletion. Figures plot time series of zonal mean and global GRACE derived non-seasonal TWS anomalies (deviation from the mean of

Genomic evidence for the Pleistocene and recent population history of Native Americans

Science.gov (United States)

Eriksson, Anders; Moltke, Ida; Metspalu, Mait; Homburger, Julian R.; Wall, Jeff; Cornejo, Omar E.; Moreno-Mayar, J. Víctor; Korneliussen, Thorfinn S.; Pierre, Tracey; Rasmussen, Morten; Campos, Paula F.; de Barros Damgaard, Peter; Allentoft, Morten E.; Lindo, John; Metspalu, Ene; Rodríguez-Varela, Ricardo; Mansilla, Josefina; Henrickson, Celeste; Seguin-Orlando, Andaine; Malmström, Helena; Stafford, Thomas; Shringarpure, Suyash S.; Moreno-Estrada, Andrés; Karmin, Monika; Tambets, Kristiina; Bergström, Anders; Xue, Yali; Warmuth, Vera; Friend, Andrew D.; Singarayer, Joy; Valdes, Paul; Balloux, Francois; Leboreiro, Ilán; Vera, Jose Luis; Rangel-Villalobos, Hector; Pettener, Davide; Luiselli, Donata; Davis, Loren G.; Heyer, Evelyne; Zollikofer, Christoph P. E.; Ponce de León, Marcia S.; Smith, Colin I.; Grimes, Vaughan; Pike, Kelly-Anne; Deal, Michael; Fuller, Benjamin T.; Arriaza, Bernardo; Standen, Vivien; Luz, Maria F.; Ricaut, Francois; Guidon, Niede; Osipova, Ludmila; Voevoda, Mikhail I.; Posukh, Olga L.; Balanovsky, Oleg; Lavryashina, Maria; Bogunov, Yuri; Khusnutdinova, Elza; Gubina, Marina; Balanovska, Elena; Fedorova, Sardana; Litvinov, Sergey; Malyarchuk, Boris; Derenko, Miroslava; Mosher, M. J.; Archer, David; Cybulski, Jerome; Petzelt, Barbara; Mitchell, Joycelynn; Worl, Rosita; Norman, Paul J.; Parham, Peter; Kemp, Brian M.; Kivisild, Toomas; Tyler-Smith, Chris; Sandhu, Manjinder S.; Crawford, Michael; Villems, Richard; Smith, David Glenn; Waters, Michael R.; Goebel, Ted; Johnson, John R.; Malhi, Ripan S.; Jakobsson, Mattias; Meltzer, David J.; Manica, Andrea; Durbin, Richard; Bustamante, Carlos D.; Song, Yun S.; Nielsen, Rasmus; Willerslev, Eske

2016-01-01

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we find that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (KYA), and after no more than 8,000-year isolation period in Beringia. Following their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 KYA, one that is now dispersed across North and South America and the other is restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative ‘Paleoamerican’ relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model. PMID:26198033

Range expansion of Oligoryzomys longicaudatus (Rodentia, Sigmodontinae in Patagonian Chile, and first record of Hantavirus in the region Ampliación del rango de distribución de Oligoryzomys longicaudatus (Rodentia, Sigmodontinae en la Patagonia de Chile y primer registro de Hantavirus en la región

Directory of Open Access Journals (Sweden)

SEBASTIÁN BELMAR-LUCERO

2009-06-01

Full Text Available At present, 20 species of Oligoryzomys (Rodentia, Sigmodontinae are recognized in the Neotropical region, most of them distinguished by their karyotypes, which fluctuates between 46-70 chromosomes. Two species are currently recognized in Chile, Oligoryzomys longicaudatus (Bennet, 1832; "colilargo" or the long-tailed pygmy rice rat; 2n = 56, which ranges from 27° to approximately 51° S, and O. magellanicus (Bennet, 1836; Magellanic pygmy rice rat; 2n = 54, south of 51° S in the Patagonian region of Chile and Argentina. As part of an ongoing research on the southern Patagonia of Chile, we report the results of small mammal samplings in six localities. We karyotyped 28 specimens and we also sequenced the hypervariable mtDNA region I in 22 individuals, aligning these sequences with an under development phylogeny of O. longicaudatus. We also evaluated the serology and viral charge in all captured specimens to detect the presence of antibodies to Andes virus (ANDV through Strip Immunoblot Assay (SIA, and of viral genome by RT-PCR. The results consistently showed that the karyotype of southern Patagonia specimens was 2n = 56, equal to that of O. longicaudatus, and that individuals from this area do not differentiate phylogenetically from those of the northern range of distribution. In addition, the serology showed the presence of antibodies IgG anti-ANDV and of viral genome in heart, kidney, spleen, and lungs of a single specimen of Oligoryzomys from the locality of Fuerte Bulnes in the Magallanes region. We conclude that all specimens trapped south of 51° S correspond to Oligoryzomys longicaudatus, thus expanding the distribution of this specie! from 51° to at least 55° S. The results also extended the disiribution of the Andes strain of Hantavirus to southernmost Patagonia.Actualmente se reconocen 20 especies de Oligoryzomys (Rodentia, Sigmodontinae en la región Neotropical, la mayoría de ellas distinguidas por sus cariotipos, los que fluct

Trophic interference by Salmo trutta on Aplochiton zebra and Aplochiton taeniatus in southern Patagonian lakes.

Science.gov (United States)

Elgueta, A; González, J; Ruzzante, D E; Walde, S J; Habit, E

2013-02-01

The length and mass ratio, diet and isotopic composition of Aplochiton zebra and Aplochiton taeniatus inhabiting a Salmo trutta-invaded and a S. trutta-free lake in southern Patagonia were compared. Results indicate that S. trutta exercises important trophic interference over A. zebra and A. taeniatus, causing changes in their dietary composition by reducing the consumption of winged Diptera through changes in feeding behaviours that involve jumping out of the water. This effect is significantly higher in A. zebra than in A. taeniatus a species that has a highly specialized diet. The dietary changes of A. zebra and A. taeniatus in sympatry with S. trutta lead to an impoverishment of their isotopic nitrogen signals (δ(15)N), suggesting a reduction of their trophic position. In the case of A. zebra, this translates into a significant decrease in its body condition factor. Such interference could lead to a population decline of this species and would explain the current distribution range decline and allopatry with S. trutta in fluvial systems. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

On the pterosaur remains from the Río Belgrano formation (Barremian, Patagonian Andes of Argentina

Directory of Open Access Journals (Sweden)

Kellner Alexander W.A.

2003-01-01

Full Text Available Pterosaur remains from the Río Belgrano Formation, Santa Cruz Province, Argentina, were found close to the Estancia Río Roble, along with several ammonoids that indicate a Barremian age for those strata. The specimens (MACN-SC 3617 consist of one ulna and one element tentatively identified as a portion of a wing metacarpal. The ulna shows morphological affinities with the Pteranodontoidea (sensu Kellner 1996, particularly with the members of the Anhangueridae by having a well developed ventral crest close to the proximal articulation, and is tentatively referred to this pterosaur clade. The oldest record of the Anhangueridae, previously limited to the Aptian/Albian, is therefore extended to the Barremian. The Argentinean material is preserved in three dimensions, an unusual condition for pterosaur fossils from that country, indicating that the site situated near the Estancia Río Roble has a great potential for new and well preserved specimens.

On the differences between Last Glacial Maximum and Mid-Holocene climates in southern South America simulated by PMIP3 models

Science.gov (United States)

Berman, Ana Laura; Silvestri, Gabriel E.; Tonello, Marcela S.

2018-04-01

Differences between climate conditions during the Last Glacial Maximum (LGM) and the Mid-Holocene (MH) in southern South America inferred from the state-of-the-art PMIP3 paleoclimatic simulations are described for the first time in this paper. The aim is to expose characteristics of past climate changes occurred without human influence. In this context, numerical simulations are an indispensable tool for inferring changes in near-surface air temperature and precipitation in regions where proxy information is scarce or absent. The analyzed PMIP3 models describe MH temperatures significantly warmer than those of LGM with magnitudes of change depending on the season and the specific geographic region. In addition, models indicate that seasonal mean precipitation during MH increased with respect to LGM values in wide southern continental areas to the east of the Andes Cordillera whereas seasonal precipitation developed in areas to the west of Patagonian Andes reduced from LGM to MH.

Application of DNA forensic techniques for identifying poached guanacos (Lama guanicoe) in Chilean Patagonia*.

Science.gov (United States)

Marín, Juan C; Saucedo, Cristian E; Corti, Paulo; González, Benito A

2009-09-01

Guanaco (Lama guanicoe) is a protected and widely distributed ungulate in South America. A poacher, after killing guanacos in Valle Chacabuco, Chilean Patagonia, transported and stored the meat. Samples were retrieved by local police but the suspect argued that the meat was from a horse. Mitochondrial cytochrome b gene (774 pb), 15 loci microsatellites, and SRY gene were used to identify the species, number of animals and their population origin, and the sex of the animals, respectively. Analysis revealed that the samples came from a female (absence of SRY gene) Patagonian guanaco (assignment probability between 0.0075 and 0.0282), and clearly distinguishing it from sympatric ungulates (E-value = 0). Based on the evidence obtained in the field in addition to forensic data, the suspect was convicted of poaching and illegally carrying fire arms. This is the first report of molecular tools being used in forensic investigations of Chilean wildlife indicating its promising future application in guanaco management and conservation.

Identification and characterization of microsatellites from calafate (Berberis microphylla, Berberidaceae)1

Science.gov (United States)

Varas, Benjamín; Castro, María H.; Rodriguez, Roberto; von Baer, Dietrich; Mardones, Claudia; Hinrichsen, Patricio

2013-01-01

• Premise of the study: Southern barberry or calafate (Berberis microphylla) is a shrub species endemic to the Patagonian region of South America that is used for human consumption. The fruit is very rich in vitamin C and anthocyanins and has a very high antioxidant capacity. There have been only a few genetic studies of this and other closely related species. • Methods and Results: Here we present the first 18 microsatellite markers of B. microphylla that were characterized using 66 accessions of calafate from Patagonia. On average, they had 7.6 alleles per marker, with an expected heterozygosity of 0.688. The informativeness of these markers was also evaluated in another 15 Berberis species, including most of the native and endemic Chilean species. • Conclusions: The results confirm that these new simple sequence repeat markers are very polymorphic and potentially useful in genetic studies in any species of the genus Berberis. PMID:25202561

Identification and Characterization of Microsatellites from Calafate (Berberis microphylla, Berberidaceae

Directory of Open Access Journals (Sweden)

Benjamín Varas

2013-07-01

Full Text Available Premise of the study: Southern barberry or calafate (Berberis microphylla is a shrub species endemic to the Patagonian region of South America that is used for human consumption. The fruit is very rich in vitamin C and anthocyanins and has a very high antioxidant capacity. There have been only a few genetic studies of this and other closely related species. Methods and Results: Here we present the first 18 microsatellite markers of B. microphylla that were characterized using 66 accessions of calafate from Patagonia. On average, they had 7.6 alleles per marker, with an expected heterozygosity of 0.688. The informativeness of these markers was also evaluated in another 15 Berberis species, including most of the native and endemic Chilean species. Conclusions: The results confirm that these new simple sequence repeat markers are very polymorphic and potentially useful in genetic studies in any species of the genus Berberis.

“Gate and Port of the South of Argentina”? Nuances and Debates in the Image of Bahia Blanca City in Its Regional Context in the Mid-twentieth Century

Directory of Open Access Journals (Sweden)

Juliana López Pascual

2016-01-01

Full Text Available For over a century the people of Bahia Blanca, Argentinian port city located at the south west of the province of Buenos Aires, they have imagined it and defined it not only as part of the Patagonian territories but also as their legitimate political, economic and cultural center. The aim of historicizing and questioning this idea, trying to account for the interests that were mobilized, the ideological postures that hinted, and the impact it had on the effective regional layout, is what motivates our research. To that end, this article does focus on economic and infrastructural dimension that some debates of mid-twentieth century used simultaneously as evidence and as ultimate goal of this alleged hegemony. For this purpose, we will analyze the writings of Domingo Pronsato and Ricardo M. Ortiz whom, from different geopolitical perspectives, devised specific roles for the city that suited their plans for the regional development of Patagonia.

Genomic evidence for the Pleistocene and recent population history of Native Americans

KAUST Repository

Raghavan, Maanasa; Steinrü cken, Matthias; Harris, Kelley; Schiffels, Stephan; Rasmussen, Simon; DeGiorgio, Michael; Albrechtsen, Anders; Valdiosera, Cristina; Á vila-Arcos, Marí a C.; Malaspinas, Anna Sapfo; Eriksson, Anders; Moltke, Ida; Metspalu, Mait; Homburger, Julian R.; Wall, Jeff; Cornejo, Omar E.; Moreno-Mayar, J. Ví ctor; Korneliussen, Thorfinn S.; Pierre, Tracey; Rasmussen, Morten; Campos, Paula F.; De Barros Damgaard, Peter; Allentoft, Morten E.; Lindo, John; Metspalu, Ene; Rodrí guez-Varela, Ricardo; Mansilla, Josefina; Henrickson, Celeste; Seguin-Orlando, Andaine; Malmstö m, Helena; Stafford, Thomas; Shringarpure, Suyash S.; Moreno-Estrada, André s; Karmin, Monika; Tambets, Kristiina; Bergströ m, Anders; Xue, Yali; Warmuth, Vera; Friend, Andrew D.; Singarayer, Joy; Valdes, Paul; Balloux, Francois; Leboreiro, Ilá n; Vera, Jose Luis; Rangel-Villalobos, Hector; Pettener, Davide; Luiselli, Donata; Davis, Loren G.; Heyer, Evelyne; Zollikofer, Christoph P E; Ponce De Leó n, Marcia S.; Smith, Colin I.; Grimes, Vaughan; Pike, Kelly Anne; Deal, Michael; Fuller, Benjamin T.; Arriaza, Bernardo; Standen, Vivien; Luz, Maria F.; Ricaut, Francois; Guidon, Niede; Osipova, Ludmila; Voevoda, Mikhail I.; Posukh, Olga L.; Balanovsky, Oleg; Lavryashina, Maria; Bogunov, Yuri; Khusnutdinova, Elza; Gubina, Marina; Balanovska, Elena; Fedorova, Sardana; Litvinov, Sergey; Malyarchuk, Boris; Derenko, Miroslava; Mosher, M. J.; Archer, David; Cybulski, Jerome

2015-01-01

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model. © 2015, American Association for the Advancement of Science. All rights reserved.

A multi-decadal remote sensing study on glacial change in the North Patagonia Ice Field Chile

Science.gov (United States)

Tetteh, Lucy Korlekwor

Glaciers in the North Patagonian Ice Fields are temperate glaciers and can be studied to understand the dynamics of climate change. However, the ice field has been neglected in mass balance studies. In this study, multi decadal study of glacial mass balance, glacier retreat and glacial lake expansion in the North Patagonia were studied. Landsat (TM, ETM+ and 8) and ASTER images were used. San Quintin glacier experienced the highest retreat. Demarcation of glacier lakes boundaries indicated an increase in glacial lake area an addition of 4 new glacial lakes. Nef glacier recorded the highest mass gain of 9.91 plus or minus 1.96 m.w.e.a.-1 and HPN-4 glacier recorded the highest mass loss of -8.9 plus or minus 1.96 m.w.e.a. -1. However, there is a high uncertainty in the elevation values in the DEM due to the rugged nature of the terrain and presence of the heavy snow cover.

POPULATION GENETICS. Genomic evidence for the Pleistocene and recent population history of Native Americans.

Science.gov (United States)

Raghavan, Maanasa; Steinrücken, Matthias; Harris, Kelley; Schiffels, Stephan; Rasmussen, Simon; DeGiorgio, Michael; Albrechtsen, Anders; Valdiosera, Cristina; Ávila-Arcos, María C; Malaspinas, Anna-Sapfo; Eriksson, Anders; Moltke, Ida; Metspalu, Mait; Homburger, Julian R; Wall, Jeff; Cornejo, Omar E; Moreno-Mayar, J Víctor; Korneliussen, Thorfinn S; Pierre, Tracey; Rasmussen, Morten; Campos, Paula F; de Barros Damgaard, Peter; Allentoft, Morten E; Lindo, John; Metspalu, Ene; Rodríguez-Varela, Ricardo; Mansilla, Josefina; Henrickson, Celeste; Seguin-Orlando, Andaine; Malmström, Helena; Stafford, Thomas; Shringarpure, Suyash S; Moreno-Estrada, Andrés; Karmin, Monika; Tambets, Kristiina; Bergström, Anders; Xue, Yali; Warmuth, Vera; Friend, Andrew D; Singarayer, Joy; Valdes, Paul; Balloux, Francois; Leboreiro, Ilán; Vera, Jose Luis; Rangel-Villalobos, Hector; Pettener, Davide; Luiselli, Donata; Davis, Loren G; Heyer, Evelyne; Zollikofer, Christoph P E; Ponce de León, Marcia S; Smith, Colin I; Grimes, Vaughan; Pike, Kelly-Anne; Deal, Michael; Fuller, Benjamin T; Arriaza, Bernardo; Standen, Vivien; Luz, Maria F; Ricaut, Francois; Guidon, Niede; Osipova, Ludmila; Voevoda, Mikhail I; Posukh, Olga L; Balanovsky, Oleg; Lavryashina, Maria; Bogunov, Yuri; Khusnutdinova, Elza; Gubina, Marina; Balanovska, Elena; Fedorova, Sardana; Litvinov, Sergey; Malyarchuk, Boris; Derenko, Miroslava; Mosher, M J; Archer, David; Cybulski, Jerome; Petzelt, Barbara; Mitchell, Joycelynn; Worl, Rosita; Norman, Paul J; Parham, Peter; Kemp, Brian M; Kivisild, Toomas; Tyler-Smith, Chris; Sandhu, Manjinder S; Crawford, Michael; Villems, Richard; Smith, David Glenn; Waters, Michael R; Goebel, Ted; Johnson, John R; Malhi, Ripan S; Jakobsson, Mattias; Meltzer, David J; Manica, Andrea; Durbin, Richard; Bustamante, Carlos D; Song, Yun S; Nielsen, Rasmus; Willerslev, Eske

2015-08-21

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model. Copyright © 2015, American Association for the Advancement of Science.

A Gondwanan Imprint on Global Diversity and Domestication of Wine and Cider Yeast Saccharomyces uvarum

Science.gov (United States)

Almeida, Pedro; Gonçalves, Carla; Teixeira, Sara; Libkind, Diego; Bontrager, Martin; Masneuf-Pomarède, Isabelle; Albertin, Warren; Durrens, Pascal; Sherman, David; Marullo, Philippe; Hittinger, Chris Todd; Gonçalves, Paula; Sampaio, José Paulo

2016-01-01

In addition to Saccharomyces cerevisiae, the cryotolerant yeast species S. uvarum is also used for wine and cider fermentation but nothing is known about its natural history. Here we use a population genomics approach to investigate its global phylogeography and domestication fingerprints using a collection of isolates obtained from fermented beverages and from natural environments on five continents. South American isolates contain more genetic diversity than that found in the Northern Hemisphere. Moreover, coalescence analyses suggest that a Patagonian sub-population gave rise to the Holarctic population through a recent bottleneck. Holarctic strains display multiple introgressions from other Saccharomyces species, those from S. eubayanus being prevalent in European strains associated with human-driven fermentations. These introgressions are absent in the large majority of wild strains and gene ontology analyses indicate that several gene categories relevant for wine fermentation are overrepresented. Such findings constitute a first indication of domestication in S. uvarum. PMID:24887054

Genomic evidence for the Pleistocene and recent population history of Native Americans

KAUST Repository

Raghavan, Maanasa

2015-07-21

How and when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericúes and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model. © 2015, American Association for the Advancement of Science. All rights reserved.

Geomorphological evidences of Quaternary tectonic activities in the Santa Cruz river valley, Patagonia, Argentina

International Nuclear Information System (INIS)

Massabie, A.; Sanguinetti, A.; Nestiero, O.

2007-01-01

From Argentin lake, at west on Andean hills, to Puerto Santa Cruz on Atlantic coast, Santa Cruz river cross eastward Santa Cruz province over 250 km in Patagonia at southern Argentina. Present bed of the river has a meandering outline with first order meanders of great ratio bends and second order meanders of minor ratio bends. Principal wanderings are 45 to 55 km spaced from near Estancia La Julia or Rio Bote at west to Comandante Luis Piedrabuena at east. On river's bed middle sector these great curvatures are located at Estancia Condor Cliff and Estancia Rincon Grande. Regional and partial detailed studies allow to recognize structural control on river's bed sketch and valley s geomorphology that relates first order bends with reactivated principal faults. These faults fit well with parallel system of northwest strike of Austral Basin.On geological, geomorphologic and structural evidences recognized in Santa Cruz river, quaternary tectonic activity, related to Andean movements in southern Patagonian foreland, is postulated. (author)

Neotropics provide insights into the emergence of New World monkeys: New dental evidence from the late Oligocene of Peruvian Amazonia.

Science.gov (United States)

Marivaux, Laurent; Adnet, Sylvain; Altamirano-Sierra, Ali J; Boivin, Myriam; Pujos, François; Ramdarshan, Anusha; Salas-Gismondi, Rodolfo; Tejada-Lara, Julia V; Antoine, Pierre-Olivier

2016-08-01

Recent field efforts in Peruvian Amazonia (Contamana area, Loreto Department) have resulted in the discovery of a late Oligocene (ca. 26.5 Ma; Chambira Formation) fossil primate-bearing locality (CTA-61). In this paper, we analyze the primate material consisting of two isolated upper molars, the peculiar morphology of which allows us to describe a new medium-sized platyrrhine monkey: Canaanimico amazonensis gen. et sp. nov. In addition to the recent discovery of Perupithecus ucayaliensis, a primitive anthropoid taxon of African affinities from the alleged latest Eocene Santa Rosa locality (Peruvian Amazonia), the discovery of Canaanimico adds to the evidence that primates were well-established in the Amazonian Basin during the Paleogene. Our phylogenetic results based on dental evidence show that none of the early Miocene Patagonian taxa (Homunculus, Carlocebus, Soriacebus, Mazzonicebus, Dolichocebus, Tremacebus, and Chilecebus), the late Oligocene Bolivian Branisella, or the Peruvian Canaanimico, is nested within a crown platyrrhine clade. All these early taxa are closely related and considered here as stem Platyrrhini. Canaanimico is nested within the Patagonian Soriacebinae, and closely related to Soriacebus, thereby extending back the soriacebine lineage to 26.5 Ma. Given the limited dental evidence, it is difficult to assess if Canaanimico was engaged in a form of pitheciine-like seed predation as is observed in Soriacebus and Mazzonicebus, but dental microwear patterns recorded on one upper molar indicate that Canaanimico was possibly a fruit and hard-object eater. If Panamacebus, a recently discovered stem cebine from the early Miocene of Panama, indicates that the crown platyrrhine radiation was already well underway by the earliest Miocene, Canaanimico indicates in turn that the "homunculid" radiation (as a part of the stem radiation) was well underway by the late Oligocene. These new data suggest that the stem radiation likely occurred in the Neotropics

Distributed ice thickness and glacier volume in southern South America

Science.gov (United States)

Carrivick, Jonathan L.; Davies, Bethan J.; James, William H. M.; Quincey, Duncan J.; Glasser, Neil F.

2016-11-01

South American glaciers, including those in Patagonia, presently contribute the largest amount of meltwater to sea level rise per unit glacier area in the world. Yet understanding of the mechanisms behind the associated glacier mass balance changes remains unquantified partly because models are hindered by a lack of knowledge of subglacial topography. This study applied a perfect-plasticity model along glacier centre-lines to derive a first-order estimate of ice thickness and then interpolated these thickness estimates across glacier areas. This produced the first complete coverage of distributed ice thickness, bed topography and volume for 617 glaciers between 41°S and 55°S and in 24 major glacier regions. Maximum modelled ice thicknesses reach 1631 m ± 179 m in the South Patagonian Icefield (SPI), 1315 m ± 145 m in the North Patagonian Icefield (NPI) and 936 m ± 103 m in Cordillera Darwin. The total modelled volume of ice is 1234.6 km3 ± 246.8 km3 for the NPI, 4326.6 km3 ± 865.2 km3 for the SPI and 151.9 km3 ± 30.38 km3 for Cordillera Darwin. The total volume was modelled to be 5955 km3 ± 1191 km3, which equates to 5458.3 Gt ± 1091.6 Gt ice and to 15.08 mm ± 3.01 mm sea level equivalent (SLE). However, a total area of 655 km2 contains ice below sea level and there are 282 individual overdeepenings with a mean depth of 38 m and a total volume if filled with water to the brim of 102 km3. Adjusting the potential SLE for the ice volume below sea level and for the maximum potential storage of meltwater in these overdeepenings produces a maximum potential sea level rise (SLR) of 14.71 mm ± 2.94 mm. We provide a calculation of the present ice volume per major river catchment and we discuss likely changes to southern South America glaciers in the future. The ice thickness and subglacial topography modelled by this study will facilitate future studies of ice dynamics and glacier isostatic adjustment, and will be important for projecting water resources and

Mycosporine-like amino acids in planktonic organisms living under different UV exposure conditions in Patagonian lakes

Science.gov (United States)

TARTAROTTI, BARBARA; BAFFICO, GUSTAVO; TEMPORETTI, PEDRO; ZAGARESE, HORACIO E.

2011-01-01

Mycosporine-like amino acids (MAAs) were studied in zooplankton from 13 Argentinian lakes covering a broad range in altitude, maximum depth and physico-chemical properties of the water. Four to nine different MAAs (predominantly porphyra-334 and shinorine) were found in the copepods Boeckella gibbosa, B. gracilipes, B. meteoris and Parabroteas sarsi, and in the ciliate Stentor amethystinus, while MAAs were undetectable in the cladoceran Daphnia middendorffiana. Among the different copepods, maximum MAA concentrations accounted for 0.25–1.31% of the dry weight, and contents were generally about three to seven times (up to 43 times) higher in the animals living in the clearest lakes compared to those occurring in low-UV systems. This variability in the content of MAAs was related to the lake altitude (r2 = 0.71), and the fraction of the water column to which 1% of the surface UV radiation at 320 nm penetrated (r2 = 0.57). Our data therefore underscore the role of MAAs as sunscreens to decrease the potential negative effects of solar radiation, but they also indicate that other environmental factors besides UV transparency play a role in determining MAA concentrations. One lake was selected to obtain additional information on the qualitative composition of MAAs in seston of <100 μm between two sampling sites and over a 2 month study period (austral summer). Six different MAAs were detected in the samples, with porphyra-334 and palythine being predominant. In the copepods collected simultaneously, there was low variation in MAA concentrations between the two sites and over time. Thus, our results suggest that under similar UV exposure conditions MAA contents of planktonic organisms show low temporal variation. PMID:21258622

Spatial structure of the meroplankton community along a Patagonian fjord - The role of changing freshwater inputs

Science.gov (United States)

Meerhoff, Erika; Tapia, Fabián J.; Castro, Leonardo R.

2014-12-01

Freshwater inputs are major drivers of circulation, hydrographic structure, and productivity patterns along estuarine systems. We assessed the degree to which meroplankton community structure in the Baker/Martinez fjord complex (Chilean Patagonia, 47.5°S) responds to spatial and temporal changes in hydrographic conditions driven by seasonal changes in Baker river outflow. Zooplankton and hydrographic measurements were conducted along the fjord in early spring (October) and late summer (February), when river outflow was minimal and maximal, respectively. Major meroplankton groups found on these surveys were larval barnacles, crabs, bivalves and gastropods. There was a clear change in community structure between October and February, explained by a switch in the numerically dominant group from barnacle to bivalve larvae. This change in community structure was related to changes in hydrographic structure along the fjord, which are mainly associated with seasonal changes in the Baker river outflow. A variance partition analysis showed no significant spatial trend that could account for the variation in meroplankton along the Martinez channel, whereas temporal variability and environmental variables accounted for 36.6% and 27.6% of the variance, respectively. When comparing meroplankton among the Baker and Martinez channels in October, changes in environmental variables explained 44.9% of total variance, whereas spatial variability accounted for 23.5%. Early and late-stage barnacle larvae (i.e. nauplii and cyprids) were more abundant in water with lower temperature, and higher dissolved oxygen and chlorophyll-a concentration, whereas bivalve larvae were more strongly associated to warmer waters. The seasonal shift in numerical dominance, from barnacle larvae in early spring to bivalve larvae in late summer, suggests that reproduction of these groups is triggered by substantially different sets of conditions, both in terms of hydrography and food availability. The analysis of a monthly zooplankton time series showed that barnacle nauplii were most abundant in spring, and one order of magnitude more abundant than cyprids. Larvae of decapods were most abundant in summer.

Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation

DEFF Research Database (Denmark)

Metcalf, Jessica L.; Turney, Chris; Barnett, Ross

2016-01-01

The causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as huma...

Echinococcosis and other parasitic infections in domestic dogs from urban areas of an argentinean Patagonian city

OpenAIRE

Flores, Verónica; Viozzi, Gustavo; Garibotti, Gilda; Zacharias, Daniela; Debiaggi, María Florencia; Kabaradjian, Surpik

2017-01-01

In urban populations of South America, dogs with free access to public areas represent a public health concern. The primary consequence of roaming dogs on human health is the transmission of infectious and parasitic diseases mainly through feces contamination. The main diseases likely to be transmitted are hydatidosis or echinococcosis, larva migrans, and giardiasis. In Argentina, hydatidosis ranks among the most prevalent zoonosis. Although it is considered a rural disease, the circulation o...

Echinococcosis and other parasitic infections in domestic dogs from urban areas of an Argentinean Patagonian city

Directory of Open Access Journals (Sweden)

Verónica Flores

2017-12-01

Full Text Available In urban populations of South America, dogs with free access to public areas represent a public health concern. The primary consequence of roaming dogs on human health is the transmission of infectious and parasitic diseases mainly through feces contamination. The main diseases likely to be transmitted are hydatidosis or echinococcosis, larva migrans, and giardiasis. In Argentina, hydatidosis ranks among the most prevalent zoonosis. Although it is considered a rural disease, the circulation of this parasite in urban areas has been documented. The aim of this work was to survey intestinal parasites in canine feces from two low-income urban neighborhoods of Bariloche city, Argentina, and to assess their seasonal variation. During 2016, 188 fresh dog feces were collected from sidewalks in 40 randomly selected blocks from the neighborhoods. Each sample was processed by Sheater flotation and tested for a coproantigen (CAg by ELISA. The percentage of parasitized feces was 65.3% (95% CI: 55.9%-73.8%. Eleven parasite species were found, 3 protozoan, 3 cestodes, and 5 nematodes. Echinococcus sp. was present in 9.3% of the samples (95% CI: 4.7%-16.1%. Canine echinococcosis rates resulted similar to rates found previously in other neighborhoods of the city. The life cycle of Echinococcus sp. is sustained in urban areas by the entry of parasitized livestock, domiciliary slaughtering, and inadequate deposition of offal. The risk of Echinococcus sp. transmission to people in these neighborhoods is very high, due to high density of free-roaming dogs and high percentages of infected feces, similar to percentages observed in rural areas.

Aquatic habitat modifications in La Plata River basin, Patagonia and associated marine areas.

Science.gov (United States)

Mugetti, Ana Cristina; Calcagno, Alberto Tomás; Brieva, Carlos Alberto; Giangiobbe, María Silvia; Pagani, Andrea; Gonzalez, Silvia

2004-02-01

This paper describes the environmental characteristics and situation of aquatic habitats and communities in southern continental and maritime areas of southeastern South America (Patagonian Shelf GIWA Subregion), resulting from an overall assessment carried out within the framework of a GIWA project, mostly on the basis of publicly available data. The main focus of the analysis was on the current situation of transboundary water resources and anthropogenic impacts. In the inland waters, habitat and community modifications result, principally, from dams and reservoirs built in the main watercourses for hydroelectric power generation and other uses. The transformation of lotic environments into lentic ones have affected habitats and altered biotic communities. In the La Plata River basin, invasive exotic species have displaced native ones. Habitats in the ocean have been degraded, as their biodiversity becomes affected by overfishing and pollution. This article includes a discussion on the causal chain and the policy options elaborated for the Coastal Ecosystem of Buenos Aires province and the Argentinean-Uruguayan Common Fishing Zone, where fishing resources are shared by both countries.

A widespread devonian methamorphic episode in northern Patagonia, Argentina

International Nuclear Information System (INIS)

Ostera, H.A.; Linares, E; Haller, M.J; Cagnoni, M.C.; Lopez de Luchi, M

2001-01-01

One of the greatest difficulties in Rb-Sr dating on metamorphic rocks is the lack of evidences of complete re-homogenization and the assumption of a common initial ratio for all the samples analyzed. The redistribution of parent-daughter elements and the concomitant partial or complete equilibration of the isotopic system could occur on mineral or regional size domains. This fact led to many authors to discard or disapprove the use of this method in metamorphic terranes. However, recent papers suggested that this opinion has been premature and that additional information could be obtained by the Rb-Sr method despite the difficulties that it implies (Patel et al., 1999). Many reports on well fitted Rb-Sr isochrons giving the age of metamorphism in regionally metamorphosed rocks, suggest that the Sr isotopic equilibrium can take place at different scales. This paper presents data and the Rb-Sr system behaviour from a metamorphic unit (Cushamen Formation) in the Northern Patagonia, as a contribution to elucidate the evolution of the North Patagonian Massif (au)

Paleozoogeography of the Wine Mouse (Akodon oenos & Late Holocene Paleoenvironments in South-Central Mendoza, Argentina

Directory of Open Access Journals (Sweden)

Fernando Julián Fernández

2011-02-01

Full Text Available Cranial remains of the wine mouse (Akodon oenos are documented from an archaeological site in south-central Mendoza, Argentina (Agua de La Mula, 35º22' S, 68º15' W, which dates to the end of the late Holocene (1610 ± 60; 1260 ± 60; 1000 ± 50 C14 yr B.P.. The taxonomic status of this small rodent is currently being assessed, but these remains represent the first fossil record for the morphotaxon A. oenos. The species’ present distribution is restricted to a few records from Mendoza province. Analysis of the remains supports paleoenvironmental reconstruction using the small mammal assemblage recovered from this site. From the late Holocene into modernity temperature decreased and winter precipitation increased, resulting in advance of Patagonian steppe grading with altitude into Monte desert. Holocene climatic conditions may explain the relatively late human occupation of ecologically marginal environments in this region, which probably favored effective human occupation of the Payunia region at sites such as Agua de La Mula between 1600 and 1000 years B.P.

Discussion of oil pollution in Argentina

Energy Technology Data Exchange (ETDEWEB)

1978-06-01

Oil pollution in Argentina, at the port of Comodora Rivadavia showed signs of long-term oil pollution of a nature which would not be tolerated in relation to the exploitation of North Sea oil. The field is operated by Yacimientos Petroliferos Fiscales (Argentine), produces 70,000 bbl/day of oil from onshore and offshore wells, and has been in operation since 1907. A very marked ''tideline'' of bituminous oil residues contaminates the harbor installations and completely covers the pebbles, boulders, and rocks in the intertidal region. This material is of a considerable thickness and has completely obliterated any form of littoral marine life in these habitats. The sandy beach does not show signs of accumulative oil, and it is used as an important recreational area. Since seriously oiled seabirds can be seen, it is surprising that Patagonian crested ducks, king cormorants, and kelp gulls occur in large numbers but show little sign of oil contamination. The Magellan penguin, which is much less abundant locally, may have been much more vulnerable to the oil.

(Discussion of) oil pollution in Argentina

Energy Technology Data Exchange (ETDEWEB)

1978-06-01

The port of Comodora Rivadavia shows signs of long-term oil pollution of a nature which would not be tolerated in relation to the exploitation of North Sea oil. The field is operated by Yacimientos Petroliferos Fiscales (Argentine), produces 70,000 bbl/day of oil from onshore and offshore wells, and has been in operation since 1907. A very marked tideline of bituminous oil residues contaminates the harbor installations and completely covers the pebbles, boulders, and rocks in the inertidal region. This material is of a considerable thickness and has completely obliterated any form of littoral marine life in these habitats. The sandy beach does not show signs of accumulative oil, and it is used as an important recretional area. Since seriously oiled seabirds can be seen, it is surprising that Patagonian crested ducks, king cormorants, and kelp gulls occur in large numbers but show little sign of oil contamination. The Magellan penguin, which is much less abundant locally, may have been much more vulnerable to the oil. Photographs are included.

Reptiles of Chubut province, Argentina: richness, diversity, conservation status and geographic distribution maps

Science.gov (United States)

Minoli, Ignacio; Morando, Mariana; Avila, Luciano Javier

2015-01-01

Abstract An accurate estimation of species and population geographic ranges is essential for species-focused studies and conservation and management plans. Knowledge of the geographic distributions of reptiles from Patagonian Argentina is in general limited and dispersed over manuscripts from a wide variety of topics. We completed an extensive review of reptile species of central Patagonia (Argentina) based on information from a wide variety of sources. We compiled and checked geographic distribution records from published literature and museum records, including extensive new data from the LJAMM-CNP (CENPAT-CONICET) herpetological collection. Our results show that there are 52 taxa recorded for this region and the highest species richness was seen in the families Liolaemidae and Dipsadidae with 31 and 10 species, respectively. The Patagónica was the phytogeographic province most diverse in species and Phymaturus was the genus of conservation concern most strongly associated with it. We present a detailed species list with geographical information, richness species, diversity analyses with comparisons across phytogeographical provinces, conservation status, taxonomic comments and distribution maps for all of these taxa. PMID:25931966

Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina

Science.gov (United States)

Hofreiter, Michael; Betancourt, Julio L.; Sbriller, Alicia Pelliza; Markgraf, Vera; McDonald, H. Gregory

2003-01-01

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.

First record of the invasive diatom Didymosphenia geminata (Lyngbye) Schmidt in a Patagonian Andean river of Argentina

OpenAIRE

Sastre, Alicia Viviana; Santinelli, Norma Herminia; Bauer, Gabriel A.; Ayesterán, M. Gabriel; Uyua, Noelia Mariel

2017-01-01

The Futaleufú River, Argentina, was monitored monthly from June 2010 to August 2011, in order to detect the invasive diatom Didymosphenia geminata, which was previously observed in Chile. Plankton and periphyton samples were taken from 10 sites. Didymosphenia geminata was not found until late winter. In August 2010, the species was first detected at isolated points of the river but in spring and summer the algal coverage extended along several kilometers. The coverage of blooms, spread to dee...

Fish waste as an alternative resource for gulls along the Patagonian coast: availability, use, and potential consequences

Energy Technology Data Exchange (ETDEWEB)

Yorio, Pablo; Caille, Guillermo

2004-04-01

We evaluated the volumes of waste from fish processing plants in Chubut Province, Argentina, and discuss its potential consequences for Kelp Gull (Larus dominicanus) population dynamics and coastal management. Mean volume of waste produced between 1989 and 2001 in three coastal cities was 49.8 {+-} 10.9 thousand tons y{sup -1}. The amount of waste varied between years and cities, being larger at Puerto Madryn and Comodoro Rivadavia than at Rawson (24.1, 19.3 and 6.4 thousand tons y{sup -1}, respectively). Waste was disposed at the three cities during all months of the sampled years. Large numbers of Kelp Gulls have been recorded taking advantage of fish waste disposed at these waste sites throughout the year. Considering its energetic content, waste generated at processing plants may support a population of between 101 000 and 209 000 Kelp Gulls. Fish waste could be contributing to their population expansion through increased survival and breeding success. Conflicts due to the use of waste and derived effects on other coastal species and human populations could be minimized by adequate fish waste management.

Variations in anthropogenic silver in a large Patagonian lake correlate with global shifts in photographic processing technology.

Science.gov (United States)

Juncos, Romina; Campbell, Linda; Arcagni, Marina; Daga, Romina; Rizzo, Andrea; Arribére, María; Ribeiro Guevara, Sergio

2017-04-01

At the beginning of the 21st century, digital imaging technology replaced the traditional silver-halide film photography which had implications in Ag contamination. Lake Nahuel Huapi is a popular Patagonia tourist destination impacted by municipal silver (Ag) contamination from photographic processing facilities since 1990's. Silver concentrations in a dated sediment core from the lake bottom showed a 10-fold increase above background levels in the second half of the 20th century, then a decrease. This trend corresponds well with published annual global photography industry demand for Ag, which clearly shows the evolution and replacement of the traditional silver-halide film photography by digital imaging technology. There were significant decreases in Ag concentrations in sediments, mussels and fish across the lake between 1998 and 2011. Lower trophic organisms had variable whole-body Ag concentrations, from 0.2-2.6 μg g -1 dry weight (DW) in plankton to 0.02-3.1 μg g -1 DW in benthic macroinvertebrates. Hepatic Ag concentrations in crayfish, mussels and predatory fish were significantly elevated relative to muscle which often have Ag concentrations below the detection limit (0.01-0.05 μg g -1 DW). Trophodynamic analyses using δ 15 N and whole-body invertebrate and muscle Ag concentrations indicated food web biodilution trends. High sedimentation rates in conjunction with the reduction of silver waste products discharged to the lake, as a result of the change to digital image processing technologies, are resulting in unplanned but welcome remediation of the Ag contamination in Lake Nahuel Huapi. Copyright © 2017 Elsevier Ltd. All rights reserved.

Magnitude, geomorphologic response and climate links of lake level oscillations at Laguna Potrok Aike, Patagonian steppe (Argentina)

DEFF Research Database (Denmark)

Kliem, P.; Buylaert, Jan-Pieter; Hahn, A.

2013-01-01

in the rain-shadow of the Andes document high Last Glacial and low Holocene lake levels that could suggest increased precipitation during the Last Glacial period. As permafrost in semiarid Patagonia is documented and dated to the Last Glacial period we argue that the frozen ground might have increased...... surficial runoff from the catchment and thus influenced the water balance of the lake. This is important for investigating the glacial to Holocene latitudinal shift and/or strengthening of the Southern Hemispheric Westerlies by using lake level reconstructions as a means to assess the regional water balance...

Seasonal changes in morphophysiological traits of two native Patagonian shrubs from Argentina with different drought resistance strategies.

Science.gov (United States)

Varela, M Celeste; Reinoso, Herminda; Luna, Virginia; Cenzano, Ana M

2018-06-01

In semi-arid regions, plants develop various biochemical and physiological strategies to adapt to dry periods. Understanding the resistance mechanisms to dry periods under field conditions is an important topic in ecology. Larrea divaricata and Lycium chilense provide various ecological services. The aim of this work is to elucidate new morpho-histological, biochemical and hormonal traits that contribute to the drought resistance strategies of two native shrubs. Green leaves and fine roots from L. divaricata and L. chilense were collected in each season for one year, and various traits were measured. The hormone (abscisic acid, ABA-glucose ester, gibberellins A 1 and A 3 , and indole acetic acid) contents were determined by liquid chromatography coupled to mass spectrometry. Rainfall data and the soil water content were also measured. A multivariate analysis showed that green leaves from L. divaricata showed high values for the leaf dry weight, blade leaf thickness and ABA content in the summer compared with those from L. chilense. Fine roots from L. divaricata had high RWC and high IAA levels during the autumn-dry period compared with those from L. chilense, but both had similar levels during the winter and spring. Our results support the notion that species with different drought resistance mechanisms (avoidance or tolerance) display different responses to dry periods throughout the year. Larrea divaricata, which exhibits more xerophytic traits, modified its morphology and maintained its physiological parameters (high RWC in leaves and roots, high ABA levels in leaves during summer, high GA 3 in leaves and high IAA in roots during autumn) to tolerate dry periods, whereas Lycium chilense, which displays more mesophytic traits, uses strategies to avoid dry periods (loss of leaves during autumn and winter, high RWC in leaves, high ABA-GE and GA 3 in leaves during summer, high GA 1 and GA 3 in roots during summer, and high IAA in roots during autumn and summer) and thus has a metabolism that is more dependent on water availability for growth. Copyright © 2018. Published by Elsevier Masson SAS.

Fish waste as an alternative resource for gulls along the Patagonian coast: availability, use, and potential consequences

International Nuclear Information System (INIS)

Yorio, Pablo; Caille, Guillermo

2004-01-01

We evaluated the volumes of waste from fish processing plants in Chubut Province, Argentina, and discuss its potential consequences for Kelp Gull (Larus dominicanus) population dynamics and coastal management. Mean volume of waste produced between 1989 and 2001 in three coastal cities was 49.8 ± 10.9 thousand tons y -1 . The amount of waste varied between years and cities, being larger at Puerto Madryn and Comodoro Rivadavia than at Rawson (24.1, 19.3 and 6.4 thousand tons y -1 , respectively). Waste was disposed at the three cities during all months of the sampled years. Large numbers of Kelp Gulls have been recorded taking advantage of fish waste disposed at these waste sites throughout the year. Considering its energetic content, waste generated at processing plants may support a population of between 101 000 and 209 000 Kelp Gulls. Fish waste could be contributing to their population expansion through increased survival and breeding success. Conflicts due to the use of waste and derived effects on other coastal species and human populations could be minimized by adequate fish waste management

Interhemispheric correlation of late pleistocene glacial events.

Science.gov (United States)

Lowell, T V; Heusser, C J; Andersen, B G; Moreno, P I; Hauser, A; Heusser, L E; Schlüchter, C; Marchant, D R; Denton, G H

1995-09-15

A radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima during the last glaciation at 13,900 to 14,890, 21,000, 23,060, 26,940, 29,600, and >/=33,500 carbon-14 years before present ((14)C yr B.P.) in a cold and wet Subantarctic Parkland environment. The last glaciation ended with massive collapse of ice lobes close to 14,000(14)C yr B.P., accompanied by an influx of North Patagonian Rain Forest species. In the Southern Alps of New Zealand, additional glacial maxima are registered at 17,720(14)C yr B.P., and at the beginning of the Younger Dryas at 11,050 (14)C yr B. P. These glacial maxima in mid-latitude mountains rimming the South Pacific were coeval with ice-rafting pulses in the North Atlantic Ocean. Furthermore, the last termination began suddenly and simultaneously in both polar hemispheres before the resumption of the modern mode of deep-water production in the Nordic Seas. Such interhemispheric coupling implies a global atmospheric signal rather than regional climatic changes caused by North Atlantic thermohaline switches or Laurentide ice surges.

Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution.

Science.gov (United States)

Ferrando, Agustina; Gonzalez, Emilia; Franco, Marcos; Commendatore, Marta; Nievas, Marina; Militon, Cécile; Stora, Georges; Gilbert, Franck; Esteves, José Luis; Cuny, Philippe

2015-10-01

The Patagonian coast is characterized by the existence of pristine ecosystems which may be particularly sensitive to oil contamination. In this study, a simulated oil spill at acute and chronic input levels was carried out to assess the effects of contamination on the macrobenthic community structure and the bioturbation activity of sediments sampled in Caleta Valdés creek. Superficial sediments were either noncontaminated or contaminated by Escalante crude oil and incubated in the laboratory for 30 days. Oil contamination induced adverse effects on macrobenthic community at both concentrations with, for the highest concentration, a marked decrease of approximately 40 and 55 % of density and specific richness, respectively. Besides the disappearance of sensitive species, some other species like Oligochaeta sp. 1, Paranebalia sp., and Ostracoda sp. 2 species have a higher resistance to oil contamination. Sediment reworking activity was also affected by oil addition. At the highest level of contamination, nearly no activity was observed due to the high mortality of macroorganisms. The results strongly suggest that an oil spill in this protected marine area with no previous history of contamination would have a deep impact on the non-adapted macrobenthic community.

The diet of the South American sea lion (Otaria flavescens at Río Negro, Patagonia, Argentina, during the winter-spring period

Directory of Open Access Journals (Sweden)

Raimundo L. Bustos

2012-12-01

Full Text Available The South American sea lion, Otaria flavescens (Shaw, 1800 population is steadily expanding along the Patagonian coast of Argentina in the last decades. However, little is known about the feeding ecology of the species in the area. The aim of this study was to analyze the food habits of O. flavescens from 91 scats collected at Río Negro province, during the winter and spring of 2005. Fish occurred in 96% of scats containing prey remains, followed by cephalopods (26%. Raneya brasiliensis (Kaup, 1856 was the most frequent and abundant species occurring in 58.6% of samples and constituting almost 50% of fish predated. Second in importance were Porichthys porosissimus (Cuvier, 1829 and Cynoscion guatucupa (Cuvier, 1830 in terms of occurrence (%FO 20.7 and numbers (29.6% respectively. The squid Loligo gahi (d'Orbigny, 1835 was the most frequent cephalopod prey (42.1%, whereas Octopus tehuelchus (d'Orbigny, 1834 was the most abundant (77%. The higher amount and diversity of prey found in the spring in comparison with the winter season might be related to a higher feeding activity of seals or to a seasonal increase in food availability in the area.

Taxonomy and ecology of a new species of Corynura (Hymenoptera: Halictidae: Augochlorini) from Chile and Argentina.

Science.gov (United States)

González-Vaquero, Rocío Ana; Polidori, Carlo; Nieves-Aldrey, José Luis

2017-01-16

We describe a new species of Corynura Spinola, a socially polymorphic genus within the bee tribe Augochlorini (Halictidae). We present a detailed description of both sexes of Corynura (Corynura) moscosensis n. sp. González-Vaquero, images of diagnostic morphological structures and antennal sensilla, floral associations, distributional data and notes on its nesting biology. Corynura moscosensis n. sp. is similar in appearance to C. (C.) chloromelas (Alfken), but it can be distinguished by the sculpturing of the mesoscutum and the hair types on the propodeum in the female, and by the genitalia and extent of the area exclusively covered by sensilla placoidea on the antennal flagellum of the male. A lectotype is designated for C. chloromelas. A Chilean Patagonian population of C. moscosensis n. sp. was observed to dig spatially clumped nests in an earth bank with a moderately hard and humid soil. The presence of multiple females within single nest tunnels is unusual and may preliminary suggest nest-sharing, but more data are necessary to define the social organization of this species. The species appears to be polylectic. Bee nests were attacked by satellite flies and possibly velvet ants.

Andes virus infections in the rodent reservoir and in humans vary across contrasting landscapes in Chile

Science.gov (United States)

Torres-Pérez, Fernando; Palma, R. Eduardo; Hjelle, Brian; Ferres, Marcela; Cook, Joseph A.

2009-01-01

Hantavirus cardiopulmonary syndrome (HCPS) is an emerging infectious disease first reported in Chile in 1995. Andes hantavirus (ANDV) is responsible for the more than 500 cases of HCPS reported in Chile. Previous work showed that ANDV is genetically differentiated in Chile across contrasting landscapes. To determine whether the reservoir rodent (Oligoryzomys longicaudatus) populations are also geographically segregated, we conducted range-wide spatial genetic analyses of O. longicaudatus in Chile using the mitochondrial DNA cytochrome b gene. Given that landscape structure influences the incidence of hantavirus infections, we also tested 772 O. longicaudatus specimens for antibodies to ANDV captured during the period 2000 − 2006. Population genetic analyses of O. longicaudatus are largely congruent with those reported for ANDV, with the host primarily differentiated according to three defined ecoregions, Mediterranean, Valdivian rain forest and North Patagonian rain forest. Significant differences in the relative prevalence of anti-ANDV antibodies in rodent samples also were found across the three ecoregions. We relate these results to the number of reported human HCPS cases in Chile, and discuss the importance of landscape differences in light of ANDV transmission to humans and among rodent populations. PMID:19632357

Little Ice Age advance and retreat of Glaciar Jorge Montt, Chilean Patagonia

Directory of Open Access Journals (Sweden)

A. Rivera

2012-03-01

Full Text Available Glaciar Jorge Montt (48°20' S/73°30' W, one of the main tidewater glaciers of the Southern Patagonian Icefield (SPI, has experienced the greatest terminal retreat observed in Patagonia during the past century, with a recession of 19.5 km between 1898 and 2011. This retreat has revealed trees laying subglacially until 2003. These trees were dated using radiocarbon, yielding burial ages between 460 and 250 cal yrs BP. The presence of old growth forest during those dates indicates that Glaciar Jorge Montt was upvalley of its present position before the commonly recognized Little Ice Age (LIA period in Patagonia. The post-LIA retreat was most likely triggered by climatically induced changes during the 20th century; however, Glaciar Jorge Montt has responded more dramatically than its neighbours. The retreat of Jorge Montt opened a 19.5 km long fjord since 1898, which reaches depths in excess of 390 m. The bathymetry is well correlated with glacier retreat rates, suggesting that dynamic responses of the glacier are at least partially connected to near buoyancy conditions at the ice front, resulting in high calving fluxes, accelerating thinning rates and rapid ice velocities.

Knowing and doing: research leading to action in the conservation of forest genetic diversity of Patagonian temperate forests.

Science.gov (United States)

Gallo, Leonardo A; Marchelli, Paula; Chauchard, Luis; Peñalba, Marcelo Gonzalez

2009-08-01

Researchers dealing with conservation subjects usually do not put the results of their work into practice, even when the primary purpose of their research is the preservation of biodiversity. In the South American temperate forests we identified an area with the highest genetic diversity in Argentina of Nothofagus nervosa, one of the most relevant southern beech species. Based on the information of our scientific study and our recommendations, the authorities of Lanin National Park changed the protection status of this area to avoid logging. The new forestry management plans include consideration of "high genetic diversity" in decisions on where logging will be allowed. Results of our initial genetic study induced the analysis of biodiversity at the species and ecosystems levels, which yielded results similar to our genetic studies. A strong connection among researchers and managers from the onset of our study and the awareness of the former about the importance of the implementation of the research work were key to bridging the gap between conservation research and conservation practice.

Abscisic acid metabolite profiling as indicators of plastic responses to drought in grasses from arid Patagonian Monte (Argentina).

Science.gov (United States)

Cenzano, Ana M; Masciarelli, O; Luna, M Virginia

2014-10-01

The identification of hormonal and biochemical traits that play functional roles in the adaptation to drought is necessary for the conservation and planning of rangeland management. The aim of this study was to evaluate the effects of drought on i) the water content (WC) of different plant organs, ii) the endogenous level of abscisic acid (ABA) and metabolites (phaseic acid-PA, dihydrophaseic acid-DPA and abscisic acid conjugated with glucose ester-ABA-GE), iii) the total carotenoid concentration and iv) to compare the traits of two desert perennial grasses (Pappostipa speciosa and Poa ligularis) with contrasting morphological and functional drought resistance traits and life-history strategies. Both species were subjected to two levels of gravimetric soil moisture (the highest near field capacity during autumn-winter and the lowest corresponding to summer drought). Drought significantly increased the ABA and DPA levels in the green leaves of P. speciosa and P. ligularis. Drought decreased ABA in the roots of P. speciosa while it increased ABA in the roots of P. ligularis. P. ligularis had the highest ABA level and WC in green leaves. While P. speciosa had the highest DPA levels in leaves. In conclusion, we found the highest ABA level in the mesophytic species P. ligularis and the lowest ABA level in the xerophytic species P. speciosa, revealing that the ABA metabolite profile in each grass species is a plastic response to drought resistance. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Nutrient additions in pristine Patagonian Sphagnum bog vegetation: can phosphorus addition alleviate (the effects of) increased nitrogen loads.

Science.gov (United States)

Fritz, C; van Dijk, G; Smolders, A J P; Pancotto, V A; Elzenga, T J T M; Roelofs, J G M; Grootjans, A P

2012-05-01

Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear whether P-addition can alleviate physiological N-stress in Sphagnum plants. A 3-year fertilisation experiment was conducted in lawns of a pristine Sphagnum magellanicum bog in Patagonia, where competing vascular plants were practically absent. Background wet deposition of nitrogen was low (≈ 0.1-0.2 g · N · m(-2) · year(-1)). Nitrogen (4 g · N · m(-2) · year(-1)) and phosphorus (1 g · P · m(-2) · year(-1)) were applied, separately and in combination, six times during the growing season. P-addition substantially increased biomass production of Sphagnum. Nitrogen and phosphorus changed the morphology of Sphagnum mosses by enhancing height increment, but lowering moss stem density. In contrast to expectations, phosphorus failed to alleviate physiological stress imposed by excess nitrogen (e.g. amino acid accumulation, N-saturation and decline in photosynthetic rates). We conclude that despite improving growth conditions by P-addition, Sphagnum-bog ecosystems remain highly susceptible to nitrogen additions. Increased susceptibility to desiccation by nutrients may even worsen the negative effects of excess nitrogen especially in windy climates like in Patagonia. © 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.

Nutrient additions in pristine Patagonian Sphagnum bog vegetation : can phosphorus addition alleviate (the effects of) increased nitrogen loads

NARCIS (Netherlands)

Fritz, C.; Dijk, G. van; Smolders, A.J.P.; Pancotto, V.A.; Elzenga, J.T.M.; Roelofs, J.G.M.; Grootjans, A.P.

Sphagnum-bog ecosystems have a limited capability to retain carbon and nutrients when subjected to increased nitrogen (N) deposition. Although it has been proposed that phosphorus (P) can dilute negative effects of nitrogen by increasing biomass production of Sphagnum mosses, it is still unclear

Source and fractionation controls on subduction-related plutons and dike swarms in southern Patagonia (Torres del Paine area) and the low Nb/Ta of upper crustal igneous rocks

Science.gov (United States)

Müntener, Othmar; Ewing, Tanya; Baumgartner, Lukas P.; Manzini, Mélina; Roux, Thibaud; Pellaud, Pierre; Allemann, Luc

2018-05-01

The subduction system in southern Patagonia provides direct evidence for the variability of the position of an active continental arc with respect to the subducting plate through time, but the consequences on the arc magmatic record are less well studied. Here we present a geochemical and geochronological study on small plutons and dykes from the upper crust of the southern Patagonian Andes at 51°S, which formed as a result of the subduction of the Nazca and Antarctic plates beneath the South American continent. In situ U-Pb geochronology on zircons and bulk rock geochemical data of plutonic and dyke rocks are used to constrain the magmatic evolution of the retro-arc over the last 30 Ma. We demonstrate that these combined U-Pb and geochemical data for magmatic rocks track the temporal and spatial migration of the active arc, and associated retro-arc magmatism. Our dataset indicates that the rear-arc area is characterized by small volumes of alkaline basaltic magmas at 29-30 Ma that are characterized by low La/Nb and Th/Nb ratios with negligible arc signatures. Subsequent progressive eastward migration of the active arc culminated with the emplacement of calc-alkaline plutons and dikes 17-16 Ma with elevated La/Nb and Th/Nb ratios and typical subduction signatures constraining the easternmost position of the southern Patagonian batholith at that time. Geochemical data on the post-16 Ma igneous rocks including the Torres del Paine laccolith indicate an evolution to transitional K-rich calc-alkaline magmatism at 12.5 ± 0.2 Ma. We show that trace element ratios such as Nb/Ta and Dy/Yb systematically decrease with increasing SiO2, for both the 17-16 Ma calc-alkaline and the 12-13 Ma K-rich transitional magmatism. In contrast, Th/Nb and La/Nb monitor the changes in the source composition of these magmas. We suggest that the transition from the common calc-alkaline to K-rich transitional magmatism involves a change in the source component, while the trace element ratios

Age of formation deposition Tunes, Sierra de la Ventana Foldbelt, Argentina

International Nuclear Information System (INIS)

Alessandretti, L.; Philipp, R.; Chemale, F.; Ramos, V.

2010-01-01

The Sierra de la Ventana, located in east-central Argentina, is the most important recharge area within the South American Plate, an extensive Paleozoic basin, which evolved from a passive margin basin to basin - ante country. The basin developed on the southwestern edge of the supercontinent Gondwana, where magmatic activity occurred in large areal and temporal scale during the Paleozoic, particularly during the Permian . Tufáceos horizons that occur in the Sierra de la Ventana and the Cape Foldbelt Basins and San Rafael, Paraná, Sauce Grande and Karoo can be correlated with this period of intense magmatic activity . Five igneous zircons in an interleaved tufácea layer with sandstones and mudstones of the Tunas Formation, through the U / Pb method were dated using LA - MC - ICP - MS . Yielded an age of 274.3 ± 4.8 Concord Ma for tuffs of the Tunas Formation . Inherited zircons with ages between 623 and 374 Ma, indicate provenance of Patagonian region. Analysis of x -ray diffraction allowed the identification of quartz, plagioclase, smectite and illite mineral constituents of the tufts . The presence of abundant quartz and plagioclase suggests a dacitic volcanism nature to volcanism of southwestern Gondwanan margin and smectite is interpreted as a product of alteration of volcanic material deposited in an aqueous environment

New insights into the phylogenetic relationships, character evolution, and phytogeographic patterns of Calceolaria (Calceolariaceae).

Science.gov (United States)

Cosacov, Andrea; Sérsic, Alicia N; Sosa, Victoria; De-Nova, J Arturo; Nylinder, Stephan; Cocucci, Andrea A

2009-12-01

Biogeographical patterns and diversification processes in Andean and Patagonian flora are not yet well understood. Calceolaria is a highly diversified genus of these areas, representing one of the most specialized plant-pollinator systems because flowers produce nonvolatile oils, a very unusual floral reward. Phylogenetic analyses with molecular (ITS and matK) and morphological characters from 103 Calceolaria species were conducted to examine relationships, to understand biogeographic patterns, and to detect evolutionary patterns of floral and ecological characters. Total evidence analysis retrieved three major clades, which strongly correspond to the three previously recognized subgenera, although only subgenus Rosula was retrieved as a monophyletic group. A single historical event explains the expansion from the southern to central Andes, while different parallel evolutionary lines show a northward expansion from the central to northern Andes across the Huancabamba Deflection, an important geographical barrier in northern Peru. Polyploidy, acquisition of elaiophores, and a nototribic pollination mechanism are key aspects of the evolutionary history of Calceolaria. Pollination interactions were more frequently established with Centris than with Chalepogenus oil-collecting bee species. The repeated loss of the oil gland and shifts to pollen as the only reward suggest an evolutionary tendency from highly to moderately specialized pollination systems.

Nutritive and xenobiotic compounds in the alien algae Undaria pinnatifida from Argentine Patagonia.

Science.gov (United States)

Gil, M N; Torres, A I; Commendatore, M G; Marinho, C; Arias, A; Giarratano, E; Casas, G N

2015-04-01

Seaweeds have been used as food since ancient times. The edible brown algae Undaria pinnatifida is native to northeast Asia; however, in 1992, the first specimens in Patagonian environments were found and, since then, have rapidly expanded. The main object of this study was to determine, for the first time in Argentina, the nutritive composition and concentrations of trace elements and hydrocarbons in these alien algae and evaluate their usefulness as food. Sexually mature U. pinnatifida samples were collected at 10-m depth in the Nuevo and San José gulfs. The first site is influenced by activities from Puerto Madryn city, and the latter place was considered as the control. Protein, dietary fiber, and mineral concentrations were similar in both gulfs and in the same order as in eastern countries. Crude protein, indigestible fiber, and calcium and magnesium concentrations were greatest in blade; lipid concentration was greatest in sporophyll; and sodium and potassium concentrations were greatest in midrib. Amino acids showed the greatest concentrations in blades, and these were greater than those reported in kelp from Japan. Cadmium (Cd), arsenic, mercury, and hydrocarbons were detected, but only Cd showed concentrations that could be a risk for consumption. In Argentina, maximum acceptable levels of these contaminants in seaweeds are not established.

Antioxidant activity and phenolic profiles of the wild currant Ribes magellanicum from Chilean and Argentinean Patagonia.

Science.gov (United States)

Jiménez-Aspee, Felipe; Thomas-Valdés, Samanta; Schulz, Ayla; Ladio, Ana; Theoduloz, Cristina; Schmeda-Hirschmann, Guillermo

2016-07-01

The Patagonian currant Ribes magellanicum is highly valued due to its pleasant flavor and sweet taste. The aim of this study was to characterize its constituents and to assess their antioxidant and cytoprotective properties. For the fruit phenolic-enriched extract (PEE), total phenolics (TP), total flavonoids (TF), and antioxidant activity (DPPH, Ferric reducing antioxidant power (FRAP), and Trolox equivalent antioxidant activity (TEAC)) were determined. Argentinean samples presented better activity in the DPPH and FRAP assays. Best cytoprotection against oxidative stress induced by H2O2 in AGS cells was found in one Argentinean sample at 500 μg mL(-1) (65.7%). HPLC MS/MS analysis allowed the tentative identification of 59 constituents, including eight anthocyanins, 11 conjugates of caffeic-, ferulic-, and coumaric acid, and 38 flavonoids, most of them quercetin and kaempferol derivatives. Argentinean samples showed a more complex pattern of anthocyanins, hydroxycinnamic acids (HCA), and flavonoids. Cyanidin rhamnoside hexoside and cyanidin hexoside were the main anthocyanins, accounting for 35 and 55% for the Argentinean and 60 and 27% for the ripe Chilean fruits. HCA content was about three times higher in Argentinean samples. The phenolic profiles of Chilean and Argentinean Ribes magellanicum show remarkable differences in chemical composition with higher HCA and flavonoid content in Argentinean samples.

Dr. S. Donald (Don) Stookey (1915-2014): Pioneering Researcher and Adventurer

Science.gov (United States)

Beall, George H.

2016-07-01

Don Stookey, the father of glass-ceramics, was a pioneer in inducing and understanding internal nucleation phenomena in glass. His early work on dense opal glasses and photosensitive precipitation of gold and silver in glass led to an amazing series of inventions: Fotalite, a photosensitive opal, chemically machined Fotoform and Fotoceram, and TiO2-nucleated Pyroceram products including missile nosecones and oven-proof cookware. He received a basic patent on glass-ceramics, which was contested and affirmed in court. Don was able to demonstrate a clear photochromic glass that showed reversible darkening for thousands of cycles. This material became a fixture in the ophthalmic industry. He went on to invent a full-color polychromatic glass, capable of yielding a permanent patterned and monolithic stained glass. In his life outside science, Don chaired an interfaith group that founded a home for the elderly in Corning. He was also a wilderness enthusiast, surviving a plane crash in the Arctic and two boat capsizings. Even in his later years, he continued fishing off the coast of Florida and on Lake Ontario and went solo on a trip to the Patagonian Andes. Don Stookey was a special person by any measure: an unassuming optimist, eminent scientist and inventor, adventurer, and a beloved family man. Introduction

From leaves to landscape: A multiscale approach to assess fire hazard in wildland-urban interface areas.

Science.gov (United States)

Ghermandi, Luciana; Beletzky, Natacha A; de Torres Curth, Mónica I; Oddi, Facundo J

2016-12-01

The overlapping zone between urbanization and wildland vegetation, known as the wildland urban interface (WUI), is often at high risk of wildfire. Human activities increase the likelihood of wildfires, which can have disastrous consequences for property and land use, and can pose a serious threat to lives. Fire hazard assessments depend strongly on the spatial scale of analysis. We assessed the fire hazard in a WUI area of a Patagonian city by working at three scales: landscape, community and species. Fire is a complex phenomenon, so we used a large number of variables that correlate a priori with the fire hazard. Consequently, we analyzed environmental variables together with fuel load and leaf flammability variables and integrated all the information in a fire hazard map with four fire hazard categories. The Nothofagus dombeyi forest had the highest fire hazard while grasslands had the lowest. Our work highlights the vulnerability of the wildland-urban interface to fire in this region and our suggested methodology could be applied in other wildland-urban interface areas. Particularly in high hazard areas, our work could help in spatial delimitation policies, urban planning and development of plans for the protection of human lives and assets. Copyright © 2016 Elsevier Ltd. All rights reserved.

Paleoparasitological finding of eggs of nematodes in rodent coprolites dated at the early Holocene from the archaeological site Cerro Casa de Piedra 7, Santa Cruz, Argentina.

Science.gov (United States)

Sardella, N H; Fugassa, M H

2011-12-01

The aim of the present study was to examine the parasite remains present in rodent coprolites collected from the archaeological site Cerro Casa de Piedra 7 (CCP7), located in the Perito Moreno National Park (47°57'S, 72°05'W), Santa Cruz Province, Argentina. Eight coprolites obtained from the layer 17, dated at 10,620 ± 40 to 9,390 ± 40 yr B.P., were examined for parasites. Feces were processed whole, rehydrated, homogenized, subjected to spontaneous sedimentation, and examined via light microscopy. Eggs of parasites were measured and photographed. Seven of 8 coprolites possessed 199 eggs of 2, probably new, species of nematodes, including 43 eggs of Heteroxynema sp. Hall, 1916 (Cavioxyura sp. Quentin, 1975) (Oxyurida, Heteroxynematidae), and 156 eggs of Trichuris sp. Roederer, 1761 (Trichinellida, Trichuridae). Heteroxynema sp. is cited for the first time from ancient material worldwide. The finding of Trichuris spp. in both rodents and other host samples from the area under study is indicative of the stability of the biological and environmental conditions for this nematode genus to establish in the Patagonian Early Holocene. The rodent host was assigned to an unknown species of Caviomorpha (Hystricognathi) that lived during the Pleistocenic transition in Patagonia.

Revision of fleas of the genus Plocopsylla belonging to the 'angusticeps-lewisi' complex in the Andean biogeographic region, with the description of a new species.

Science.gov (United States)

Sanchez, J; Beaucournu, J-C; Lareschi, M

2015-06-01

In Argentina, the Andean biogeographic region accommodates the most diverse population of fleas in the country. The Craneopsyllinae (Siphonaptera: Stephanocircidae) represent one of the most commonly found subfamilies in this region and show some endemism and high diversity. Plocopsylla is the most diverse genus of Craneopsyllinae; it includes 10 species mainly distributed in the Patagonian subregion, which parasitize sigmodontine rodents (Rodentia: Cricetidae). We describe and illustrate the morphology of the aedeagus in species of Plocopsylla that belong to the 'angusticeps-lewisi' complex. This character is of diagnostic value in differentiating among species. A new species of this complex, Plocopsylla (Plocopsylla) linardii sp. n., is described and identified by the shape and chaetotaxy of the distal arm of sternite IX, as well as by the shape of the median dorsal lobe of the aedeagus. New host associations for this complex and range extensions for most of its species are reported. Plocopsylla (P.) silewi is recorded for the first time in Argentina. The southern limits of the distributions of Plocopsylla (P.) lewisi and Plocopsylla (P.) wilesi are extended to Santa Cruz Province. The angusticeps-lewisi complex is found for the first time in San Juan Province. The information may be useful in epidemiological studies of flea-borne diseases. © 2015 The Royal Entomological Society.

A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae) from the Late Cretaceous of Patagonia

Science.gov (United States)

2016-01-01

A skeleton discovered in the Upper Cretaceous Sierra Barrosa Formation (Turonian-Coniacian) of Neuquén Province, Argentina represents a new species of theropod dinosaur related to the long snouted, highly pneumatized Megaraptoridae. The holotype specimen of Murusraptor barrosaensis n.gen et n.sp. (MCF-PVPH-411) includes much of the skull, axial skeleton, pelvis and tibia. Murusraptor is unique in having several diagnostic features that include anterodorsal process of lacrimal longer than height of preorbital process, and a thick, shelf-like thickening on the lateral surface of surangular ventral to the groove between the anterior surangular foramen and the insert for the uppermost intramandibular process of the dentary. Other characteristic features of Murusraptor barrosaensis n.gen. et n. sp.include a large mandibular fenestra, distal ends of caudal neural spines laterally thickened into lateral knob-like processes, short ischia distally flattened and slightly expanded dorsoventrally. Murusraptor belongs to a Patagonian radiation of megaraptorids together with Aerosteon, Megaraptor and Orkoraptor. In spite being immature, it is a larger but more gracile animal than existing specimens of Megaraptor, and is comparable in size with Aerosteon and Orkoraptor. The controversial phylogeny of the Megaraptoridae as members of the Allosauroidea or a clade of Coelurosauria is considered analyzing two alternative data sets. PMID:27439002

Serological evidence of Toxoplasma gondii infection in captive marine mammals in Mexico.

Science.gov (United States)

Alvarado-Esquivel, C; Sánchez-Okrucky, R; Dubey, J P

2012-03-23

Toxoplasma gondii infection in marine mammals is important because they are considered as a sentinel for contamination of seas with T. gondii oocysts, and toxoplasmosis causes mortality in these animals, particularly sea otters. Serological evidence of T. gondii infection was determined in 75 captive marine mammals from four facilities in southern and central geographical regions in Mexico using the modified agglutination test (MAT). Antibodies (MAT, 1:25 or higher) to T. gondii were found in 55 (87.3%) of 63 Atlantic bottlenose dolphins (Tursiops truncatus truncatus), 3 of 3 Pacific bottlenose dolphins (Tursiops truncatus gillii), 2 of 4 California sea lions (Zalophus californianus), but not in 3 West Indian manatees (Trichechus manatus), and 2 Patagonian sea lions (Otaria flavescens). Seropositive marine mammals were found in all 4 (100%) facilities sampled. All marine mammals were healthy and there has not been any case of clinical toxoplasmosis in the facilities sampled for at least the last 15 years. The seroprevalence of T. gondii infection in marine mammals of the same species did not vary significantly with respect to sex and age. This is the first report on the detection of antibodies to T. gondii in marine mammals in Mexico. Published by Elsevier B.V.

Seed dormancy responses to temperature relate to Nothofagus species distribution and determine temporal patterns of germination across altitudes in Patagonia.

Science.gov (United States)

Arana, María V; Gonzalez-Polo, Marina; Martinez-Meier, Alejandro; Gallo, Leonardo A; Benech-Arnold, Roberto L; Sánchez, Rodolfo A; Batlla, Diego

2016-01-01

Seeds integrate environmental cues that modulate their dormancy and germination. Although many mechanisms have been identified in laboratory experiments, their contribution to germination dynamics in existing communities and their involvement in defining species habitats remain elusive. By coupling mathematical models with ecological data we investigated the contribution of seed temperature responses to the dynamics of germination of three Nothofagus species that are sharply distributed across different altitudes in the Patagonian Andes. Seed responsiveness to temperature of the three Nothofagus species was linked to the thermal characteristics of their preferred ecological niche. In their natural distribution range, there was overlap in the timing of germination of the species, which was restricted to mid-spring. By contrast, outside their species distribution range, germination was temporally uncoupled with altitude. This phenomenon was described mathematically by the interplay between interspecific differences in seed population thermal parameters and the range in soil thermic environments across different altitudes. The observed interspecific variations in seed responsiveness to temperature and its environmental regulation, constitute a major determinant of the dynamics of Nothofagus germination across elevations. This phenomenon likely contributes to the maintenance of patterns of species abundance across altitude by placing germinated seeds in a favorable environment for plant growth. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Ground level and Lidar monitoring of volcanic dust and dust from Patagonia

Science.gov (United States)

Otero, L. A.; Losno, R.; Salvador, J. O.; Journet, E.; Qu, Z.; Triquet, S.; Monna, F.; Balkanski, Y.; Bulnes, D.; Ristori, P. R.; Quel, E. J.

2013-05-01

A combined approach including ground level aerosol sampling, lidar and sunphotometer measurements is used to monitor suspended particles in the atmosphere at several sites in Patagonia. Motivated by the Puyehue volcanic eruption in June 2011 two aerosol monitoring stations with several passive and active instruments were installed in Bariloche and Comodoro Rivadavia. The main goal which is to monitor ground lifted and transported ashes and dust involving danger to civil aviation, is achieved by measuring continuously aerosol concentration at ground level and aerosol vertical distribution using lidar. In addition, starting from December 2011, continuous series of weekly accumulated aerosol concentrations at Rio Gallegos are being measured to study the impact of Patagonian dust over the open ocean on phytoplankton primary productivity and CO2 removal. These measurements are going to be coupled with LIDAR monitoring and a dust optical response models to test if aerosol extrapolation can be done from the ground to the top of the layer. Laboratory chemical analysis of the aerosols will include elemental composition, solubilisation kinetic and mineralogical determination. Expected deliverables for this study is the estimation of the amount of dust exported from Patagonia towards the South Atlantic, its chemical properties, including bioavailability simulation, from model and comparison to experimental measurements.

Freezing avoidance by supercooling in Olea europaea cultivars: the role of apoplastic water, solute content and cell wall rigidity.

Science.gov (United States)

Arias, Nadia S; Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo

2015-10-01

Plants can avoid freezing damage by preventing extracellular ice formation below the equilibrium freezing temperature (supercooling). We used Olea europaea cultivars to assess which traits contribute to avoid ice nucleation at sub-zero temperatures. Seasonal leaf water relations, non-structural carbohydrates, nitrogen and tissue damage and ice nucleation temperatures in different plant parts were determined in five cultivars growing in the Patagonian cold desert. Ice seeding in roots occurred at higher temperatures than in stems and leaves. Leaves of cold acclimated cultivars supercooled down to -13 °C, substantially lower than the minimum air temperatures observed in the study site. During winter, leaf ice nucleation and leaf freezing damage (LT50 ) occurred at similar temperatures, typical of plant tissues that supercool. Higher leaf density and cell wall rigidity were observed during winter, consistent with a substantial acclimation to sub-zero temperatures. Larger supercooling capacity and lower LT50 were observed in cold-acclimated cultivars with higher osmotically active solute content, higher tissue elastic adjustments and lower apoplastic water. Irreversible leaf damage was only observed in laboratory experiments at very low temperatures, but not in the field. A comparative analysis of closely related plants avoids phylogenetic independence bias in a comparative study of adaptations to survive low temperatures. © 2015 John Wiley & Sons Ltd.

A New Megaraptoran Dinosaur (Dinosauria, Theropoda, Megaraptoridae from the Late Cretaceous of Patagonia.

Directory of Open Access Journals (Sweden)

Rodolfo A Coria

Full Text Available A skeleton discovered in the Upper Cretaceous Sierra Barrosa Formation (Turonian-Coniacian of Neuquén Province, Argentina represents a new species of theropod dinosaur related to the long snouted, highly pneumatized Megaraptoridae. The holotype specimen of Murusraptor barrosaensis n.gen et n.sp. (MCF-PVPH-411 includes much of the skull, axial skeleton, pelvis and tibia. Murusraptor is unique in having several diagnostic features that include anterodorsal process of lacrimal longer than height of preorbital process, and a thick, shelf-like thickening on the lateral surface of surangular ventral to the groove between the anterior surangular foramen and the insert for the uppermost intramandibular process of the dentary. Other characteristic features of Murusraptor barrosaensis n.gen. et n. sp.include a large mandibular fenestra, distal ends of caudal neural spines laterally thickened into lateral knob-like processes, short ischia distally flattened and slightly expanded dorsoventrally. Murusraptor belongs to a Patagonian radiation of megaraptorids together with Aerosteon, Megaraptor and Orkoraptor. In spite being immature, it is a larger but more gracile animal than existing specimens of Megaraptor, and is comparable in size with Aerosteon and Orkoraptor. The controversial phylogeny of the Megaraptoridae as members of the Allosauroidea or a clade of Coelurosauria is considered analyzing two alternative data sets.

Depositional Environments of Late Danian Plant Localities: Chubut Provice, Patagonia, Argentina

Science.gov (United States)

Comer, E.; Slingerland, R. L.; Wilf, P.

2010-12-01

Diverse, well-preserved macroflora are observed within Cretaceous and Paleocene sediments of Chubut Province, Patagonia, Argentina. These macroflora are the most well preserved early Paleocene flora from Gondwana and add new insight into the diversity and environments of that epoch. Two major sites of fossil preservation, Palacio de los Loros and Parque Provincial Ormachea, sit near the top of the Late Danian (65.5-61.7 Ma) Salamanca Formation. Understanding the depositional history of the Salamanca is important in characterizing paleoenvironments in which these flora lived and relating these Patagonian macroflora to concurrent Paleocene flora within the Gondwanan supercontinent. During a two week field season, twenty stratigraphic sections were measured along the outcrop belt at Palacio de los Loros and Ormachea Park as well as two minor sites; Las Flores, and Rancho Grande. Photo mosaics, laser ranger data, and stratigraphic columns were merged with elevated geologic maps and imported into Fledermaus to generate a 3-D visualization of facies relationships. Rock samples were also collected and will be thin sectioned and analyzed for petrography and grain size. The Salamanca Fm. consists of 7 facies, listed here in stratigraphically ascending order: 1)Transgressive sands, 2)Wispy-bedded claystone, 3)Banco Verde, 4)White Cross bedded sandstone, 5)Accretion set siltstone, 6)Transitional silty claystone and 7)Banco Negro. Based on these facies, the Salamanca Fm. is interpreted as a marine-shelf to brackish, tide-dominated, estuarine deposit. The base of the Salamanca Fm. rests on an unconformity representing a marine flooding surface and lower sections of the Salamanca, facies 1 and 2, contain abundant glauconite and fossils indicative of a marine shelf environment. These facies give way upwards to bi-directional trough cross bedded sandstones interspersed with flaser bedded sandy siltstones (facies 3 and 4) indicating a less marine estuary with strong flow regimes

Mechanism of removal and retention of heavy metals from the acid mine drainage to coastal wetland in the Patagonian marsh.

Science.gov (United States)

Idaszkin, Yanina L; Carol, Eleonora; María Del Pilar, Alvarez

2017-09-01

The attenuation of the acid mine drainage is one of the most important environmental challenges facing the mining industry worldwide. Mining waste deposits from an ancient metallurgical extraction of heavy metals were found near to the San Antonio marsh in Patagonia. The aim of this work was to determinate which mechanisms regulate the mobilization and retention of metals by acid drainage. A geological and geomorphological survey was carried out and samples from the mining waste deposits and the marsh were collected to determine soil texture, Eh pH, organic matter, Cu, Pb, Zn and Fe content, and soil mineralogical composition. Metals in marsh plants were determined in above- and below-ground structures. In the mining waste deposits polymetallic sulphides were recognized where the oxidation and formation of oxy-hydroxides and sulphates of Fe, Cu, Pb and Zn occurs. Then, by the alteration of those minerals, the metals enter in solution and are mobilized with the surface drainage towards the marsh where adsorption in the soils fine fraction and organic matter and/or by plants occurs. Locally, in the mining waste deposits, the precipitation/dissolution of Cu, Pb, and Zn sulphates take place in small centripetal drainage basins. In topographically lower portions of the marsh desorption and removal of metals by tidal flow could also be happen. The results allow to concluding that the marsh adjacent to the mining waste deposits is a geochemically active environment that naturally mitigates the contamination caused by acid drainage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mitochondrial and nuclear markers reveal a lack of genetic structure in the entocommensal nemertean Malacobdella arrokeana in the Patagonian gulfs

Science.gov (United States)

Alfaya, José E. F.; Bigatti, Gregorio; Machordom, Annie

2013-06-01

Malacobdella arrokeana is an entocommensal nemertean exclusively found in the bivalve geoduck Panopea abbreviata, and it is the only representative of the genus in the southern hemisphere. To characterize its genetic diversity, population structure and recent demographic history, we conducted the first genetic survey on this species, using sequence data for the cytochrome oxidase I gene (COI), 16S rRNA (16S) and the internal transcribed spacer (ITS2). Only four different ITS2 genotypes were found in the whole sample, and the two main haplotypes identified in the mitochondrial dataset were present among all localities with a diversity ranging from 0.583 to 0.939. Nucleotide diversity was low (π = 0.001-0.002). No significant genetic structure was detected between populations, and mismatch distribution patterns and neutrality tests results are consistent with a population in expansion or under selection. Analysis of molecular variance (AMOVA) revealed that the largest level of variance observed was due to intrapopulation variation (100, 100 and 94.39 % for 16S, COI and ITS2, respectively). F st values were also non-significant. The observed lack of population structure is likely due to high levels of genetic connectivity in combination with the lack or permeability of biogeographic barriers and episodes of habitat modification.

Bacterial community dynamics during polysaccharide degradation at contrasting sites in the Southern and Atlantic Oceans.

Science.gov (United States)

Wietz, Matthias; Wemheuer, Bernd; Simon, Heike; Giebel, Helge-Ansgar; Seibt, Maren A; Daniel, Rolf; Brinkhoff, Thorsten; Simon, Meinhard

2015-10-01

The bacterial degradation of polysaccharides is central to marine carbon cycling, but little is known about the bacterial taxa that degrade specific marine polysaccharides. Here, bacterial growth and community dynamics were studied during the degradation of the polysaccharides chitin, alginate and agarose in microcosm experiments at four contrasting locations in the Southern and Atlantic Oceans. At the Southern polar front, chitin-supplemented microcosms were characterized by higher fractions of actively growing cells and a community shift from Alphaproteobacteria to Gammaproteobacteria and Bacteroidetes. At the Antarctic ice shelf, chitin degradation was associated with growth of Bacteroidetes, with 24% higher cell numbers compared with the control. At the Patagonian continental shelf, alginate and agarose degradation covaried with growth of different Alteromonadaceae populations, each with specific temporal growth patterns. At the Mauritanian upwelling, only the alginate hydrolysis product guluronate was consumed, coincident with increasing abundances of Alteromonadaceae and possibly cross-feeding SAR11. 16S rRNA gene amplicon libraries indicated that growth of the Bacteroidetes-affiliated genus Reichenbachiella was stimulated by chitin at all cold and temperate water stations, suggesting comparable ecological roles over wide geographical scales. Overall, the predominance of location-specific patterns showed that bacterial communities from contrasting oceanic biomes have members with different potentials to hydrolyse polysaccharides. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Comparison between remotely-sensed sea-surface temperature (AVHRR and in situ records in San Matías Gulf (Patagonia, Argentina

Directory of Open Access Journals (Sweden)

Gabriela N Williams

2014-03-01

Full Text Available In situ records of sea surface temperature collected between 2005 and 2009 were used to compare, for the first time, the temperature estimated by the Multichannel algorithms (MCSST of the Advanced Very High Resolution Radiometer (AVHRR sensors in San Matías Gulf, in the north of the Argentinean Patagonian Continental Shelf (between 40°47'-42°13'S. Match-ups between in situ records and satellite sea surface temperature (SST were analyzed. In situ records came from fixed stations and oceanographic cruises, while satellite data came from different NOAA satellites. The fitting of temperature data to a Standard Major Axis (SMA type II regression model indicated that a high proportion of the total variance (0.53< r² <0.99 was explained by this model showing a high correlation between in situ data and satellite estimations. The mean differences between satellite and in situ data for the full data set were 1.64 ± 1.49°C. Looking separately into in situ data from different sources and day and night estimates from different NOAA satellites, the differences were between 0.30 ± 0.60°C and 2.60 ± 1.50°C. In this paper we discuss possible reasons for the above-mentioned performance of the MCSST algorithms in the study area.

Uplift of quaternary shorelines in eastern Patagonia: Darwin revisited

Science.gov (United States)

Pedoja, Kevin; Regard, Vincent; Husson, Laurent; Martinod, Joseph; Guillaume, Benjamin; Fucks, Enrique; Iglesias, Maximiliano; Weill, Pierre

2011-04-01

During his journey on the Beagle, Darwin observed the uniformity in the elevation of coastal Eastern Patagonia along more than 2000 km. More than one century later, the sequences of Quaternary shorelines of eastern Patagonia have been described and their deposits dated but not yet interpreted in terms of geodynamics. Consequently, we i) mapped the repartition of the Quaternary coastal sequences in Argentinean Patagonia, ii) secured accurate altitudes of shoreline angles associated with erosional morphologies (i.e. marine terraces and notches), iii) took into account previous chrono-stratigraphical interpretations in order to calculate mean uplift rates since ~ 440 ka (MIS 11) and proposed age ranges for the higher and older features (up to ~ 180 m), and iv) focused on the Last Interglacial Maximum terrace (MIS 5e) as the best constrained marine terrace (in terms of age and altitude) in order to use it as a tectonic benchmark to quantify uplift rates along the entire passive margin of Eastern South America. Our results show that the eastern Patagonia uplift is constant through time and twice the uplift of the rest of the South American margin. We suggest that the enhanced uplift along the eastern Patagonian coast that interested Darwin during his journey around South America on the Beagle could originate from the subduction of the Chile ridge and the associated dynamic uplift.

Dr. S. Donald (Don Stookey: (1915-2014: Pioneering Researcher and Adventurer

Directory of Open Access Journals (Sweden)

George Halsey Beall

2016-08-01

Full Text Available Don Stookey was a special person by any measure: an unassuming optimist, eminent scientist and inventor, adventurer, and a beloved family man. Don Stookey, the father of glass-ceramics, was a pioneer in inducing and understanding internal nucleation phenomena in glass. His early work on dense opal glasses and photosensitive precipitation of gold and silver in glass led to an amazing series of inventions: Fotalite®, a photosensitive opal, chemically machined Fotoform® and Fotoceram®, and TiO2-nucleated Pyroceram™ products including missile nosecones and oven-proof cookware. He received a basic patent on glass-ceramics which was contested and affirmed in court.Don was able to demonstrate a clear photochromic glass that showed reversible darkening for thousands of cycles. This material became a fixture in the ophthalmic industry. He went on to invent a full-color polychromatic glass capable of yielding a permanent patterned and monolithic stained glass.In his life outside science, Don chaired an interfaith group that founded a home for the elderly in Corning. He was also a wilderness enthusiast, surviving a plane crash in the Arctic and two boat capsizings. Even In his later years, he continued fishing off the coast of Florida and on Lake Ontario, and went solo on a trip to the Patagonian Andes.

A numerical study of the Magellan Plume

Science.gov (United States)

Palma, Elbio D.; Matano, Ricardo P.

2012-05-01

In this modeling study we investigate the dynamical mechanisms controlling the spreading of the Magellan Plume, which is a low-salinity tongue that extends along the Patagonian Shelf. Our results indicate that the overall characteristics of the plume (width, depth, spreading rate, etc.) are primarily influenced by tidal forcing, which manifests through tidal mixing and tidal residual currents. Tidal forcing produces a homogenization of the plume's waters and an offshore displacement of its salinity front. The interaction between tidal and wind-forcing reinforces the downstream and upstream buoyancy transports of the plume. The influence of the Malvinas Current on the Magellan Plume is more dominant north of 50°S, where it increases the along-shelf velocities and generates intrusions of saltier waters from the outer shelf, thus causing a reduction of the downstream buoyancy transport. Our experiments also indicate that the northern limit of the Magellan Plume is set by a high salinity discharge from the San Matias Gulf. Sensitivity experiments show that increments of the wind stress cause a decrease of the downstream buoyancy transport and an increase of the upstream buoyancy transport. Variations of the magnitude of the discharge produce substantial modifications in the downstream penetration of the plume and buoyancy transport. The Magellan discharge generates a northeastward current in the middle shelf, a recirculation gyre south of the inlet and a region of weak currents father north.

Germ cell transplantation using sexually competent fish: an approach for rapid propagation of endangered and valuable germlines.

Directory of Open Access Journals (Sweden)

Sullip K Majhi

Full Text Available The transplantation of germ cells into adult recipient gonads is a tool with wide applications in animal breeding and conservation of valuable and/or endangered species; it also provides a means for basic studies involving germ cell (GC proliferation and differentiation. Here we describe the establishment of a working model for xenogeneic germ cell transplantation (GCT in sexually competent fish. Spermatogonial cells isolated from juveniles of one species, the pejerrey Odontesthes bonariensis (Atherinopsidae, were surgically transplanted into the gonads of sexually mature Patagonian pejerrey O. hatcheri, which have been partially depleted of endogenous GCs by a combination of Busulfan (40 mg/kg and high water temperature (25 degrees C treatments. The observation of the donor cells' behavior showed that transplanted spermatogonial cells were able to recolonize the recipients' gonads and resume spermatogenesis within 6 months from the GCT. The presence of donor-derived gametes was confirmed by PCR in 20% of the surrogate O. hatcheri fathers at 6 months and crosses with O. bonariensis mothers produced hybrids and pure O. bonariensis, with donor-derived germline transmission rates of 1.2-13.3%. These findings indicate that transplantation of spermatogonial cells into sexually competent fish can shorten considerably the production time of donor-derived gametes and offspring and could play a vital role in germline conservation and propagation of valued and/or endangered fish species.

Ash resuspension related to the 2011-2012 Cordón Caulle eruption, Chile, in a rural community of Patagonia, Argentina

Science.gov (United States)

Forte, Pablo; Domínguez, Lucia; Bonadonna, Costanza; Gregg, Chris E.; Bran, Donaldo; Bird, Deanne; Castro, Jonathan M.

2018-01-01

The 2011-2012 Cordón Caulle eruption emitted about 1 km3 of rhyodacitic tephra. Dominant westerly winds in the region caused most of the primary tephra to deposit in neighboring Argentina. In addition to the impact of widespread dispersal and fallout of primary tephra during the eruption, Argentina was also significantly affected by remobilization of the primary ash even several years after the climactic phase of the eruption. In this mixed methods study, we combine aspects of natural and social sciences to characterize the ash resuspension events associated with the 2011-2012 Cordón Caulle deposits and assess the impacts on the Argentinian farming community of Ingeniero Jacobacci in the Patagonian Steppe. Our findings show the primary importance of wind, rainfall and ash availability in controlling the occurrence and persistence of ash resuspension events. The role played by these variables was also reflected in the seasonal distribution of events observed. Regarding the impacts, our results complement those of earlier studies and demonstrate that ash resuspension events can exacerbate the negative impact of primary tephra fallout events from the time of deposition to many years after the eruption. Only after five years has the environment and the farming community begun to show signs of recovery. Our findings also highlight the importance of assessing ash resuspension events in multi-hazard scenarios involving volcanic and hydrometeorologic hazards.

On the correct name for some subfamilies of Mustelidae (Mammalia, Carnivora

Directory of Open Access Journals (Sweden)

Fabio Oliveira do Nascimento

2014-01-01

Full Text Available Mustelids (Mustelidae exhibit a wide morphological and ecological diversity, ranging from aquatic to semi arboreal and fossorial forms. It is the most diversity family in Carnivora, and this has promoted a great number of taxonomic arrangements for subfamilies, which can range from two to 15 depending on the author. The relatively recent use of molecular data has helped to elucidate the classification of mustelids, and eight subfamilies are currently recognized: Mustelinae, Galictinae, Helictidinae, Martinae, Melinae, Mellivorinae, Taxidiinae and Lutrinae. However, some of these subfamilies have nomenclatural problems, not receiving the oldest available name. The subfamily that includes martens (Martes, Charronia and Pekania, tayra (Eira and wolverine (Gulo has received the name of Martinae Wagner, 1841, but the oldest available name is Guloninae Gray, 1825. This problem also occurs for the subfamily that includes the grisons (Galictis, Patagonian weasel (Lyncodon, marbled polecat (Vormela and striped weasels (Ictonyx and Poecilogale, which are known as Grisoninae Pocock, 1921, but the correct name for this group is Ictonychinae, Pocock, 1921. The subfamily that includes ferret badgers (Melogale retains the name Helictidinae Gray, 1865, because its validity is not affected when the type-genus of the subfamily becomes a junior synonym of another genus. Furthermore, a list of the extant subfamilies of Mustelidae and their respective synonyms and included genera is provided.

Differential use of the Argentine shelf by wintering adults and juveniles southern giant petrels, Macronectes giganteus, from Patagonia

Science.gov (United States)

Blanco, Gabriela S.; Quintana, Flavio

2014-08-01

To study habitat use and at-sea movements of southern giant petrels (SGP) during non-breeding period, we deployed 15 satellite transmitters (six adults, nine juveniles) at Isla Arce and Isla Gran Robredo colonies in Patagonia, Argentina. Birds were instrumented during 81.4 ± 37 days. Adult birds used 74% of the Argentine shelf concentrating mainly at the shelf break, middle shelf waters, and the surroundings of the colony. After fledging, juveniles spread to the Argentine, Uruguayan and Brazilian shelves within the South Atlantic. Adults alternated at-sea excursions (12 ± 5 days) with periods at the colony of 3 ± 0.3 days. Contrarily, juveniles moved first to the shelf break and then traveled northwards reaching the south of Brazil. There was some spatial overlap between age classes, but only during the first 30 days after juveniles had fledged; thereafter there was not overlap between the areas used by both age classes. The Argentine shelf is widely used by different species offering a suitable environment for foraging; this may be why adults SGP from Patagonian colonies spend all year-round within the Argentine shelf. The identification of used areas of non-breeding SGP fills a gap in the species knowledge contributing not only to the preservation the species, but also to the management of marine areas globally recognized as important for many other Procellariiformes.

Albatrosses following fishing vessels: how badly hooked are they on an easy meal?

Directory of Open Access Journals (Sweden)

José P Granadeiro

Full Text Available Fisheries have major impacts on seabirds, both by changing food availability and by causing direct mortality of birds during trawling and longline setting. However, little is known about the nature and the spatial-temporal extent of the interactions between individual birds and vessels. By studying a system in which we had fine-scale data on bird movements and activity, and near real-time information on vessel distribution, we provide new insights on the association of a threatened albatross with fisheries. During early chick-rearing, black-browed albatrosses Thalassarche melanophris from two different colonies (separated by only 75 km showed significant differences in the degree of association with fisheries, despite being nearly equidistant to the Falklands fishing fleet. Most foraging trips from either colony did not bring tracked individuals close to vessels, and proportionally little time and foraging effort was spent near ships. Nevertheless, a few individuals repeatedly visited fishing vessels, which may indicate they specialise on fisheries-linked food sources and so are potentially more vulnerable to bycatch. The evidence suggests that this population has little reliance on fisheries discards at a critical stage of its nesting cycle, and hence measures to limit fisheries waste on the Patagonian shelf that also reduce vessel attractiveness and the risk of incidental mortality, would be of high overall conservation benefit.

Relationships between nuclear magnetic resonance parameters used to characterize weathering spilled oil and soil toxicity in central Patagonia.

Science.gov (United States)

Ríos, Stella Maris; Barquin, Mercedes; Katusich, Ofelia; Nudelman, Norma

2014-01-01

Oil spill in the Central Patagonian zone was studied to evaluate if any relationship exists between the parameters used to characterize weathering spilled oil and soil toxicity for two plant species and to evaluate if the phytotoxicity to local species would be a good index for the soil contamination. Nuclear magnetic resonance (NMR) structural indexes and column chromatography compositional indexes were determined to characterize the oil spill in the soil samples. Bioassays were also carried out using Lactuca sativa L (reference) and Atriplex lampa (native species) as test organisms. Measurements of the total petroleum hydrocarbon (TPH) and the electrical conductivity (EC) of the soil were carried out to evaluate the effect on the bioassays. The principal components analysis of the parameters determined by NMR, compositional indexes, EC, TPH, and toxicology data shows that the first three principal components accounted for the 78% of the total variance (40%, 25%, and 13% for the first, second, and third PC, respectively). A good agreement was found between information obtained by compositional indexes and NMR structural indexes. Soil toxicity increases with the increase of EC and TPH. Other factors, such as, the presence of branched and aromatic hydrocarbons is also significant. The statistical evaluation showed that the Euclidean distances (3D) between the background and each one of the samples might be a better indicator of the soil contamination, compared with chemical criterion of TPH.

Geochemical and Os–Hf–Nd–Sr Isotopic Characterization of North Patagonian Mantle Xenoliths: Implications for Extensive Melt Extraction and Percolation Processes

Czech Academy of Sciences Publication Activity Database

Mundl, A.; Ntaflos, T.; Ackerman, Lukáš; Bizimis, M.; Bjerg, E. A.; Wegner, W.; Hauzenberger, Ch. A.

2016-01-01

Roč. 57, č. 4 (2016), s. 685-715 ISSN 0022-3530 Institutional support: RVO:67985831 Keywords : metasomatism * Patagonia * radiogenic isotopes * Re–Os * SCLM Subject RIV: DD - Geochemistry Impact factor: 3.280, year: 2016

Health status and bioremediation capacity of wild freshwater mussels (Diplodon chilensis) exposed to sewage water pollution in a glacial Patagonian lake.

Science.gov (United States)

Bianchi, Virginia A; Castro, Juan M; Rocchetta, Iara; Bieczynski, Flavia; Luquet, Carlos M

2014-04-01

Deleterious effects on health and fitness are expected in mussels chronically exposed to sewage water pollution. Diplodon chilensis inhabiting SMA, an area affected by untreated and treated sewage water, shows increased hemocyte number and phagocytic activity, while bacteriolytic and phenoloxidase activities in plasma and reactive oxygen species production in hemocytes are lower compared to mussels from an unpolluted area (Yuco). There are not differences in cell viability, lysosomal membrane stability, lipid peroxidation and total oxygen scavenging capacity between SMA and Yuco mussels' hemocytes. Energetic reserves and digestive gland mass do not show differences between groups; although the condition factor is higher in SMA than in Yuco mussels. Gills of SMA mussels show an increase in mass and micronuclei frequency compared to those of Yuco. Mussels from both sites reduce bacterial loads in polluted water and sediments, improving their quality with similar feeding performance. These findings suggest that mussels exposed to sewage pollution modulate physiological responses by long-term exposure; although, gills are sensitive to these conditions and suffer chronic damage. Bioremediation potential found in D. chilensis widens the field of work for remediation of sewage bacterial pollution in water and sediments by filtering bivalves. Copyright © 2014 Elsevier Ltd. All rights reserved.

Breizacanthus aznari sp. n. (Acanthocephala: Arhythmacanthidae) from the banded cusk-eel Raneya brasiliensis (Ophidiiformes: Ophidiidae) from the Patagonian coast in Argentina

Czech Academy of Sciences Publication Activity Database

Hernandez-Orts, J.S.; Alama-Bermejo, Gema; Crespo, E.A.; García, N.A.; Raga, J. A.; Montero, E. E.

2012-01-01

Roč. 59, č. 4 (2012), s. 264-271 ISSN 0015-5683 R&D Projects: GA ČR GBP505/12/G112 Institutional support: RVO:60077344 Keywords : spiny-headed worms * Palaeacanthocephala * Euzetacanthus * taxonomy * marine fish * southwestern Atlantic * Patagonia Subject RIV: EA - Cell Biology Impact factor: 2.515, year: 2012 http://folia.paru.cas.cz/pdfs/showpdf.php?pdf=22090

Refuse dumps from leaf-cutting ant nests reduce the intensity of above-ground competition among neighboring plants in a Patagonian steppe

Science.gov (United States)

Farji-Brener, Alejandro G.; Lescano, María Natalia

2017-11-01

In arid environments, the high availability of sunlight due to the scarcity of trees suggests that plant competition take place mainly belowground for water and nutrients. However, the occurrence of soil disturbances that increase nutrient availability and thereby promote plant growth may enhance shoot competition between neighboring plants. We conducted a greenhouse experiment to evaluate the influence of the enriched soil patches generated by the leaf-cutting ant, Acromyrmex lobicornis, on the performance of the alien forb Carduus thoermeri (Asteraceae) under different intraspecific competition scenarios. Our results showed that substrate type and competition scenario affected mainly aboveground plant growth. As expected, plants growing without neighbors and in nutrient-rich ant refuse dumps showed more aboveground biomass than plants growing with neighbors and in nutrient-poor steppe soils. However, aboveground competition was more intense in nutrient-poor substrates: plants under shoot and full competition growing in the nutrient-rich ant refuse dumps showed higher biomass than those growing on steppe soils. Belowground biomass was similar among focal plants growing under different substrate type. Our results support the traditional view that increments in resource availability reduce competition intensity. Moreover, the fact that seedlings in this sunny habitat mainly compete aboveground illustrates how limiting factors may be scale-dependent and change in importance as plants grow.

Abiotic factors affect the recruitment and biomass of perennial grass and evergreen shrub seedlings in denuded areas of Patagonian Monte rangelands.

Science.gov (United States)

Bosco, Tomás; Bertiller, Mónica Beatriz; Carrera, Analía Lorena

2018-07-15

Assessing the ability of key species to cope with environmental stresses in disturbed areas is an important issue for recovery of degraded arid ecosystem. Our objective was to evaluate the effect of soil moisture, exposure to UV radiation, and presence/absence of litter with different chemistry on soil N, recruitment and biomass of seedlings of perennial grass (Poa ligularis and Nassella tenuis) and evergreen shrub species (Atriplex lampa and Larrea divaricata) in denuded areas. We carried out a microcosm experiment with soil blocks (28 cm depth) sowed with seeds of the target species, subjected to different levels of litter type (perennial grass-evergreen shrub mixture, evergreen shrub mixture, and no litter), UV radiation (near ambient and reduced UV), and soil water (high: 15-25% and low 5-15%). Periodically, during 6 months, we assessed soil-N (total and inorganic) at two depths and species seedling recruitment at microcosms. Additionally, emerged seedlings of each species were transplanted to individual pots containing soil and subjected to the same previous factors during 12 months. Then, all plants were harvested and biomass assessed. Only inorganic soil-N at the upper soil varied among treatments increasing with the presence of evergreen shrub litter, exposure to ambient UV, and high soil water. Inorganic soil-N, promoted by near ambient UV and high soil water, had a positive effect on recruitment of perennial grasses and A. lampa. Both litter types promoted the recruitment of perennial grasses. Evergreen shrub litter and high soil water promoted the recruitment of L. divaricata. Seedling biomass of perennial grasses increased with high soil water and reduced UV. Ambient UV had positive or null effects on biomass of evergreen shrub seedlings. High soil water increased biomass of L. divaricata seedlings. We concluded that soil water appeared as the most limiting factor for seedling recruitment of all species whereas inorganic soil N limited the recruitment of the small-seeded perennial grasses and A. lampa. Ambient UV had negative effects on seedling biomass of perennial grasses. These complex relationships among abiotic factors and seed and plant traits should be taken into account when planning management actions after disturbances. Copyright © 2018 Elsevier Ltd. All rights reserved.

Arbuscular mycorrhizal infection in two morphological root types of Araucaria araucana (Molina K. Koch Infección por micorrizas arbusculares en dos tipos de raíces de Araucaria araucana (Molina K. Koch

Directory of Open Access Journals (Sweden)

P. Diehl

2010-06-01

Full Text Available Araucaria araucana (Molina K. Koch is a conifer distributed in the Andean-Patagonian forests in the south of Argentina and Chile. The main objective of this work was to relate the different root classes appearing in A. araucana to mycorrhizal behavior. Samples were collected in three different sites in the Lanín National Park (NW Patagonia, Argentina. Two different root classes were present in A. araucana: longitudinal fine roots (LFR and globular short roots (GSR. Both had extensive mycorrhizal arbuscular symbiosis (AM and presented abundant hyphae and coils in root cells, a characteristic of the anatomical Paris-type. Dark septate fungal endophytes were also observed. Values of total AM colonization were high, with similar partial AM% values for each root class. Seasonal differences were found for total and partial colonization, with higher values in spring compared to autumn. Regarding the percentage of fungal structures between root classes, values were similar for vesicles and arbuscules, but higher coil percentages were observed in GSR compared to LFR. The percentages of vesicles increased in autumn, whereas the arbuscule percentages increased in spring, coinciding with the plant growth peak. Results show that both root classes of A. araucana in Andean-Patagonian forests are associated with AM fungi, which may have ecological relevance in terms of the importance of this symbiosis, in response to soil nutrient-deficiencies, especially high P-retention.La conífera Araucaria araucana (Molina K. Koch se encuentra distribuida en los bosques Andino-Patagónicos de Argentina y Chile. En este trabajo se relacionaron las diferentes clases morfológicas de raíces presentes en la especie con el comportamiento micorrícico. Las muestras fueron tomadas en tres sitios del Parque Nacional Lanín (NO de Patagonia, Argentina. Se observaron dos clases diferentes de raíces: raíces finas longitudinales (RFL y raíces cortas globulares (RCG. Ambas clases

Energy and Mass Balance At Gran Campo Nevado, Patagonia, Chile

Science.gov (United States)

Schneider, C.; Kilian, R.; Casassa, G.

The Gran Campo Nevado (GCN) Ice Cap on Peninsula Muñoz Gamero, Chile, is lo- cated in the southernmost part of the Patagonian Andes at 53S. It comprises an ice cap and numerous outlet glaciers which mostly end in proglacial lakes at sea level. The total ice covered area sums up to approximately 250 km2. GCN forms the only major ice body between the Southern Patagonian Icefield and the Street of Magallan. Its almost unique location in the zone of the all-year westerlies makes it a region of key interest in terms of glacier and climate change studies of the westwind zone of the Southern Hemisphere. Mean annual temperature of approximately +5C at sea level and high precipitation of about 8.000 mm per year lead to an extreme turn-over of ice mass from the accumulation area of the GCN Ice Cap to the ablation areas of the outlet glaciers. Since October 1999 an automated weather station (AWS) is run continuously in the area at Bahia Bahamondes for monitoring climate parameters. From February to April 2000 an additional AWS was operated on Glaciar Lengua a small outlet glacier of GCN to the north-west. Ablation has been measured at stakes during the same pe- riod. The aim of this study, was to obtain point energy and mass balance on Glaciar Lengua. The work was conducted as part of the international and interdisciplinary working group SGran Campo NevadoT and supported by the German Research Foun- & cedil;dation (DFG). Energy balance was calculated using the bulk approach formulas and calibrated to the measured ablation. It turns out, that sensible heat transfer is the major contribution to the energy balance. Since high cloud cover rates prevail, air tempera- ture is the key factor for the energy balance of the glacier. Despite high rain fall rates, energy input from rain fall is of only minor importance to the overall energy balance. From the energy balance computed, it was possible to derive summer-time degree-day factors for Glaciar Lengua. With data from the nearby

Mapping the recovery of the burnt vegetation by classifying pre- and post-fire spectral indices

Directory of Open Access Journals (Sweden)

M. A Peña

2017-12-01

Full Text Available This study analyzed the state of recovery of the burnt vegetation in the National Park of Torres del Paine between December, 2011 and March, 2012. The calculation and comparison of the NVDI (normalized difference vegetation index of the burnt area throughout a time series of 24 Landsat images acquired before, during and after the fire (2009- 2015, showed the temporal variation in the biomass levels of the burnt vegetation. The subsequent classification and comparison of the spectral indices: NDVI, NBR (normalized burnt ratio and NDWI (normalized difference water index on a full-data available and phenologically matched pre- and post-fire image pair (acquired in October 2009 and 2014, enabled to analyze and mapping the state of recovery of the burnt vegetation. The results show that the area of the lowest classes of all the spectral indices of the pre-fire date became the most dominant on the post-fire date. The pre- and post- fire NDVI class crossing by a confusion matrix showed that the highest and most prevailing pre-fire NDVI classes, mostly corresponding to hydromorphic forests and Andean scrubs, turned into the lowest class in 2014. The remaining area, comprising Patagonian steppe, reestablished its biomass levels in 2014, mostly exhibiting the same pre-fire NDVI classes. These results may provide guidelines to monitor and manage the regeneration of the vegetation impacted by this fire.

Determination of mycotoxin profiles characteristic of Alternaria strains isolated from Malbec grapes

Directory of Open Access Journals (Sweden)

Vargas Trinidad Andrea

2015-01-01

Full Text Available The world grape production has increased, reaching 751 million quintals (Mql in 2013. Many Alternaria species have been studied for their ability to produce secondary metabolites in foods, some of which have toxic properties with tenu- azonic acid (TA, alternariol (AOH, alternariol methyl ether (AME being the most important ones. The aim was to determine the characteristic mycotoxin production profiles of Alternaria strains isolated from Malbec grapes in the Patagonian region of Argentina. Fifty Alternaria isolates (5 A. alternata, 5 A. arborescens and 40 A. tenuissima were analyzed for the produc- tion of mycotoxins (TA, AOH and AME in autoclaved rice media by High Performance Liquid Chromatography (HPLC. All isolates were found to be producers of mycotoxins; the 100% was producer of TA (0.016–21.031 mg/kg, 98% produced AOH (0.003–0.057 mg/kg and 36% produced AME (0.001–0.133 mg/kg. Thirty-three isolates co-produced the three mycotoxins. In this study, it was demonstrated a high toxigenic potential of Alternaria isolates. Although Alternaria growth on grapes has been amply demonstrated, there are few studies about the incidence their more characteristic mycotoxin sand their toxicogenic capac- ity determination in grapes, wines and derivatives. In addition, mycotoxins studied in this work are not regulated in oenology. Therefore, further studies should be conducted to assess the health risk due to the presence of Alternaria toxins in grapes, wine, grape juice and raisins.

Vessel and oil spill early detection using COSMO satellite imagery

Science.gov (United States)

Revollo, Natalia V.; Delrieux, Claudio A.

2017-10-01

Oil spillage is one of the most common sources of environmental damage in places where coastal wild life is found in natural reservoirs. This is especially the case in the Patagonian coast, with a littoral more than 5000 km long and a surface above a million and half square km. In addition, furtive fishery activities in Argentine waters are depleting the food supplies of several species, altering the ecological equilibrium. For this reason, early oil spills and vessel detection is an imperative surveillance task for environmental and governmental authorities. However, given the huge geographical extension, human assisted monitoring is unfeasible, and therefore real time remote sensing technologies are the only operative and economically feasible solution. In this work we describe the theoretical foundations and implementation details of a system specifically designed to take advantage of the SAR imagery delivered by two satellite constellations (the SAOCOM mission, developed by the Argentine Space Agency, and the COSMO mission, developed by the Italian Space Agency), to provide real-time detection of vessels and oil spills. The core of the system is based on pattern recognition over a statistical characterization of the texture patterns arising in the positive and negative conditions (i.e., vessel, oil, or plain sea surfaces). Training patterns were collected from a large number of previously reported contacts tagged by experts in the National Commission on Space Activities (CONAE). The resulting system performs well above the sensitivity and specificity of other avalilable systems.

Cirque Glacier on South Georgia Shows Centennial Variability over the Last 7000 Years

Directory of Open Access Journals (Sweden)

Lea T. Oppedal

2018-02-01

Full Text Available A 7000 year-long cirque glacier reconstruction from South Georgia, based on detailed analysis of fine-grained sediments deposited downstream in a bog and a lake, suggests continued presence during most of the Holocene. Glacier activity is inferred from various sedimentary properties including magnetic susceptibility (MS, dry bulk density (DBD, loss-on-ignition (LOI and geochemical elements (XRF, and tallied to a set of terminal moraines. The two independently dated sediment records document concurring events of enhanced glacigenic sediment influx to the bog and lake, whereas the upstream moraines afford the opportunity to calculate past Equilibrium Line Altitudes (ELA which has varied in the order of 70 m altitude. Combined, the records provide new evidence of cirque glacier fluctuations on South Georgia. Based on the onset of peat formation, the study site was deglaciated prior to 9900 ± 250 years ago when Neumayer tidewater glacier retreated up-fjord. Changes in the lake and bog sediment properties indicate that the cirque glacier was close to its maximum Holocene extent between 7200 ± 400 and 4800 ± 200 cal BP, 2700 ± 150 and 2000 ± 200 cal BP, 500 ± 150–300 ± 100 cal BP, and in the Twentieth century (likely 1930s. The glacier fluctuations are largely in-phase with reconstructed Patagonian glaciers, implying that they respond to centennial climate variability possibly connected to corresponding modulations of the Southern Westerly Winds.

Climate change and American Bullfrog invasion: what could we expect in South America?

Directory of Open Access Journals (Sweden)

Javier Nori

Full Text Available BACKGROUND: Biological invasion and climate change pose challenges to biodiversity conservation in the 21(st century. Invasive species modify ecosystem structure and functioning and climatic changes are likely to produce invasive species' range shifts pushing some populations into protected areas. The American Bullfrog (Lithobates catesbeianus is one of the hundred worst invasive species in the world. Native from the southeast of USA, it has colonized more than 75% of South America where it has been reported as a highly effective predator, competitor and vector of amphibian diseases. METHODOLOGY/PRINCIPAL FINDINGS: We modeled the potential distribution of the bullfrog in its native range based on different climate models and green-house gases emission scenarios, and projected the results onto South America for the years of 2050 and 2080. We also overlaid projected models onto the South American network of protected areas. Our results indicate a slight decrease in potential suitable area for bullfrog invasion, although protected areas will become more climatically suitable. Therefore, invasion of these sites is forecasted. CONCLUSION/SIGNIFICANCE: We provide new evidence supporting the vulnerability of the Atlantic Forest Biodiversity Hotspot to bullfrog invasion and call attention to optimal future climatic conditions of the Andean-Patagonian forest, eastern Paraguay, and northwestern Bolivia, where invasive populations have not been found yet. We recommend several management and policy strategies to control bullfrog invasion and argue that these would be possible if based on appropriate articulation among government agencies, NGOs, research institutions and civil society.

The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Numerical simulations.

Science.gov (United States)

Matano, Ricardo P; Combes, Vincent; Piola, Alberto R; Guerrero, Raul; Palma, Elbio D; Ted Strub, P; James, Corinne; Fenco, Harold; Chao, Yi; Saraceno, Martin

2014-11-01

A high-resolution model is used to characterize the dominant patterns of sea surface salinity (SSS) variability generated by the freshwater discharges of the Rio de la Plata (RdlP) and the Patos/Mirim Lagoon in the southwestern Atlantic region. We identify three dominant modes of SSS variability. The first two, which have been discussed in previous studies, represent the seasonal and the interannual variations of the freshwater plumes over the continental shelf. The third mode of SSS variability, which has not been discussed hitherto, represents the salinity exchanges between the shelf and the deep ocean. A diagnostic study using floats and passive tracers identifies the pathways taken by the freshwater plumes. During the austral winter (JJA) , the plumes leave the shelf region north of the BMC. During the austral summer (DJF), the plumes are entrained more directly into the BMC. A sensitivity study indicates that the high - frequency component of the wind stress forcing controls the vertical structure of the plumes while the low-frequency component of the wind stress forcing and the interannual variations of the RdlP discharge controls the horizontal structure of the plumes. Dynamical analysis reveals that the cross-shelf flow has a dominant barotropic structure and, therefore, the SSS anomalies detected by Aquarius represent net mass exchanges between the shelf and the deep ocean. The net cross-shelf volume flux is 1.21 Sv. This outflow is largely compensated by an inflow from the Patagonian shelf.

Combining fossil and molecular data to date the diversification of New World Primates.

Science.gov (United States)

Schrago, C G; Mello, B; Soares, A E R

2013-11-01

Recent methodological advances in molecular dating associated with the growing availability of sequence data have prompted the study of the evolution of New World Anthropoidea in recent years. Motivated by questions regarding historical biogeography or the mode of evolution, these works aimed to obtain a clearer scenario of Platyrrhini origins and diversification. Although some consensus was found, disputed issues, especially those relating to the evolutionary affinities of fossil taxa, remain. The use of fossil taxa for divergence time analysis is traditionally restricted to the provision of calibration priors. However, new analytical approaches have been developed that incorporate fossils as terminals and, thus, directly assign ages to the fossil tips. In this study, we conducted a combined analysis of molecular and morphological data, including fossils, to derive the timescale of New World anthropoids. Differently from previous studies that conducted total-evidence analysis of molecules and morphology, our approach investigated the morphological clock alone. Our results corroborate the hypothesis that living platyrrhines diversified in the last 20 Ma and that Miocene Patagonian fossils compose an independent evolutionary radiation that diversified in the late Oligocene. When compared to the node ages inferred from the molecular timescale, the inclusion of fossils augmented the precision of the estimates for nodes constrained by the fossil tips. We show that morphological data can be analysed using the same methodological framework applied in relaxed molecular clock studies. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Rainbow trout adaptation to a warmer Patagonia and its potential to increase temperature tolerance in cultured stocks

Directory of Open Access Journals (Sweden)

Sonia Alejandra Crichigno

2018-02-01

Full Text Available The viability of rainbow trout Oncorhynchus mykiss (Walbaum, 1792 culture is being challenged progressively by global warming. Previous trials with Australian and Japanese rainbow trout lines suggested that improvements in thermal performance may be possible. Here, we hypothesized that strain-related differences in physiological response to temperature exist between a north Patagonian hatchery stock (CENSALBA, a Neotropical one (Criadero Boca de Río, and a thermal stream (Valcheta population of wild introduced rainbow trout. This was tested by comparing, at 20 °C, the thermal preference, specific metabolic rate, thermal tolerance, growth, and condition on juveniles of the three strains, and on a Valcheta stream male x CENSALBA female F1 cross. Preferred temperature (PT and loss of equilibrium temperature (LET, a measure of thermal tolerance of Valcheta stream and F1 were significantly higher than those of CENSALBA, and the average PTs of Valcheta stream and F1 were higher than the 95% confidence interval of available reference data for rainbow trout. These results suggest that the F1, reared under standard hatchery conditions and selected by growth and thermal preference, presents higher thermal preference and higher thermal tolerance than the current CENSALBA hatchery stock. Introduction of this naturally adapted strain to hatchery stocks would likely result in the improvement of their temperature resistance to warmer waters. Current studies on adults of this F1 generation are underway.

Analysis of admixture and genetic structure of two Native American groups of Southern Argentinean Patagonia.

Science.gov (United States)

Sala, Andrea; Corach, Daniel

2014-03-01

Argentinean Patagonia is inhabited by people that live principally in urban areas and by small isolated groups of individuals that belong to indigenous aboriginal groups; this territory exhibits the lowest population density of the country. Mapuche and Tehuelche (Mapudungun linguistic branch), are the only extant Native American groups that inhabit the Argentinean Patagonian provinces of Río Negro and Chubut. Fifteen autosomal STRs, 17 Y-STRs, mtDNA full length control region sequence and two sets of Y and mtDNA-coding region SNPs were analyzed in a set of 434 unrelated individuals. The sample set included two aboriginal groups, a group of individuals whose family name included Native American linguistic root and urban samples from Chubut, Río Negro and Buenos Aires provinces of Argentina. Specific Y Amerindian haplogroup Q1 was found in 87.5% in Mapuche and 58.82% in Tehuelche, while the Amerindian mtDNA haplogroups were present in all the aboriginal sample contributors investigated. Admixture analysis performed by means of autosomal and Y-STRs showed the highest degree of admixture in individuals carrying Mapuche surnames, followed by urban populations, and finally by isolated Native American populations as less degree of admixture. The study provided novel genetic information about the Mapuche and Tehuelche people and allowed us to establish a genetic correlation among individuals with Mapudungun surnames that demonstrates not only a linguistic but also a genetic relationship to the isolated aboriginal communities, representing a suitable proxy indicator for assessing genealogical background.

Cirque glacier on South Georgia shows centennial variability over the last 7000 years

Science.gov (United States)

Oppedal, Lea T.; Bakke, Jostein; Paasche, Øyvind; Werner, Johannes P.; van der Bilt, Willem G. M.

2018-02-01

A 7000 year-long cirque glacier reconstruction from South Georgia, based on detailed analysis of fine-grained sediments deposited downstream in a bog and a lake, suggests continued presence during most of the Holocene. Glacier activity is inferred from various sedimentary properties including magnetic susceptibility (MS), dry bulk density (DBD), loss-on-ignition (LOI) and geochemical elements (XRF), and tallied to a set of terminal moraines. The two independently dated sediment records document concurring events of enhanced glacigenic sediment influx to the bog and lake, whereas the upstream moraines afford the opportunity to calculate past Equilibrium Line Altitudes (ELA) which has varied in the order of 70 m altitude. Combined, the records provide new evidence of cirque glacier fluctuations on South Georgia. Based on the onset of peat formation, the study site was deglaciated prior to 9900±250 years ago when Neumayer tidewater glacier retreated up-fjord. Changes in the lake and bog sediment properties indicate that the cirque glacier was close to its maximum Holocene extent between 7200±400 and 4800±200 cal BP, 2700±150 and 2000±200 cal BP, 500±150-300±100 cal BP, and in the 20th century (likely 1930s). The glacier fluctuations are largely in-phase with reconstructed Patagonian glaciers, implying that they respond to centennial climate variability possibly connected to corresponding modulations of the Southern Westerly Winds.

­Genomic data mining of the marine actinobacteria Streptomyces sp. H-KF8 unveils insights into multi-stress related genes and metabolic pathways involved in antimicrobial synthesis

Directory of Open Access Journals (Sweden)

Agustina Undabarrena

2017-02-01

Full Text Available Streptomyces sp. H-KF8 is an actinobacterial strain isolated from marine sediments of a Chilean Patagonian fjord. Morphological characterization together with antibacterial activity was assessed in various culture media, revealing a carbon-source dependent activity mainly against Gram-positive bacteria (S. aureus and L. monocytogenes. Genome mining of this antibacterial-producing bacterium revealed the presence of 26 biosynthetic gene clusters (BGCs for secondary metabolites, where among them, 81% have low similarities with known BGCs. In addition, a genomic search in Streptomyces sp. H-KF8 unveiled the presence of a wide variety of genetic determinants related to heavy metal resistance (49 genes, oxidative stress (69 genes and antibiotic resistance (97 genes. This study revealed that the marine-derived Streptomyces sp. H-KF8 bacterium has the capability to tolerate a diverse set of heavy metals such as copper, cobalt, mercury, chromate and nickel; as well as the highly toxic tellurite, a feature first time described for Streptomyces. In addition, Streptomyces sp. H-KF8 possesses a major resistance towards oxidative stress, in comparison to the soil reference strain Streptomyces violaceoruber A3(2. Moreover, Streptomyces sp. H-KF8 showed resistance to 88% of the antibiotics tested, indicating overall, a strong response to several abiotic stressors. The combination of these biological traits confirms the metabolic versatility of Streptomyces sp. H-KF8, a genetically well-prepared microorganism with the ability to confront the dynamics of the fjord-unique marine environment.

Growth and reproduction investment of the young of the year of the squat lobster Munida gregaria (Crustacea: Anomura in the Patagonian coast

Directory of Open Access Journals (Sweden)

Martin Varisco

2015-09-01

Full Text Available The growth and reproduction investment of the young of the year (0+ of the squat lobster Munida gregaria in San Jorge Gulf, Argentina, were analysed. Moult cycle and size frequency distribution were studied in monthly field samples. Experiments to determine moult increments and intermoult duration were conducted. Sexual maturity, fecundity and reproductive output were analysed in field samples. In addition, maturity experiments in laboratory cultures were conducted. After settlement (November, juveniles showed fast growth until winter (July and growth restarted in September-October. At the beginning of the mating period (early June, males 0+ exhibited mature gonads, whereas females 0+ only showed previtellogenic oocytes. Experimental data showed that females with developed gonads had smaller-size increments in the previous moult. Fecundity and reproductive output were significantly lower in females 0+ than in older females. The early life history of M. gregaria in San Jorge Gulf differs from that of southern populations as those of Beagle Channel and Strait of Magellan due to faster growth and early reproductive investment. Our results suggest that females 0+ of M. gregaria have two investment strategies: early maturity with low fecundity and delayed maturity with higher future fecundity.

Growth and consumption of L-malic acid in wine-like medium by acclimated and non-acclimated cultures of Patagonian Oenococcus oeni strains.

Science.gov (United States)

Bravo-Ferrada, Bárbara Mercedes; Hollmann, Axel; Brizuela, Natalia; La Hens, Danay Valdés; Tymczyszyn, Elizabeth; Semorile, Liliana

2016-09-01

Five Oenococcus oeni strains, selected from spontaneous malolactic fermentation (MLF) of Patagonic Pinot noir wine, were assessed for their use as MLF starter cultures. After the individual evaluation of tolerance to some stress conditions, usually found in wine (pH, ethanol, SO2, and lysozyme), the behavior of the strains was analyzed in MLO broth with 14 % ethanol and pH 3.5 in order to test for the synergistic effect of high ethanol level and low pH and, finally, in a wine-like medium. Although the five strains were able to grow in MLO broth under low pH and/or high ethanol, they must be acclimated to grow in a wine-like medium. Additionally, glycosidase and tannase activities were evaluated, showing differences among the strains. The potential of the strains to ferment citrate was tested and two of the five strains showed the ability to metabolize this substrate. We did not detect the presence of genes encoding histidine, tyrosine descarboxylase, and putrescine carbamoyltransferase. All the strains tested exhibited good growth capacity and ability to consume L-malic acid in a wine-like medium after cell acclimation, and each of them showed a particular enzyme profile, which might confer different organoleptic properties to the wine.

Temporal Genetic Variance and Propagule-Driven Genetic Structure Characterize Naturalized Rainbow Trout (Oncorhynchus mykiss) from a Patagonian Lake Impacted by Trout Farming.

Science.gov (United States)

Benavente, Javiera N; Seeb, Lisa W; Seeb, James E; Arismendi, Ivan; Hernández, Cristián E; Gajardo, Gonzalo; Galleguillos, Ricardo; Cádiz, Maria I; Musleh, Selim S; Gomez-Uchida, Daniel

2015-01-01

Knowledge about the genetic underpinnings of invasions-a theme addressed by invasion genetics as a discipline-is still scarce amid well documented ecological impacts of non-native species on ecosystems of Patagonia in South America. One of the most invasive species in Patagonia's freshwater systems and elsewhere is rainbow trout (Oncorhynchus mykiss). This species was introduced to Chile during the early twentieth century for stocking and promoting recreational fishing; during the late twentieth century was reintroduced for farming purposes and is now naturalized. We used population- and individual-based inference from single nucleotide polymorphisms (SNPs) to illuminate three objectives related to the establishment and naturalization of Rainbow Trout in Lake Llanquihue. This lake has been intensively used for trout farming during the last three decades. Our results emanate from samples collected from five inlet streams over two seasons, winter and spring. First, we found that significant intra- population (temporal) genetic variance was greater than inter-population (spatial) genetic variance, downplaying the importance of spatial divergence during the process of naturalization. Allele frequency differences between cohorts, consistent with variation in fish length between spring and winter collections, might explain temporal genetic differences. Second, individual-based Bayesian clustering suggested that genetic structure within Lake Llanquihue was largely driven by putative farm propagules found at one single stream during spring, but not in winter. This suggests that farm broodstock might migrate upstream to breed during spring at that particular stream. It is unclear whether interbreeding has occurred between "pure" naturalized and farm trout in this and other streams. Third, estimates of the annual number of breeders (Nb) were below 73 in half of the collections, suggestive of genetically small and recently founded populations that might experience substantial genetic drift. Our results reinforce the notion that naturalized trout originated recently from a small yet genetically diverse source and that farm propagules might have played a significant role in the invasion of Rainbow Trout within a single lake with intensive trout farming. Our results also argue for proficient mitigation measures that include management of escapes and strategies to minimize unintentional releases from farm facilities.

Distribución estival del stock sureño de la merluza argentina (Merluccius hubbsi Marini, 1933 en el área de cría (44°-47°S en relación con parámetros oceanógraficos (1996-2001 Summer distribution of the southern stock of the Argentine hake (Merluccius hubbsi Marini, 1933 in the nursery area (44°-47°S in relation to oceanographic parameters (1996-2001

Directory of Open Access Journals (Sweden)

Elena Louge

2011-01-01

Full Text Available Se analizaron las variables temperatura y salinidad en verano, durante el período 1996-2001 en el área de cría del efectivo patagónico de la merluza argentina Merluccius hubbsi. Estas variables oceanógraficas se relacionaron con las variaciones en la abundancia de la población, a través de un modelo lineal general. Se determinaron los valores medios y las anomalías de temperatura y salinidad de fondo. Las anomalías térmicas positivas más extremas se produjeron en 1999 y 2000, mientras que el año más frío fue 1996. La anomalía de salinidad más baja se registró en 1996 y la más alta en el 2000. La merluza se concentró principalmente en las zonas de gradientes térmicos y salinos Los juveniles se hallaron preferentemente en el Golfo San Jorge en aguas con temperaturas entre 8º y 10°C y salinidades entre 33,2 y 33,6 y los adultos dentro y fuera del mismo, con temperaturas de fondo entre 8º y 12°C y salinidades 33,2 y 33,5. Las mayores densidades de juveniles se hallaron en aguas de menor profundidad, con valores elevados de salinidad y menores valores de temperatura respecto de los adultos. Estos se concentraron tanto en el sector norte del golfo y en la Bahía Camarones, en aguas con relativamente alta temperatura y escasa profundidad, como sobre la plataforma frente al golfo, donde las aguas tienen menor salinidad debido a la deriva de la Corriente Patagónica de aguas diluidas. No se observaron cambios en la distribución de la población en los años con anomalías ambientales marcadas.Summer temperature and salinity data in the nursery ground of the Patagonian stock of Argentine hake Merluccius hubbsi recorded from 1996 to 2001 were analyzed. These oceanographic variables were related to variations in the hake population abundance by means of a general linear model. Mean values and anomalies of bottom temperatures and salinity fields were determined. The most extreme positive thermal anomalies occurred in 1999 and 2000

Do coastal fronts influence bioerosion patterns along Patagonia? Late Quaternary ichnological tools from Golfo San Jorge

Science.gov (United States)

Richiano, Sebastián; Aguirre, Marina; Castellanos, Ignacio; Davies, Karen; Farinati, Ester

2017-12-01

, Iramena, Pinaceocladichnus, at Bustamante) differs across time. These variations, particularly the highest abundance in the Late Pleistocene (mainly Last Interglacial) of traces made by bryozoans- associated at present with modern enhanced productivity levels and coastal fronts in the Argentine continental shelf- point to higher productivity and more intensified northern Patagonia Front, as a result of a different palaeocirculation pattern, reinforcing previous independent sources of evidence based on molluscan palaeobiogeographical analyses. Supplementary Appendix 2 List of ichnotaxa recorded in gastropod and bivalve taxa as observed in shells from the Quaternary deposits sampled, authors and corresponding ethological classification. Abbreviations are those used along the text. Full references in Richiano et al. (2012, 2015). Supplementary Appendix 3 General biogenic composition of the beach ridge systems (Marine Terraces) at Camarones and Bustamante coastal areas and along the adjacent modern littoral. List of molluscan species and other invertebrates recovered from the deposits sampled. Modified from Aguirre et al. (2005, 2006). See also Table 1 of this paper, Aguirre et al. (2008, 2011a), Richiano et al. (2012, 2015). Supplementary Appendix 4 Independent palaeobiogeographical evidence for lower SST during the Late Pleistocene against higher during the Mid-Holocene. Geographical patterns of relationships between areas through time. PCO (Principal Coordinate analyses), CA (Cluster Analysis) and PAE (Parsimony Analysis of Endemicity) (modified from Aguirre et al., 2011a, 2013). (A1): PCO (top) and (A2): CA (middle) for Late Pleistocene, Holocene and modern molluscs. (A3): PAE showing patterns between localities for the Pleistocene (only time interval with records of Tegula atra) compared to the present. __: Areas of endemism. Note the isolation of SAO (SMCF) relative to the remaining Patagonian localities at present and during the mid-Holocene vs. its linkage to the

A revision of the genus Neogrubea Dillon & Hargis, 1968 (Monogenea: Mazocraeidae): new morphological and molecular data from off the Patagonian coast of Argentina

Czech Academy of Sciences Publication Activity Database

Hernández-Orts, Jesús S.; Alama-Bermejo, Gema; Crespo, E.A.; Raga, J. A.; Montero, F. E.

2014-01-01

Roč. 89, č. 1 (2014), s. 59-72 ISSN 0165-5752 Institutional support: RVO:60077344 Keywords : kuhnia-scombri monogenea * 28s rdna sequences * host size * platyhelminthes * polyopisthocotylea * phylogeny * digenea * hamuli Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Biochemistry and molecular biology Impact factor: 1.336, year: 2014

Genetic variation among the Mapuche Indians from the Patagonian region of Argentina: mitochondrial DNA sequence variation and allele frequencies of several nuclear genes.

Science.gov (United States)

Ginther, C; Corach, D; Penacino, G A; Rey, J A; Carnese, F R; Hutz, M H; Anderson, A; Just, J; Salzano, F M; King, M C

1993-01-01

DNA samples from 60 Mapuche Indians, representing 39 maternal lineages, were genetically characterized for (1) nucleotide sequences of the mtDNA control region; (2) presence or absence of a nine base duplication in mtDNA region V; (3) HLA loci DRB1 and DQA1; (4) variation at three nuclear genes with short tandem repeats; and (5) variation at the polymorphic marker D2S44. The genetic profile of the Mapuche population was compared to other Amerinds and to worldwide populations. Two highly polymorphic portions of the mtDNA control region, comprising 650 nucleotides, were amplified by the polymerase chain reaction (PCR) and directly sequenced. The 39 maternal lineages were defined by two or three generation families identified by the Mapuches. These 39 lineages included 19 different mtDNA sequences that could be grouped into four classes. The same classes of sequences appear in other Amerinds from North, Central, and South American populations separated by thousands of miles, suggesting that the origin of the mtDNA patterns predates the migration to the Americas. The mtDNA sequence similarity between Amerind populations suggests that the migration throughout the Americas occurred rapidly relative to the mtDNA mutation rate. HLA DRB1 alleles 1602 and 1402 were frequent among the Mapuches. These alleles also occur at high frequency among other Amerinds in North and South America, but not among Spanish, Chinese or African-American populations. The high frequency of these alleles throughout the Americas, and their specificity to the Americas, supports the hypothesis that Mapuches and other Amerind groups are closely related.(ABSTRACT TRUNCATED AT 250 WORDS)

Lake-level variations and tides in Lago Argentino, Patagonia: insights from pressure tide gauge records

Directory of Open Access Journals (Sweden)

Andreas Richter

2015-08-01

Full Text Available Based on precise pressure tide gauge observations lake-level records are derived for two sites in Lago Argentino, southern Patagonia, of 2.5 and 1 years of duration. Applying the tools of time series analysis, the principal processes affecting the lake level are identified and quantified. Lake-level changes reflecting variations in lake volume are dominated by a seasonal cycle of 1.2 m in amplitude. Lake-volume changes occur in addition with a daily period in response to melt water influx from surrounding glaciers. Sporadic lake-volume jumps are caused by bursting of the ice dam of Perito Moreno glacier. Water movements in Lago Argentino are dominated by surface seiches reaching 20 cm in amplitude. Lake tides reach a maximum amplitude of 3 mm. The comparison of the tidal signal extracted from the lake-level observations with a model composed of the contributions of body tide and ocean tidal loading indicates a phase shift of 23° which is most likely explained by an 1 hour phase lag of global ocean tide models in the region of the highly fragmented Pacific coast. The comparison of the obtained results with those of a previous study of Lago Fagnano, Tierra del Fuego, allows to relate differences in the hydrological and hydrodynamic processes between both lakes to morphological properties. This leads to a tentative prediction of the lake-level variability to be expected from other great Patagonian lakes. The presented geodetic results shall serve as a starting point for a detailed limnological investigation of these aquatic ecosystems.

Glacial Hazards in Chile: Processes, Assessment, Mitigation and Risk Management Strategies

Science.gov (United States)

Glasser, N. F.; Wilson, R.; Casassa, G., Sr.; Reynolds, J.; Harrison, S.; Shannon, S. R.; Schaefer, M.; Iribarran, P.

2017-12-01

Glacial Lake Outburst Floods (GLOFs) are capable of travelling considerable distances from their source and they represent one of the most important glacial hazards. In line with observations in other parts of the world, the frequency of GLOF events in Chile has increased in recent decades highlighting the need to quantify the flood risk posed to downstream areas. This poster presents the work of the `Glacial Hazards in Chile' project which aims to (1) better understand the processes that govern the development of GLOFs in Chile, (2) estimate the socio-economic effects of GLOFs in Chile, and (3) provide a GLOF risk assessment framework that can be applied to Chile and other lower income countries globally. As an initial step towards the completion of these aims, we have recently compiled the first glacial lake inventory for the central and Patagonian Andes, which details the temporal development of glacial lakes in this region over the past three decades. This analysis was used to identify two lakes of interest that were visited during a fieldwork expedition in February 2017. The first of these, Lago Chileno in Patagonia, has recently produced a large GLOF causing significant damage to the downstream floodplain, whilst the second was identified as one of the fastest growing lakes in the central Andes. Both these lakes were surveyed using aerial imagery acquired with a drone and a custom-built bathymetry boat, data from which will help to improve our understanding of the physical processes associated with glacial lake development and failure within the Chilean Andes.

Homeostasis in leaf water potentials on leeward and windward sides of desert shrub crowns: water loss control vs. high hydraulic efficiency.

Science.gov (United States)

Iogna, Patricia A; Bucci, Sandra J; Scholz, Fabián G; Goldstein, Guillermo

2013-11-01

Phenotypic plasticity in morphophysiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind-exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (ΨL). The two species were able to maintain homeostasis in minimum ΨL using different physiological mechanisms. Berberis microphylla avoided a decrease in the minimum ΨL in the exposed side of the crown by reducing water loss by stomatal control, loss of cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind-exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum ΨL and thus contribute to the maintenance of homeostasis, assuring the hydraulic integrity of the plant under unfavorable conditions. The responses of leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) differed from those of large physiological traits by exhibiting low phenotypic plasticity. The results of this study help us to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.

Subregional characterization of mesoscale eddies across the Brazil-Malvinas Confluence

Science.gov (United States)

Mason, Evan; Pascual, Ananda; Gaube, Peter; Ruiz, Simón; Pelegrí, Josep L.; Delepoulle, Antoine

2017-04-01

Horizontal and vertical motions associated with coherent mesoscale structures, including eddies and meanders, are responsible for significant global transports of many properties, including heat and mass. Mesoscale vertical fluxes also influence upper ocean biological productivity by mediating the supply of nutrients into the euphotic layer, with potential impacts on the global carbon cycle. The Brazil-Malvinas Confluence (BMC) is a western boundary current region in the South Atlantic with intense mesoscale activity. This region has an active role in the genesis and transformation of water masses and thus is a critical component of the Atlantic meridional overturning circulation. The collision between the Malvinas and Brazil Currents over the Patagonian shelf/slope creates an energetic front that translates offshore to form a vigorous eddy field. Recent improvements in gridded altimetric sea level anomaly fields allow us to track BMC mesoscale eddies with high spatial and temporal resolutions using an automated eddy tracker. We characterize the eddies across fourteen 5° × 5° subregions. Eddy-centric composites of tracers and geostrophic currents diagnosed from a global reanalysis of surface and in situ data reveal substantial subregional heterogeneity. The in situ data are also used to compute the evolving quasi-geostrophic vertical velocity (QG-ω) associated with each instantaneous eddy instance. The QG-ω eddy composites have the expected dipole patterns of alternating upwelling/downwelling, however, the magnitude and sign of azimuthally averaged vertical velocity varies among subregions. Maximum eddy values are found near fronts and sharp topographic gradients. In comparison with regional eddy composites, subregional composites provide refined information about mesoscale eddy heterogeneity.

Thermal sensitivity of cold climate lizards and the importance of distributional ranges.

Science.gov (United States)

Bonino, Marcelo F; Moreno Azócar, Débora L; Schulte, James A; Abdala, Cristian S; Cruz, Félix B

2015-08-01

One of the fundamental goals in macroecology is to understand the relationship among species' geographic ranges, ecophysiology, and climate; however, the mechanisms underlying the distributional geographic patterns observed remain unknown for most organisms. In the case of ectotherms this is particularly important because the knowledge of these interactions may provide a robust framework for predicting the potential consequences of climate change in these organisms. Here we studied the relationship of thermal sensitivity and thermal tolerance in Patagonian lizards and their geographic ranges, proposing that species with wider distributions have broader plasticity and thermal tolerance. We predicted that lizard thermal physiology is related to the thermal characteristics of the environment. We also explored the presence of trade-offs of some thermal traits and evaluated the potential effects of a predicted scenario of climate change for these species. We examined sixteen species of Liolaemini lizards from Patagonia representing species with different geographic range sizes. We obtained thermal tolerance data and performance curves for each species in laboratory trials. We found evidence supporting the idea that higher physiological plasticity allows species to achieve broader distribution ranges compared to species with restricted distributions. We also found a trade-off between broad levels of plasticity and higher optimum temperatures of performance. Finally, results from contrasting performance curves against the highest environmental temperatures that lizards may face in a future scenario (year 2080) suggest that the activity of species occurring at high latitudes may be unaffected by predicted climatic changes. Copyright © 2015 Elsevier GmbH. All rights reserved.

Foraging behaviour of the exotic wasp Vespula germanica (Hymenoptera: Vespidae) on a native caterpillar defoliator.

Science.gov (United States)

Pietrantuono, A L; Moreyra, S; Lozada, M

2017-09-19

Vespula germanica is a social wasp and an opportunistic predator. While foraging, these wasps learn and integrate different kinds of cues. They have successfully invaded many parts of the world, including native Nothofagus and Lophozonia forests located in the Andean-Patagonian region, where they forage on native arthropods. Perzelia arda, a lepidopteron defoliator of Lophozonia obliqua, uses the foliage to hide in and feed on. The purpose of this work is to study whether V. germanica use olfactory cues when foraging on P. arda. To do this, we used a Y-tube olfactometer and established three treatments to compare pairs of all combinations of stimuli (larvae, leaves with larval traces, and leaves without larval traces) and controls. Data were analysed via two developed models that showed decisions made by V. germanica and allowed to establish a scale of preferences between the stimuli. The analysis demonstrates that V. germanica wasps choose P. arda as larval prey and are capable of discriminating between the offered stimuli (deviance information criterion (DIC) null model = 873.97; DIC simple model = 84.5, n = 152). According to the preference scale, V. germanica preferred leaves with traces of larvae, suggesting its ability to associate these traces with the presence of the prey. This may be because, under natural conditions, larvae are never exposed outside their shelters of leaves and therefore V. germanica uses indirect signals. The presence of V. germanica foraging on P. arda highlights the flexible foraging behaviour of this wasp which may also act as a positive biological control, reducing lepidopteran populations.

Copernicus Big Data and Google Earth Engine for Glacier Surface Velocity Field Monitoring: Feasibility Demonstration on San Rafael and San Quintin Glaciers

Science.gov (United States)

Di Tullio, M.; Nocchi, F.; Camplani, A.; Emanuelli, N.; Nascetti, A.; Crespi, M.

2018-04-01

The glaciers are a natural global resource and one of the principal climate change indicator at global and local scale, being influenced by temperature and snow precipitation changes. Among the parameters used for glacier monitoring, the surface velocity is a key element, since it is connected to glaciers changes (mass balance, hydro balance, glaciers stability, landscape erosion). The leading idea of this work is to continuously retrieve glaciers surface velocity using free ESA Sentinel-1 SAR imagery and exploiting the potentialities of the Google Earth Engine (GEE) platform. GEE has been recently released by Google as a platform for petabyte-scale scientific analysis and visualization of geospatial datasets. The algorithm of SAR off-set tracking developed at the Geodesy and Geomatics Division of the University of Rome La Sapienza has been integrated in a cloud based platform that automatically processes large stacks of Sentinel-1 data to retrieve glacier surface velocity field time series. We processed about 600 Sentinel-1 image pairs to obtain a continuous time series of velocity field measurements over 3 years from January 2015 to January 2018 for two wide glaciers located in the Northern Patagonian Ice Field (NPIF), the San Rafael and the San Quintin glaciers. Several results related to these relevant glaciers also validated with respect already available and renown software (i.e. ESA SNAP, CIAS) and with respect optical sensor measurements (i.e. LANDSAT8), highlight the potential of the Big Data analysis to automatically monitor glacier surface velocity fields at global scale, exploiting the synergy between GEE and Sentinel-1 imagery.

Uptake of Hg2+ by picocyanobacteria in natural water from four Andean lakes

Directory of Open Access Journals (Sweden)

Diéguez M.C.

2014-07-01

Full Text Available In lake food webs, planktonic bacteria and algae represent the greatest bioconcentration step for Hg2+ and monomethyl-Hg (MeHg. As they are the most abundant organisms in planktonic trophic webs and also the main food resource for herbivorous plankton, they can mobilize large amounts of Hg to higher trophic levels. In Andean Patagonian lakes (Argentina, dissolved organic matter (DOM concentration and character, coupled with photo-reactions, play a central role in the complexation of Hg2+ in the water column and can even regulate the uptake of Hg2+ by planktonic algae. In this investigation we evaluated the DOM character of natural waters (NW from four Andean lakes and studied its influence on the uptake of 197Hg2+ in a strain of the picocyanobacteria Synechococcus by using Hg2+ labeled with 197Hg2+. The uptake of radiolabeled Hg2+ by Synechococcus showed different magnitude in NW of lakes Moreno, El Trébol, Morenito and Escondido. Increasing lake DOM concentration reduced the bioavailability of Hg2+ as indicated by the lower uptakes rates found in NW with higher complexity and concentration of the DOM pool. Uptakes of Hg2+ by this picocyanobacteria contrasted among NW from pelagic (surface and bottom and littoral compartments of Lake Escondido which suggest that the entry of this metal may be highly variable even in the same environment. The study of the uptake of radiolabeled Hg2+ in a set of dilutions of NW from Lake Escondido demonstrated that the bioavailability of Hg2+ decrease with increasing DOM concentration.

Genomic insights into the origin and diversification of late maritime hunter-gatherers from the Chilean Patagonia.

Science.gov (United States)

de la Fuente, Constanza; Ávila-Arcos, María C; Galimany, Jacqueline; Carpenter, Meredith L; Homburger, Julian R; Blanco, Alejandro; Contreras, Paloma; Cruz Dávalos, Diana; Reyes, Omar; San Roman, Manuel; Moreno-Estrada, Andrés; Campos, Paula F; Eng, Celeste; Huntsman, Scott; Burchard, Esteban G; Malaspinas, Anna-Sapfo; Bustamante, Carlos D; Willerslev, Eske; Llop, Elena; Verdugo, Ricardo A; Moraga, Mauricio

2018-04-24

Patagonia was the last region of the Americas reached by humans who entered the continent from Siberia ∼15,000-20,000 y ago. Despite recent genomic approaches to reconstruct the continental evolutionary history, regional characterization of ancient and modern genomes remains understudied. Exploring the genomic diversity within Patagonia is not just a valuable strategy to gain a better understanding of the history and diversification of human populations in the southernmost tip of the Americas, but it would also improve the representation of Native American diversity in global databases of human variation. Here, we present genome data from four modern populations from Central Southern Chile and Patagonia ( n = 61) and four ancient maritime individuals from Patagonia (∼1,000 y old). Both the modern and ancient individuals studied in this work have a greater genetic affinity with other modern Native Americans than to any non-American population, showing within South America a clear structure between major geographical regions. Native Patagonian Kawéskar and Yámana showed the highest genetic affinity with the ancient individuals, indicating genetic continuity in the region during the past 1,000 y before present, together with an important agreement between the ethnic affiliation and historical distribution of both groups. Lastly, the ancient maritime individuals were genetically equidistant to a ∼200-y-old terrestrial hunter-gatherer from Tierra del Fuego, which supports a model with an initial separation of a common ancestral group to both maritime populations from a terrestrial population, with a later diversification of the maritime groups.

Killer whales attack on South American sea lion associated with a fishing vessel: predator and prey tactics Ataque de orcas a un lobo marino sudamericano asociado a un barco pesquero: tácticas del predador y la presa

Directory of Open Access Journals (Sweden)

M. Florencia Grandi

2012-11-01

Full Text Available Interactions between killer whales and sea lions are widely known. This work describes the predator-prey behaviour of killer whales and South American sea lion associated with a trawling fishery. In Argentina the predatory behaviours of killer whales and anti-predatory behaviours of South American sea lions have been described from costal based observations, but predator-prey behaviour of these species is poorly known at open waters. Here we describe a killer whale group attack on an individual sea lion, using a video recorded from a trawling vessel and an interview of the ship captain. This predator-prey behaviour represents an example of the complexity of interactions between marine mammals and fisheries along the Patagonian coast.Las interacciones entre orcas y lobos marinos son ampliamente conocidas. Este trabajo describe el comportamiento predador-presa entre orcas y un lobo marino sudamericano asociados a un barco pesquero de arrastre. Particularmente en Argentina el comportamiento predatorio de las orcas y el anti-predatorio de los lobos marinos comunes fueron descriptos mediante observaciones costeras, pero se sabe poco sobre el comportamiento de estas especies en aguas abiertas. En este trabajo, a partir de un video grabado desde un barco de pesca arrastrero, junto con la entrevista del capitán del barco, se describe cómo un grupo de orcas ataca a un lobo marino Sudamericano. Este comportamiento predador-presa representa un ejemplo sobre la complejidad de las interacciones entre mamíferos marinos y las pesquerías a lo largo de la costa patagónica.

Rainforest conifers of Eocene Patagonia: attached cones and foliage of the extant Southeast Asian and Australasian genus Dacrycarpus (Podocarpaceae).

Science.gov (United States)

Wilf, Peter

2012-03-01

Eocene caldera-lake beds at Laguna del Hunco (LH, ca. 52.2 Ma) and Río Pichileufú (RP, ca. 47.7 Ma) in Argentine Patagonia provide copious information about the biological history of Gondwana. Several plant genera from these sites are known as fossils from southern Australia and New Zealand and survive only in Australasian rainforests. The potential presence of Dacrycarpus (Podocarpaceae) holds considerable interest due to its extensive foliage-fossil record in Gondwana, its remarkably broad modern distribution in Southeast Asian and Australasian rainforests, its high physiological moisture requirements, and its bird-dispersed seeds. However, the unique seed cones that firmly diagnose Dacrycarpus were not previously known from the fossil record. I describe and interpret fertile (LH) and vegetative (LH and RP) material of Dacrycarpus and present a nomenclatural revision for fossil Dacrycarpus from South America. Dacrycarpus puertae sp. nov. is the first fossil occurrence of the unusual seed cones that typify living Dacrycarpus, attached to characteristic foliage, and of attached Dacrycarpus pollen cones and foliage. Dacrycarpus puertae is indistinguishable from living D. imbricatus (montane, Burma to Fiji). Dacrycarpus chilensis (Engelhardt) comb. nov. is proposed for Eocene vegetative material from Chile. Modern-aspect Dacrycarpus was present in Eocene Patagonia, demonstrating an astonishingly wide-ranging paleogeographic history and implying a long evolutionary association with bird dispersers. Dacrycarpus puertae provides the first significant Asian link for Eocene Patagonian floras, strengthens the biogeographic connections from Patagonia to Australasia across Antarctica during the warm Eocene, and indicates high-rainfall paleoenvironments.

HLA genetic profile of Mapuche (Araucanian) Amerindians from Chile.

Science.gov (United States)

Rey, Diego; Parga-Lozano, Carlos; Moscoso, Juan; Areces, Cristina; Enriquez-de-Salamanca, Mercedes; Fernández-Honrado, Mercedes; Abd-El-Fatah-Khalil, Sedeka; Alonso-Rubio, Javier; Arnaiz-Villena, Antonio

2013-07-01

Amerindian Mapuche (Araucanians) are now living in Chile and Argentina at both sides of Andean Mountains. They are anthropologically and genetically different from southernmost South America Patagonian Amerindians. Most of the HLA alleles found in our Mapuche sample are frequent or very frequent in North and South America Amerindians: (1) Class I: A*02:01, A*03:01, A*68:01, B*39:09, B*51:01, (2) Class II: DRB1*03:01, DRB1*04:03, DRB1*07:01, DRB1*08:02, DRB1*14:02, DRB1*16:02. One of the nine most frequent extended haplotypes seems to be from European origin, suggesting the existence of a degree of admixture with Europeans in our Mapuche sample. It has been calculated of about 11 % admixture. Three of the extended haplotypes are also found in other Amerindians and five of them are newly found in Mapuche Amerindians: A*68:01-B*39:09-DRB1*08:02-DQB1*04:02; A*68:01-B*51:01-DRB1*04:03-DQB1*03:02; A*29:01-B*08:01-DRB1*03:01-DQB1*02:01; A*02:01-B*15:01-DRB1*04:03-DQB1*03:02; A*33:01-B*14:02-DRB1*07:01-DQB1*03:03. The medical importance of calculating HLA profile is discussed on the diagnostic (HLA and disease) and therapeutical bases of HLA pharmacogenomics and on the construction of a virtual transplantation HLA list profile. Also, anthropological conclusions are drawn.

Comparación de métodos analíticos para la determinación de materia orgánica en suelos de la región Andino-Patagónica: efectos de la vegetación y el tipo de suelo Comparison of analytical methods for determining soil organic matter in Patagonian Andean Region: effects of vegetation and soil types

Directory of Open Access Journals (Sweden)

Ludmila La Manna

2007-12-01

ambiente y tipo de suelo de la estepa herbácea, que aún se mantienen por el escaso tiempo transcurrido desde la implantación del bosque. Se generaron dos modelos de regresión lineal que evidencian la relación entre MO CH y MO PI para distintos tipos de vegetación: Plantación de pino ponderosa y estepa herbácea MO PI (% = 1,37 x MO CH (% + 0,81 (R² = 0,86; n = 40 Estepa arbustiva, arbustal, y bosque denso de ciprés MO PI (% = 1,19 x MO CH (% + 1,58 (R² = 0,93; n = 60 Las ecuaciones generadas permiten comparar datos de contenido de MO obtenidos por los distintos métodos analíticos.The determination of organic matter (OM content is key for the knowledge of agricultural and forestry soil productivity. This study evaluated the relationship between OM content determined by weight loss-on ignition (OM WLOI and Walkley-Black wet oxidation method (OM WO in soils of the Patagonian Andean Region. The relation was evaluated for volcanic soils with and without amorphous components and with different vegetation types: Pinus ponderosa plantations, herbaceous steppe, shrubly steppe, shrubs and Austrocedrus chilensis forests. One hundred sampling sites were selected and composed samples were obtained from horizon A. Data were analyzed by means of analysis of variance and simple regressions. OM WO was always lower than OM WLOI. This is expectable since OM WLOI includes the total OM, whereas MO WO discriminates the strongly condensed carbon forms. Although differences in the relationship between the analytical methods for soils with and without amorphous components were not detected, a great relationship between these components and organic matter content was found. The relationship between the analytical methods varied according to the vegetation type. Soils with herbaceous steppe and pine plantations presented the greatest differences between the analytical methods. OM WO was in average 37% lower than OM WLOI for these types of vegetation, being significantly greater than

Submarine earthquake rupture, active faulting and volcanism along the major Liquiñe-Ofqui Fault Zone and implications for seismic hazard assessment in the Patagonian Andes Ruptura sísmica submarina, tectónica y volcanismo activo a lo largo de la Falla Liquiñe-Ofqui e implicancias para el peligro sísmico en los Andes patagónicos

Directory of Open Access Journals (Sweden)

Gabriel Vargas

2013-01-01

Full Text Available The Liquiñe-Ofqui fault zone (LOFZ in the Patagonian Andes is an active major transpressional intra-arc fault system along which Quaternary faulting and volcanism develop. Subaerial and submarine geomorphologic and structural characterization of latest Pleistocene-Holocene faults and monogenetic volcanoes allows us to assess geological cartography of active faults and the kinematic model for recent tectonics during postglacial times, since 12,000 cal. years BP. This allows increasing the basic geological knowledge necessary for determining the seismic hazard associated with cortical structures in the Aysén region in southern Chile. Fault cartography and field observations suggest dominant dextral-reverse strike slip along north-south and locally NNW-striking faults, dextral-normal strike slip along NE to NNE- striking faults, and sinistral strike slip along east-west faults. This kinematics is consistent with regional SW-NE shortening in the context of a major transpressional fault zone. Holocene and even historic monogenetic and sub-aquatic volcanism occurred in this tectonic setting in a close spatial relationship and probably favored by the activity and local architecture of faults. Submarine fault scarps and deformed sediments observed at the bottom of the Aysén Fjord were associated with the destructive April 2007 Mw6.2 earthquake located along the LOFZ. Our observations show that this earthquake occurred along dextral 15-20 km long N-S structure named Punta Cola Fault (PCF. This fault system is located some kilometres to the east of the main N-S Río Cuervo Fault (RCF. Most of the epicentres of the seismic swarm during 2007 were located along or in between both structures. The study area is a transference zone between N-S regional branches of the LOFZ. The cartography of fault segments proposed here together with geophysical and geologic data suggest that large earthquakes Mw6.2-6.5 can be typically expected along most of the active

Mycosporine-like amino acids and xanthophyll-cycle pigments favour a massive spring bloom development of the dinoflagellate Prorocentrum minimum in Grande Bay (Argentina), an ozone hole affected area

Science.gov (United States)

Carreto, José I.; Carignan, Mario O.; Montoya, Nora G.; Cozzolino, Ezequiel; Akselman, Rut

2018-02-01

In Grande Bay (Southern Patagonian Shelf) in a eutrophic and recirculating area slightly stratified during spring, we observed an intense (up to 1 × 107 cells L- 1) and shallow, quasi mono-specific bloom of the dinoflagellate Prorocentrum minimum. Peridinin was the most abundant carotenoid, but the relative amounts of the xanthophyll cycle carotenoids (diadinoxanthin + diatoxanthin = DT) to light-harvesting pigments were high (DT/Chl a ratio = 0.32 and DT/peridinin ratio = 0.40). Shinorine, usujirene, palythene, mycosporine-serine-glycine methyl ester and palythenic acid were the primary mycosporine-like amino acids (MAAs), followed by mycosporine-glycine, palythine, and porphyra-334. The ΣMAAs/Chl a ratios (up to 27.9 nmol/nmol) were in the upper range reported either in nutrient-replete dinoflagellate cultures or natural populations. We monitored, from space (using satellite ocean colour data), the spatial and temporal bloom variability (from September 22 to October 31, 2005) using an approach to discriminate dinoflagellate from diatom blooms. The results indicated that an intense diatom bloom started in early spring but was rapidly replaced by an intense bloom of the dinoflagellate P. minimum, although the nutrient concentrations were apparently not limiting. The most notorious change in this period was a sharp increase in the levels of solar UVB radiation (UVB index 9.0) as a consequence of the overpass of the polar vortex over this area. We postulated that the synthesis and accumulation of MAAs and xanthophyll pigments, were competitive advantages for the opportunistic red tide dinoflagellate P. minimum over the sensitive diatoms, favouring the development of their surface blooms in this seasonally solar UVB radiation (UVBR) affected area.

Incorporation of inorganic mercury (Hg²⁺) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: the role of different plankton size fractions and species assemblages.

Science.gov (United States)

Soto Cárdenas, Carolina; Diéguez, Maria C; Ribeiro Guevara, Sergio; Marvin-DiPasquale, Mark; Queimaliños, Claudia P

2014-10-01

In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg(2+)) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg(2+) by four plankton fractions (picoplankton: 0.2-2.7 μm; pico+nanoplankton: 0.2-20 μm; microplankton: 20-50 μm; and mesoplankton: 50-200 μm) obtained from four Andean Patagonian lakes, using the radioisotope (197)Hg(2+). Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg(2+) in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico+nanoplankton play a central role leading the incorporation of Hg(2+) in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg(2+) by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria-nanoflagellates-crustaceans; bacteria-ciliates-crustaceans; endosymbiotic algae-ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg(2+) observed in all the plankton fractions. Copyright © 2014 Elsevier B.V. All rights reserved.

Validating numerical simulations of snow avalanches using dendrochronology: the Cerro Ventana event in Northern Patagonia, Argentina

Directory of Open Access Journals (Sweden)

A. Casteller

2008-05-01

Full Text Available The damage caused by snow avalanches to property and human lives is underestimated in many regions around the world, especially where this natural hazard remains poorly documented. One such region is the Argentinean Andes, where numerous settlements are threatened almost every winter by large snow avalanches. On 1 September 2002, the largest tragedy in the history of Argentinean mountaineering took place at Cerro Ventana, Northern Patagonia: nine persons were killed and seven others injured by a snow avalanche. In this paper, we combine both numerical modeling and dendrochronological investigations to reconstruct this event. Using information released by local governmental authorities and compiled in the field, the avalanche event was numerically simulated using the avalanche dynamics programs AVAL-1D and RAMMS. Avalanche characteristics, such as extent and date were determined using dendrochronological techniques. Model simulation results were compared with documentary and tree-ring evidences for the 2002 event. Our results show a good agreement between the simulated projection of the avalanche and its reconstructed extent using tree-ring records. Differences between the observed and the simulated avalanche, principally related to the snow height deposition in the run-out zone, are mostly attributed to the low resolution of the digital elevation model used to represent the valley topography. The main contributions of this study are (1 to provide the first calibration of numerical avalanche models for the Patagonian Andes and (2 to highlight the potential of Nothofagus pumilio tree-ring records to reconstruct past snow-avalanche events in time and space. Future research should focus on testing this combined approach in other forested regions of the Andes.

Southern westerly winds: a pacemaker of Holocene glacial fluctuations in Patagonia?

Science.gov (United States)

Sagredo, E. A.; Reynhout, S.; Kaplan, M. R.; Patricio, M. I.; Aravena, J. C.; Martini, M. A.; Schaefer, J. M.

2017-12-01

A well-resolved glacial chronology is crucial to compare sequences of glacial/climate events within and between regions, and thus, to unravel mechanisms underlying past climate changes. Important efforts have been made towards understanding the Holocene climate evolution of the Southern Andes; however, the timing, patterns and causes of glacial fluctuations during this period still remain elusive. Recent advances in terrestrial cosmogenic nuclide surface exposure dating, together with the establishment of a Patagonian 10Be production rate, have opened new possibilities for establishing high-resolution glacial chronologies at centennial/decadal scale. Here we present a 10Be surface exposure chronology of fluctuations of a small, climate-sensitive mountain glacier at Mt. Fitz Roy area (49.3°S), spanning from the last glacial termination to the present. Thirty new 10Be ages show glacial advances and moraine building events at 17.1±0.9 ka, 13.5±0.5 ka, 10.2±0.7 ka or 9.9±0.5 ka, 6.9±0.2 ka, 6.1±0.3 ka, 4.5±0.2 ka and 0.5±0.1 ka. Similar to the pattern observed in New Zealand, this sequence features progressively less extensive glacial advances during the late-glacial and early Holocene, followed by advances of roughly similar extent during the mid- to late-Holocene. We suggest that while the magnitude of Holocene glacial fluctuations in Patagonia is modulated by SH summer insolation ("modulator"), the specific timing of these glacial events is influenced by centennial-scale shifts of the Southern Westerly Winds ("pacemaker").

Mistletoes and epiphytic lichens contribute to litter input in Nothofagus antarctica forests

Science.gov (United States)

Soler, Rosina; Pastur, Guillermo Martínez; Lencinas, María Vanessa; Peri, Pablo Luis

2015-10-01

Litter input is one of the key components that define nutrient cycling in forests and the majority of studies only consider the tree components of litterfall. However, epiphytic species can play a crucial role in litter input throughout the growing season. This work evaluates changes in litter production by mistletoe (Misodendrum sp.) and epiphytic lichen (Usnea sp.), related to crown cover in mature unmanaged, second-growth and managed (thinned for silvopastoral use) forests in Tierra del Fuego (Argentina). We used plastic traps to collect litterfall biomass from trees, lichens and mistletoes on a monthly basis over three consecutive years. Tree litter was considerable during autumn (March to May), which is typical of Nothofagus deciduous species in the Southern hemisphere. In contrast, peak litterfall from mistletoes and lichens occurred during spring and summer seasons. Tree litter (1954-3398 kg dry matter ha-1 year-1) was correlated with crown cover gradient being highest in second-growth forests and lowest in thinned sites. While litter input from mistletoes did not vary among forest types (307-333 kg dry matter ha-1 year-1), lichen litter (11-40 kg dry matter ha-1 year-1) was higher in unmanaged and thinned mature forests despite differences in tree crown cover. Contrary to what we expected, the management practices investigated here did not affect the biomass of canopy communities compared to unmanaged mature forests. Mistletoes and lichens significantly increased the spatial (forest type) and temporal complexity (extended period of falling) of litterfall in Nothofagus antarctica forests. This study provides a starting point to understand the ecological relevance of canopy communities in the Patagonian forests of southern Argentina.

The Tunas Formation (Permian) in the Sierras Australes foldbelt, east central Argentina: evidence for syntectonic sedimentation in a foreland basin

Science.gov (United States)

Lopez-Gamundi, O. R.; Conaghan, P. J.; Rossello, E. A.; Cobbold, P. R.

1995-04-01

The Tunas Formation, extensively exposed in the Sierras Australes foldbelt of eastern central Argentina, completes the sedimentation of the Gondwanan (Late Carboniferous-Permian) sequence, locally known as the Pillahuincó Group. The underlying units of the Group show an integrated depositional history which can be explained in terms of glaciomarine sedimentation (Sauce Grande Formation) and postglacial transgression (Piedra Azul and Bonete Formations). This succession also has a rather uniform quartz-rich, sand-sized composition indicative of a cratonic provenance from the Tandilia Massif to the northeast. Early to Late Permian deformation folded and thrusted the southwestern basin margin (Sierras Australes) and triggered the deposition of a 1,500 m — thick, synorogenic prograding wedge, the Tunas Formation, in the adjacent foreland basin (Sauce Grande or Claromecó Basin). Sandstone detrital modes for the Tunas deposits show moderate to low contents of quartz and abundant lithics, mostly of volcanic and metasedimentary origin. Paleocurrents are consistently from the SW. Tuffs interbedded with sandstones in the upper half of Tunas Formation (Early — early Late? Permian) are interpreted as being derived from volcanic glass-rich tuffs settled in a body of water. Extensive rhyolitic ignimbrites and consanguineous airborne tuffaceous material erupted in the northern Patagonian region during that period. The age constraints and similarities in composition between these volcanics and the tuffaceous horizons present in the Sauce Grande, Parana and Karoo Basins suggest a genetic linkage between these two episodes. The intimate relationship between volcanic activity inboard of the paleo-Pacific margin, deformation in the adjacent orogenic belt and subsidence and sedimentation in the contiguous foreland basin constitutes a common motif in the Sauce Grande and Karoo Basins of southwestern Gondwana.

Surrogate production of eggs and sperm by intrapapillary transplantation of germ cells in cytoablated adult fish.

Directory of Open Access Journals (Sweden)

Sullip Kumar Majhi

Full Text Available Germ cell transplantation (GCT is a promising assisted reproductive technology for the conservation and propagation of endangered and valuable genetic resources. In teleost fish, GCT in adult gonads has been achieved only in male recipients, limiting greatly the usefulness of this technique in situations where both sexes need equal and timely attention for conservation and/or propagation. Here we describe a simplified GCT approach that ultimately leads to production of donor-derived eggs and sperm in considerably short time. Donor germ cells isolated from young pejerrey Odontesthes bonariensis (Atherinopsidae were transplanted non-surgically through the genital papilla into the sexually mature gonads of Patagonian pejerrey O. hatcheri recipients whose gonads have been depleted of endogenous GCs by heat (26°C and chemical treatment (four doses of Busulfan at 30 mg/kg and 40 mg/kg for females and males, respectively. Transplanted spermatogonial and oogonial cells were able to recolonize the recipients' gonads and produce functional donor origin eggs and sperm within 7 months from the GCT. We confirmed the presence of donor-derived gametes by PCR in 17% and 5% of the surrogate O. hatcheri fathers and mothers, respectively. The crosses between surrogate fathers and O. bonariensis mothers yielded 12.6-39.7% pure O. bonariensis and that between a surrogate mother and an O. bonariensis father yielded 52.2% pure O. bonariensis offspring. Our findings confirm that transplantation of germ cells into sexually competent adult fish by non-surgical methods allows the production of functional donor-derived eggs and sperm in a considerably short time. The methods described here could play a vital role in conservation and rapid propagation of endangered fish genetic resources.

Surrogate production of eggs and sperm by intrapapillary transplantation of germ cells in cytoablated adult fish.

Science.gov (United States)

Majhi, Sullip Kumar; Hattori, Ricardo Shohei; Rahman, Sheikh Mustafizur; Strüssmann, Carlos Augusto

2014-01-01

Germ cell transplantation (GCT) is a promising assisted reproductive technology for the conservation and propagation of endangered and valuable genetic resources. In teleost fish, GCT in adult gonads has been achieved only in male recipients, limiting greatly the usefulness of this technique in situations where both sexes need equal and timely attention for conservation and/or propagation. Here we describe a simplified GCT approach that ultimately leads to production of donor-derived eggs and sperm in considerably short time. Donor germ cells isolated from young pejerrey Odontesthes bonariensis (Atherinopsidae) were transplanted non-surgically through the genital papilla into the sexually mature gonads of Patagonian pejerrey O. hatcheri recipients whose gonads have been depleted of endogenous GCs by heat (26°C) and chemical treatment (four doses of Busulfan at 30 mg/kg and 40 mg/kg for females and males, respectively). Transplanted spermatogonial and oogonial cells were able to recolonize the recipients' gonads and produce functional donor origin eggs and sperm within 7 months from the GCT. We confirmed the presence of donor-derived gametes by PCR in 17% and 5% of the surrogate O. hatcheri fathers and mothers, respectively. The crosses between surrogate fathers and O. bonariensis mothers yielded 12.6-39.7% pure O. bonariensis and that between a surrogate mother and an O. bonariensis father yielded 52.2% pure O. bonariensis offspring. Our findings confirm that transplantation of germ cells into sexually competent adult fish by non-surgical methods allows the production of functional donor-derived eggs and sperm in a considerably short time. The methods described here could play a vital role in conservation and rapid propagation of endangered fish genetic resources.

Holocene glacial fluctuations in southern South America

Science.gov (United States)

Reynhout, S.; Sagredo, E. A.; Kaplan, M. R.; Aravena, J. C.; Martini, M. A.; Strelin, J. A.; Schaefer, J. M.

2016-12-01

Understanding the timing and magnitude of former glacier fluctuations is critical to decipher long-term climatic trends and to unravel both natural cycles and human impact on the current glacial behavior. Despite more than seven decades of research efforts, a unifying model of Holocene glacial fluctuations in Southern South America remains elusive. Here, we present the state-of-the-art regarding the timing of Holocene glacial fluctuation in southern Patagonia-Tierra del Fuego, with a focus on a new generation of high-resolution radiocarbon and 10Be surface exposure dating chronologies. Recently acquired evidence suggest that after receding from advanced Late Glacial positions, Patagonian glaciers were for the most part close to, or even behind, present ice margins during the Early Holocene. On the other hand, emerging chronologies indicate that in some areas there were extensive expansions (century scale?) that punctuated the warm interval. Subsequently, we have evidence of multiple millennial timescale glacial advances starting in the middle Holocene. Several glacial maxima are defined by moraines and other landforms from 7000 years ago to the 19th century, with a gap sometime between 4,500 and 2,500 years ago. The last set of advances began around 800-600 years ago. Although glacial activity is documented in Patagonia at the same time as the European Little Ice Age, the extent of these glacial events are less prominent than those of the mid-Holocene. The causes that may explain these glacial fluctuations remain elusive. Finally, we discuss ongoing efforts to better define the timing and extent of Holocene glaciations in southern South America, and to establish the basis to test competing hypothesis of regional Holocene climate variability.

Potential zooplankton preys (Copepoda and Appendicularia for Engraulis anchoita in relation to early larval and spawning distributions in the Patagonian frontal system (SW Atlantic Ocean

Directory of Open Access Journals (Sweden)

Mariela L. Spinelli

2011-11-01

Full Text Available We investigated the spatial distribution of the abundance, biomass and size of zooplankton (nauplii, calanoids, cyclopoids and appendicularians in relation to the distribution of first-feeding larvae and eggs of Engraulis anchoita across the frontal system of Peninsula Valdés. Twelve samples of zooplankton and ichthyoplankton were taken with small Bongo (67 μm and Pairovet (200 μm nets during the spring of 2004 along two transects. The total abundance of zooplankton and the chlorophyll a concentration were higher in homogeneous waters, while total biomasses were higher in stratified waters. Temperature was negatively correlated with biological variables and was the main factor affecting the zooplankton distribution. In both transects, abundance peaks of first-feeding larvae were detected at coastal stations along with the smallest fraction of zooplankton ( < 500 μm, while the largest fraction was dominant at the external stations, coinciding with the highest egg abundance. The physical structure of this front generates different levels of food availability for first-feeding larvae. Calanoids (southern transect and cyclopoids (northern transect are predominant followed by nauplii and appendicularians. The biomass of zooplankton preys contributes to the carbon transfer to the upper trophic levels and is probably important for the survival and growth of anchovy larvae in this frontal system.

First Patagonian Course on 'Diagnosis and Therapy of Injuries Induced by Ionizing Radiation'; Primer curso patagonico 'Diagnostico y Tratamiento de Lesiones Inducidas por Radiaciones Ionizantes'

Energy Technology Data Exchange (ETDEWEB)

Bellotti, Mariela I., E-mail: bellotti@cab.cnea.gov.ar [Comision Nacional de Energia Atomica (CAB/CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche. Lab. de Cavitacion y Biotecnologia; Andres, Pablo A., E-mail: andresp@cab.cnea.gov.ar [Comision Nacional de Energia Atomica (CAB/CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche. Division Proteccion Radiologica; Cascón, Adriana S., E-mail: adrianacascon@yahoo.com [Instituto de Medicina, Radiomedicina y Seguridad (IMERASE SA), Buenos Aires, (Argentina)

2013-07-01

In Patagonia there are academic centers, health and industrial facilities that use ionizing radiations in its usual practices. However, they do not have protocols that respond to local needs. For this reason was held from October 5 to November 10, 2012 in Bariloche Atomic Center, a training course for health personnel. The range of topics covered ranged from the definition of dosimetry quantities, types of radiation and biological dosimetry, biological effects, radiation acute syndrome, radiation-induced cutaneous syndrome, internal contamination, screening in radiological emergencies, etc.The course provided a theoretical and practical guide about how to recognize and treat people exposed to radiations, guidelines for acting in radiological emergencies and a perception of the psychosocial impact of the radiation accidents.The result was a pocket book for health personnel that will be used in case of having a patient with radiation induced injury.

Relaciones polen-vegetación de algunos taxa de la estepa patagónica (Argentina Pollen-vegetation relationships of some taxa from the Patagonian steppe (Argentina

Directory of Open Access Journals (Sweden)

LIDIA S. BURRY

2001-06-01

Full Text Available La aplicación de un análisis de regresión lineal simple a datos de lluvia de polen y de vegetación, en una zona de la Patagonia (Provincia de Chubut, Argentina permitió relacionar cuantitativamente los porcentajes de lluvia polínica y de cobertura de la vegetación para los taxa Poaceae, Papilionoideae, tipo Senecio y Mulinum spinosum. Se obtuvo un buen ajuste de las rectas de regresión para cada uno de los taxa considerados, con coeficientes de correlación r de Pearson altos para M. spinosum (0,82 y tipo Senecio (0,81 y coeficientes algo menores en el caso de Poaceae (0,66 y Papilionoideae (0,61. Estas regresiones permitieron inferir la presencia o ausencia de polen regional y el valor predictivo de la presencia de polen en ausencia de la vegetación que lo produce. Al respecto, la lluvia de polen estudiada incluye el aporte regional (excepto Papilionoideae aun cuando M. spinosum tiene una baja contribución. Esta sobrerrepresentación es atribuible al transporte de larga distancia, a través de los vientos que provienen del oeste. Estas relaciones cuantitativas nos permitirán extrapolar cambios vegetacionales pasados en estos taxa a partir de espectros de polen fósil para el área de estudioThe use of simple linear regression to data of pollen rain and vegetation cover in Patagonia (Province of Chubut, Argentina allowed us to develop quantitative relationships between modern pollen rain perecentages and vegetation cover for the taxa Poaceae, Papilionoideae, Senecio type, and Mulinum spinosum. The analysis revealed a good fit of data to regression lines for all taxa, with high Pearson r coefficient values in the case of M. spinosum (0.82 and Senecio type (0.81, and somewhat lower values in the case of Poaceae (0.66 and Papilionoideae (0.61. These regressions allowed us to infer the presence or absence of regional pollen and predict the quantity of pollen in the absence of the vegetation producing it. In this regard, the studied pollen rain includes the regional contribution (except Papilionoideae, even though M. spinosum has a low contribution. This overrepresentation is attributed to long-distance transport associated to the westerly winds. These quantitative relationships will allow us to know past vegetational changes of these taxa from fossil pollen spectra in the studied area

A new species of Bothriocephalus Rudolphi, 1808 (Eucestoda: Bothriocephalidea) from the channel bull blenny Cottoperca gobio (Günther) (Perciformes: Bovichtidae) on the Patagonian shelf off Argentina

Czech Academy of Sciences Publication Activity Database

Gil de Pertierra, A.A.; Arredondo, N.J.; Kuchta, Roman; Incorvaia, I.S.

2015-01-01

Roč. 90, č. 3 (2015), s. 247-256 ISSN 0165-5752 R&D Projects: GA ČR GBP505/12/G112 Institutional support: RVO:60077344 Keywords : Cestoda * fishes * parasites Subject RIV: EG - Zoology Impact factor: 1.316, year: 2015

Fun in the Sun: Effects of Solar Radiation on Carbon Cycling in Semiarid Ecosystems of South America

Science.gov (United States)

Austin, A.; Berenstecher, P.; Méndez, M. S.; Ballare, C. L.

2016-12-01

Plant litter decomposition is an essential process in the first stages of carbon turnover in terrestrial ecosystems, and together with soil microbial biomass, provide the principal inputs of carbon for the formation of soil organic matter. Photodegradation, the photochemical mineralization of organic matter due to exposure to solar radiation, has been recently identified as a mechanism for previously unexplained high rates of litter mass loss in arid and semiarid ecosystems. Nevertheless, the indirect effects of photodegradation and wavelength dependence on biotic stimulation or inhibition of carbon turnover have been debated in recent studies. In controlled conditions of a two-phase experiment, we demonstrated that in a wide range of plant species, previous exposure to solar radiation, and visible light in particular, enhanced subsequent biotic degradation of leaf litter. Field studies in Patagonian woodland ecosystems confirm the importance of biotic facilitation on litter decomposition, which appears to have larger stimulatory effects than those observed in controlled conditions. Litter decomposition of previously exposed grass litter decomposed more than two times faster than unexposed litter in a one year field experiment, while strong seasonal effects of direct photodegradation and biotic facilitation of solar radiation were observed in a second experiment with changes in solar irradiance using attenuation filters. The generalized positive effect of solar radiation exposure on subsequent microbial activity appears to be mediated by increased accessibility to cell wall polysaccharides, which is consistent in both field and controlled condition experiments. These results suggests that photodegradation is quantitatively important in determining rates of mass loss and nutrient release through its impacts on biotic decomposition, which has implications for the potential alterations in carbon turnover in semiarid ecosystems to predicted climate or land-use change.

Volcanic ash supply to the surface ocean – remote sensing of biological responses and their wider biogeochemical significance

Directory of Open Access Journals (Sweden)

Thomas J. Browning

2015-03-01

Full Text Available Transient micronutrient enrichment of the surface ocean can enhance phytoplankton growth rates and alter microbial community structure with an ensuing spectrum of biogeochemical feedbacks. Strong phytoplankton responses to micronutrients supplied by volcanic ash have been reported recently. Here we: (i synthesize findings from these recent studies; (ii report the results of a new remote sensing study of ash fertilization; and (iii calculate theoretical bounds of ash-fertilized carbon export. Our synthesis highlights that phytoplankton responses to ash do not always simply mimic that of iron amendment; the exact mechanisms for this are likely biogeochemically important but are not yet well understood. Inherent optical properties of ash-loaded seawater suggest rhyolitic ash biases routine satellite chlorophyll-a estimation upwards by more than an order of magnitude for waters with 0.5 mg chlorophyll-a m-3. For this reason post-ash-deposition chlorophyll-a changes in oligotrophic waters detected via standard Case 1 (open ocean algorithms should be interpreted with caution. Remote sensing analysis of historic events with a bias less than a factor of 2 provided limited stand-alone evidence for ash-fertilization. Confounding factors were poor coverage, incoherent ash dispersal, and ambiguity ascribing biomass changes to ash supply over other potential drivers. Using current estimates of iron release and carbon export efficiencies, uncertainty bounds of ash-fertilized carbon export for 3 events are presented. Patagonian iron supply to the Southern Ocean from volcanic eruptions is less than that of windblown dust on thousand year timescales but can dominate supply at shorter timescales. Reducing uncertainties in remote sensing of phytoplankton response and nutrient release from ash are avenues for enabling assessment of the oceanic response to large-scale transient nutrient enrichment.

Permian depositional age of metaturbidites of the Duque de York Complex, southern Chile: U-Pb SHRIMP data and palynology Edad pérmica de sedimentación de las metaturbiditas del Complejo Duque de York, sur de Chile: datos mediante U-Pb SHRIMP y palinología

Directory of Open Access Journals (Sweden)

Fernando A Sepúlveda

2010-07-01

Full Text Available The Duque de York Complex (DYC is part of the low grade metamorphic accretionary complexes of the pre-Andean Patagonian 'basement'. It is a sedimentary succession exposed along the western margin of southernmost South America. New U-Pb zircon ages and palynological data restrict the maximum depositional age of the DYC to the limit between the early Permian (Kungurian and the middle Permian (Roadian. The palynological association recorded in the DYC, characterized mainly by Gymnospermopsida pollen, indicates a humid environment of forest with an under-growth of ferns. Regional paleogeographic correlations point out that an interpretation of DYC as an autochthonous terrane cannot be discarded, contrasting with previous hypotheses which suggest an allochthonous character for this complex.El Complejo Duque de York (CDY forma parte de los complejos metamórficos acrecionarios del 'basamento' pre-Andino de la Patagonia, correspondiendo a una sucesión sedimentaria que añora a lo largo del margen occidental austral de Sudamérica. Nuevas edades U-Pb en circón, en combinación con información palinológica, permiten acotar la maxima edad de depósito posible del CDY al límite entre el Pérmico temprano (Kunguriano y el Pérmico medio (Roadiano. La asociación palinológica registrada en el CDY está caracterizada por Gymnospermopsida, e indica un ambiente húmedo de bosque con sotobosque de heléchos. Las correlaciones paleogeográñcas apuntan a que la condición de terreno autóctono del CDY no puede ser descartada, lo que se contrapone a hipótesis anteriores, las que sugieren un carácter alóctono para este complejo.

Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

Directory of Open Access Journals (Sweden)

Alvaro G Gutiérrez

Full Text Available Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S. The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area. We compared the responses of a young stand (YS, ca. 60 years-old and an old-growth forest (OG, >500 years-old in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

Science.gov (United States)

Gutiérrez, Alvaro G; Armesto, Juan J; Díaz, M Francisca; Huth, Andreas

2014-01-01

Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S). The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area). We compared the responses of a young stand (YS, ca. 60 years-old) and an old-growth forest (OG, >500 years-old) in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

Does Nature and Persistence of Substrate at a Mesohabitat Scale Matter for Chironomidae Assemblages? a Study of Two Perennial Mountain Streams in Patagonia, Argentina

Science.gov (United States)

Epele, Luis Beltrán; Miserendino, María Laura; Brand, Cecilia

2012-01-01

Chironomid substrate—specific associations regarding the nature (organic—inorganic) and stability (stable—unstable) of different habitats were investigated at two low order Patagonian streams, during high and low water periods. Nant y Fall and Glyn rivers were visited twice (October 2007 and March 2008) and seven different habitat types were identified. A total of 60 samples were collected using a Surber sampler (0.09 m -2 and 250 µm) and a set of 23 environmental descriptors including physicochemical parameters and different fractions of particulate organic matter were assessed. 35 Chironomidae taxa were recorded with Orthocladiinae (20), Chironominae (7), and Podonominae (4) being the most well—represented subfamilies. Paratrichocladius sp. 1, Parapsectrocladius sp. 2, Parametriocnemus sp. 1, Pseudochironomus sp., and Rheotanytarsus sp. were the most abundant taxa. According to the relative preference index, at least 14 taxa showed strong affinity for a particular substrate. The structurally complex macrophyte Myriophyllum quitense supported 11 taxa compared with only five taxa found on the less complex Isoetes savatieri. Generally, stable substrates (boulders, cobbles, and rooted plants) supported significantly higher chironomids richness, abundance, and diversity than unstable ones (gravel—sand). Canonical correspondence analysis revealed that detritus (leaves, seeds, and biomass), macrophyte biomass, and secondarily hydraulic variables had high explanatory power on chironomids species composition and structure. This work suggests that more complex substrates showing persistence in the temporal dimension supported a diverse array of chironomids, meaning that the maintenance of natural habitat heterogeneity is essential for the community. Land—use practices having significant effects on ecological stream attributes such as increased turbidity, sediment deposition, and runoff patterns will alter assemblages. Understanding environmental associations

Glacier Melt Detection in Complex Terrain Using New AMSR-E Calibrated Enhanced Daily EASE-Grid 2.0 Brightness Temperature (CETB) Earth System Data Record

Science.gov (United States)

Ramage, J. M.; Brodzik, M. J.; Hardman, M.

2016-12-01

Passive microwave (PM) 18 GHz and 36 GHz horizontally- and vertically-polarized brightness temperatures (Tb) channels from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) have been important sources of information about snow melt status in glacial environments, particularly at high latitudes. PM data are sensitive to the changes in near-surface liquid water that accompany melt onset, melt intensification, and refreezing. Overpasses are frequent enough that in most areas multiple (2-8) observations per day are possible, yielding the potential for determining the dynamic state of the snow pack during transition seasons. AMSR-E Tb data have been used effectively to determine melt onset and melt intensification using daily Tb and diurnal amplitude variation (DAV) thresholds. Due to mixed pixels in historically coarse spatial resolution Tb data, melt analysis has been impractical in ice-marginal zones where pixels may be only fractionally snow/ice covered, and in areas where the glacier is near large bodies of water: even small regions of open water in a pixel severely impact the microwave signal. We use the new enhanced-resolution Calibrated Passive Microwave Daily EASE-Grid 2.0 Brightness Temperature (CETB) Earth System Data Record product's twice daily obserations to test and update existing snow melt algorithms by determining appropriate melt thresholds for both Tb and DAV for the CETB 18 and 36 GHz channels. We use the enhanced resolution data to evaluate melt characteristics along glacier margins and melt transition zones during the melt seasons in locations spanning a wide range of melt scenarios, including the Patagonian Andes, the Alaskan Coast Range, and the Russian High Arctic icecaps. We quantify how improvement of spatial resolution from the original 12.5 - 25 km-scale pixels to the enhanced resolution of 3.125 - 6.25 km improves the ability to evaluate melt timing across boundaries and transition zones in diverse glacial environments.

Special issue: Comparative biogeography of Neotropical primates.

Science.gov (United States)

Lynch Alfaro, Jessica W; Cortés-Ortiz, Liliana; Di Fiore, Anthony; Boubli, Jean P

2015-01-01

New research presented in this special issue of Molecular Phylogenetics and Evolution on the "Phylogeny and Biogeography of Neotropical Primates" greatly improves our understanding of the evolutionary history of the New World monkeys and provides insights into the multiple platyrrhine radiations, diversifications, extinctions, and recolonizations that have taken place over time and over space in the Neotropics. Here, we synthesize genetic and biogeographic research from the past several years to construct an overarching hypothesis for platyrrhine evolution. We also highlight continuing controversies in Neotropical primate biogeography, such as whether the location of origin of platyrrhines was Africa or Asia; whether Patagonian fossil primates are stem or crown platyrrhines; and whether cis- and trans-Andean Neotropical primates were subject to vicariance through Andes mountain building, or instead diversified through isolation in mountain valleys after skirting around the Andes on the northwestern coast of South America. We also consider the role of the Amazon River and its major tributaries in shaping platyrrhine biodiversity, and how and when primates from the Amazon reached the Atlantic Forest. A key focus is on primate colonizations and extirpations in Central America, the Andes, and the seasonally dry tropical forests and savannas (such as the Llanos, Caatinga, and Cerrado habitats), all ecosystems that have been understudied up until now for primates. We suggest that most primates currently inhabiting drier open habitats are relatively recent arrivals, having expanded from rainforest habitats in the Pleistocene. We point to the Pitheciidae as the taxonomic group most in need of further phylogenetic and biogeographic research. Additionally, genomic studies on the Platyrrhini are deeply needed and are expected to bring new surprises and insights to the field of Neotropical primate biogeography. Copyright © 2014 Elsevier Inc. All rights reserved.

Primer registro de Naupactus ruizi (Coleoptera: Curculionoidea asociado con Pinus ponderosa (Gymnospermae: Pinaceae en Patagonia First record of Naupactus ruizi (Coleoptera: Curculionoidea associated to Pinus ponderosa (Gymnospermae: Pinaceae in Patagonia

Directory of Open Access Journals (Sweden)

Cecilia A. Gómez

2006-07-01

Full Text Available Naupactus ruizi (Brèthes es un gorgojo de rostro corto, distribuido en la Argentina y Chile, que habita en ambientes áridos asociado con vegetación xerofítica y alcanza el rango más austral entre los miembros de la tribu Naupactini. Un relevamiento de insectos y de patógenos como plagas potenciales, realizado durante el 2005 en plantaciones de Pinus spp. en la Patagonia andina argentina, resultó en el hallazgo de adultos de N. ruizi que se alimentaban de acículas de Pinus ponderosa Dougl. ex Laws. Este hallazgo es sorprendente dado que las especies de Naupactini, consumen casi exclusivamente angiospermas. Interpretamos que el cambio de huésped, habría ocurrido como consecuencia de una colonización reciente favorecida por la amplia distribución geográfica del gorgojo y su capacidad para sobrevivir en hábitats marginales, donde probablemente las plantas nativas son escasas y el nuevo huésped presenta una gran abundancia local.Naupactus ruizi (Brèthes is a broad-nosed weevil recorded from Argentina and Chile , that inhabits arid environments with xerophitic vegetation and reaches the southern most distribution of the tribe Naupactini. A survey of potential insect pests and pathogens of plantations of Pinus spp. and other forest species, conducted during 2005 in Argentinean Patagonian Andean forestations, allowed to find N. ruizi feeding on pine needles of Pinus ponderosa Dougl. ex Laws. This finding was unexpected, since species of Naupactini consume almost exclusively angiosperms. We interpret that the new host association may represent a recent host shift, probably facilitated by the broad range of the weevil, its capacity to survive in marginal habitats where natural hosts are scarce, and the local abundance of the new host.

Cryophenomena in the Cold Desert of Atacama

Science.gov (United States)

Buchroithner, Dr.; Trombotto, Dr.

2012-04-01

The study area of the Valle de Barrancas Blancas in the High Atacama Andes of Chile (68°39' W, 27°02' S), a kind of Patagonian "bajo sin salida", shows well preserved landforms resulting from a combination of slope, eolian, lacustrine/litoral, fluvial, glacial and periglacial regimes. They permit the reconstruction of geomorphological processes within this isolated catchment of approximately 160 km2. The mean annual air temperature varies between -2 and -4 °C and the precipitation is approximately 150 mm/a. Snowfall is frequent but the snow is quickly sublimated, redeposited and/or covered by cryosediments, i.e. mainly pumice pebbles. Water bodies present icings, even in summer. Regarding its climatic conditions the study area represents an extremely cold desertic region. Extremophile microfauna was also found. The area displays both in situ mountain permafrost and creeping permafrost. The active layer is 30 to 45 cm thick. It is a periglacial macro-environment where interdependent processes, and not only cryogenic processes but also erosion and eolian deposition and the action of fluvial washout mainly caused by precipitation, accumulation, retransportation/redeposition and melting of snow, play an important role. The cryogenic geomorphology of the Valle de Barrancas Blancas is varied and contains microforms such as patterned ground and microforms caused by cryoturbation, as well as mesoforms like rockglaciers and cryoplanation surfaces. Slopes are strongly affected by gelifluction. New cryoforms in South America and in the Southern Hemisphere like the Atacama Pingo (Pingo atacamensis) and Permafrosted Dunes ("Dunas heladas") were found. Intense niveo-eolian processes participate in the erosion of preexisting landforms, in the formation of subterraneous ice layers, and the retransportation/redeposition of snow and sediments. Studies of this periglacial environment are crucial for the understanding of Tundrean paleoenvironments and Martian conditions.

Antarctic fellfield response to climate change: a tripartite synthesis of experimental data.

Science.gov (United States)

Kennedy, Andrew D

1996-07-01

This paper explores the biological consequences of climate change by integrating the results of a tripartite investigation involving fumarole, field manipulation and laboratory incubation experiments. The geographical region for this research is the maritime Antarctic. Under contemporary climate conditions, the lithosols in this region support only a sparse cryptogamic flora of limited taxonomic diversity and low structural complexity. However, the existence in geothermal areas of temperate species (e.g. Campylopus introflexus, Marchantia polymorpha, Philonotis acicularis) growing outside their normal biogeographical range suggests that elevated temperature and humidity may alter the trajectory of community development towards Magellanic or Patagonian composition. Productivity is also likely to increase, as indicated by significantly greater vegetative biomass recorded beneath climate-ameliorating soil covers than in controls. Barren fellfield soil samples transplanted to the laboratory and incubated at temperatures of 2-25°C show rapid development of moss, algae and lichen propagules in the range 15-25°C. A variety of species develop that have not been recorded in the field. The presence of exotic taxa indicates the existence of a dormant propagule bank in maritime Antarctic soils and suggests that no significant delay is likely to occur between the onset of climate warming and community development: instead, rapid establishment of those species favoured by the new climate conditions will yield a distinct founder effect, with increasing above- and below-ground biomass stimulating biogeochemical cycling. It is argued that the combined results of this synthesis identify generic responses to climate change arising from the importance at high latitudes of low temperature and water availability as limiting factors: subject to other growth resources being non-limiting, a more consistent stimulatory response to climate change may be expected than in temperate or

Does nature and persistence of substrate at a mesohabitat scale matter for Chironomidae assemblages? A study of two perennial mountain streams in Patagonia, Argentina.

Science.gov (United States)

Epele, Luis Beltrán; Miserendino, María Laura; Brand, Cecilia

2012-01-01

Chironomid substrate-specific associations regarding the nature (organic-inorganic) and stability (stable-unstable) of different habitats were investigated at two low order Patagonian streams, during high and low water periods. Nant y Fall and Glyn rivers were visited twice (October 2007 and March 2008) and seven different habitat types were identified. A total of 60 samples were collected using a Surber sampler (0.09 m(-2) and 250 µm) and a set of 23 environmental descriptors including physicochemical parameters and different fractions of particulate organic matter were assessed. 35 Chironomidae taxa were recorded with Orthocladiinae (20), Chironominae (7), and Podonominae (4) being the most well-represented subfamilies. Paratrichocladius sp. 1, Parapsectrocladius sp. 2, Parametriocnemus sp. 1, Pseudochironomus sp., and Rheotanytarsus sp. were the most abundant taxa. According to the relative preference index, at least 14 taxa showed strong affinity for a particular substrate. The structurally complex macrophyte Myriophyllum quitense supported 11 taxa compared with only five taxa found on the less complex Isoetes savatieri. Generally, stable substrates (boulders, cobbles, and rooted plants) supported significantly higher chironomids richness, abundance, and diversity than unstable ones (gravel-sand). Canonical correspondence analysis revealed that detritus (leaves, seeds, and biomass), macrophyte biomass, and secondarily hydraulic variables had high explanatory power on chironomids species composition and structure. This work suggests that more complex substrates showing persistence in the temporal dimension supported a diverse array of chironomids, meaning that the maintenance of natural habitat heterogeneity is essential for the community. Land-use practices having significant effects on ecological stream attributes such as increased turbidity, sediment deposition, and runoff patterns will alter assemblages. Understanding environmental associations of the

Do native grazers from Patagonia, Argentina, consume the invasive kelp Undaria pinnatifida? ¿Pueden los pastoreadores nativos de Patagonia, Argentina, consumir al alga invasora Undaria pinnatifida?

Directory of Open Access Journals (Sweden)

S. Valeria Teso

2009-06-01

Full Text Available The invasive kelp Undaria pinnatifida (Phaeophyceae, Laminariales was first reported in Golfo Nuevo in 1992 and since then it has spread widely over more than 170 km, all along the northern Patagonian coast, Argentina. Field observations in the region have indicated the potential role of invertebrate grazers, like the sea urchins Arbacia dufresnii and Pseudechinus magellanicus and the gastropod Tegula patagonica, in controlling algal density. Laboratory experiments were conducted to ascertain whether, and if so, to what extent these grazers actually feed on the algae. The studied sea urchins fed on the alga, whereas the snail scraped off biofouling adhered to its surface. Higher densities of grazers were observed on the kelp during summer and might be attributed to increasing in metabolism with increasing temperature, and degradation of blades and sporophylls, which possibly increase their palatability.El alga invasora Undaria pinnatifida (Phaeophyceae, Laminariales fue reportada por primera vez en Golfo Nuevo en 1992, dispersándose ampliamente a lo largo de 170 km de costa en el norte de la Patagonia, Argentina. Observaciones de campo hechas en los erizos de mar Arbacia dufresnii y Pseudechinus magellanicus y en el gasterópodo Tegula patagonica evidenciaron que son posibles consumidores de Undaria pinnatifida en la población local. Se realizaron experimentos de laboratorio con el objetivo de probar si estos pastoreadores eran capaces de consumir el alga. Los erizos de mar estudiados consumen el alga, mientras que el gasterópodo ramonea los epibiontes presentes sobre su superficie. Altas densidades de ramoneadores fueron encontradas sobre el alga durante el verano y podrían ser atribuidas a un aumento del su metabolismo con el aumento de la temperatura y a la degradación de las láminas y esporofilos, lo cual posiblemente aumente la palatabilidad del alga.

Uruguay Roselli 1938 and Rosellichnus, N. Ichnogenus: Two ichnogenera for clusters of fossil bee cells

Science.gov (United States)

Genise, Jorge F.; Bown, Thomas M.

1996-01-01

The systematics of the fossil bee nest ichnogenus Uruguay from the Uruguayan Cretaceous or lower Tertiary is reviewed and two new ichnospecies of a new ichnogenus, Rosellichnus, are proposed for fossil bee nests from the Miocene of the United Arab Emirates and Patagonian Argentina. Uruguay contains U. auroranormae(the ich‐notype) and U. rivasi, which differs from the type ichnospecies in having clustered cells arranged in three rows, with one central and two marginal rows of subparallel cells. No bee nest architecture known to us unequivocally fits with any ichnospecies described herein. Uruguay was constructed in the subsoil and may be of halictid origin; however, its large cell size, thick cell walls, and the presence of a vestibular cell do not fit the architecture of nests of extant halictids. Rosellichnus arabicus lacks the complete cavity surrounding the cell cluster that is typical in nests of Old World halictids, but it may, nonetheless, still be of halictid origin. R. pa‐tagonicus has an architecture more similar to nests of anthophorine bees than to those of Neotropical Halictidae. Therefore, the ichnogenus Rosellichnus may include both halictid and anthophorine constructions. Although the smooth inner cell walls, spiral cell caps, and clustering of cells indicate that both Uruguay and Rosellichnus are trace fossils of bee origin, it is likely that both represent nest architectures that are no longer employed by extant bees, or those that are as yet unknown. The paleoenvironments of both the Argentine and Emirates species of Rosellichnus indicate that the trace‐makers of this ichnogenus constructed their nests in open ground sandy soils.

Oldest Known Eucalyptus Macrofossils Are from South America

Science.gov (United States)

Zamaloa, María C.; Nixon, Kevin C.; González, Cynthia C.; Wilf, Peter; Cúneo, N. Rubén; Johnson, Kirk R.

2011-01-01

Patagonian Eucalyptus dominated volcanically disturbed areas adjacent to standing rainforest surrounding an Eocene caldera lake. PMID:21738605

Growth and Mortality of Coccolithophores during spring in the Celtic Sea

Science.gov (United States)

Mayers, K.; Poulton, A. J.; Giering, S. L. C.; Daniels, C. J.; Wells, S. R.; Tarran, G.

2016-02-01

Coccolithophores are an important group of single celled protists which dominate pelagic calcite production, however little is currently known about the mortality rates within this group, or their importance in shelf seas regarding productivity and nutrient recycling. Measurements of coccolithophore calcification and cellular calcite quotas, as well as dilution experiments for microzooplankton grazing rates, were made during a spring cruise (April, 2015) in the Celtic Sea (NW European Shelf) and within an April bloom of Emiliania huxleyi. Calcite production and coccolithophore cell numbers showed a general positive trend throughout the progression of the spring bloom, ranging from 15 - 34µmol C m-3d-1 and 6 - 94 cells ml-1. Cell normalised calcification rates declined from 3 - 0.6 pmol C cell-1d-1 due to a shift from a mixed community to an E. huxleyi dominated one. Within the E. huxleyi bloom we recorded high daily calcite production (6049 µmol C m-3d-1) and cell normalised calcification of 3 pmol C cell-1d-1. This is significantly higher than E. huxleyi dominated sites in the Iceland Basin and more similar to a bloom on the Patagonian Shelf. Within the E. huxleyi bloom, mortality rates were 0.23 d-1 compared with growth rates of 0.29 d-1, meaning 80% of daily calcification was removed by grazers. In this study, coccolithophore mortality rates are presented from the central Celtic Sea throughout spring, and compared with an April E. huxleyi bloom in terms of species composition, trends in calcite production and composition of the phytoplankton community. These observations will potentially elucidate the role grazing plays in the fate of calcium carbonate, bloom formation and community composition.

Elevation Changes of Ice Caps in the Canadian Arctic Archipelago

Science.gov (United States)

Abdalati, W.; Krabill, W.; Frederick, E.; Manizade, S.; Martin, C.; Sonntag, J.; Swift, R.; Thomas, R.; Yungel, J.; Koerner, R.

2004-01-01

Precise repeat airborne laser surveys were conducted over the major ice caps in the Canadian Arctic Archipelago in the spring of 1995 and 2000 in order to measure elevation changes in the region. Our measurements reveal thinning at lower elevations (below 1600 m) on most of the ice caps and glaciers, but either very little change or thickening at higher elevations in the ice cap accumulation zones. Recent increases in precipitation in the area can account for the slight thickening where it was observed, but not for the thinning at lower elevations. For the northern ice caps on the Queen Elizabeth Islands, thinning was generally less than 0.5 m/yr , which is consistent with what would be expected from the warm temperature anomalies in the region for the 5-year period between surveys and appears to be a continuation of a trend that began in the mid 1980s. Further south, however, on the Barnes and Penny ice caps on Baffin Island, this thinning was much more pronounced at over 1 m/yr in the lower elevations. Here temperature anomalies were very small, and the thinning at low elevations far exceeds any associated enhanced ablation. The observations on Barnes, and perhaps Penny are consistent with the idea that the observed thinning is part of a much longer term deglaciation, as has been previously suggested for Barnes Ice Cap. Based on the regional relationships between elevation and elevation-change in our data, the 1995-2000 mass balance for the region is estimated to be 25 cu km/yr of ice, which corresponds to a sea level increase of 0.064 mm/ yr . This places it among the more significant sources of eustatic sea level rise, though not as substantial as Greenland ice sheet, Alaskan glaciers, or the Patagonian ice fields.

Oldest known Eucalyptus macrofossils are from South America.

Directory of Open Access Journals (Sweden)

María A Gandolfo

indicate that the Patagonian Eucalyptus dominated volcanically disturbed areas adjacent to standing rainforest surrounding an Eocene caldera lake.

The cephalic lateral line system of temperate perches (Perciformes: Percichthyidae from Argentinean Patagonia

Directory of Open Access Journals (Sweden)

Rocío M. Vega

Full Text Available ABSTRACT The species of Percichthys (Percichthyidae are endemic to southern South America. Some authors have pointed out that the genus includes four valid species, based on the morphology of the head, jaws, and fins. A phylogenetic analysis published by other authors suggests that three of them are morphotypes belonging to the same species, Percichthys trucha (Valenciennes, 1833. The aim of this study is to describe for the first time the morphology of the cephalic seismosensory system of Patagonian perches, and how these characters vary in the three morphotypes, in order to provide morphological elements to analyze the taxonomy of these fish species. Comparisons of the cephalic seismosensory system between juveniles and adults were also conducted. Juvenile and adult specimens were collected in the northwestern Argentinean Patagonia. Specimens were bleached in 5% H2O2 and the canal systems of their cephalic lateral line were filled with hematoxylin. Specimens were deposited in the Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Argentina. The cephalic lateral line of the studied specimens is a widened type of canal systems, is not connected to the trunk lateral line, and consists of preopercular-mandibular canal, infraorbital canal, supraorbital canal, temporal canal, supratemporal canal, and a supraorbital commisure. The number of pores increases during the ontogeny, while their diameters decrease. The number, position and size of infraorbital canal pores showed significant differences among morphotypes and juveniles. The interpopulation variation regarding the number, position, and size of pores seems to signal an ongoing process of speciation, which is the result adaptations to different environmental conditions. Our study contributes to the knowledge of the morphology of percichthids and describes for the first time the seismosensory system of temperate perches.

Modulating effects of orally supplied Euglena gracilis on the physiological responses of the freshwater mussel Diplodon chilensis, exposed to sewage water pollution in a Patagonian river (Argentina).

Science.gov (United States)

Bianchi, Virginia A; Castro, Juan M; Rocchetta, Iara; Conforti, Visitación; Pascual, Mariano; Luquet, Carlos M

2016-04-01

In order to test if orally supplied Euglena sp. cells modulate the physiological status of bivalves during bioremediation procedures, we evaluated the effect of Euglena gracilis diet on the immune response, oxidative balance and metabolic condition of Diplodon chilensis exposed to sewage water pollution. Mussels were fed for 90 days with E. gracilis (EG) or Scenedesmus vacuolatus (SV, control diet), and then exposed for 10 days at three sites along the Pocahullo river basin: 1) an unpolluted site, upstream of the city (control, C); 2) upstream (UpS) and 3) downstream (DoS) from the main tertiary-treated sewage discharge, in the city of San Martín de los Andes, Northwest Patagonia, Argentina. Our results show that the total hemocyte number decreases while pollution load increases along the river course for both, EG and SV mussels. Phagocytic activity is higher in EG mussels than in SV ones under all conditions. Reactive oxygen species (ROS) production in hemocytes increases with the increase in the pollution load, being significantly higher for EG mussels than for SV ones at DoS; no changes are observed for total oxyradical scavenging capacity (TOSC). Hemocytes' viability is increased for E. gracilis diet at C and remains unchanged in this group of mussels when exposed at the polluted sites. Lysosomal membrane stability is higher in EG mussels than in SV ones for all conditions, although it is decreased at polluted sites compared with that at C. Antioxidant (catalase) and detoxifying (gluthatione S-transferase) defenses are generally lower in gills and digestive gland of EG mussels than in SV ones. Lipid peroxidation (TBARS) is evident in gills of EG mussels at C, and in digestive gland of the same group, at all the sites. Gill mass factor (GF) is affected by the E. gracilis diet; it is increased at C and decreased at polluted sites when compared with that of SV ones. Digestive gland mass factor (DGF) is higher in EG mussels than in SV ones. In D. chilensis, continuous and long term feeding with E. gracilis cells favors immune response and reduces the damage caused by sewage pollution exposure on hemocytes. Nevertheless, diet and transplantation procedures may produce negative effects on the oxidative balance of gills and digestive gland and should be taken into account for bioremediation strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

How many populations set foot through the Patagonian door? Genetic composition of the current population of Bahía Blanca (Argentina) based on data from 19 Alu polymorphisms.

Science.gov (United States)

Resano, M; Esteban, E; González-Pérez, E; Vía, M; Athanasiadis, G; Avena, S; Goicoechea, A; Bartomioli, M; Fernández, V; Cabrera, A; Dejean, C; Carnese, F; Moral, P

2007-01-01

The city of Bahía Blanca occupies a strategic place in Argentina south of the Pampean region in the north-east corner of the Patagonia. Since 1828, this city has been the historical and political border between Amerindian lands in the south, and the lands of European colonists. Nowadays, Bahía Blanca is an urban population mainly composed by descendents of immigrants from Spain and other European countries with apparently low admixture with Amerindians. In view of the unexpectedly high Amerindian admixture levels (about 46.7%) suggested by mtDNA data, and protein markers (19.5%), we analyzed a set of 19 Alu polymorphisms (18 autosomal, 1 of Chromosome Y) in a well-documented genealogical sample from Bahía Blanca. The genotyped sample was made up of 119 unrelated healthy individuals whose birth place and grandparent origins were fully documented. According to available genealogical records, the total sample has been subdivided into two groups: Bahía Blanca Original (64 individuals with all 4 gandparents born in Argentina) and Bahía Blanca Mix (55 individuals with one to three grandparents born out of Argentina). Allele frequencies and gene diversity values in Bahía Blanca fit well into the European ranges. Population relationships have been tested for 8 Alu markers, whose variation has been described in several Amerindian and European samples. Reynolds genetic distances underline the significant genetic similarity of Bahía Blanca to Europeans (mean distance 0.044) and their differentiation from Amerindians (0.146). Interestingly enough, when the general sample is divided, Bahía Blanca Original appears slightly closer to Amerindians (0.127) in contrast to Bahía Blanca Mix (0.161). Furthermore, the genetic relationships depicted through a principal components analysis emphasize the relative similarity of Bahía Blanca Original to Amerindians. A thorough knowledge of the sample origins has allowed us to make a subtle distinction of the genetic composition of Bahía Blanca. Copyright 2007 Wiley-Liss, Inc.

Contribution of bacterial respiration to plankton respiration from 50°N to 44°S in the Atlantic Ocean

Science.gov (United States)

García-Martín, E. E.; Aranguren-Gassis, M.; Hartmann, M.; Zubkov, M. V.; Serret, P.

2017-11-01

Marine bacteria play an important role in the global cycling of carbon and therefore in climate regulation. However, the paucity of direct measurements means that our understanding of the magnitude and variability of bacterial respiration in the ocean is poor. Estimations of respiration in the 0.2-0.8 μm size-fraction (considered as bacterial respiration), total plankton community respiration, and the contribution of bacterial respiration to total plankton community respiration were made along two latitudinal transects in the Atlantic Ocean (ca. 50°N-44°S) during 2010 and 2011. Two different methodologies were used: determination of changes in dissolved O2 concentration after standard 24 h dark bottle incubations, and measurements of in vivo reduction of 2-(ρ-iodophenyl)-3-(ρ-nitrophenyl)-5phenyl tetrazolium salt (INT). There was an overall significant correlation (r = 0.44, p community respiration estimated by both methods. Depth-integrated community respiration varied as much as threefold between regions. Maximum rates occurred in waters of the western European shelf and Patagonian shelf, and minimum rates in the North and South oligotrophic gyres. Depth-integrated bacterial respiration followed the same pattern as community respiration. There was a significantly higher cell-specific bacterial respiration in the northern subtropical gyre than in the southern subtropical gyre which suggests that bacterial carbon turnover is faster in the northern gyre. The relationships between plankton respiration and physicochemical and biological variables were different in different years. In general, INTT was correlated to both chlorophyll-a and bacterial abundance, while INT0.2-0.8 was only correlated with bacterial abundance. However, in 2010 INTT and INT0.2-0.8 were also correlated with temperature and primary production while in 2011 they were correlated with nitrate + nitrite concentration. The bacterial contribution to depth integrated community respiration was

Vein-type and similar uranium deposits of Argentina

International Nuclear Information System (INIS)

Stipanicic, P.

1982-01-01

Some vein-type and similar uranium deposits and occurrences are briefly described to show different models identified in Argentina. Practically all of them were formerly thought to be related to hydrothermal-magmatic processes, but at present few are considered to be so; some are classified as typically exogenous and opinions differ about the genesis of the remaining ones, especially because of a lack of sufficient research on the matter since this group of accumulations only contributes less than 10% to the entire uranium resources of Argentina. The typical vein-type ore bodies are small (including less than 200t U) with grades varying from 0.1 to near 1%U. Other deposits, resolved as stockworks, could be from small to medium size (more than 200t U to 2000t U) with a uranium content from 0.7 to 0.03%, respectively. The mineralogical associations are variable, from complex ones in veins considered as magmatic-endogenous (with U, Ni, Co, Pb, Cu, Zn, etc.) to very simple ones in the exogenetic accumulations, which only comprise uranium minerals. The paragenetic studies available are not complete enough to define the possible relation of uranium with the other metals in the complex ores. The age of the mineralization has been defined in some cases, but not in others. There are examples of mineralizing processes occurring from Palaeozoic to very recent times. Some of the uranium deposits mentioned here have been exploited in the past; one of them will be re-opened very shortly; and a new one will be put into operation in 1981. The geological composition of Argentina is not favourable for uranium deposits related to the Proterozoic unconformity, and the best possibilities for finding interesting accumulations of vein and similar type are in the large Hercynian granitic environments which have outcrops that cover more than 150,000km 2 (Pampean Hills and North Patagonian Massif). (author)

A Tenebrionid beetle’s dataset (Coleoptera, Tenebrionidae from Peninsula Valdés (Chubut, Argentina

Directory of Open Access Journals (Sweden)

German Cheli

2013-12-01

Full Text Available The Natural Protected Area Peninsula Valdés, located in Northeastern Patagonia, is one of the largest conservation units of arid lands in Argentina. Although this area has been in the UNESCO World Heritage List since 1999, it has been continually exposed to sheep grazing and cattle farming for more than a century which have had a negative impact on the local environment. Our aim is to describe the first dataset of tenebrionid beetle species living in Peninsula Valdés and their relationship to sheep grazing. The dataset contains 118 records on 11 species and 198 adult individuals collected. Beetles were collected using pitfall traps in the two major environmental units of Peninsula Valdés, taking into account grazing intensities over a three year time frame from 2005–2007. The Data quality was enhanced following the best practices suggested in the literature during the digitalization and geo-referencing processes. Moreover, identification of specimens and current accurate spelling of scientific names were reviewed. Finally, post-validation processes using DarwinTest software were applied. Specimens have been deposited at Entomological Collection of the Centro Nacional Patagónico (CENPAT-CONICET. The dataset is part of the database of this collection and has been published on the internet through GBIF Integrated Publishing Toolkit (IPT (http://data.gbif.org/datasets/resource/14669/. Furthermore, it is the first dataset for tenebrionid beetles of arid Patagonia available in GBIF database, and it is the first one based on a previously designed and standardized sampling to assess the interaction between these beetles and grazing in the area. The main purposes of this dataset are to ensure accessibility to data associated with Tenebrionidae specimens from Peninsula Valdés (Chubut, Argentina, also to contribute to GBIF with primary data about Patagonian tenebrionids and finally, to promote the Entomological Collection of Centro Nacional Patag

A Tenebrionid beetle's dataset (Coleoptera, Tenebrionidae) from Peninsula Valdés (Chubut, Argentina).

Science.gov (United States)

Cheli, Germán H; Flores, Gustavo E; Román, Nicolás Martínez; Podestá, Darío; Mazzanti, Renato; Miyashiro, Lidia

2013-12-18

The Natural Protected Area Peninsula Valdés, located in Northeastern Patagonia, is one of the largest conservation units of arid lands in Argentina. Although this area has been in the UNESCO World Heritage List since 1999, it has been continually exposed to sheep grazing and cattle farming for more than a century which have had a negative impact on the local environment. Our aim is to describe the first dataset of tenebrionid beetle species living in Peninsula Valdés and their relationship to sheep grazing. The dataset contains 118 records on 11 species and 198 adult individuals collected. Beetles were collected using pitfall traps in the two major environmental units of Peninsula Valdés, taking into account grazing intensities over a three year time frame from 2005-2007. The Data quality was enhanced following the best practices suggested in the literature during the digitalization and geo-referencing processes. Moreover, identification of specimens and current accurate spelling of scientific names were reviewed. Finally, post-validation processes using DarwinTest software were applied. Specimens have been deposited at Entomological Collection of the Centro Nacional Patagónico (CENPAT-CONICET). The dataset is part of the database of this collection and has been published on the internet through GBIF Integrated Publishing Toolkit (IPT) (http://data.gbif.org/datasets/resource/14669/). Furthermore, it is the first dataset for tenebrionid beetles of arid Patagonia available in GBIF database, and it is the first one based on a previously designed and standardized sampling to assess the interaction between these beetles and grazing in the area. The main purposes of this dataset are to ensure accessibility to data associated with Tenebrionidae specimens from Peninsula Valdés (Chubut, Argentina), also to contribute to GBIF with primary data about Patagonian tenebrionids and finally, to promote the Entomological Collection of Centro Nacional Patagónico (CENPAT

Depression storage and infiltration effects on overland flow depth-velocity-friction at desert conditions: field plot results and model

Directory of Open Access Journals (Sweden)

M. J. Rossi

2012-09-01

Full Text Available Water infiltration and overland flow are relevant in considering water partition among plant life forms, the sustainability of vegetation and the design of sustainable hydrological models and management. In arid and semi-arid regions, these processes present characteristic trends imposed by the prevailing physical conditions of the upper soil as evolved under water-limited climate. A set of plot-scale field experiments at the semi-arid Patagonian Monte (Argentina were performed in order to estimate the effect of depression storage areas and infiltration rates on depths, velocities and friction of overland flows. The micro-relief of undisturbed field plots was characterized at z-scale 1 mm through close-range stereo-photogrammetry and geo-statistical tools. The overland flow areas produced by controlled water inflows were video-recorded and the flow velocities were measured with image processing software. Antecedent and post-inflow moisture were measured, and texture, bulk density and physical properties of the upper soil were estimated based on soil core analyses. Field data were used to calibrate a physically-based, mass balanced, time explicit model of infiltration and overland flows. Modelling results reproduced the time series of observed flow areas, velocities and infiltration depths. Estimates of hydrodynamic parameters of overland flow (Reynolds-Froude numbers are informed. To our knowledge, the study here presented is novel in combining several aspects that previous studies do not address simultaneously: (1 overland flow and infiltration parameters were obtained in undisturbed field conditions; (2 field measurements of overland flow movement were coupled to a detailed analysis of soil microtopography at 1 mm depth scale; (3 the effect of depression storage areas in infiltration rates and depth-velocity friction of overland flows is addressed. Relevance of the results to other similar desert areas is justified by the accompanying

A Tenebrionid beetle’s dataset (Coleoptera, Tenebrionidae) from Peninsula Valdés (Chubut, Argentina)

Science.gov (United States)

Cheli, Germán H.; Flores, Gustavo E.; Román, Nicolás Martínez; Podestá, Darío; Mazzanti, Renato; Miyashiro, Lidia

2013-01-01

Abstract The Natural Protected Area Peninsula Valdés, located in Northeastern Patagonia, is one of the largest conservation units of arid lands in Argentina. Although this area has been in the UNESCO World Heritage List since 1999, it has been continually exposed to sheep grazing and cattle farming for more than a century which have had a negative impact on the local environment. Our aim is to describe the first dataset of tenebrionid beetle species living in Peninsula Valdés and their relationship to sheep grazing. The dataset contains 118 records on 11 species and 198 adult individuals collected. Beetles were collected using pitfall traps in the two major environmental units of Peninsula Valdés, taking into account grazing intensities over a three year time frame from 2005–2007. The Data quality was enhanced following the best practices suggested in the literature during the digitalization and geo-referencing processes. Moreover, identification of specimens and current accurate spelling of scientific names were reviewed. Finally, post-validation processes using DarwinTest software were applied. Specimens have been deposited at Entomological Collection of the Centro Nacional Patagónico (CENPAT-CONICET). The dataset is part of the database of this collection and has been published on the internet through GBIF Integrated Publishing Toolkit (IPT) (http://data.gbif.org/datasets/resource/14669/). Furthermore, it is the first dataset for tenebrionid beetles of arid Patagonia available in GBIF database, and it is the first one based on a previously designed and standardized sampling to assess the interaction between these beetles and grazing in the area. The main purposes of this dataset are to ensure accessibility to data associated with Tenebrionidae specimens from Peninsula Valdés (Chubut, Argentina), also to contribute to GBIF with primary data about Patagonian tenebrionids and finally, to promote the Entomological Collection of Centro Nacional Patag

Incorporation of inorganic mercury (Hg2+) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

International Nuclear Information System (INIS)

Soto Cárdenas, Carolina; Diéguez, Maria C.; Ribeiro Guevara, Sergio; Marvin-DiPasquale, Mark; Queimaliños, Claudia P.

2014-01-01

In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg 2+ ) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg 2+ by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope 197 Hg 2+ . Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg 2+ in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg 2+ in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg 2+ by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg 2+ observed in all the plankton fractions. - Highlights: • Hg 2+ incorporation in lake plankton fractions was studied using the isotope 197 Hg 2+ . • Hg 2+ incorporation was assessed using three different

Incorporation of inorganic mercury (Hg{sup 2+}) in pelagic food webs of ultraoligotrophic and oligotrophic lakes: The role of different plankton size fractions and species assemblages

Energy Technology Data Exchange (ETDEWEB)

Soto Cárdenas, Carolina, E-mail: sotocardenascaro@gmail.com [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Diéguez, Maria C. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina); Ribeiro Guevara, Sergio [Laboratorio de Análisis por Activación Neutrónica, CAB, CNEA, Av. Bustillo Km 9.5, 8400, San Carlos de Bariloche, Río Negro (Argentina); Marvin-DiPasquale, Mark [United States Geological Survey, 345 Middlefield Rd./MS 480, Menlo Park, CA 94025 (United States); Queimaliños, Claudia P. [Laboratorio de Fotobiología, Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA, UNComahue-CONICET), Quintral 1250, 8400 San Carlos de Bariloche, Río Negro (Argentina)

2014-10-01

In lake food webs, pelagic basal organisms such as bacteria and phytoplankton incorporate mercury (Hg{sup 2+}) from the dissolved phase and pass the adsorbed and internalized Hg to higher trophic levels. This experimental investigation addresses the incorporation of dissolved Hg{sup 2+} by four plankton fractions (picoplankton: 0.2–2.7 μm; pico + nanoplankton: 0.2–20 μm; microplankton: 20–50 μm; and mesoplankton: 50–200 μm) obtained from four Andean Patagonian lakes, using the radioisotope {sup 197}Hg{sup 2+}. Species composition and abundance were determined in each plankton fraction. In addition, morphometric parameters such as surface and biovolume were calculated using standard geometric models. The incorporation of Hg{sup 2+} in each plankton fraction was analyzed through three concentration factors: BCF (bioconcentration factor) as a function of cell or individual abundance, SCF (surface concentration factor) and VCF (volume concentration factor) as functions of individual exposed surface and biovolume, respectively. Overall, this investigation showed that through adsorption and internalization, pico + nanoplankton play a central role leading the incorporation of Hg{sup 2+} in pelagic food webs of Andean lakes. Larger planktonic organisms included in the micro- and mesoplankton fractions incorporate Hg{sup 2+} by surface adsorption, although at a lesser extent. Mixotrophic bacterivorous organisms dominate the different plankton fractions of the lakes connecting trophic levels through microbial loops (e.g., bacteria–nanoflagellates–crustaceans; bacteria–ciliates–crustaceans; endosymbiotic algae–ciliates). These bacterivorous organisms, which incorporate Hg from the dissolved phase and through their prey, appear to explain the high incorporation of Hg{sup 2+} observed in all the plankton fractions. - Highlights: • Hg{sup 2+} incorporation in lake plankton fractions was studied using the isotope {sup 197}Hg{sup 2+}. • Hg{sup 2

Glacial History of Southernmost South America and Implications for Movement of the Westerlies and Antarctic Frontal Zone

Science.gov (United States)

Kaplan, M. R.; Fogwill, C. J.; Hulton, N. R.; Sugden, D. E.; Peter, K. W.

2004-12-01

The ~1 Myr glacial geologic record in southern South American is one of the few available terrestrial paleoclimate proxies at orbital and suborbital time scales in the middle latitudes of the Southern Hemisphere. Presently, southernmost Patagonia lies about 3\\deg north of the Antarctic frontal zone and within the middle latitude westerlies and the climate is controlled by the surrounding maritime conditions. Thus, the long-term glacial record provides insight into the history of climatic boundaries over the middle and high latitude southern ocean, including the upwind SE Pacific Ocean, tectonic-glacial evolution of the Andes, and global climate. To date, cosmogenic nuclide and 14C dating have focused on glacial fluctuations between 51 and 53\\deg S (Torres del Paine to northern Tierra del Fuego) during the last glacial cycle, including the late glacial period. At least 4 advances occurred between ca. 25 and 17 ka, with the maximum expansion of ice ca. 25-24 ka. Major deglaciation commenced after ca. 17.5 ka, which was interrupted by a major glacial-climate event ca. 14-12 ka. Modelling experiments suggest that the ice mass needed to form the glacial maximum moraines required about a 6\\deg cooling and a slight drying relative to the present. Such a fundamental temperature reduction, despite high summer isolation, strongly suggests northward movement of the westerlies and the polar front on millennial timescales. The Patagonian record also indicates that on orbital timescales equatorward movement of climate boundaries and glacial growth was in phase with major Northern Hemisphere ice volume change, despite high local summer insolation. At suborbital timescales, the picture is more complex. While major facets of the last glacial maximum appear to be in phase between the hemispheres, at least some late glacial events may be in step with Antarctic climate change. Present and future research will further constrain the timing of glacial events over the last 1 Myr and

Diving of great shearwaters (Puffinus gravis in cold and warm water regions of the South Atlantic Ocean.

Directory of Open Access Journals (Sweden)

Robert A Ronconi

Full Text Available BACKGROUND: Among the most widespread seabirds in the world, shearwaters of the genus Puffinus are also some of the deepest diving members of the Procellariiformes. Maximum diving depths are known for several Puffinus species, but dive depths or diving behaviour have never been recorded for great shearwaters (P. gravis, the largest member of this genus. This study reports the first high sampling rate (2 s of depth and diving behaviour for Puffinus shearwaters. METHODOLOGY/PRINCIPAL FINDINGS: Time-depth recorders (TDRs were deployed on two female great shearwaters nesting on Inaccessible Island in the South Atlantic Ocean, recording 10 consecutive days of diving activity. Remote sensing imagery and movement patterns of 8 males tracked by satellite telemetry over the same period were used to identify probable foraging areas used by TDR-equipped females. The deepest and longest dive was to 18.9 m and lasted 40 s, but most (>50% dives were <2 m deep. Diving was most frequent near dawn and dusk, with <0.5% of dives occurring at night. The two individuals foraged in contrasting oceanographic conditions, one in cold (8 to 10°C water of the Sub-Antarctic Front, likely 1000 km south of the breeding colony, and the other in warmer (10 to 16°C water of the Sub-tropical Frontal Zone, at the same latitude as the colony, possibly on the Patagonian Shelf, 4000 km away. The cold water bird spent fewer days commuting, conducted four times as many dives as the warm water bird, dived deeper on average, and had a greater proportion of bottom time during dives. CONCLUSIONS/SIGNIFICANCE: General patterns of diving activity were consistent with those of other shearwaters foraging in cold and warm water habitats. Great shearwaters are likely adapted to forage in a wide range of oceanographic conditions, foraging mostly with shallow dives but capable of deep diving.

RECOGNITION OF DRAINAGE TUNNELS DURING GLACIER LAKE OUTBURST EVENTS FROM TERRESTRIAL IMAGE SEQUENCES

Directory of Open Access Journals (Sweden)

E. Schwalbe

2016-06-01

Full Text Available In recent years, many glaciers all over the world have been distinctly retreating and thinning. One of the consequences of this is the increase of so called glacier lake outburst flood events (GLOFs. The mechanisms ruling such GLOF events are still not yet fully understood by glaciologists. Thus, there is a demand for data and measurements that can help to understand and model the phenomena. Thereby, a main issue is to obtain information about the location and formation of subglacial channels through which some lakes, dammed by a glacier, start to drain. The paper will show how photogrammetric image sequence analysis can be used to collect such data. For the purpose of detecting a subglacial tunnel, a camera has been installed in a pilot study to observe the area of the Colonia Glacier (Northern Patagonian Ice Field where it dams the Lake Cachet II. To verify the hypothesis, that the course of the subglacial tunnel is indicated by irregular surface motion patterns during its collapse, the camera acquired image sequences of the glacier surface during several GLOF events. Applying tracking techniques to these image sequences, surface feature motion trajectories could be obtained for a dense raster of glacier points. Since only a single camera has been used for image sequence acquisition, depth information is required to scale the trajectories. Thus, for scaling and georeferencing of the measurements a GPS-supported photogrammetric network has been measured. The obtained motion fields of the Colonia Glacier deliver information about the glacier’s behaviour before during and after a GLOF event. If the daily vertical glacier motion of the glacier is integrated over a period of several days and projected into a satellite image, the location and shape of the drainage channel underneath the glacier becomes visible. The high temporal resolution of the motion fields may also allows for an analysis of the tunnels dynamic in comparison to the changing

Telón de fondo: Paisajes de desierto y alteridad en la fotografía de la Patagonia (1880-1900 Backdrop: Desert and Alterity Landscapes in the Photography of Patagonia (1880-1900

Directory of Open Access Journals (Sweden)

Carlos Masotta

2009-12-01

Full Text Available El paisaje patagónico construido por la fotografía del período 1880-1900 fue un marco en donde se llevó a cabo el ingreso civilizatorio. Luego de una caracterización general del problema (el paisaje desierto como «escenificación de ausencia» en torno a los primeros álbumes de Estado sobre la región, centro el análisis de este artículo en dos obras que describieron el Territorio de Chubut: Viaje a la Patagonia Austral (1886 del Coronel Luis Fontana y la Excursión a la Patagonia y a los Andes de Aarón Anchorena (1902. Entre ellas puede observarse la articulación de una mirada militar y civil donde el paisaje fotográfico del desierto se involucra en la toma material y simbólica del territorio como un escenario donde se «naturaliza» la actuación de un ingreso civilizatorio y la desaparición de los pueblos indígenas.The Patagonian landscape built up by photography during the 1880-1900 periods was the framework in which the civilizing entrance took action. After a general description of the problem (the deserted landscape as the staging of absence about the first State's albums on the region, I focus the analysis on two works describing the Territory of Chubut: Viaje a la Patagonia Austral (Trip to Southern Patagonia by Coronel Luis Fontana (1886 and Excursion a la Patagonia y a los Andes (Tour to Patagonia and the Andes, de Aaron Anchorena (1902. The articulation of a military and civil glance can be observed between them, where the photographic landscape of the desert is involved in the material and symbolic shot of the territory as a stage where the acting of a civilizing entrance and the disappearance of the indigenous peoples is naturalized.

Detrital zircon geochronology and provenance of the Chubut Group in the northeast of Patagonia, Argentina

Science.gov (United States)

Navarro, Edgardo L.; Astini, Ricardo A.; Belousova, Elena; Guler, M. Verónica; Gehrels, George

2015-11-01

The Chubut Group constitutes the most widespread sedimentary unit in NE Patagonia, characterized by variable-energy fluvial deposits. U-Pb analysis of detrital zircons from two sections of the Chubut Group constraint the age of the oldest sedimentary rocks in the northeast of the Somuncurá - Cañadón Asfalto Basin. In the Cañadón Williams area, at San Jorge section, 20 km NW of Telsen locality, dating of 56 detrital zircons from a medium to coarse sandstone indicated a maximum depositional age of 109 ± 1 Ma (n = 4). These sandstones were interpreted to represent shallow channels, associated with a lacustrine system. In the Telsen locality, a laser ablation analysis of 115 detrital zircons from a medium to coarse-grained sandstone, from fluvial channel facies, yielded a maximum depositional age of ca. 106 ± 1 Ma (n = 8). Both ages are consistent with volcanic events of the Barremian to Albian age in the central Patagonian Andes Region. Cathodoluminescence images of zircons from the San Jorge sample suggest an igneous origin, which is further supported by Th/U values above 0.5 in most of the grains. The distribution of the statistical modes of the main age populations of detrital zircons for the two samples [182, 185 and 189 Ma for Telsen sample (T2S) and 181 ± 1 Ma for San Jorge sample (SJS)] matches the age of the volcanic Marifil Formation. The rocks of the Marifil Formation of these ages are exposed NE to SE of the study area. The abundance of zircons of similar Jurassic ages (n = 52 for SJS and n = 105 for T2S) and the external morphology of the zircons in the sample SJS, implies a close proximity of the source area. Suggestion that the Marifil Formation was the main provenance source is also supported by northeast-southeasterly paleocurrents measured at the San Jorge and Telsen sections.

Human effects in Holocene fire dynamics of Central Western Patagonia (~44° S, Chile

Directory of Open Access Journals (Sweden)

César Méndez

2016-08-01

Full Text Available The forest-steppe ecotone of the eastern slope of the Andes in Central Western Patagonia (43°40'-49°15' S, Chile, South America provides a unique area for assessing long and short term dynamics between humans and past environments. Central Western Patagonian was a demographically marginal zone inhabited intermittently and with low intensity by hunter-gatherers during the Holocene. This paper adopts a novel approach in order to assess the relationship between trends in the archaeological, pollen and charcoal records. The recognition of temporal and spatial scales in both archaeology and paleoecology is crucial for defining roles in paleofire records. The main goal of the paper is to assess the role of climate and human beings as potential ignitors of wildfires by acknowledging the scales in which they operate and the different roles either one played in paleofire trends. We investigated a case study in the Cisnes River Valley where the frequencies and magnitudes of fire episodes – reconstructed from macro-charcoal particles from the Lake Shaman intermoraine sequence – can be attributed to human action, while acknowledging the driving role of climate over broader time scales. The Lake Shaman charcoal record spanning the last 19000 cal years is compared to the archaeological record starting at 11500 cal years BP. After comparing paleofires, reconstructed from the charcoal record, with peaks and troughs in the radiocarbon record and archaeological evidence at local and site scales, we argue that this approach provides insights for assessing the timing and magnitude of human effects on the environment. We examine collation and correlation scenarios for comparative trends between the archaeological, pollen and charcoal records. The correlation of occupational events at the El Chueco 1 archaeological site and other sites along the Cisnes River Valley with the results obtained at Lake Shaman is suggestive of a combination of human agency and

Weak trophic links between a crab-spider and the effective pollinators of a rewardless orchid

Science.gov (United States)

Quintero, Carolina; Corley, Juan C.; Aizen, Marcelo A.

2015-01-01

Sit and wait predators hunting on flowers are considered to be exploiters of plant-pollinator mutualisms. Several studies have shown that plant-pollinator interactions can be highly susceptible to the impact of a third trophic level, via consumptive (direct) and non-consumptive (indirect) effects that alter pollinator behavior and, ultimately, plant fitness. However, most flowering plants attract a wide array of flower visitors, from which only a subset will be effective pollinators. Hence, a negative effect of an ambush predator on plant fitness should be expected only when: (i) the effective pollinators are part of the predators' diet and/or (ii) the non-consumptive effects of predator presence (e.g. dead prey) alter the behavior of effective pollinators and pollen movement among individual plants. We analyzed the direct and indirect effects of a crab-spider (Misumenops pallidus), on the pollination and reproductive success of Chloraea alpina, a Patagonian rewardless orchid. Our results indicate that most of the flower visitors do not behave as effective pollinators and most effective pollinators were not observed as prey for the crab-spider. In terms of non-consumptive effects, inflorescences with and without spiders and/or dead-prey did not vary the frequency of flower visitors, nor pollinia removal or deposition. Hence, it is not surprising that M. pallidus has a neutral effect on pollinia removal and deposition as well as on fruit and seed set. Similar to other rewardless orchids, the low reproductive success of C. alpina (∼6% fruit set) was associated with the limited number of visits by effective pollinators. Negative top-down effects of a flower-visitor predator on plant pollination may not be anticipated without studying the direct and indirect effects of this predator on the effective pollinators. In pollination systems where effective pollinators visited flowers erratically, such as in deceptive orchids, we expect weak or no effect of predators on

Description of the immature stages of Sigara (Tropocorixa jensenhaarupi (Hemiptera: Heteroptera: Corixidae: Corixini, with ecological notes Descripción de los estadios larvales de Sigara (Tropocorixa jensenhaarupi (Heteroptera: Corixidae, con notas acerca de su ecología

Directory of Open Access Journals (Sweden)

María Cecilia Melo

2011-03-01

Full Text Available Sigara (Tropocorixa jensenhaarupi Jaczewski is the smallest species of the subgenus ranging from 4.2-4.7 mm, and it is characterized by the absence of a strigil, the small and narrow genital capsule with a short hypandrium in males, and the shape of the abdominal tergite VII in females. This species is endemic to the Patagonian subregion (Andean region in Argentina. A monthly sampling study was performed during a year in northern Mendoza, and additional material was collected in southern Mendoza, more precisely from Bañado Carilauquen in the Llancanelo Lake Reserve (Malargüe Department. Since little is known about the ecological requirements of S. (T. jensenhaarupi, herein we describe its habitat, the environmental conditions and its association with other macroinvertebrates. Also, we provide a morphological description of larval stages, and provide new records of this species.Sigara (Tropocorixa jensenhaarupi Jaczewski es la especie más pequeña del subgénero (4.2-4.7 mm, y se caracteriza por la ausencia de estrigilo, la cápsula genital masculina pequeña y angosta con el hipandro corto, y la forma característica del tergito abdominal VII en las hembras. Esta especie es endémica de la subregión Patagónica (región Andina en Argentina. Se realizaron muestreos mensuales durante un año en el norte de la provincia de Mendoza, material adicional fue recolectado en el sur de la provincia, más precisamente en el Bañado Carilauquen en la Reserva Laguna Llancanelo (Departamento de Malargüe. Poco se conoce acerca de los requerimientos ecológicos de S. (T. jensenhaarupi, por lo que en este trabajo describimos su hábitat, las condiciones ambientales y su asociación con otros macroinvertebrados. Además, describimos los estadios larvales y damos nuevos registros de esta especie.

Combined effects of leaf litter and soil microsite on decomposition process in arid rangelands.

Science.gov (United States)

Carrera, Analía Lorena; Bertiller, Mónica Beatriz

2013-01-15

The objective of this study was to analyze the combined effects of leaf litter quality and soil properties on litter decomposition and soil nitrogen (N) mineralization at conserved (C) and disturbed by sheep grazing (D) vegetation states in arid rangelands of the Patagonian Monte. It was hypothesized that spatial differences in soil inorganic-N levels have larger impact on decomposition processes of non-recalcitrant than recalcitrant leaf litter (low and high concentration of secondary compounds, respectively). Leaf litter and upper soil were extracted from modal size plant patches (patch microsite) and the associated inter-patch area (inter-patch microsite) in C and D. Leaf litter was pooled per vegetation state and soil was pooled combining vegetation state and microsite. Concentrations of N and secondary compounds in leaf litter and total and inorganic-N in soil were assessed at each pooled sample. Leaf litter decay and soil N mineralization at microsites of C and D were estimated in 160 microcosms incubated at field capacity (16 month). C soils had higher total N than D soils (0.58 and 0.41 mg/g, respectively). Patch soil of C and inter-patch soil of D exhibited the highest values of inorganic-N (8.8 and 8.4 μg/g, respectively). Leaf litter of C was less recalcitrant and decomposed faster than that of D. Non-recalcitrant leaf litter decay and induced soil N mineralization had larger variation among microsites (coefficients of variation = 25 and 41%, respectively) than recalcitrant leaf litter (coefficients of variation = 12 and 32%, respectively). Changes in the canopy structure induced by grazing disturbance increased leaf litter recalcitrance, and reduced litter decay and soil N mineralization, independently of soil N levels. This highlights the importance of the combined effects of soil and leaf litter properties on N cycling probably with consequences for vegetation reestablishment and dynamics, rangeland resistance and resilience with implications

First Patagonian Course on 'Diagnosis and Therapy of Injuries Induced by Ionizing Radiation'; Primer curso patagonico 'Diagnostico y Tratamiento de Lesiones Inducidas por Radiaciones Ionizantes'

Energy Technology Data Exchange (ETDEWEB)

Bellotti, Mariela I., E-mail: bellotti@cab.cnea.gov.ar [Comision Nacional de Energia Atomica (CAB/CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche. Lab. de Cavitacion y Biotecnologia; Andres, Pablo A., E-mail: andresp@cab.cnea.gov.ar [Comision Nacional de Energia Atomica (CAB/CNEA), San Carlos de Bariloche (Argentina). Centro Atomico Bariloche. Division Proteccion Radiologica; Cascón, Adriana S., E-mail: adrianacascon@yahoo.com [Instituto de Medicina, Radiomedicina y Seguridad (IMERASE SA), Buenos Aires, (Argentina)

2013-07-01

In Patagonia there are academic centers, health and industrial facilities that use ionizing radiations in its usual practices. However, they do not have protocols that respond to local needs. For this reason was held from October 5 to November 10, 2012 in Bariloche Atomic Center, a training course for health personnel. The range of topics covered ranged from the definition of dosimetry quantities, types of radiation and biological dosimetry, biological effects, radiation acute syndrome, radiation-induced cutaneous syndrome, internal contamination, screening in radiological emergencies, etc.The course provided a theoretical and practical guide about how to recognize and treat people exposed to radiations, guidelines for acting in radiological emergencies and a perception of the psychosocial impact of the radiation accidents.The result was a pocket book for health personnel that will be used in case of having a patient with radiation induced injury.

Fish thermal habitat current use and simulation of thermal habitat availability in lakes of the Argentine Patagonian Andes under climate change scenarios RCP 4.5 and RCP 8.5.

Science.gov (United States)

Vigliano, Pablo H; Rechencq, Magalí M; Fernández, María V; Lippolt, Gustavo E; Macchi, Patricio J

2018-09-15

Habitat use in relation to the thermal habitat availability and food source as a forcing factor on habitat selection and use of Percichthys trucha (Creole perch), Oncorhynchus mykiss (rainbow trout), Salmo trutta (brown trout) and Salvelinus fontinalis (brook trout) were determined as well as future potential thermal habitat availability for these species under climate change scenarios Representative Concentration Pathways 4.5 and 8.5. This study was conducted in three interconnected lakes of Northern Patagonia (Moreno Lake system). Data on fish abundance was obtained through gill netting and hydroacoustics, and thermal profiles and fish thermal habitat suitability index curves were used to identify current species-specific thermal habitat use. Surface air temperatures from the (NEX GDDP) database for RCP scenarios 4.5 and 8.5 were used to model monthly average temperatures of the water column up to the year 2099 for all three lakes, and to determine potential future habitat availability. In addition, data on fish diet were used to determine whether food could act as a forcing factor in current habitat selection. The four species examined do not use all the thermally suitable habitats currently available to them in the three lakes, and higher fish densities are not necessarily constrained to their "fundamental thermal niches" sensu Magnuson et al. (1979), as extensive use is made of less suitable habitats. This is apparently brought about by food availability acting as a major forcing factor in habitat selection and use. Uncertainties related to the multidimensionality inherent to habitat selection and climate change imply that fish resource management in Patagonia will not be feasible through traditional incremental policies and strategic adjustments based on short-term predictions, but will have to become highly opportunistic and adaptive. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluación de riesgo por plaguicidas sobre aguas superficiales de la Región Norpatagónica argentina Assessing Pesticide Hazards On Surface Water From The Northern Patagonian Region-Argentina

Directory of Open Access Journals (Sweden)

Analía P. Tosi

2009-07-01

Full Text Available Aunque el manejo integrado de plagas se aplica en forma creciente en la Región Norpatagónica, todavía una amplia gama de plaguicidas es utilizada con el fin de controlar apropiadamente las principales plagas agrícolas. Otros agroquímicos también son aplicados en las actividades industriales asociadas. El objetivo del presente trabajo es evaluar el impacto potencial causado por estos plaguicidas sobre los organismos acuáticos y para ello se utilizan datos bibliográficos de toxicidad aguda y resultados analíticos locales. Se utilizó un procedimiento escalonado, permitiendo la selección de aquellos xenobióticos ambientales que justificarían un estudio de ecotoxicidad posterior. Los residuos máximos de metil azinfos (S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]- triazin-3-ylmethylO,O-dimethyl phosphordithioate, indican la probabilidad de efectos agudos en el 37% de las especies estudiadas en el río, principalmente peces y zooplancton. Este valor se incrementa en los drenajes hasta un 42%. En el caso del carbaril (1-napthylmethylcarbamate los residuos encontrados en drenajes afectarían al 14% de las especies estudiadas, mientras que en el río el impacto es despreciable.Although the Integrated Pest Management (IPM is increasingly being applied in the Northern Patagonia Region, different pesticides are still used in order to properly control agricultural pests. Other agrochemicals are also applied in the agriculture associated activities like conservation and packaging industries. The potential impact caused by these pesticides on aquatic organisms is assessed in the present study by means of acute toxicity data available in the literature and local analytical results. A tiered procedure was used allowing the selection of those environmental xenobiotics that need further ecotoxicity studies. The observed maximum residues of azinphos-methyl, (S-(3,4-dihydro-4-oxobenzo[d]-[1,2,3]-triazin-3-ylmethylO,O-dimethyl phosphordithioate, indicate the probability of acute effects in 37 % of the studied species in the river, mainly fish and zooplankton. This value increased in drainage channels samples up to 42 %. Additionally, carbaryl (1-napthylmethylcarbamate residues found in drainage channels affect 14 % of the studied species, while in the river samples the impact was negligible.

Fault-controlled permeability and fluid flow in low-porosity crystalline rocks: an example from naturally fractured geothermal systems in the Southern Andes

Science.gov (United States)

Arancibia, G.; Roquer, T.; Sepúlveda, J.; Veloso, E. A.; Morata, D.; Rowland, J. V.

2017-12-01

Fault zones can control the location, emplacement, and evolution of economic mineral deposits and geothermal systems by acting as barriers and/or conduits to crustal fluid flow (e.g. magma, gas, oil, hydro-geothermal and groundwater). The nature of the fault control permeability is critical in the case of fluid flow into low porosity/permeability crystalline rocks, since structural permeability provides the main hydraulic conductivity to generate a natural fractured system. However, several processes accompanying the failure of rocks (i.e. episodic permeability given by cycling ruptures, mineral precipitation from fluids in veins, dissolution of minerals in the vicinity of a fracture) promote a complex time-dependent and enhancing/reducing fault-controlled permeability. We propose the Southern Volcanic Zone (Southern Andes, Chile) as a case study to evaluate the role of the structural permeability in low porosity crystalline rocks belonging to the Miocene North Patagonian Batholith. Recently published studies propose a relatively well-constrained first-order role of two active fault systems, the arc-parallel (NS to NNE trending) Liquiñe Ofqui Fault System and the arc-oblique (NW trending) Andean Transverse Fault Zones, in fluid flow at crustal scales. We now propose to examine the Liquiñe ( 39°S) and Maihue ( 40°S) areas as sites of interaction between these fault systems, in order to evaluate a naturally fractured geothermal system. Preliminary results indicate upwelling of thermal water directly from fractured granite or from fluvial deposits overlying granitoids. Measured temperatures of thermal springs suggest a low- to medium-enthalpy system, which could potentially be harnessed for use in geothermal energy applications (e.g. heating, wood dryer and green house), which are much needed in Southern Chile. Future work will aim to examine the nature of structural permeability from the regional to the microscopic scale connecting the paleo- and current- fluid

Difilobotriasis humana en la Patagonia, Argentina Human diphyllobothriasis in Patagonia, Argentina

Directory of Open Access Journals (Sweden)

Liliana Semenas

1997-06-01

Full Text Available OBJETIVO: El objetivo del trabajo fué detectar hospedadores humanos en la zona andino patagónica argentina, teniendo en cuenta las prácticas de pesca desportiva y la importancia de los salmónidos dentro de la zona. MATERIAL Y METODO: Entre 1986 y 1995 se implementaron Campañas de Información en los laboratorios de Análisis Clínicos de la región andinopatagónica argentina, destinadas a lograr una detección más eficiente de la difilobotriasis, a través de análisis coproparasitológicos. RESULTADOS: Adicionalmente, se confeccionaron planillas destinadas a recoger información sobre las características de la infección, del tratamiento y del paciente. Durante este período se detectaron 13 nuevos casos humanos, por identificación directa del parásito o por la presencia de huevos en materia fecal. Las características de las infecciones responden a las descriptas para el género Diphyllobothrium. CONCLUSIONES: En la región, los salmónidos son los peces predilectos en la pesca deportiva. Estos peces, frecuentemente parasitados con larvas, constituyen la principal fuente de contagio para el hombre al ser consumidos insuficientemente cocidos o ahumados en frío.OBJECTIVE: In view of the amateur fishing practices and the importance of salmonids in the region the study sets out to detect human hosts in the Andean-Patagonian zone. MATERIAL AND METHOD: Information campaigns were carried out by Clinical Analysis Laboratories of Andean Patagonia between 1986 and 1995 to detect diphyllobothriasis more efficiently by means of coproparasitological analysis. RESULTS: Further, forms were prepared for the collection of information about infection, treatment and the characteristics of the human host. During this period 13 new cases were registered either through direct identification of the parasite or through the presence of eggs in the faeces. The characteristics of infection are similar to those described for the genus Diphyllobothrium

Global Implications of late Pleistocene Megafaunal Extinctions in the Holarctic

Science.gov (United States)

Cooper, Alan; Turney, Chris

2017-04-01

ández, P.M., Gasco, A., Duran, V., Seymour, K.L., Otaola, C., Gil, A., Paunero, R., Prevosti, F.J., Bradshaw, C.J.A., Wheeler, J.C., Borrero, L., Austin, J.J., Cooper, A., 2016. Synergistic roles of climate warming and human occupation in Patagonian megafaunal extinctions during the Last Deglaciation. Science Advances 2, doi: 10.1126/sciadv.1501682.

The Aysen Glacier Trail (AGT): Fostering leadership and personal growth towards understanding our place in the environment through experiential learning and scientific inquiry in northern Patagonia, Chile

Science.gov (United States)

Sincavage, R.; Chambers, F. B.; Leidich, J.

2017-12-01

The Colonia Glacier, a low elevation mid-latitude glacier, drains the lee side of the central division of the Northern Patagonian Ice Field (NPI). As such, it serves as a microcosm of conditions on the NPI as a whole. Glaciers of this type have experienced extreme variability in Holocene thickness and extent, making them excellent indicators of local and regional climate conditions. Glacial lake outburst floods (GLOFs) originating in the remote Cachet Basin, dammed by the Colonia Glacier, have increased in frequency from once every 10 years to 3 times annually since 2008. These flood events are important in that they 1.) directly impact the livelihoods of downstream residents, 2.) may be linked to the overall health of the Colonia Glacier and, to a larger extent, the NPI, 3.) provide a natural laboratory for studying the dynamics of large flood events, and 4.) have downcut the sediments sequestered in the upper basin, revealing a rich Holocene sedimentologic and climate record. With improved access to this remote region through local partners in recent years, outstanding opportunities for scientific discovery, education, and outreach exist in one of the most beautiful and least-studied glacial regions on Earth. We propose establishing an NSF REU site here to further develop the abundant educational and research opportunities in this spectacular locale. We envision students participating under the REU will receive a broad-based background in glaciology and sedimentology prior to the field experience, and then participate in basic field research led by the PIs into understanding recent and Holocene linkages between climate change and the glacio-fluvio geomorphology of the NPI. A pilot program of 13 U.S. and Chilean students with wide-ranging backgrounds and degree levels was conducted in the winter of 2015-16. A two week backcountry trek across rocky terrain, mountain streams, active glaciers, and proglacial lakes in this seldom-visited region immersed the students

Rock avalanche occurrence in the San Juan province (Argentina): an analysis of their spatial distribution and main forcing factors

Science.gov (United States)

Penna, Ivanna; Tonini, Marj; Vega Orozco, Carmen D.; Longchamp, Céline; Derron, Marc-Henri; Jaboyedoff, Michel

2013-04-01

Rock avalanches are frequent phenomena in the Argentinean Andes and a particular high concentration of these events is observed in the Northwest (~25°S) and in the Central Andes from 30°S until the transition with the Patagonian Andes (~38°S). Tectonic deformation and seismicity are generally proposed as main driving factors, with weather and lithologic conditions playing a subordinate role. From 28°S to 33°S, the subhorizontal subduction of the Nazca plate drives higher shortening rates than in the surrounding areas, and an intense seismicity. Main morphotectonic units in this regions are the Cordillera and Precordillera, separated by the Barreal-Calingasta depression. In the southern central part of the flat subduction area (30°30'°-32°30'S), it is observed high valley incision and maximum local relief of 2900 m, while in the Precordillera main fluvial courses developed in the inter-thrust valleys, where local relief is up to 2400 m. In both mountain ranges, we recognized 34 rock avalanches deposits with volumes up to 0.3 km3. There is no apparent lithologic control on detachments, which involved sedimentary, volcanic and granite rocks, even though ~20% of them were favored by layering orientation. However, about 50% of the inventoried rock avalanches with the greatest volumes, developed along tectonic structures or less than 1 km far from them. The main objective of the present study is to explore the spatial distribution of rock avalanche deposits, and compare it with the instrumental seismicity and landscape conditions by means of statistical tools (e.g. exploratory data analyses, Ripley's K-function). Those analyses allow to highlight the spatial correlation between the geological events. Moreover, to visually display the detected cluster spatial patterns we elaborated kernel density maps. Our findings revealed that most of the rock avalanches show a high spatial aggregation mainly between 31°20'S-31°50'S. Main concentration of bedrock landslides

Seasonal and interannual variabilities of coccolithophore blooms in the Bay of Biscay and the Celtic Sea observed from a 18-year time-series of non-algal Suspended Particulate Matter images

Science.gov (United States)

Perrot, Laurie; Gohin, Francis; Ruiz-Pino, Diana; Lampert, Luis

2016-04-01

Coccolithophores belong to the nano-phytoplankton size-class and produce CaCO3 scales called coccoliths which form the «shell» of the algae cell. Coccoliths are in the size range of a few μm and can also be detached from the cell in the water. This phytoplankton group has an ubiquitous distribution in all oceans but blooms only in some oceanic regions, like the North East Atlantic ocean and the South Western Atlantic (Patagonian Sea). At a global scale coccolithopore blooms are studied in regard of CaCO3 production and three potential feedback on climate change: albedo modification by the way of dimethylsulfide (DMS) production and atmospheric CO2 source by calcification and a CO2 pump by photosynthesis. As the oceans are more and more acidified by anthropogenic CO2 emissions, coccolithophores generally are expected to be negatively affected. However, recent studies have shown an increase in coccolithophore occurrence in the North Atlantic. A poleward expansion of the coccolithophore Emiliana Huxleyi has also been pointed out. By using a simplified fuzzy method applied to a 18-year time series of SeaWiFS (1998-2002) and MODIS (2003-2015) spectral reflectance, we assessed the seasonal and inter-annual variability of coccolithophore blooms in the vicinity of the shelf break in the Bay of Biscay and the Celtic Sea After identification of the coccolith pixels by applying the fuzzy method, the abundance of coccoliths is assessed from a database of non-algal Suspended Particulate Matter (SPM). Although a regular pattern in the phenology of the blooms is observed, starting south in April in Biscay and moving northwards until July in Ireland, there is a high seasonal and interannual variability in the extent of the blooms. Year 2014 shows very low concentrations of detached coccoliths (twice less than average) from space and anomalies point out the maximum level in 2001. Non-algal SPM, derived from a procedure defined for the continental shelf, appears to be well

How landscape dynamics link individual- to population-level movement patterns: A multispecies comparison of ungulate relocation data

Science.gov (United States)

Mueller, Thomas; Olson, K.A.; Dressler, G.; Leimgruber, Peter; Fuller, Todd K.; Nicholson, Craig; Novaro, A.J.; Bolgeri, M.J.; Wattles, David W.; DeStefano, Stephen; Calabrese, J.M.; Fagan, William F.

2011-01-01

Aim  To demonstrate how the interrelations of individual movements form large-scale population-level movement patterns and how these patterns are associated with the underlying landscape dynamics by comparing ungulate movements across species.Locations  Arctic tundra in Alaska and Canada, temperate forests in Massachusetts, Patagonian Steppes in Argentina, Eastern Steppes in Mongolia.Methods  We used relocation data from four ungulate species (barren-ground caribou, Mongolian gazelle, guanaco and moose) to examine individual movements and the interrelation of movements among individuals. We applied and developed a suite of spatial metrics that measure variation in movement among individuals as population dispersion, movement coordination and realized mobility. Taken together, these metrics allowed us to quantify and distinguish among different large-scale population-level movement patterns such as migration, range residency and nomadism. We then related the population-level movement patterns to the underlying landscape vegetation dynamics via long-term remote sensing measurements of the temporal variability, spatial variability and unpredictability of vegetation productivity.Results  Moose, which remained in sedentary home ranges, and guanacos, which were partially migratory, exhibited relatively short annual movements associated with landscapes having very little broad-scale variability in vegetation. Caribou and gazelle performed extreme long-distance movements that were associated with broad-scale variability in vegetation productivity during the peak of the growing season. Caribou exhibited regular seasonal migration in which individuals were clustered for most of the year and exhibited coordinated movements. In contrast, gazelle were nomadic, as individuals were independently distributed and moved in an uncoordinated manner that relates to the comparatively unpredictable (yet broad-scale) vegetation dynamics of their landscape.Main conclusions�

The ``Problem of the quaternary'' and the taxonomic rank of the late cenozoic in the international stratigraphic scale

Science.gov (United States)

Zubakov, V. A.

2011-02-01

An international scientific conflict has arisen around the International Stratigraphic Scale, the main document that regulates the rules of reading of geological records and, hence, concerns all Earth sciences. The matter of debate is the geological time scale of 2004, developed by the International Commission on Stratigraphy, where the Quaternary system was abandoned. This ICS decision triggered a protest among Quaternary geologists, members of INQUA, and became the subject of much controversy. This article provides a comprehensive analysis of the Quaternary problem and proposes a reasonable scientific solution that may be appropriate for both parties. The subject of Late Cenozoic geology is discussed: glaciations, human evolution, and recent deposits. In contrast to Charles Lyell's definition of the Plio-Pleistocene according to the percentage of modern mollusk species, it is defined here as a blanket formation, which is correlative to the topography and consists of mapped stratogens hosting fossils of modern biogeocenoses. Features of the description of the Plio-Pleistocene in terms of gravitational orbital tuning are considered. Four paleogeographic phases of modern environment evolution are recognized and ranked as stages: (1) The Messinian evolutionary explosion involved the appearance of many biogeocenoses and the bipedal walking of our extinct ancestors armed with sticks. It was a consequence of the Early Greenland (7.6 Ma BP) and Patagonian (6.7 Ma BP) hyperglaciations. (2) The Zanclean age is marked by climatic and hydrological but not evolutionary boundaries. (3) The appearance of the Villafranchian animal assemblage and Australopithecus, who used stones as weapon: 4.0-3.6 Ma BP. Orogeny and isolation of the Arctic Ocean changed the global climate dramatically. (4) The sexual revolution became the third evolutionary jump: the appearance of the first woman, "Eve", and the genus Homo with her: 1.9 Ma BP. According to the current view, the Plio

Interacciones macho-hembra del pulpo rojo patagónico Enteroctopus megalocyathus (Cephalopoda: Octopodidae durante el comportamiento de apareamiento Male-female interactions of Patagonian red octopus Enteroctopus megalocyathus (Cephalopoda: Octopodidae during mating behavior

Directory of Open Access Journals (Sweden)

Ranferi Gutiérrez

2012-09-01

Full Text Available Se evalúa, en condiciones de laboratorio, el comportamiento de apareamiento de ocho parejas de Enteroctopus megalocyathus mediante videograbaciones durante 24 h. El comportamiento precopulatorio (CP se caracterizó por presentar tres eventos (natación, exhibición y contacto y el comportamiento copulatorio (CC se caracterizó por mostrar un solo evento (cópula. Del tiempo total de interacción de las parejas, el 34,4% correspondió al CP y el 65,6% correspondió al CC. Entre los tiempos de machos y hembras no hubo diferencias significativas por evento. Al compararse todos los eventos entre sí en relación al tiempo de duración, se presentó el siguiente orden: cópula > contacto > exhibición > natación. Se observó una tendencia a periodos de apareamiento más largos donde el peso de la hembra fue superior al macho, sugiriendo que el peso de la hembra es un factor determinante en la duración de los encuentros de apareamiento.The mating behavior of eight couples of Enteroctopus megalocyathus was evaluated under laboratory conditions by videotaping for 24 h. The precopulatory behavior (CP was characterized by three patterns (swimming, exhibition and contact and copulatory behavior (CC was characterized by display of a single pattern (copulation. Of the total interaction time between octopuses, 34.4% corresponds to CP and 65.6% corresponds to CC. Between times of males and females were not significantly different by pattern. In all events, compared to each other for the duration, presented the following order: copulation > contact > exhibition > swimming. There was a trend towards longer periods of mating where the female weight was higher than the male, suggesting that female weight is a determining factor in the duration of mating encounters.

Simulation of Dry Matter Productivity and Water Dynamics in a Chilean Patagonian Range Simulación de la Productividad de Materia Seca y Dinámica del Agua en Praderas de la Patagonia Chilena

Directory of Open Access Journals (Sweden)

Giorgio Castellaro G

2010-09-01

Full Text Available This paper describes a simulation model combining the main components of water balance and growth of perennial grassland steppe in Chilean Patagonia, to estimate long-term annual production (Yr, kg ha-1 and sheep carrying capacity (GC, sheep equivalent [EO] ha-1. The model is based on climate-water balance relationships, where the basic process is evapotranspiration. The model calculates Yr depending on the accumulation of transpiration and the water use efficiency from the time of growth initiation until the grassland accumulates the maximum amount of dry matter (DM. Depending on Yr, the DM requirement of EO, the proper use factor of grassland and a slope correction factor, a range site GC is calculated. Simulations were performed using actual climate data sets of eight growing seasons at Kampenaike (52º41' S; 70°54'W; 12 m.a.s.l. and a long-term simulation in the same location, using a stochastic weather variables generator. Through the model it was possible to estimate the water loss associated with the components of water balance and estimate the restriction imposed by water deficit on Yr. By simulating many years, it was possible to establish a normal distribution of GC with 0.629 EO ha-1 yr-1, associated with 80% probability of being exceeded, which is lower than values reported in field assessments. This method calculates GC with a conservational approach, taking into account soil and climatic variability in semiarid ecosystems.Se describe un modelo de simulación para pastizales esteparios de la Patagonia chilena, que estima a largo plazo los principales componentes del balance hídrico, la producción anual de MS (Yr, kg ha-1 y la capacidad de carga ovina (GC, equivalente ovino [EO] ha-1 de éstos. El modelo se basa en la relación clima-balance hídrico, siendo el proceso básico la evapotranspiración. Yr es función de la acumulación de transpiración durante la temporada de crecimiento y de la eficiencia del uso del agua. La GC del pastizal se calcula en función de Yr, del requerimiento de MS del EO, del factor de uso apropiado de la pradera y de un factor de corrección por pendiente. Se efectuaron simulaciones utilizando datos climáticos reales de ocho temporadas en la localidad de Kampenaike (52º41’ S; 70º54’ O; 12 m s.n.m y una simulación en el largo plazo para l misma localidad, utilizando un generador estocástico de variables climatológicas. Se cuantificaron las pérdidas de agua asociadas a los componentes del balance hídrico y se estimó el efecto del déficit hídrico sobre Yr. Al simular muchos años fue posible establecer una función de distribución de la GC, la cual fue del tipo normal y a través de ella se estimó una GC de 0,629 EO ha-1 año-1 asociada al 80% de probabilidad de excedencia, valor que resultó más bajo que los reportados en evaluaciones en terreno. Este método permite calcular la GC con un criterio conservacionista, tomando en consideración la variabilidad edafoclimática de los ecosistemas semiáridos.

Patrones de distribución espacial de ensambles de macroinvertebrados bentónicos de un sistema fluvial Andino Patagónico Spatial distribution patterns of benthic macroinvertebrates assemblages in an Andean Patagonian fluvial system

Directory of Open Access Journals (Sweden)

CAROLINA MOYA

2009-01-01

Full Text Available En enero de 2006 se estudiaron los patrones espaciales de distribución de comunidades de macroinvertebrados bentónicos de la cuenca hidrográfica del río Baker (45°50' O y 47°55' S y los principales factores controladores, intentando cubrir la mayor variedad de ecosistemas lóticos. Para llevar a cabo el estudio se seleccionaron 27 estaciones de muestreo ubicadas en las diferentes subcuencas del río. En cada estación se realizó una caracterización fisicoquímica del agua (conductividad, oxígeno disuelto, pH, temperatura y turbidez, y se documentaron las características del tramo de río (e.g. ancho del cauce y tipo de sedimento e información cartográfica utilizando un sistema de información geográfica (SIG. Se identificaron un total de 51 taxa que correspondieron en su mayoría a larvas de insectos (80 %. Los grupos con mayor riqueza fueron los órdenes Ephemeroptera (15 taxa, Plecoptera (8 taxa y Trichoptera (8 taxa. Los análisis de clasificación y ordenación realizados con los datos de abundancia, permitieron reconocer siete grupos de estaciones diferentes (A-F que fueron estadísticamente significativos (P In January of 2006 we studied the distributional patterns of benthic macroinvertebrate communities of the Baker river basin (45°50' O and 47°55' S and their main controlling factors trying to cover the greater variety of the lotic ecosystems. To carry out the study, 27 sampling stations were located in the different sub basins of the river. In each station, physical-chemical parameters of the column of water were quantified (conductivity, dissolved oxygen, pH, temperature and turbidity, and documented characteristics of the segment (e.g. wide of the channel and sediment type and cartographic information using a geographic information system (GIS and complemented with cartographic information using GIS. Identified a total of 51 taxa, are mostly insect larvae (80 %. The groups most richness were orders Ephemeroptera (15 taxa, Plecoptera (8 taxa and Trichoptera (8 taxa. The classification and ordination analyses carried out with the data of abundance, allowed to recognize seven groups stations (A-F statistically significant (P < 0.05. The múltiple regression analysis, showed that the environmental variable that accounts for the observed biological patterns, was coverage cobble, explaining 45.1 % the variance of the biological data (r² = 0.44 P < 0.05.

Cuatro nuevas especies del género Liolaemus (Iguania: Liolaemidae, pertenecientes al grupo boulengeri, de la Patagonia, Argentina

Directory of Open Access Journals (Sweden)

Abdala, Cristian Simón

2003-12-01

primarily in color pattern and some aspects of squamation. The new species are distributed over three Patagonian regions with differing geological histories and plant associations. The new species described from central and southwestern Río Negro Province experience substantial differences in daily and seasonal temperature. All four new species eat insects.

Glacier Mass Changes of Lake-Terminating Grey and Tyndall Glaciers at the Southern Patagonia Icefield Derived From Geodetic Observations and Energy and Mass Balance Modeling

Directory of Open Access Journals (Sweden)

Stephanie S. Weidemann

2018-06-01

Full Text Available In this study we demonstrate how energy and mass fluxes vary in space and time for Grey and Tyndall glaciers at the Southern Patagonia Icefield (SPI. Despite the overall glacier retreat of most Patagonian glaciers, a recent increase in mass loss has been observed, but individual glaciers respond differently in terms of spatial and temporal changes. In this context, the detailed investigation of the effect of mass balance processes on recent glacier response to climate forcing still needs refinement. We therefore quantify surface energy-fluxes and climatic mass balance of the two neighboring glaciers, Grey and Tyndall. The COupled Snow and Ice energy and MAss balance model COSIMA is applied to assess recent surface energy and climatic mass balance variability with a high temporal and spatial resolution for a 16-year period between April 2000 and March 2016. The model is driven by downscaled 6-hourly atmospheric data derived from ERA-Interim reanalysis and MODIS/Terra Snow Cover and validated against ablation measurements made in single years. High resolution precipitation fields are determined by using an analytical orographic precipitation model. Frontal ablation is estimated as residual of climatic mass balance and geodetic mass balance derived from TanDEM-X/SRTM between 2000 and 2014. We simulate a positive glacier-wide mean annual climatic mass balance of +1.02 ± 0.52 m w.e. a−1 for Grey Glacier and of +0.68 ± 0.54 m w.e. a−1 for Tyndall Glacier between 2000 and 2014. Climatic mass balance results show a high year to year variability. Comparing climatic mass balance results with previous studies underlines the high uncertainty in climatic mass balance modeling with respect to accumulation on the SPI. Due to the lack of observations accumulation estimates differ from previous studies based on the methodological approaches. Mean annual ice loss by frontal ablation is estimated to be 2.07 ± 0.70 m w.e. a−1 for Grey Glacier and 3.26 ± 0

UAV-based Radar Sounding of Antarctic Ice

Science.gov (United States)

Leuschen, Carl; Yan, Jie-Bang; Mahmood, Ali; Rodriguez-Morales, Fernando; Hale, Rick; Camps-Raga, Bruno; Metz, Lynsey; Wang, Zongbo; Paden, John; Bowman, Alec; Keshmiri, Shahriar; Gogineni, Sivaprasad

2014-05-01

deep temperate glaciers—examples from the Northern Patagonian Icefield, 14th International Conference on Ground Penetrating Radar (GPR) June 4-8, 2012, Shanghai, China, ISBN 978-1-4673-2663-6.

A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria

Science.gov (United States)

Martínez, Rubén D. F.; Lamanna, Matthew C.; Novas, Fernando E.; Ridgely, Ryan C.; Casal, Gabriel A.; Martínez, Javier E.; Vita, Javier R.; Witmer, Lawrence M.

2016-01-01

We describe Sarmientosaurus musacchioi gen. et sp. nov., a titanosaurian sauropod dinosaur from the Upper Cretaceous (Cenomanian—Turonian) Lower Member of the Bajo Barreal Formation of southern Chubut Province in central Patagonia, Argentina. The holotypic and only known specimen consists of an articulated, virtually complete skull and part of the cranial and middle cervical series. Sarmientosaurus exhibits the following distinctive features that we interpret as autapomorphies: (1) maximum diameter of orbit nearly 40% rostrocaudal length of cranium; (2) complex maxilla—lacrimal articulation, in which the lacrimal clasps the ascending ramus of the maxilla; (3) medial edge of caudal sector of maxillary ascending ramus bordering bony nasal aperture with low but distinct ridge; (4) ‘tongue-like’ ventral process of quadratojugal that overlaps quadrate caudally; (5) separate foramina for all three branches of the trigeminal nerve; (6) absence of median venous canal connecting infundibular region to ventral part of brainstem; (7) subvertical premaxillary, procumbent maxillary, and recumbent dentary teeth; (8) cervical vertebrae with ‘strut-like’ centroprezygapophyseal laminae; (9) extremely elongate and slender ossified tendon positioned ventrolateral to cervical vertebrae and ribs. The cranial endocast of Sarmientosaurus preserves some of the most complete information obtained to date regarding the brain and sensory systems of sauropods. Phylogenetic analysis recovers the new taxon as a basal member of Lithostrotia, as the most plesiomorphic titanosaurian to be preserved with a complete skull. Sarmientosaurus provides a wealth of new cranial evidence that reaffirms the close relationship of titanosaurs to Brachiosauridae. Moreover, the presence of the relatively derived lithostrotian Tapuiasaurus in Aptian deposits indicates that the new Patagonian genus represents a ‘ghost lineage’ with a comparatively plesiomorphic craniodental form, the evolutionary

Postfire encroachment of Fabiana imbricata is real? Assessing changes of shrubland occupation during 40 years in NW Patagonia steppe

Science.gov (United States)

Lasaponara, Rosa; Oddi, Facundo; Ghermandi, Luciana

2014-05-01

Landscapes are dynamic in space and time, being spatio-temporal processes of particular interest for landscape ecology. In particular, grasslands can change their structure through the expansion of shrubs in the landscape matrix. Shrub encroachment affect biodiversity as well as forage availability that is the key component of the productive use of rangelands. However, despite its recognition as a global problem, knowledge on the rates, dynamics and encroachment patterns is even scarce. For example, although it is generally accepted that fire control shrub encroachment, certain shrubby species could be favored by the occurrence of fire. In northwestern Patagonian steppe, Fabiana imbricata form large monospecific shrublands that are part of the landscape mosaic and its dynamics of regeneration is strongly related to fire. This long-lived shrub (≡ 150 years) is a typical seeder that is killed by fire and recruits seedlings almost exclusively in post-fire, establishing even-age patches. Our objective was to determine whether F. imbricata shrublands have expanded during the last 40 years in a landscape fire prone. The study area corresponds to San Ramon ranch (22,000 ha) located in northwestern Patagonia steppe, Argentina (latitude -41° 04'; longitude -70° 51'). Two distribution maps of the species were made that corresponds to the study area in 1968 and 2011. The 1968 map was elaborated from the digitalization of aerial photographs (1:45000) while the 2011 map was produced with very high resolution satellite images, current aerial photographs and GPS field data. Both maps were loaded into a GIS environment, in which landscape metrics at patch and class level were determined and then compared. From remote sensing and dendroecological techniques, we know that the study area was almost entirely affected by fires during the study period. Therefore, the comparison of both maps allows us to know post-fire changes in the shrublands spatial configuration at the landscape

Species replacement along a linear coastal habitat: phylogeography and speciation in the red alga Mazzaella laminarioides along the south east pacific

Directory of Open Access Journals (Sweden)

Montecinos Alejandro

2012-06-01

Full Text Available Abstract Background The Chilean shoreline, a nearly strait line of coast expanding across 35 latitudinal degrees, represents an interesting region to assess historical processes using phylogeographic analyses. Stretching along the temperate section of the East Pacific margin, the region is characterized by intense geologic activity and has experienced drastic geomorphological transformations linked to eustatic and isostatic changes during the Quaternary. In this study, we used two molecular markers to evaluate the existence of phylogeographic discontinuities and detect the genetic footprints of Pleistocene glaciations among Patagonian populations of Mazzaella laminarioides, a low-dispersal benthic intertidal red seaweed that inhabits along ~3,700 km of the Chilean coastal rocky shore. Results Three main genetic lineages were found within M. laminarioides. They are distributed along the Chilean coast in strict parapatry. The deep divergence among lineages suggests that they could be considered putative genetic sibling species. Unexpectedly, genetic breaks were not strictly concordant with the biogeographic breaks described in the region. A Northern lineage was restricted to a broad transition zone located between 30°S and 33°S and showed signals of a recent bottleneck. The reduction of population size could be related to warm events linked to El Niño Southern Oscillation, which is known to cause massive seaweed mortality in this region. To the south, we propose that transient habitat discontinuities driven by episodic tectonic uplifting of the shoreline around the Arauco region (37°S-38°S; one of the most active forearc-basins in the South East Pacific; could be at the origin of the Central/South genetic break. The large beaches, located around 38°S, are likely to contribute to the lineages’ integrity by limiting present gene flow. Finally, the Southern lineage, occupies an area affected by ice-cover during the last glaciations

Holocene sea-level changes in the Falkland Islands

Science.gov (United States)

Newton, Tom; Gehrels, Roland; Daley, Tim; Long, Antony; Bentley, Mike

2014-05-01

In many locations in the southern hemisphere, relative sea level (RSL) reached its maximum position during the middle Holocene. This highstand is used by models of glacial isostatic adjustment (GIA) to constrain the melt histories of the large ice sheets, particularly Antarctica. In this paper we present the first Holocene sea-level record from the Falkland Islands (Islas Malvinas), an archipelago located on the Patagonian continental shelf about 500 km east of mainland South America at a latitude of ca. 52 degrees. Unlike coastal locations in southernmost South America, Holocene sea-level data from the Falklands are not influenced by tectonics, local ice loading effects and large tidal ranges such that GIA and ice-ocean mass flux are the dominant drivers of RSL change. Our study site is a salt marsh located in Swan Inlet in East Falkland, around 50 km southwest of Stanley. This is the largest and best developed salt marsh in the Falkland Islands. Cores were collected in 2005 and 2013. Lithostratigraphic analyses were complemented by analyses of foraminifera, testate amoebae and diatoms to infer palaeoenvironments. The bedrock, a Permian black shale, is overlain by grey-brown organic salt-marsh clay, up to 90 cm thick, which, in a landward direction, is replaced by freshwater organic sediments. Overlying these units are medium-coarse sands with occasional pebbles, up to 115 cm thick, containing tidal flat foraminifera. The sandy unit is erosively overlain by a grey-brown organic salt-marsh peat which extends up to the present surface. Further away from the sea this unit is predominantly of freshwater origin. Based on 13 radiocarbon dates we infer that prior to ~9.5 ka sea level was several metres below present. Under rising sea levels a salt marsh developed which was suddenly drowned around 8.4 ka, synchronous with a sea-level jump known from northern hemisphere locations. Following the drowning, RSL rose to its maximum position around 7 ka, less than 0.5 m above

Experimental thermomechanical damage as first approach to understand the petrophysical behavior of the granitic host-rocks from an active fractured-geothermal system (Liquiñe, Chile - 39º S)

Science.gov (United States)

Molina Piernas, E.; Sepúlveda, J.; Arancibia, G.; Roquer, T.; Morata, D.; Bracke, R.; Vázquez, P.

2017-12-01

Chile's location along an active subduction zone has endowed it with a high geothermal potential. However, a better understanding of the thermomechanical and fluid transport properties of rocks is required to assess the potential of geothermal systems and thereby enhance the possibilities for their use. We have focused in the area surrounding Liquiñe, in the Southern Andean Volcanic Zone (Chile, 39º S). This area hosts several recent thermal manifestations, predominantly hot springs, and it is affected by the Liquiñe-Ofqui Fault Zone (LOFZ), which controls the position of the modern volcanic arc in southern Chile and cuts the Patagonian batholith. We have carried out experimental analyzes in order to understand this geothermal system and the influence of the thermomechanical features over the granitic host-rocks (low-porous crystalline rocks). To do this, physical properties such as capillary water absorption coefficient, Vp-wave velocity and compressive resistance were evaluated before and after heating rock samples at 150 ºC and 210 ºC (at ambient pressure) in an oven at a heating rate of 6 °C/min and maintaining the maximum temperature for 4 hours. The cooling rate was less than 2 °C/min to avoid shrinkage phenomena. The results show that the damage by heat was greater at 210 ºC than 150 ºC, likely due to an increased capillary coefficient ( 30% and 25%). On the contrary, Vpvelocity ( -19% and -13%) and compressive resistance ( -27% in both cases) decreased, with respect to unheated samples. Consequently, we can infer an inherent effect on the later fracture process due to the thermal stress when this granitic body was at depth. After that, and considering the local and regional strain-stress state, both factors have facilitated the fluid flow, increasing the permeability of this granitic host-rock allowing the presence of hot-springs. Future work will be to acquire complementary petrophysical parameters, such as porosity, permeability, thermal

Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

Science.gov (United States)

Rigual Hernández, Andrés S.; Flores, José A.; Sierro, Francisco J.; Fuertes, Miguel A.; Cros, Lluïsa; Trull, Thomas W.

2018-03-01

) coccoliths captured by the traps experienced weight and length reduction during summer (December-February); (3) the estimated annual coccolith weight of E. huxleyi at both sediment traps (2.11 ± 0.96 and 2.13 ± 0.91 pg at 2000 and 3700 m) was consistent with previous studies for morphotype B/C in other Southern Ocean settings (Scotia Sea and Patagonian shelf); and (4) coccolithophores accounted for approximately 2-5 % of the annual deep-ocean CaCO3 flux. Our results are the first annual record of coccolithophore abundance, composition and degree of calcification in the Antarctic zone. They provide a baseline against which to monitor coccolithophore responses to changes in the environmental conditions expected for this region in coming decades.

Evolution of the Great Tehuelche Paleolake in the Torres del Paine National Park of Chilean Patagonia during the Last Glacial Maximum and Holocene Evolución del Gran Paleolago Tehuelche en el Parque Nacional Torres del Paine de la Patagonia chilena durante el Último Máximo Glacial y Holoceno

Directory of Open Access Journals (Sweden)

Marcelo A Solari

2012-01-01

Full Text Available A number of glacial moraines are distributed from the eastern margin of the Torres del Paine drainage basin to near the present margin of the Patagonian Ice Fields, together with a set of regionally continuous lacustrine terraces related to glacial fluctuations. The geomorphology, supported by lake sediment evidence, indicates the existence of a single proglacial paleolake in this area, here referred to as the Great Tehuelche Paleolake. This concept helps to clarify the chronology of glacial events and leads to a better understanding of the evolution of the hydrologic system in the Torres del Paine area. Glacial advances previously referred to as A, B and C occurred during the Last Glacial Maximum and fed the Great Tehuelche Paleolake with meltwater, allowing it to reach its maximum extension. The discovery of thrombolites at Laguna Amarga suggests that the drainage of the paleolake towards the Última Esperanza Fjord took place at 7,113 Cal. yr BP, after the melting of an ice barrier that existed during the earlier glacial advance. This gave rise to the development of a complex fluvio-lacustrine hydrologic system that persists to the present day.Un grupo de morrenas glaciales están distribuidas desde el margen este de la cuenca de drenaje de Torres del Paine hacia el margen actual de los Campos de Hielo Patagónicos. Las morrenas se observan en conjunto con un grupo de terrazas lacustres regionales, las cuales están vinculadas a las fluctuaciones glaciales. La geomorfología y evidencias de sedimentos lacustres indican la existencia de un único lago proglacial, referido en este estudio como Gran Paleolago Tehuelche. Este concepto ayuda a clarificar la cronología de los eventos glaciales y permite una mejor comprensión de la evolución del sistema hidrológico del sector de Torres del Paine. Los eventos glaciales, previamente referidos como Avance A, B y C, ocurrieron durante el Último Máximo Glacial y alimentaron con aguas de fusión al

Panorama de la familia Asteraceae (= Compositae en la Republica Argentina An overview of the plant family Asteraceae ( = Compositae in Argentina

Directory of Open Access Journals (Sweden)

Liliana Katinas

2007-07-01

genera and species occurring in the country when compared with the rest of the tribes. The highest number of native species occurs in the Altoandean and Patagonian phytogeographic provinces. The most represented tribe in number of genera is Heliantheae, and in number of species is the tribe Senecioneae.

Factors influencing the characteristics and distribution or surface organic matter in the Pacific-Atlantic connection

Science.gov (United States)

Barrera, Facundo; Lara, Rubén J.; Krock, Bernd; Garzón-Cardona, John Edison; Fabro, Elena; Koch, Boris P.

2017-11-01

The present work reports the first data set on particulate organic carbon (POC) and nitrogen (PON), and the high-resolution modelling of their stable isotope variability in the Patagonian Cold Estuarine System (PCES), with focus on particulate organic matter (POM) origin and distribution in dependence on physical, chemical and biological parameters. POC, PON, stable carbon (δ13C) and nitrogen isotopes (δ15N), dissolved organic nitrogen, phaeopigments, diatom, dinoflagellate and heterotrophic bacteria (HB) abundance are reported for 17 stations in different waters masses in the southern end of the Argentine shelf in late summer 2012. Most parameters denote clear differences between Beagle - Magellan Water (BMW), Subantarctic Shelf Water (SSW) and Subantarctic Water (SAW). POC and PON decreased from maxima in BMW to intermediate values in SSW and minima in SAW. There was a highly significant correlation among POC, PON and fluorescence indicators of diagenetic maturity of dissolved humic matter. This, together with the inverse correlations of salinity with POC and PON, and the wide range of C:N ratios indicate that POM in the study area is partly derived from terrestrial runoff, superimposed by autochthonous components from plankton of different life stages. HB abundance was significantly correlated with POC and dissolved organic matter (DOM), likely reflecting a resource control of HB and a significant contribution of bacterial biomass to POM in the nanoparticle fraction. The direct relationship between HB and dissolved humics suggests bacterial uptake of DOM fractions otherwise considered refractory. POM complexity was reflected in a wide variation of δ13C, despite the narrow temperature range of this region. The variability of stable isotopes of POC could be accounted for by a model with a degree of detail hitherto not reported in the literature. A multiple regression including C:N ratio, ammonium and the quotient between log abundance of diatoms

Post-breeding migration and connectivity of red knots in the Western Atlantic

Science.gov (United States)

Lyons, James E.; Winn, Bradford; Keyes, Timothy; Kalasz, Kevin S.

2018-01-01

Red knots (Calidris canutus rufa) have 3 distinct nonbreeding regions: 1 in the southeastern United States and Caribbean, another on the northeast coast of Brazil in the Maranhão region, and a third along the Patagonian coasts of Chile and Argentina. Effective conservation and recovery of this threatened long-distance migrant will require knowledge of population structure, migration ecology, and abundance and distribution throughout the annual cycle. We conducted a stopover population and biogeographic assessment of knots at the Altamaha River Delta, Georgia, an important stopover area in the southeastern United States. We estimated stopover population size and stopover duration during post-breeding migration in 2011 at the Altamaha study area using mark-resight data, and we inferred nonbreeding regions for this stopover population using stable isotope ratios of carbon and nitrogen in feathers, and observations (sightings and captures) during boreal winter from across the hemisphere. With an integrated Bayesian analysis of all these data, we also estimated the number of birds in the southeastern United States and northern Brazil during boreal winter. For mark-resight analyses in Georgia, we made observations of marked individuals during 14 weeks from early August to early November 2011 and detected 814 individually marked birds. We used the Jolly-Seber mark-recapture model and estimated the southbound passage population at approximately 23,400 red knots. In ongoing studies elsewhere, isotope samples were collected from 175 (21%) of the 814 birds detected in our study, and ≥1 sighting or capture record during boreal winter was located in data repositories for 659 birds (81%). Isotopic signatures and boreal winter records indicate that the majority (82–96%) of the birds that stopped at the Altamaha Delta spend the boreal winter in the northern part of the nonbreeding range (southeast USA, Caribbean, and northern Brazil). Knots migrating to the southeastern

Seasonal plankton variability in Chilean Patagonia fjords: Carbon flow through the pelagic food web of Aysen Fjord and plankton dynamics in the Moraleda Channel basin

Science.gov (United States)

González, H. E.; Castro, L.; Daneri, G.; Iriarte, J. L.; Silva, N.; Vargas, C. A.; Giesecke, R.; Sánchez, N.

2011-03-01

Two research cruises ( CIMAR 13 Fiordos) were conducted in the N-S oriented macrobasin of the Moraleda Channel (42-47°S), which includes the E-W oriented Puyuhuapi Channel and Aysen Fjord, during two contrasting productive seasons: austral winter (27 July-7 August 2007) and spring (2-12 November 2007). These campaigns set out to assess the spatio-temporal variability, defined by the local topography along Moraleda Channel, in the biological, physical, and chemical oceanographic characteristics of different microbasins and to quantify the carbon budget of the pelagic trophic webs of Aysen Fjord. Seasonal carbon fluxes and fjord-system functioning vary widely in our study area. In terms of spatial topography, two constriction sills (Meninea and Elefantes) define three microbasins along Moraleda Channel, herein the (1) north (Guafo-Meninea), (2) central (Meninea-Elefantes), and (3) south (Elefantes-San Rafael Lagoon) microbasins. In winter, nutrient concentrations were high (i.e. nitrate range: 21-14 μM) and primary production was low (153-310 mgC m -2 d -1), suggesting that reduced light radiation depressed the plankton dynamics throughout Moraleda Channel. In spring, primary production followed a conspicuous N-S gradient, which was the highest (5167 mgC m -2 d -1) in the north microbasin and the lowest (742 mgC m -2 d -1) in the south microbasin. The seasonal pattern of the semi-enclosed Puyuhuapi Channel and Aysen Fjord, however, revealed no significant differences in primary production (˜800 mgC m -2 d -1), and vertical fluxes of particulate organic carbon were nearly twice as high in spring as in winter (266 vs. 168 mgC m -2 d -1). At the time-series station (St. 79), the lithogenic fraction dominated the total sedimented matter (seston). The role of euphausiids in the biological carbon pump of the Patagonian fjords was evident, given the predominance of zooplankton fecal material, mostly euphausiid fecal strings (46% of all fecal material), among the

Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

Science.gov (United States)

Sottile, G. D.; Echeverria, M. E.; Mancini, M. V.; Bianchi, M. M.; Marcos, M. A.; Bamonte, F. P.

2015-06-01

The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40-45° S) and Southern Patagonia (48-52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750-200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase

Revisión del género PerezIa (compositae

Directory of Open Access Journals (Sweden)

Liliana Katinas

2012-06-01

Full Text Available El género Perezia Lag. (Compositae se compone de 30 especies de hierbas perennes distribuidas principalmente en la región andino-patagónica, desde Colombia hasta el sur de Argentina y Chile, con algunas especies en el este de Brasil y de la Argentina, Paraguay y Uruguay. Sus corolas bilabiadas, anteras sagitadas, estilos truncados con una coronita apical de pelos colectores y su estructura polínica ubican al género en la tribu Nassauvieae, subfamilia Mutisioideae. Se propone en este trabajo: a la rehabilitación de Perezia atacamensis, P. burkartii y P. capito; b la transferencia de P. ciliosa var. dentata a la categoría de especie [P. dentata (Cabrera comb. nov.]; c la inclusión de Perezia catharinensis Cabrera, P. eryngioides (Cabrera Crisci y P. volcanensis Cabrera, descritas o transferidas posteriormente a la primer revisión del género en 1969; d la eliminación de subespecies en P. lactucoides; e el establecimiento de la sinonimia entre P. pinnatifida, P. pygmaea y P. coerulescens; f el establecimiento de la sinonimia entre P. pungens, P. ciliaris, P. mandonii, P. purpurata, P. carduncelloides y P. sublyrata; g la rehabilitación de Perezia recurvata subsp. recurvata, subsp. beckii y subsp. triceps. Se designaron dos lectotipos y cinco neotipos, y se excluyeron 86 nombres del género.Revision of the genus Perezia (Compositae. The genus Perezia Lag. (Compositae, with 30 species, is distributed in the Andean-Patagonian region from Colombia to southern Argentina and Chile, and in eastern Brasil and Argentina, Paraguay and Uruguay. It belongs to the tribe Nassauvieae, subfamily Mutisioideae by its bilabiate corollas, caudate anthers, truncate style branches with a crown of collector hairs, and a particular pollen structure. It is proposed in this paper: a the rehabilitation of Perezia atacamensis, P. burkartii, and P. capito; b the change of P. ciliosa var. dentata to the species category [P. dentata (Cabrera comb. nov.]; c the

Evaluación del modelo WEPP para predecir la erosión hídrica en pastizales semiáridos del noreste de la Patagonia Evaluation of the WEPP model to predict soil erosion in northeastern Patagonian rangelands

Directory of Open Access Journals (Sweden)

Marcelo P Chartier

2010-07-01

Full Text Available Los modelos matemáticos son herramientas útiles para la predicción de las pérdidas de suelo por erosión hídrica. El desarrollo reciente del modelo WEPP y su utilización para evaluar los riesgos de erosión en pastizales naturales ha significado un avance interesante en el campo de la erosión y la conservación de suelos de estos ecosistemas. En este trabajo examinamos la eficiencia del modelo WEPP para predecir los procesos hidrológicos y de erosión del suelo en los pastizales naturales semiáridos del noreste de la provincia de Chubut. Se identificaron tres comunidades de plantas ubicadas a lo largo de un gradiente de degradación del suelo: estepa herbácea con arbustos aislados (EH, estepa herbáceo-arbustiva (EHA y estepa arbustiva degradada (EA. En cada una de estas comunidades se aplicó una lluvia simulada (100 mm h-1 durante 30 min sobre parcelas de 1 m² (0,6 x 1,67 m y se colectó el escurrimiento y los sedimentos totales. A partir de los datos de la condición superficial de cada parcela se estimó el escurrimiento y la producción de sedimentos mediante el modelo WEPP. En este trabajo se observó una baja eficiencia del modelo WEPP para predecir el escurrimiento (Eficiencia, E = 0,14 y la erosión del suelo (E = -0,93. La predicción del escurrimiento y pérdida de suelo del modelo WEPP mostró mayor sensibilidad a cambios en los parámetros de lluvia y pendiente del terreno y una sensibilidad moderada a cambios en la cobertura, textura, erodabilidad del suelo y conductividad hidráulica efectiva. El escurrimiento y la producción de sedimentos estimados por WEPP fueron significativamente diferentes en las distintas comunidades de plantas (p Mathematical models are useful tools to predict soil loss by water erosion. The recent development of the WEPP model and its use in assessing the risks of erosion in rangelands has led to significant advances in the field of erosion and soil conservation of these ecosystems. In this work we examine the efficiency of the WEPP model in predicting the hydrological processes and soil erosion in semiarid rangelands of the northeast Chubut Province. Three plant communities along a soil degradation gradient were identified: grass with scattered shrubs (EH, grass-shrubs (EHA, and degraded shrub steppes (EA. In each of these communities simulated rainfall (100 mm h-1 for 30 min was applied on 1 m² (0.6 x 1.67 m plots and total runoff and sediment production were collected. Using the soil surface condition data from each plot, runoff and sediment production were estimated by means of the WEPP model. We found a low efficiency of the WEPP model to predict runoff (Efficiency, E = 0.14 and soil erosion (E = -0.93. The WEPP-estimated runoff and soil losses showed high sensitivity to changes in rainfall and slope parameters and moderate sensitivity to changes in soil cover, texture, soil erodability and effective hydraulic conductivity. The runoff and sediment production estimated by the WEPP model were significantly different among plant communities (p < 0.05. The difference between the estimated and observed mean values varied in the different plant communities: runoff according to the WEPP model was 55.5% greater in the EH and sediment production was 69.6, 62.7 and 17.5% lower, respectively, in the EH, EHA, and EA than the observed values. These results suggest that it is necessary to calibrate the model for local conditions and to incorporate rangeland stratification according to the different soil-vegetation units.

Reconstrucción espacial y temporal de la ocurrencia de avalanchas de nieve en los Andes patagónicos utilizando técnicas dendrocronológicas Dendrochronological reconstruction of spatial and temporal patterns of snow avalanches in the Patagonian Andes

Directory of Open Access Journals (Sweden)

ALEJANDRO CASTELLER

2009-06-01

Full Text Available Las avalanchas de nieve representan un importante riesgo natural en diversas regiones montañosas alrededor del mundo. Daños a infraestructura y pérdidas de vidas humanas son reportados frecuentemente en relación a eventos catastróficos de avalanchas. En los Andes, numerosas obras de infraestructura se ubican en zonas vecinas a senderos de avalanchas, de las que poco se conoce sobre sus alcances máximos, periodos de retorno y presiones de impacto. A través de la implementación de técnicas dendrocronológicas hemos reconstruido las fechas de ocurrencia y áreas de influencia de eventos pasados de avalanchas de nieve. Ejemplares de Nothofagus pumilio con perturbaciones visibles de avalanchas fueron muestreados en sectores del canal, bordes y zonas de frenado de 11 senderos de avalanchas ubicados en Loma de las Pizarras, próximo a El Chaltén, Santa Cruz, Argentina. Además, áreas de control fueron muestreadas para determinar las condiciones de crecimiento en árboles no afectados por avalanchas. Nuestros análisis indican que las cicatrices, las variaciones de excentricidad en el leño, los cambios abruptos de crecimiento y la presencia de leño de tensión son los principales indicadores dendrocronológicos en N. pumilio asociados a la ocurrencia de avalanchas. Basados en una ponderación cuantitativa de los indicadores y en la profundidad de muestreo, calculamos un índice de ocurrencia de eventos, el cual nos permitió determinar para cada sendero los años con ocurrencia de avalanchas. Considerando de manera integral la actividad de avalanchas en los 11 senderos muestreados, los años con mayor ocurrencia de eventos fueron 1936, 1966, 1978 y 1995. Complementariamente, registros climáticos fueron analizados con el objetivo de determinar las relaciones entre los años con ocurrencia de avalanchas y las variaciones mensuales de precipitación y temperatura. Se observa que los años con gran frecuencia de avalanchas están significativamente correlacionados con la ocurrencia de abundantes precipitaciones invernales; no se detectaron relaciones significativas con las variaciones de temperatura. Los resultados alcanzados en esta investigación prueban el potencial dendrocronológico de N. pumilio para reconstruir patrones espaciales y temporales de avalanchas de nieve en los Andes patagónicos.

Can we use ice calving on glacier fronts as a proxy for rock slope failures?

Science.gov (United States)

Abellan, Antonio; Penna, Ivanna; Daicz, Sergio; Carrea, Dario; Derron, Marc-Henri; Jaboyedoff, Michel; Riquelme, Adrian; Tomas, Roberto

2015-04-01

Ice failures on glacier terminus show very similar fingerprints to rock-slope failure (RSF) processes, nevertheless, the investigation of gravity-driven instabilities that shape rock cliffs and glacier's fronts are currently dissociated research topics. Since both materials (ice and rocks) have very different rheological properties, the development of a progressive failure on mountain cliffs occurs at a much slower rate than that observed on glacier fronts, which leads the latter a good proxy for investigating RSF. We utilized a terrestrial Laser Scanner (Ilris-LR system from Optech) for acquiring successive 3D point clouds of one of the most impressive calving glacier fronts, the Perito Moreno glacier located in the Southern Patagonian Ice Fields (Argentina). We scanned the glacier terminus during five days (from 10th to 14th of March 2014) with very high accuracy (0.7cm standard deviation of the error at 100m) and a high density of information (200 points per square meter). Each data series was acquired at a mean interval of 20 minutes. The maximum attainable range for the utilized wavelength of the Ilris-LR system (1064 nm) was around 500 meters over massive ice (showing no-significant loss of information), being this distance considerably reduced on crystalline or wet ice short after the occurrence of calving events. As for the data treatment, we have adapted our innovative algorithms originally developed for the investigation of both precursory deformation and rockfalls to study calving events. By comparing successive three-dimensional datasets, we have investigated not only the magnitude and frequency of several ice failures at the glacier's terminus (ranging from one to thousands of cubic meters), but also the characteristic geometrical features of each failure. In addition, we were able to quantify a growing strain rate on several areas of the glacier's terminus shortly after their final collapse. For instance, we investigated the spatial extent of the

Caracterización y variación espacio-temporal del néctar en anarthrophyllum desideratum (Fabaceae: Influencia del clima y los polinizadores

Directory of Open Access Journals (Sweden)

Valeria Paiaro

2012-12-01

Full Text Available En este trabajo se caracterizó el volumen, la concentración y la composición de azúcares del néctar floral en Anarthrophyllum desideratum (DC Benth., un arbusto endémico de la estepa Patagónica polinizado por aves Passeriformes, y se evaluó su variación espacio-temporal. Se analizaron las diferencias entre áreas ecológicas, poblaciones, plantas y años, y las relaciones entre rasgos, la temperatura, precipitación y tasa de visitas de las poblaciones. El néctar mostró un volumen promedio de 8,1 µl, una concentración de 28% y estuvo dominado por hexosas, como en otras especies ornitófilas. Los atributos del néctar estuvieron correlacionados a nivel poblacional, y las diferencias entre poblaciones explicaron la mayor parte de su variabilidad espacial. El volumen y la concentración variaron entre años, mientras que la composición de azúcares se mantuvo constante. La proporción de glucosa disminuyó con el aumento de la temperatura, pero el resto de los caracteres no se asoció con las variaciones climáticas de la región. El volumen de néctar disminuyó a medida que aumentó la tasa de visitas de las poblaciones. Los resultados sugieren la existencia de una importante variación espacio-temporal del néctar en A. desideratum que no respondería a gradientes ambientales simples sino a un escenario complejo con múltiples factores.Characterization and spatio-temporal variation of nectar in Anarthrophyllum desideratum (Fabaceae: Influence of climate and pollinators. In this study we characterized the volume, concentration and sugar composition of floral nectar in Anarthrophyllum desideratum (DC Benth., an endemic shrub from the Patagonian steppe pollinated by Passerine birds, and we evaluated it spatio-temporal variation. We analyzed the differences among ecological areas, populations, plants and years, and the relationships between traits, the temperature, rainfall and visitation rate of populations. Nectar showed an average

Dimorfismo sexual y relaciones morfométricas de Atlantoraja platana (Günther, 1880 en aguas del golfo San Matías, Patagonia dimorphism and morphometric relationships of Atlantoraja platana (Günther, 1880 in San Matías gulf waters, Patagonia

Directory of Open Access Journals (Sweden)

Nidia Marina Coller

2011-06-01

Full Text Available Resumen: La "raya platana" (Atlantoraja platana, es una especie endémica del Atlántico Sudoccidental, habita desde los 22° S (Uruguay y sur de Brasil hasta los 42° S, región del golfo de San Matías, no siendo encontrada para el resto de la plataforma del mar argentino. Se describen en este estudio aspectos morfométricos de esta raya. En el Golfo San Matías (41°-42°S y 64°-65°O, un total de 778 hembras y 709 machos fueron muestreados de diversas fuentes, entre 2004 y 2006. La longitud total fue de 19 a 89 cm para las hembras y de 19 a 79 cm para los machos. Atlantoraja platana presentó dimorfismo sexual en las relaciones largo-peso y largo-ancho de disco. Desde 41 cm en adelante las hembras fueron más pesadas que los machos. La relación longitud total -peso total fue PT= 0,0132 x LT2,91 para las hembras y PT= 0,0222 x LT2,77 para los machos. Las relaciones de longitud total-ancho de disco fue de AD= 7,27 + 0,762LT para las hembras y AD= 7,768 + 0,798LT para los machos. Este es el primer informe sobre relaciones morfométricas en esta especie del Mar Argentino y puede ser utilizado para fines comparativos entre diferentes localizaciones latitudinales de esta raya.The skate Atlantoraja platana, commonly known in Argentina as "raya platana", is endemic to the Southwest Atlantic. It is distributed from Brasil (24°S to north Patagonian waters (42°11'S. In this study the morphometric aspects of this skate were described. In the San Matías gulf (41°-42°S y 64°-65°W, a total of 778 females and 709 males were sampled from different sources between 2004 and 2006. The total length ranged was 19 to 89 cm for females and 19 to 79 cm for males. Atlantoraja platana was sexually dimorphic in total length-weight and total length-disc width relationships. Since 41 cm onwards the females are being heavier than males. The total length-weight relationship was Pt= 0.0132 x Lt2.91 for females and Pt= 0.0222 x Lt2.77 for males. The total length

Intrusion of basaltic magma into a crystallizing granitic magma chamber: The Cordillera del Paine pluton in southern Chile

Science.gov (United States)

Michael, Peter J.

1991-10-01

, sodic plagioclase, mica and quartz. The early formed gabbroic minerals (and their coronas) are very similar to phenocrysts in late basaltic dikes that cut the upper levels of the CP granite. The inferred parental magmas of both dikes and gabbros were very similar to subalkaline basalts of the Patagonian Plateau that erupted at about the same time, 35 km to the east. Mafic and silicic magmas at Cordillera del Paine are consanguineous, as demonstrated by alkalinity and trace-element ratios. However, the contemporaneity of mafic and silicic magmas precludes a parent-daughter relationship. The granitic magma most likely was derived by differentiation of mafic magmas that were similar to those that later intruded it. Or, the granitic magma may have been contaminated by mafic magmas similar to the PMC magmas before its shallow emplacement. Mixing would be favored at deeper levels when the cooling rate was lower and the granitic magma was less solidified.

The diet of the South American sea lion (Otaria flavescens at Río Negro, Patagonia, Argentina, during the winter-spring period Dieta del lobo marino de un pelo sudamericano (Otaria flavescens en Río Negro, Patagonia, Argentina, durante el invierno y primavera

Directory of Open Access Journals (Sweden)

Raimundo L. Bustos

2012-12-01

Full Text Available The South American sea lion, Otaria flavescens (Shaw, 1800 population is steadily expanding along the Patagonian coast of Argentina in the last decades. However, little is known about the feeding ecology of the species in the area. The aim of this study was to analyze the food habits of O. flavescens from 91 scats collected at Río Negro province, during the winter and spring of 2005. Fish occurred in 96% of scats containing prey remains, followed by cephalopods (26%. Raneya brasiliensis (Kaup, 1856 was the most frequent and abundant species occurring in 58.6% of samples and constituting almost 50% of fish predated. Second in importance were Porichthys porosissimus (Cuvier, 1829 and Cynoscion guatucupa (Cuvier, 1830 in terms of occurrence (%FO 20.7 and numbers (29.6% respectively. The squid Loligo gahi (d'Orbigny, 1835 was the most frequent cephalopod prey (42.1%, whereas Octopus tehuelchus (d'Orbigny, 1834 was the most abundant (77%. The higher amount and diversity of prey found in the spring in comparison with the winter season might be related to a higher feeding activity of seals or to a seasonal increase in food availability in the area.La población del lobo marino de un pelo sudamericano Otaria flavescens (Shaw, 1800 ha experimentado un crecimiento continuo en las ultimas décadas en las costas de la Patagonia Argentina. Sin embargo, poco se conoce sobre la ecología trófica de la especie en el área. El objetivo de este estudio fue analizar los hábitos alimentarios de O. flavescens a partir de 91 fecas colectadas en la provincia de Río Negro, durante el invierno y la primavera del 2005. Los peces estuvieron presentes en el 96% de las fecas que contenían remanentes presas, seguidos por los cefalópodos (26%. Raneya brasiliensis (Kaup, 1856 fue la especie mas frecuente y abundante ocurriendo en el 58.6% de las muestras y constituyendo casi el 50% de los peces predados. Le siguieron en importancia Porichthys porosissimus (Cuvier, 1829 y

Expansión geográfica del síndrome pulmonar por hantavirus en la Argentina: Informe del caso más austral Geographic expansion of hantavirus pulmonary syndrome in Argentina: The southernest case report

Directory of Open Access Journals (Sweden)

Carla Bellomo

2009-12-01

Full Text Available Desde 1995 se han informado más de 1000 casos de síndrome pulmonar por hantavirus (SPH en la Argentina, enfermedad grave y muchas veces fatal para los humanos. La mayoría de los casos fueron asociados al virus Andes (AND único hantavirus que ha sido informado como causante de transmisión persona a persona. Se han descrito varios linajes patogénicos del virus AND, de los cuales AND Sur, cuyo reservorio es el roedor Oligoryzomys longicaudatus, afecta a la región patagónica de Argentina y Chile. En el presente estudio se informan las manifestaciones clínicas y las características epidemiológicas de un caso de SPH. El objetivo fue describir la presentación clínica del caso, su entorno epidemiológico, el sitio probable de contagio, la variante viral implicada y su relación con los casos más cercanos notificados. Se realizó el seguimiento clínico, el diagnóstico serológico y molecular y la investigación epidemiológica, incluyendo un estudio de la población de roedores reservorios en las áreas involucradas. Se trató de una presentación clásica de SPH moderada, causada por el linaje viral AND sur y su secuencia nucleotídica se comparó con casos del sur argentino y chileno. El caso de hantavirus investigado resultó ser el más austral (48° 46´ 1.2´´ S; 70° 15´ 0´´ O notificado hasta el momento e involucró a una nueva provincia argentina.Since 1995 more than 1000 cases of hantavirus pulmonary syndrome (HPS were reported in Argentina, a severe disease and often fatal to humans. Most cases were associated with Andes virus (AND that caused few events of person-to-person transmission. Several lineages of pathogenic AND viruses have been described, including AND South, hosted by the rodent Oligoryzomys longicaudatus which affects the Patagonian region of Argentina and Chile. We studied the clinical and epidemiological characteristics of a HPS case. The objective was to describe the clinical presentation of the case, its

Air-Sea CO2 fluxes in the Atlantic as measured during boreal spring and autumn

Directory of Open Access Journals (Sweden)

A. F. Ríos

2010-05-01

Oscillation episodes. Contrary the surface waters of the Patagonian Sea behaved as an intense sink of CO2 in March and November. The oceanic waters of the convergence of Falkland and Brazil Currents showed the strongest CO2 absorption with a rate of −5.4 ± 3.6 mol m−2 yr−1 in November. The Southern Oceans sampled in the Drake Passage behave as an average uptake rate of −1.1 ± 0.9 mol m−2 yr−1 while the distal shelf of the Livingston Island acted as a slight source of CO2 to the atmosphere.

Estrés oxidativo en cefalópodos: I. Determinación de TBARS Oxidative stress in cephalopods: I. TBARS determination

Directory of Open Access Journals (Sweden)

Anabella Victoria Fassiano

2012-12-01

predictive capability of showing the impact of pollutants on organisms. One of the most frequently used indexes to estimate the oxidative damage to lipids is the determination of reactive thiobarbituric acid substances (TBARs (fnal product of lipid peroxidation. Octopus tehuelchus is an important fshery resource in the Patagonian coast exposed to anthropogenic pollution. The study of oxidative stress parameters has not been yet tackled in this class of molluscs. Taking into account that, in many biological models, environmental pollutants generate oxidative stress, it is important to fnd their targets of action, to start to characterize metabolic and physiological alterations associated to their mechanisms of action. The aim of this work was to adjust the method of determination of oxidative damage to lipids in various tissues of the octopus, Octopus tehuelchus, from models previously tested in the laboratory.

Biogeography in deep time - What do phylogenetics, geology, and paleoclimate tell us about early platyrrhine evolution?

Science.gov (United States)

Kay, Richard F

2015-01-01

America has been a center for platyrrhine diversification since platyrrhines arrived on the continent in the middle Cenozoic. Platyrrhines dispersed from tropical South America to Patagonia at ∼25-24 Ma via a "Paraná Portal" through eastern South America across a retreating Paranense Sea. Phylogenetic bracketing suggests Antillean primates arrived via a sweepstakes route or island chain from northern South America in the Early Miocene, not via a proposed land bridge or island chain (GAARlandia) in the Early Oligocene (∼34 Ma). Patagonian and Antillean platyrrhines went extinct without leaving living descendants, the former at the end of the Early Miocene and the latter within the past six thousand years. Molecular evidence suggests crown platyrrhines arrived in Central America by crossing an intermittent connection through the Isthmus of Panama at or after 3.5Ma. Any more ancient Central American primates, should they be discovered, are unlikely to have given rise to the extant Central American taxa in situ. Copyright © 2013 Elsevier Inc. All rights reserved.

Bioaccumulation of photoprotective compounds in copepods: environmental triggers and sources of intra-specific variability

Science.gov (United States)

Zagarese, H. E.; García, P.; Diéguez, M. D.; Ferraro, M. A.

2012-12-01

Ultraviolet radiation (UVR) and temperature are two globally important abiotic factors affecting freshwater ecosystems. Planktonic organisms have developed a battery of counteracting mechanisms to minimize the risk of being damaged by UVR, which respond to three basic principles: avoid, protect, repair. Copepods are among the most successful zooplankton groups. They are highly adaptable animals, capable of displaying flexible behaviors, physiologies, and life strategies. In particular, they are well equipped to cope with harmful UVR. Their arsenal includes vertical migration, accumulation of photoprotective compounds, and photorepair. The preference for a particular strategy is affected by a plethora of environmental (extrinsic) parameters, such as the existence of a depth refuge, the risk of visual predation, and temperature. Temperature modifies the environment (e.g. the lake thermal structure), and animal metabolism (e.g., swimming speed, bioaccumulation of photoprotective compounds). In addition, the relative weight of UVR-coping strategies is also influenced by the organism (intrinsic) characteristics (e.g., inter- and intra-specific variability). The UV absorbing compounds, mycosporine-like amino acids (MAAs), are widely distributed among freshwater copepods. Animals are unable to synthesize MAAs, and therefore depend on external sources for accumulating these compounds. Although copepods may acquire MAAs from their food, for the few centropagic species investigated so far, the main source of MAAs are microbial (most likely prokaryotic) organisms living in close association with the copepods. Boeckella gracilipes is a common centropagic copepod in Patagonian lakes. We suspected that its occurrence in different types of lakes, hydrologically unconnected, but within close geographical proximity, could have resulted in different microbial-copepod associations (i.e., different MAAs sources) that could translate into intra-specific differences in the accumulation

Micro-phytoplankton photosynthesis, primary production and potential export production in the Atlantic Ocean

Science.gov (United States)

Tilstone, Gavin H.; Lange, Priscila K.; Misra, Ankita; Brewin, Robert J. W.; Cain, Terry

2017-11-01

Micro-phytoplankton is the >20 μm component of the phytoplankton community and plays a major role in the global ocean carbon pump, through the sequestering of anthropogenic CO2 and export of organic carbon to the deep ocean. To evaluate the global impact of the marine carbon cycle, quantification of micro-phytoplankton primary production is paramount. In this paper we use both in situ data and a satellite model to estimate the contribution of micro-phytoplankton to total primary production (PP) in the Atlantic Ocean. From 1995 to 2013, 940 measurements of primary production were made at 258 sites on 23 Atlantic Meridional Transect Cruises from the United Kingdom to the South African or Patagonian Shelf. Micro-phytoplankton primary production was highest in the South Subtropical Convergence (SSTC ∼ 409 ± 720 mg C m-2 d-1), where it contributed between 38 % of the total PP, and was lowest in the North Atlantic Gyre province (NATL ∼ 37 ± 27 mg C m-2 d-1), where it represented 18 % of the total PP. Size-fractionated photosynthesis-irradiance (PE) parameters measured on AMT22 and 23 showed that micro-phytoplankton had the highest maximum photosynthetic rate (PmB) (∼5 mg C (mg Chl a)-1 h-1) followed by nano- (∼4 mg C (mg Chl a)-1 h-1) and pico- (∼2 mg C (mg Chl a)-1 h-1). The highest PmB was recorded in the NATL and lowest in the North Atlantic Drift Region (NADR) and South Atlantic Gyre (SATL). The PE parameters were used to parameterise a remote sensing model of size-fractionated PP, which explained 84 % of the micro-phytoplankton in situ PP variability with a regression slope close to 1. The model was applied to the SeaWiFS time series from 1998-2010, which illustrated that micro-phytoplankton PP remained constant in the NADR, NATL, Canary Current Coastal upwelling (CNRY), Eastern Tropical Atlantic (ETRA), Western Tropical Atlantic (WTRA) and SATL, but showed a gradual increase in the Benguela Upwelling zone (BENG) and South Subtropical Convergence (SSTC

Compositional variations revealed by ASTER image analysis of the Viedma Volcano, southern Andes Volcanic Zone Variaciones composicionales reveladas mediante análisis de imágenes ASTER del volcán Viedma, Zona Volcánica Andina Austral

Directory of Open Access Journals (Sweden)

Chiaki Kobayashi

2010-07-01

Full Text Available We conducted a lithological mapping of the Viedma volcano, one of five volcanoes in the Andean Austral Volcanic Zone (AVZ, using remote sensing techniques. We used data of the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER sensor which is highly effective in geological research, to understand build-up processes and to deduce compositional variation of the Viedma volcano emerging from the South Patagonian ice field. The volcanic edifice was divided into bright parts that mainly compose the eastern flank of the volcano and dark parts at the central crater area based on the observation in visible and near infrared ranges. The SiO2 concentration was cal-culated using the bands in the visible and thermal infrared regions. The dark part and the bright part have approximately 51 wt% and 63 wt% average SiO2 content respectively, indicating that the exposures of the Viedma volcano have a wide variation in SiO2 concentration. Although, according to other authors, ejecta from the Viedma volcano have 64-66 wt% SiO2 and other AV Z volcanoes are essentially monolithologic dacite/andesite volcanoes, the edifice of the Viedma volcano appears to be composed mostly of basalts or older rocks/basement with low silica contents.Mediante el uso de técnica de sensoría remota se ha desarrollado un mapeo litológico del volcán Viedma, uno de los cinco volcanes de la Zona Volcánica Andina Austral (ZVA. Para este efecto, se ha utilizado el radiómetro ‘Advanced Spaceborne Thermal Emission and Reflection’ (ASTER que es muy efectivo en investigación geológica, para entender los procesos que han controlado la estructura y deducir las variaciones composi-cionales del volcán Viedma, que sobresale levemente de la superficie del campo de hielo Patagónico Sur. Sobre la base de la observación en el intervalo del espectro visible e infrarrojo cercano, en el edificio se distinguen partes brillantes que corresponden al flanco oriental del volcán y

Dissipation of Tidal Energy

Science.gov (United States)

2002-01-01

The moon's gravity imparts tremendous energy to the Earth, raising tides throughout the global oceans. What happens to all this energy? This question has been pondered by scientists for over 200 years, and has consequences ranging from the history of the moon to the mixing of the oceans. Richard Ray at NASA's Goddard Space Flight Center, Greenbelt, Md. and Gary Egbert of the College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Ore. studied six years of altimeter data from the TOPEX/Poseidon satellite to address this question. According to their report in the June 15 issue of Nature, about 1 terawatt, or 25 to 30 percent of the total tidal energy dissipation, occurs in the deep ocean. The remainder occurs in shallow seas, such as on the Patagonian Shelf. 'By measuring sea level with the TOPEX/Poseidon satellite altimeter, our knowledge of the tides in the global ocean has been remarkably improved,' said Richard Ray, a geophysicist at Goddard. The accuracies are now so high that this data can be used to map empirically the tidal energy dissipation. (Red areas, above) The deep-water tidal dissipation occurs generally near rugged bottom topography (seamounts and mid-ocean ridges). 'The observed pattern of deep-ocean dissipation is consistent with topographic scattering of tidal energy into internal motions within the water column, resulting in localized turbulence and mixing', said Gary Egbert an associate professor at OSU. One important implication of this finding concerns the possible energy sources needed to maintain the ocean's large-scale 'conveyor-belt' circulation and to mix upper ocean heat into the abyssal depths. It is thought that 2 terawatts are required for this process. The winds supply about 1 terawatt, and there has been speculation that the tides, by pumping energy into vertical water motions, supply the remainder. However, all current general circulation models of the oceans ignore the tides. 'It is possible that properly

Temporal variations in the diet of the exotic rainbow trout (Oncorhynchus mykiss in an Andean-Patagonian canopied stream Variación temporal en la dieta de la trucha exótica arco iris (Oncorhynchus mykiss en un arroyo forestado de los Andes patagónicos

Directory of Open Access Journals (Sweden)

LEONARDO M BURIA

2009-03-01

Full Text Available We examined seasonal and diel variation in prey species composition and biomass in the diet of the exotic rainbow trout Oncorhynchus mykiss (Walbaum, 1972. The study was carried out in the upper-forested sections of a low order stream in Andean-Patagonia. We studied the importance of functional feeding groups of aquatic invertebrates and the relative contribution of terrestrial and aquatic prey items in order to assess the pathways connecting terrestrial and aquatic ecosystems along a stream food web. Trout fed on approximately 40 invertebrate species and scrapers were consistently selected, suggesting their increased vulnerability to predation. However in terms of biomass, rainbow trout diet was mostly composed by shredders which emphasized the role of the allochthonous plant detritus pathway in food webs of forested small streams. Trout individuals fed more intensively in spring and summer and during daytime. Terrestrial items constituted a minor proportion of the diet implying that this component did not represent a significant subsidy for this fish population. As a consequence, the top-down effect on the aquatic community does not appear to be dampened since trout do not strongly preyed on terrestrial invertebrates.Se estudió la variación estacional y diaria en la composición y biomasa de las especies presa en la dieta de la exótica trucha arco iris Oncorhynchus mykiss (Walbaum, 1972 en la sección superior de un arroyo boscoso de bajo orden en los Andes patagónicos. Se analizó la importancia de los grupos funcionales alimentarios de invertebrados acuáticos y la contribución relativa de las presas de origen terrestre y acuático para evaluar las vías tróficas que conectan los ecosistemas acuático y terrestre circundantes. Las truchas consumieron aproximadamente unas 40 especies de invertebrados y los raspadores fueron consistentemente seleccionados, sugiriendo una alta vulnerabilidad a la depredación. Sin embargo en términos de biomasa, la dieta de la trucha arco iris fue mayormente compuesta de fragmentadores, enfatizando así el papel del detrito vegetal alóctono dentro de las tramas tróficas de pequeños arroyos boscosos. Los ejemplares de trucha capturados se alimentaron con mayor intensidad en primavera y verano y durante las horas del día. Los ítemes terrestres constituyeron una porción minoritaria en la dieta sugiriendo que este componente no representa un subsidio significativo para esta población de peces. Como consecuencia, los efectos del control "desde arriba" ("top-down" en la comunidad acuática no parecen ser amortiguados ya que las truchas no consumen intensamente presas de origen terrestre.

Paralichthys patagonicus spawning areas and reproductive potential in the Bonaerense Coastal Zone, Argentina (34°-42°S Áreas de desove y potencial reproductivo de Paralichthys patagonicus en la Zona Costera Bonaerense, Argentina (34°-42°S

Directory of Open Access Journals (Sweden)

María Inés Militelli

2011-01-01

Full Text Available The reproductive biology of Patagonian flounder (Paralichthys patagonicus was studied in the Bonaerense Coastal Zone (34°-42°S using samples collected in December 2003 and 2005. According to the literature, the data were analyzed considering two population groups: one in the northern zone (34°-38°S and another in El Rincón (38°-42°S. The estimated size at first maturity for both sexes in 2003 was 31.57 cm TL for the northern zone and 29.58 cm TL for El Rincón. In 2005, the L50 was only estimated for the northern zone, and the value obtained was less than that of 2003 (27.82 cm TL. In December 2003, the greatest reproductive activity took place in El Rincón. However, in December 2005, the highest proportions of hydrated fe-males were observed in the northern area. This could be due to the cooler temperatures recorded for this zone, as compared with 2003. Batch fecundity showed a potential fit to size and a lineal fit to weight and ranged from 14,685 (30 cm TL to 153,717 ( 59 cm TL hydrated oocytes. Relative fecundity oscillated between 24 and 170 hydrated oocytes/g. The values of these parameters differed between years and among population groups. These differences could be attributed in part to the difference in seawater temperature between the two years, especially the high temperatures observed in 2005.Se estudió la biología reproductiva del lenguado (Paralichthys patagonicus en la Zona Costera Bonaerense (34°-42°S. El material provino de muestreos realizados durante diciembre de 2003 y 2005. En base a la bibliografía los datos fueron analizados teniendo en cuenta dos grupos poblacionales, uno en el norte (34-38°S y otro en El Rincón (38-42°S. La estimación de la talla de primera madurez en 2003 para ambos sexos fue de 31.57 cm. LT para la zona norte y de 29.58 cm LT para El Rincón. En 2005 solo se pudo estimar el L50 para la zona norte y el valor obtenido fue menor al 2003 (27.82 cm. LT. En diciembre del 2003 la mayor

Traditional Mapuche ecological knowledge in Patagonia, Argentina: fishes and other living beings inhabiting continental waters, as a reflection of processes of change.

Science.gov (United States)

Aigo, Juana; Ladio, Ana

2016-12-07

Understanding how people interpret environmental change and develop practices in response to such change is essential to comprehend human resource use. In the cosmology of the American indigenous peoples, as among the Mapuche people, freshwater systems are considered a living entity, where animals have an enormous role to play in the universe of meaning. However, human adaptive responses to freshwater system dynamics are scarcely examined. In this work a survey is carried out in three Mapuche communities of Argentine Patagonia to assess their traditional knowledge of the fishes and other non-human living beings that inhabit lakes and rivers. Both material and symbolic aspects are included, as are the differences in knowledge and use of the fishes between past and present times. Our methods were based on a quali-quantitative fieldwork approach. In-depth interviews were carried out with 36 individuals from three rural Mapuche populations in Neuquén province (Patagonia, Argentina). Free listing was used for inquiring about fish knowledge and use. Fishes were identified scientifically and ethnotaxonomically. In-depth analysis of the discourses was conducted, documenting the recognition, perception, and cultural significance of fluvial environments and their inhabitants. Quantitative survey results were analyzed with categorical statistical methods. The body of knowledge of the communities studied reflects the socio-environmental changes experienced by Patagonian freshwater bodies. According to local perception, non-human beings live in these water bodies, guarding the environment, and they should not be disturbed. At present, five different fish species are identified, three of which are exotic, having been introduced at the beginning of the 20th century by the white man. These exotic trout (Oncorhynchus mykiss and Salvelinus fontinalis) are considered ill omens, indicators of the white man's presence, and therefore their appearance presages negative events for the

Seroprevalencia de hantavirus en roedores y casos humanos en el sur de la Argentina Hantavirus seroprevalence in rodents and human cases in southern Argentina

Directory of Open Access Journals (Sweden)

Edmundo Larrieu

2003-04-01

Full Text Available En la Provincia de Río Negro, Argentina, se presentaron casos humanos de síndrome pulmonar por hantavirus (SPH en la región de la cordillera andino patagónica. El virus Andes ha sido identificado en la región, tanto en el roedor Oligoryzomys longicaudatus como en seres humanos, demostrándose la transmisión principalmente del roedor al hombre y la factibilidad de la transmisión de persona a persona. El objetivo del presente trabajo es presentar nueva información sobre especies de roedores portadores de hantavirus en Argentina, su prevalencia de anticuerpos para hantavirus (período 1999-2001 y la relación del tamaño de las poblaciones de roedores y su seroprevalencia con la ocurrencia de casos humanos (período 1996-2001. Para ello, se procedió a la colocación de 3973 trampas para captura viva de roedores, tipo sherman en seis operativos efectuados entre octubre de 1999 y mayo de 2001. Se obtuvieron muestras de sangre de los roedores las que fueron procesadas mediante enzimoinmunoensayo con antígenos elaborados a partir de virus Andes. Una síntesis de los resultados indica 397 roedores capturados, con un éxito de trampeo del 10% y una prevalencia de anticuerpos contra hantavirus del 1.0%. Se observaron importantes diferencias en las especies capturadas en cada una de las regiones. Se capturaron O. longicaudatus y A. Olivaceus seropositivos y O. flavescens y C. Laucha potencialmente portadores de hantavirus Se registraron 6 casos humanos en el período 1993-1995 (correspondientes a estudios retrospectivos, 21 casos se notificaron en el período 1996-1998 y 6 en el período 1999-2001 Se analiza la correlación entre ocurrencia de casos humanos, seroprevalencia en roedores y éxito de trampeo.In the Province of Río Negro, Argentina, human cases of hantavirus pulmonary syndrome (HPS have occurred in the region of the Patagonian Andean range. The Andes virus has been identified in the region, both in the rodent Oligoryzomys

Respuesta dietaria de tres rapaces frente a una presa introducida en Patagonia Dietary response of three raptor species to an introduced prey in Patagonia

Directory of Open Access Journals (Sweden)

ANA L. MONSERRAT

2005-09-01

Predators with strong functional responses may be able to help stabilize prey population levels. This is worth noting mainly in the case of introduced prey, whose impact on native ecosystems often involves significant economic and environmental damage. The current Patagonian situation is critical with respect to introduced species. Previous studies have shown that native vertebrate predators are able to change their feeding patterns, switching from native to exotic prey. We assessed the food habits of the grey buzzard-eagle (Geranoaetus melanoleucus, the Magellanic horned owl (Bubo magellanicus, and the red-backed hawk (Buteo polyosoma, the three most important avian predators of the introduced European hare (Lepus europaeus in north-western Patagonia. We analysed 321, 115 and 78 eagle, owl, and hawk pellets respectively. We evaluated their functional responses to hare densities and compared their diets between different sites. Sigmodontine rodents were the hawk's and owl's main prey, followed by the tuco-tuco (Ctenomys spp.. The eagle consumed mainly European hares and then tuco-tucos, showing a significant functional response to the introduced prey. This raptor also had different diets in sites with high and low hare density. The other two raptors did not show a significant functional response to hare densities. However, the hawk's diet varied according to geographic location. We conclude that eagles and hawks are generalist predators, whereas the owl tends to specialize on small mammals. The changes in the eagle's diet in relation to European hare densities provide the potential to contribute to regulate the hare population

Slab-derived components in the subcontinental lithospheric mantle beneath Chilean Patagonia: Geochemistry and Sr-Nd-Pb isotopes of mantle xenoliths and host basalt

Science.gov (United States)

Jalowitzki, Tiago; Gervasoni, Fernanda; Conceição, Rommulo V.; Orihashi, Yuji; Bertotto, Gustavo W.; Sumino, Hirochika; Schilling, Manuel E.; Nagao, Keisuke; Morata, Diego; Sylvester, Paul

2017-11-01

In subduction zones, ultramafic xenoliths hosted in alkaline basalts can yield significant information about the role of potential slab-derived components in the subcontinental lithospheric mantle (SCLM). Chemical and isotopic heterogeneities in such xenoliths are usually interpreted to reflect melt extraction followed by metasomatic re-enrichment. Here we report new whole-rock major, trace element and isotopic (Sr-Nd-Pb) data for a Proterozoic suite of 17 anhydrous spinel-lherzolites and Eocene (new K-Ar data) host alkaline basalt found near Coyhaique ( 46°S), Aysén Region, Chile. These Patagonian nodules are located in a current back-arc position, 100 km east of the present day volcanic arc and 320 km from the Chile Trench. The mantle xenoliths consist of coarse- to medium-grained spinel-lherzolites with trace element compositions characteristic of a subduction zone setting, such as pronounced negative Nb, Ta and Ti anomalies coupled with significant enrichment of LILEs (e.g., U) and chalcophile elements (W, Pb and Sn). Most of them are characterized by flat to depleted light-rare earth element (LREE) patterns (Ce/YbN = 0.6-1.1) coupled with less radiogenic Sr-Pb (87Sr/86Sr = 0.702422-0.703479; 206Pb/204Pb = 18.212-18.539) and more radiogenic Nd isotopic compositions (143Nd/144Nd = 0.512994-0.513242), similar to the depleted mantle component (DMM or PREMA). In contrast, samples with slight LREE enrichment (Ce/YbN = 1.3-1.8) show more radiogenic Sr-Pb (87Sr/86Sr = 0.703791-0.704239; 206Pb/204Pb = 18.572-18.703) and less radiogenic Nd isotopic compositions (143Nd/144Nd = 0.512859-0.512934), similar to the EM-2 reservoir. These new geochemical and isotope data suggest that the Coyhaique spinel-lherzolites are derived from a heterogeneous SCLM resulting from mixing between a depleted mantle component and up to 10% of slab-derived components. The enriched component added to the SCLM represents variable extents of melts of both subducted Chile Trench sediments and

Comunidades microplanctônicas no Oceano Atlântico Sul Ocidental: biomassa e distribuição em novembro de 1992 Microplankton communities in the Southwestern Atlantic Ocean: biomass and distribution in November/1992

Directory of Open Access Journals (Sweden)

Luciano F. Fernandes

1999-01-01

.a/l. Adjacent waters showed low biomass indicating low productivity, with similar average values for Antarctic Water (0.18 J.1g/l and 8ubtropical Water (0.27 J.1g11, where a bloom of Trichodesmium erythraeum was detected. 8ubantarctic waters over the oceanic province around the Patagonian shelf represented a notable exception, with peaks in phytoplankton biomass (up to 2.46 J.1g Chl.a/l. Those areas of enhanced biomass were diatom-dominated; the Prymnesiophyceae Phaeocystis was abundant in some stations. Both fronts presented similar values of chlorophyll-a, indicating that environments with distinctive characteristics could support blooms of the same magnitude. Weakly silicified diatoms (Hemiaulus, Leptocylindrus, Thalassiosira dominated to the north of the BMCZ, while heavily silicified species (Asteromphalus, Chaetoceros aff.neglectus, Fragillariopsis kerguelensis, Proboscia, Pseudonitzschia sp., Rhizosolenia formed the buIk of phytoplankton at the PF, reflecting the different chemical characteristics of the water masses. The diatoms occurring in the PF appear to be recurrent and widely distributed along different longitudes over the Antarctic Circumpolar Current. Ciliates and heterotrophic dinoflagellates were dominant at 8ubtropical Water and to the north ofBMCZ, and seemed to respond quickly to the increasing phytoplankton biomass.

La privatización de YPF en Comodoro Rivadavia: Algunas características y consecuencias sociales y laborales The YPF privatization in Comodoro Rivadavia: Some social and laboral characteristics and consequences

Directory of Open Access Journals (Sweden)

Fernanda Torres

2012-06-01

in terms of the labour market, but also paying attention to the cultural, social, and political aspects that were also altered. First, I will present a brief description and analysis of the characteristics of the oil company's privatization, and of the peculiar production conditions it had in the Patagonian region. Then, I will stop on the different labor strategies which originated after the sale of the company, which are related to proposals of labor rehabilitation or of reconfiguration of the labor market structure, and on their results. Finally, I am interested in introducing the topic of the "indirect" consequences of the reconfiguration of the main economic company of the region, i.e. the redefinition of the main variables of the social, political, cultural, and economical life of the area. I am particularly interested in analyzing whether a change in the concept of "work" can be observed, and also the territorial displacements which occurred in the City of Comodoro and its area of influence. This analysis will be carried through the study of an unemployed people's movement of the region: "Coordinadora de Trabajadores Desocupados - Anibal Verón."

Estación Biológica Senda Darwin: Investigación ecológica de largo plazo en la interfase ciencia-sociedad Senda Darwin Biological Station: Long-term ecological research at the interface between science and society

Directory of Open Access Journals (Sweden)

MARTÍN R CARMONA

2010-03-01

bogs, Eucalyptus plantations and other anthropogenic cover types, constituting an agricultural frontier similar to other regions in Chile and Latin America. Since 1994, we have conducted long-term research on selected species of plants (e.g., Pilgerodendron uviferum and animals (e.g., Aphrastura spinicauda, Dromiciops glirioides that are considered threatened, poorly known or important for their ecological functions in local ecosystems, and on ecosystems of regional and global relevance (e.g., Sphagnum bogs, North Patagonian and Valdivian rain forests. Research has assessed the responses of species and ecosystems to anthropogenic land-use change, climate change, and the impact of management. During this period, more than 100 scientific publications in national and international journals, and 30 theses (graduate and undergraduate have been produced by scientists and students associated with SDBS. Because of our understanding of the key role that humans play in ecological processes at this agricultural frontier, since the establishment of SDBS we have been committed to creative research on the communication of science to society and ecological education. The integration of SDBS to the nascent Chilean network of long-term socio-ecological research will consolidate and strengthen basic and applied research to project our work into the next decade.

Microcrustacean assemblages composition and environmental variables in lakes and ponds of the Andean region - South of Chile (37-39° S Composição de comunidades de microcustáceos e variáveis ambientais em lagos e lagoas da região andina - sul do Chile (37-39° S

Directory of Open Access Journals (Sweden)

P. De los Ríos-Escalante

2011-05-01

Full Text Available The zooplankton assemblages in Chilean Patagonian lakes are characterised mainly by their low biodiversity and high predominance of calanoids copepods, a pattern that has been studied for large and deep lakes between 38-51° S, and shallow ponds at 51° S. The aim of the present study was analyse the zooplankton assemblages in different water bodies located in coastal zones, middle valleys and mountain zones between 37-39° S. For this purpose, the following variables were considered: maximum depth, latitude, altitude, chlorophyll-a and species number, and to these variables, a Principal Component Analysis (PCA was applied. A co-occurrence null model analysis was also applied for determining the existence of a random process in crustacean species associations. The results denoted low species richness, and different species associations for studied sites, and the null model analysis revealed the absence of a random process as regulator of species associations. Furthermore, a low species/genera ratio was identified, which denotes low productivity of the studied sites. These results were supported by a PCA analysis which denoted that the main determinant factors are chlorophyll concentration and species number that are directly associated. The obtained results are in agreement with descriptions in the literature for species diversity for lakes of Chilean Patagonia that describes oligotrophy as the main regulator of zooplankton assemblages. Other ecological and limnological topics are discussed in the present study.As comunidades zooplantônicas em lagos chilenos são caracterizadas, principalmente, por sua baixa biodiversidade e alta predominância de copépodos calanoides, um padrão que tem sido estudado em lagos grandes e profundos entre 38-51° S, e lagoas rasas em 51° S. O objetivo do presente estudo foi analisar as comunidades zooplantônicas em diferentes corpos de água localizados em zonas costeiras, vales intermediários e regiões de

Pleistocene changes in the fauna and flora of South america.

Science.gov (United States)

Vuilleumier, B S

1971-08-27

In recent years, the view that Pleistocene climatic events played a major role in the evolution of the biotas of southern, primarily tropical continents has begun to displace the previously held conviction that these areas remained relatively stable during the Quaternary. Studies of speciation patterns of high Andean plant and avian taxa (7-14) have led to the conclusion that Pleistocene climatic events were the factors that ultimately shaped the patterns now observed in the paramo-puna and the related Patagonian flora and fauna. The final uplift of the Andes at the end of the Tertiary automatically limits the age of the high Andean habitats and their biotas to the Quaternary. Within this period, the number of ecological fluctuations caused by the glaciations could easily have provided the mechanism behind the patterns now present in these habitats (Appendix, 1; Figs. 1 and 2; Table 1). In glacial periods, when vegetation belts, were lowered, organisms in the paramo-puna habitat were allowed to expand their ranges. In interglacial periods, these taxa were isolated on disjunct peaks, where differentiation could occur. At times of ice expansion, glacial tongues and lakes provided local barriers to gene exchange, whereas in warm, interglacial times, dry river valleys were a major deterrent to the interbreeding of populations on different mountains (Fig. 2; Table 2). A preliminary analysis of about 10 to 12 percent of the total South American avifauna (14), subsequent to the study of the high Andean biota, suggested that the birds of all the major habitats of the continent possess, with about equal frequency, similar stages of speciation. This correspondence in levels of evolution indicated that the avifauna of vegetation zones which were thought to have been more stable (for example, tropical rainforests) are as actively speciating as are those of the more recent paramo-puna habitats. More intensive work on lowland tropical taxa (16, 19-21) and recent work on montane

Identificación de los mecanismos subyacentes a la invasión de Castor canadensis (Rodentia en el archipiélago de Tierra del Fuego, Chile Identifying the mechanisms underlying the invasion of Castor canadensis (Rodentia into Tierra del Fuego archipelago, Chile

Directory of Open Access Journals (Sweden)

PETRA K WALLEM

2007-09-01

conceptual sobre el cual se pueden desarrollar futuras investigaciones referentes a esta invasiónCastor canadensis is considered an archetypical ecosystem engineer, which modifies the state of biotic and abiotic factors through non-trophic interactions. This species was introduced by the Argentinean government into Tierra del Fuego island in 1946, and subsequently colonized autonomously the neighboring islands of Navarino, Dawson and Hoste. Currently this invader occupies contrasting ecosystems such as the Magellan subpolar beech forest and Patagonian scrub and steppe. This ability to colonize contrasting habitats suggests that beaver expansion will be limited mainly by hydrological resources, threatening to colonize the complete extent of temperate beech forests on the mainland (from 35 to 55° S. The present review proposes three hypotheses regarding the underlying mechanisms to this successful invasion: natural enemy escape, resource opportunities, and self-facilitation through non-trophic interactions. Current knowledge regarding beaver colonization and foraging behavior (e.g., habitat selection independently of forest availability, irruptive population growth, and apparent selective exploitation of Nothofagus pumilio, dominant species in the Magellan forest suggests that enemy escape and resource opportunity are the main mechanisms underlying this invasion. The observation of higher densities of active colonies, where the extent of beaver habitat modification is larger, suggests that self-facilitation may be relevant to the success of this invasion. Current information does not allow testing these hypotheses, but it provides a framework to develop future investigations regarding this invasion in Tierra del Fuego

High resolution analysis of northern Patagonia lake sediments

Science.gov (United States)

Jarvis, S. W.; Croudace, I. W.; Langdon, P. G.; Rindby, A.

2009-04-01

Sediment cores covering the period from the last glacial maximum through the Holocene to the present have been collected from sites in the Chacubuco valley, southern Chile (around 47°08'S, 72°25'W, to the east of the North Patagonian Icecap). Cores were taken from five lakes and one recently dried lake bed. Short cores (0.2 to 0.5m), covering approximately the last two hundred years, were taken from all the lakes. Additionally, long sequences were obtained from one of the lakes and from the dried lake bed, the latter sequence extending back to the last glacial maximum as indicated by thick clay at the base. Each of the lakes are small-medium sized and are open systems situated at 300-1000m above sea level. The shorter cores comprise predominantly clastic gyttja but show a number of distinct changes in colour and chemical composition that suggest major environmental changes over the period of sediment accumulation. This is also reflected in variations in the loss on ignition of samples from the cores and in elemental profiles produced by scanning the cores with the Itrax micro-XRF corescanner at 200μm resolution. The long sequence from the dried lake bed has very low organic content glacial clay at the base, interpreted as last glacial maximum basal clay following determination in the field that this layer exceeded 2m in thickness. Similar sediments occur within a stratigraphically discrete section of approximately 14cm and may relate to a stadial event. The latter section also shows a drop in organic content and appears to be glacial clay incorporating some coarse sandy components indicative of detrital input from the catchment. The second long sequence, from a carbonate lake, includes two mineral layers indicating increased detrital input from the catchment. The deeper and thicker of these layers appears similar to the 14cm layer in the first long sequence, while the upper layer comprises a fine grain size indicative of rock flour and hence also of glacial

Efecto de la estructuración por macrófitas y por recursos alimentarios en la distribución horizontal de tecamebas y rotíferos en un lago andino patagónico Effect of macrophytes and food resources on the horizontal distribution of testate amoebae and rotifers in an Andean-Patagonian lake

Directory of Open Access Journals (Sweden)

MARCELA BASTIDAS-NAVARRO

2007-09-01

Full Text Available La presencia de macrófitas en la zona litoral lacustre trae aparejada condiciones diferentes con respecto a la zona pelágica, en particular en la disponibilidad de recursos. Por esta razón, las zonas litorales pueden presentar una mayor biodiversidad. En este trabajo se analizó la distribución horizontal de tecamebas y rotíferos en el lago Escondido (Argentina, vinculándola con los recursos alimentarios presentes en las diferentes zonas. Se tomaron muestras para el estudio del fitoplancton y zooplancton durante verano y primavera (2001-2003 en cuatro estaciones litorales y una pelágica. Se realizó el recuento de rotíferos y tecamebas y se determinó la abundancia y la biomasa fitoplanctónica. Los recursos alimentarios fueron clasificados en nanoplancton ( 20 μm. El nanoplancton estuvo compuesto por nanoflagelados y el fitoplancton de red por diatomeas, cianófitas y clorófitas. La biomasa de estas fracciones varió significativamente, observándose una predominancia del nanoplancton en la zona pelágica y del fitoplancton de red en la zona litoral. Los mayores valores de riqueza y de diversidad de tecamebas y rotíferos fueron observados en las estaciones litorales, no hallándose diferencias significativas entre las zonas con diferentes macrófitas. El análisis de ACC evidenció cuatro grupos. Por un lado, Keratella cochlearis, Synchaeta spp., Polyarthra vulgaris y Collotheca mutabilis, asociadas a las muestras pelágicas, se relacionaron con una alta abundancia de nanoplancton. Por otro lado, los rotíferos Trichocerca spp., Lecane spp. y Euchlanis spp., y las tecamebas Dijflugia pyriformis y Trinema enchelys se relacionaron con el fitoplancton de red y las muestras litorales. Además, un tercer grupo reunió a especies (Lecane spp. y Arcella spp. presentes en ambas zonas y en relación con una baja abundancia del fitoplancton de red. Por último, el rotífero Synchaeta spp. y las muestras pelágicas de primavera se relacionaron con el aumento de la abundancia de la cianofita Coelosphaerium kuetzingianum. Las diferencias señaladas indican que los recursos alimentarios serían un factor determinante en la distribución de especies de tecamebas y rotíferos en el lago Escondido. Para estos zoopláncteres de pequeño tamaño las macrófitas litorales brindarían alimento al favorecer el incremento del fitoplancton de redThe presence of macrophytes in the littoral zone of lakes produces particular conditions including higher resource availability for consumers. For this reason, the littoral zone is generally the area with the highest diversity of lakes and rivers. In this work we studied the horizontal distribution of testate amoebae and rotifers in Lago Escondido (Argentina in relation to food resources availability. The study was carried out along a north-south transect that includes the littoral and the pelagic zone of the lake. Phytoplankton and zooplankton were sampled during summer and spring (2001-2003 in five sampling stations: one pelagic and four littoral. Rotifers and testate amoebae, as well as phytoplanktonic algae abundance and biomass were estimated. Food resources were classified as nanoplankton ( 20 μm and the biovolume of these fractions varied significantly within the pelagic and littoral zones of the lake. Nanoplankon dominated the pelagic zone and was mainly composed by nanoflagellates while net phytoplankton prevailed in the littoral zone and was composed by diatoms, cyanophytes and chlorophytes. The highest number of species and diversity of testate amoebae and rotifers were observed in the littoral stations; nevertheless, no significant differences between the zones colonized by different macrophytes were observed. The CCA analysis showed four different groups. Keratella cochlearis, Synchaeta spp., Polyarthra vulgaris and Collotheca mutabilis characterized the pelagic samples and were related with a high abundance of nanoplankton. On the other hand, rotifers like Trichocerca spp., Lecane spp. and Euchlanis spp. and the testate amoebae Dijflugia pyriformis and Trinema enchelys associated with the littoral samples were related with high abundances of net phytoplankton. Besides, a third group of species {Lecane spp. and Arcella spp., presented in both zones, was mainly related with a decrease in abundance of net phytoplankton. Finally, the rotifer Synchaeta spp. was associated with the spring pelagic samples when the cyanophyte Coelosphaerium kuetzingianum increased its abundance. Summarizing, in Lago Escondido, food resources could be an important factor driving testate amoeba and rotifer distribution. Therefore the major role of macrophytes for this small-bodied zooplankton is food supply through an increment of net phytoplankton

Paleomadrigueras de roedores, un nuevo método para el estudio del Cuaternario en zonas áridas de Sudamérica Rodent middens, a new method for Quaternary research in arid zones of South America

Directory of Open Access Journals (Sweden)

Julio L. Betancourt

2002-09-01

formadores. Basados en la experiencia Norteamericana entregamos además, un resumen de los métodos existentes para la detección y análisis de dichos depósitos, los sesgos asociados, así como el aporte potencial que su análisis podría representar en futuros estudios paleoecológicos en las zonas áridas y semiáridas de SudaméricaIn arid and semi-arid regions of South America, historical evidence for climate and vegetation change is scarce despite its importance for determining reference conditions and rates of natural variability in areas susceptible to modern desertification. Normal lines of evidence, such as pollen stratigraphies from lakes, are either rare or unobtainable in deserts; studies of late Quaternary vegetation history are few and generally inconclusive. This gap in knowledge may be corrected with discovery and development of fossil rodent middens in rocky environments throughout arid South America. These middens, mostly the work of Lagidium, Phyllotis, Abrocoma and Octodontomys, are rich in readily identifiable plant macrofossils, cuticles and pollen, as well as vertebrate and insect remains. In the North American deserts, more than 2,500 woodrat (Neotoma middens analyzed since 1960 have yielded a detailed history of environmental change during the past 40,000 years. Preliminary work in the pre-puna, Monte and Patagonian Deserts of western Argentina, the Atacama Desert of northern Chile/southern Peru, the Mediterranean matorral of central Chile, and the Puna of the Andean altiplano suggest a similar potential for rodent middens in South America. Here we borrow from the North American experience to synthesize methodologies and approaches, summarize preliminary work, and explore the potential of rodent midden research in South America

Mio-Pliocene glaciations of Central Patagonia: New evidence and tectonic implications Glaciaciones mio-pliocenas en Patagonia central: nueva evidencia e implicancias tectónicas

Directory of Open Access Journals (Sweden)

Yves Lagabrielle

2010-07-01

Full Text Available Patagonia is well known for spectacular oceurrences of a variety of glacial-derived landforms and deposits and for a long history of ancient glaciations. In this paper, we first review the diverse evidence that demonstrates the development of glacial-related sedimentary units within the Central Patagonian Cordillera since 7 Ma. Well preserved glacial landforms at the top surface of mesetas on both sides of the Lago General Carrera-Buenos Aires are described: the Meseta Guenguel to the north, and the volcanic Meseta del Lago Buenos Aires to the south. The latter meseta corresponds to a 3 Ma old, morphologically inverted paleo-piedmont, based on Ar/Ar dates of the uppermost lava flows. It shows evidence of glacier advances to the NE direction. Over a distance of 20 km, glacial landforms observed by remote sensing data and digital elevation model define glacial tongues that were fed by the Cordillera reliefs to the west. These lobes are now beheaded from their westward sources along a morpho-structural corridor that bounds the Meseta del Lago Buenos Aires to the west. These remnants can be correlated with the oldest glacial landforms recognized north of Lago General Carrera-Buenos Aires, on the Meseta Guenguel that form the Chipanque moraine system. From these features it is concluded that the glacial drainage network of Central Patagonia has been strongly modified following relief inversion in response to erosion processes and to tectonic causes. Changes occurred after 3 Ma, from a smooth piedmont surface covered by an extensive ice mantle ending with ampie glacial lobes, to the current series of deeply incised glacial valleys such as the Lago General Carrera-Buenos Aires depression. These new data bear important con-straints on the history and development of the first glaciations in southern South America.Patagonia es bien conocida por una espectacular geomorfología glacial y por una larga historia de antiguas glaciaciones. En este art

Quantifying coastal erosion rates using anatomical change in exposed tree roots at Porquerolles Island (Var, France).

Science.gov (United States)

Morel, Pauline; Corona, Christophe; Lopez-Saez, Jérôme; Rovéra, Georges; Dewez, Thomas; Stoffel, Markus; Berger, Frédéric

2017-04-01

tree roots: Two examples from central Spain. Catena 64 : 81-102. Fantucci R. 2007. Dendrogeomorphological analysis of shore erosion along Bolsena lake (central Italy). Dendrochronologia 24 : 130-140. Giuliano J. Érosion des falaises de la région Provence-Alpes-Côte d'Azur : évolution et origine de la morphologie côtière en Méditerranée : télédétection, géochronologie, géomorphologie. Sciences de la Terre. Université Nice Sophia Antipolis, 2015. Français. . Hitz O, Gärtner H, Heinrich I, Monbaron M, 2008a. Application of ash (Fraxinus excelsior l.) roots to determine erosion rates in mountain torrents. Catena 72 : 248-258. Lopez Saez J, Corona C, Stoffel M, Rovéra G, Astrade L, Berger F. 2011. Mapping of erosion rates in marly badlands based on a coupling of anatomical changes in exposed roots with slope maps derived from LiDAR data. Earth Surface Processes and Landforms 36 : 1162-1171. Lucía, A., Laronne, J. B., & Martín-Duque, J. F. (2011). Geodynamic processes on sandy slope gullies in central Spain field observations, methods and measurements in a singular system. Geodinámica acta, 24(2), 61-79. Malik I. 2008. Dating of small gully formation and establishing erosion rates in old gullies under forest by means of anatomical changes in exposed tree roots (Southern Poland). Geomorphology 93 : 421-436.
 Malik I. 2006. Gully erosion dating by means of anatomical changes in exposed roots (Proboszczowicka plateau, Southern Poland). Geochronometria 25 : 57-66. Stoffel M, Casteller A, Luckman B H, Villalba R, 2012. Spatiotemporal analysis of channel wall erosion in ephemeral torrents using tree roots - An example from the Patagonian Andes. Geology40 : 247-250. Vandekerckhove L. 2001. Short-term bank gully retreat rates in Mediterranean environments. Catena 44 : 133-161.

Nevadas en el Sudeste Bonaerense: climatología sinóptica y un caso de estudio

Directory of Open Access Journals (Sweden)

Paola Salio

2006-12-01

present weather information 32 events were found and only 7 events show snow over more than one synoptic station. A synoptic climatology of the cold air incursions that are responsible for snow-fall in the study region is shown in order to understand the circulation patterns. Atmospheric circulation patterns are characterized by extreme anomalies linked to the trough associated to cold front and the ridge in post-frontal areas that denote the intensity of these systems,. The anomalies field of geopotencial height shows a negative extreme over the frontal trough in the cases of generalized snow duplicate the intensity in cases with isolated snow. The intense cyclonic regime favors the convergence at low levels and the strong cooling, evident in the anomalies of temperature at mid-levels, indicating the instability generated in the air mass that is lead towards the northern Patagonian coast and the Argentinean Sea. A case study of a generalized snow-fall related to a strong cold air incursion occurred on 10 July 2004 over the Southeast coast of the Buenos Aires province. The synoptic situation is analyzed in relation to the long period sample and the polar air mass evolution is characterized using RAMS model in a diagnostic mode. The snow-fall is related to a persistent destabilization favored by heating and moisturizing in a prevalently maritime trajectory and by convergence in a cyclonic regime.

Oligotrophic patterns in southern Chilean lakes: the relevance of nutrients and mixing depth Patrones oligotróficos en lagos del sur de Chile: relevancia de los nutrientes y de la profundidad de mezcla

Directory of Open Access Journals (Sweden)

DORIS SOTO

2002-06-01

Full Text Available Southern Chilean monomictic, temperate lakes are generally oligotrophic with high water transparency, low productivity and some apparent resistance to disturbances such as phosphorus additions. This paper attempts to explain low chlorophyll-a values using descriptive and experimental approaches. Three different scales are used, (a a micro scale both in space and time, with experimental manipulations of N, P and total light in 24 enclosures in lake Llanquihue, (b a longer time scale analysing 18 months of data in several sites within lake Llanquihue grouped as salmon farming sites, town bays and control sites, and (c a broader time scale (9 years by monitoring lakes Puyehue, Rupanco and Llanquihue, all in the Araucanian lake region and Yelcho lake in the north Patagonian region. In the Llanquihue in-lake sampling, total phosphorus values varied between 1 and 12 mug L-1 between sites, showing marginal site effects, P = 0.09 (salmon sites had greater values, however, chlorophyll a (Chl-a concentrations were generally low (Los lagos monomicticos templados del sur de Chile son generalmente oligotróficos de gran transparencia, baja productividad y aparente resistencia a perturbaciones tales como adiciones de fósforo. Este trabajo intenta explicar los bajos valores de clorofila de acuerdo a aproximaciones descriptivas y experimentales. Se utilizan aquí tres escalas de aproximación; (a una microescala en espacio y tiempo con manipulaciones experimentales de nitrógeno (N, fósforo (P y luz en 24 limnocorrales ubicados en una bahía del lago Llanquihue, (b una escala mayor analizando 18 meses de muestreo en 10 sitios del lago Llanquihue agrupados como sitios de cultivo de salmones, bahías de ciudades y sitios de control, (c una escala aún mayor en tiempo y espacio monitoreando semestralmente por 9 años los lagos Puyehue, Rupanco, Llanquihue en la región de los Lagos Araucanos y el lago Yelcho en la región nor- patagónica. En el muestreo intra

Diplodon shells from Northwest Patagonia as continental proxy archives: Oxygen isotopic results and sclerochronological analyses

Science.gov (United States)

Soldati, A. L.; Beierlein, L.; Jacob, D. E.

2009-04-01

Freshwater mussels of the genus Diplodon (Bivalvia, Hyriidae) are the most abundant bivalve (today and in the past) in freshwater bodies at both sides of the South-Andean Cordillera. There are about 25 different Diplodon genera in Argentina and Chile that could be assigned almost completely to the species Diplodon chilensis (Gray, 1828) and two subspecies: D. ch. chilensis and D. ch. patagonicus; this latter species is found in Argentina between Mendoza (32˚ 52' S; 68˚ 51' W) and Chubut (45˚ 51' S; 67˚ 28' W), including the lakes and rivers of the target area, the Nahuel Huapi National Park (Castellanos, 1960). Despite their wide geographic distribution, Diplodon species have only rarely been used as climate archives in the southern hemisphere. Kaandorp et al. (2005) demonstrated for Diplodon longulus (Conrad 1874) collected from the Peruvian Amazonas that oxygen isotopic patterns in the shells could be used in order to reconstruct the precipitation regime and dry/wet seasonal of the monsoonal system in Amazonia. Although this study demonstrated the potential of Diplodon in climatological and ecological reconstructions in the southern hemisphere, as of yet, no systematic study of Diplodon as a multi-proxy archive has been undertaken for the Patagonian region. In this work we present sclerochronological analyses supported by ^18Oshell in recent mussel of Diplodon chilensis patagonicus (D'Orbigny, 1835) collected at Laguna El Trébol (42°S-71°W, Patagonia Argentina), one of the best studied water bodies in the region for paleoclimate analysis. Water temperature was measured every six hours for one year using a temperature sensor (Starmon mini®) placed at 5m depth in the lake, close to a mussel bank. Additionally, ^18Owater was measured monthly for the same time range.g^18Oshell values obtained by micro-milling at high spatial resolution in the growth increments of three Diplodon shells were compared to these records, and to air temperature and

Determinación de nitrógeno inorgánico y fosfatos a distintas profundidades de suelo bajo pilas de abonos Determination of inorganic nitrogen and phosphates at different soil depths beneath manure piles

Directory of Open Access Journals (Sweden)

Javier Luis Ferrari

2012-12-01

meses de invierno.In the Andean - Patagonian region, nutrient supply for different crops is frequently made using wood chips mixed with manure. These materials are accumulated in piles of 1.5 - 2 m height. As the piles remain for a period of time outdoors, a partial composting may occur, which would be beneficial. Composting is a biooxidative process, involving an organic substrate, a thermophilic phase that must be reached (55°C and a maturity stage. If the manure piles remain outdoors, nutrients can also be transported by water and lost from the soil through percolation (particulary during winter months of higher precipitations. With the objective of studying if extractable phosphorus in NaHCO3 0.5M (P-Ol of phosphorus Olsen and inorganic nitrogen (Nin;ammonium plus nitrates move beneath the piles of manure, composites soil samples were taken from three blocks at different depths in a farm near the town of El Bolsón. The relationship between P-Ol (agronomic threshold and extractable P in 0.01 M CaCl2 (environmental threshold was also studied. Manure temperatures were taken in different seasons. Nin showed a high data dispersion and excessively high mean values up to the 200 cm depth. Average values (of three blocks found for P exceeded the threshold limit of 60 mg kg-1 P-Ol only on the first sampling date in the 0-20cm depth, although individual data for each block reached 52 mg kg-1 in the 40-60 cm depth. A statistically significant linear regression between P-Ol and P-CaCl2 in soils was obtained, and a threshold near 50/60 mg kg-1, similar to the values reported in the literature. High values for both parameters were found in manures. It is advisable to protect piles of manure from rainfall in winter months.

Variaciones glaciales durante el Holoceno en Patagonia Central, Aisén, Chile: evidencias geomorfológicas Holocene glacial variations in Central Patagonia, Aisén, Chile: geomorphological evidences

Directory of Open Access Journals (Sweden)

María Mardones

2011-07-01

en la temperatura y precipitación atmosférica.During the Holocene, the patagonian glaciers were characterized by geomorphologically registered advances and retreats. This paper presents the geomorphological evolution and evidences of Holocene glacial advances within a segment in Central Patagonia Cordillera. This area will be used as a reference for studying the postglacial paleoclimatic evolution in the southernmost part of South America. The study area is the río Blanco basin (45°30'S, located in Central Patagonia (Aisén Region, Chile. Radiometric dating of organic sediments, within terminal moraines, provides preliminary data of two glacial advances. The first one is represented by the Lake Elizalde frontal moraine, which yielded a 14C age of 9.370±50 years BP (10,700 to 10,480 cal. yr BP. According to this chronological age, this glacial event took place in the Early Holocene. This glacial advance, being 100 to 200 years older than that observed immediately south of the study area, on the eastern edge of General Carrera Lake (or Buenos Aires Lake, in Argentina and approximately 100 years younger than the event recorded in the Puerto Banderas I moraine (Argentino Lake, 50°S. These results show that the behavior patterns of the Central Patagonia glaciers differ from that observed both in the Lake District (41°S, Chile and in the Magallanes District (54°S, Chile, where there are no traces of glacial readvancement recorded during the Early Holocene. After a major retreat to the west, a more recent glacial advance occurred in the Quetro river valley (a tributary river of the Blanco river, at an age prior to 2.250±40 BP (2.340 to 2.150 cal. yr BP, comparable to the cold stage of the Middle Neoglacial, interpreted to have occurred in different parts of Patagonia. Confronting these results with previously published pollen records, we postulate that the cause of both glacier fluctuations are regional variations in the atmospheric temperature and precipitations.

Leaf phenology and its associated traits in the wintergreen species Aristotelia chilensis (Mol. Stuntz (Elaeocarpaceae Fenología foliar y sus caracteres asociados en la especie invierno-verde Aristotelia chilensis (Mol. Stuntz (Elaeocarpaceae

Directory of Open Access Journals (Sweden)

MARÍA ANGÉLICA DAMASCOS

2001-12-01

Full Text Available The post-summer leaf demography of the wintergreen species Aristotelia chilensis growing near San Carlos de Bariloche, Argentina, is described. Its specific leaf mass (SLM, g m-2 is compared to that of the deciduous and evergreen species of the Andean-Patagonian forests and to that of other communities abroad. The pattern of leaf emergence is intermediate, with leaf flush in spring (basal cohort, BC, followed by successive unfolding of the remaining leaves (distal cohort, DC during summer. The senescence of the BC occurs mainly in autumn, with a loss of 11-31 % of its SLM. The DC falls synchronously in mid-spring and the SLM loss in winter is 10-13 %. The SLM of A. chilensis (103.6 ± 6.2 g m-2 is intermediate when compared to the general mean values of deciduous (73.7 ± 15.9 g m-2 and evergreen species (154.8 ± 45.8 g m-2. The SLM of deciduous and evergreen species of three different forests near San Carlos de Bariloche varied significantly at the end of the growing season while that of A. chilensis showed more constant values. The periodicity of leaf production and senescence in A. chilensis allows the maintenance of one leaf cohort throughout the year, covering the carbon demand for flowering and leaf production in spring. This differentiates the deciduous from the wintergreen species, despite their similar mean leaf life span values, while the evergreen species have a longer leaf turnover. Considering the conditions for growth in each studied forest, the leaf life span was not the only factor determining the SLM value. This variable would also depend on multiple stresses that may act during the ontogenesis and evolution of the leaves in each phenological groupSe describe la demografía foliar después del verano de la especie invierno-verde Aristotelia chilensis, creciendo cerca de la ciudad de San Carlos de Bariloche, Argentina. Se compara su peso específico foliar (SLM, g m-2 con los valores de especies deciduas y siempreverdes de los

Contributions of GRACE to Climate Monitoring

Science.gov (United States)

Rodell, Matthew; Famiglietti, James; Chambers, Don P.; Wahr, John

2011-01-01

western Antarctica. For 2002 to present, the rate of ice mass loss has been 200 to 300 GT/yr in Greenland and 70 to 210 GT/yr in Antarctica, and some scientists are suggesting that the rates are accelerating. Similarly, GRACE has been used to monitor mass changes in alpine glaciers. Tamisiea et al. first characterized glacier melt along the southern coast of Alaska, more recently estimated to be occurring at a rate of 84 GT/yr. Chen et al. estimated that Patagonian glaciers are melting at a rate of 28 GT/yr, and estimated that the high mountains of central Asia lose ice at a rate of 47 GT/yr. Tapley et al. and Wahr et al. presented the first GRACE based estimates of changes in column-integrated terrestrial water storage (TWS; the sum of ground-water, soil moisture, surface waters, snow, ice, and water stored in vegetation) at continental scales. Since then, dozens of studies have shown that GRACE based estimates of regional to continental scale TWS variations agree with independent information, and some innovative uses of GRACE data have been developed. Rodell et al. (2004) and Swenson and Wahr (2006) demonstrated that by combining GRACE derived terrestrial water storage changes with observations of precipitation and runoff in a river basin scale water budget, it was possible to produce new estimates of evapotranspiration and atmospheric moisture convergence, essential climate variables that are difficult to estimate accurately. Similarly, GRACE has been used to constrain estimates of global river discharge and the contribution of changes in TWS to sea level rise. Crowley et al. observed a negative correlation between interannual TWS anomalies in the Amazon and the Congo River basin. Yeh et al. and Rodell et al. estimated regionally averaged groundwater storage variations based on GRACE and auxiliary observations. Rodell et al. and Tiwari et al. applied that method to quantify massive groundwater depletion in northern India caused by over reliance on aquifers for irration

Caracterización geosísmica de un sector de traza de la Ruta Nº 40: Provincia de Santa Cruz - Argentina

Directory of Open Access Journals (Sweden)

Armando Luis Imhof

2010-12-01

determination permitted to assess blasting or ripper. The study area presents a typical steppe patagonian landscape with basaltic formations indicating old volcanism. At surface, fine to medium-coarse alluvial soil was observed detecting on occasions organic material and besides great basaltic rocks spreading somewhere. Fifty seismic arrays were performed, deployed linearly one after the other along the trace. At each one, five records were taken, symmetrically upon the array center. Geophones and shooting points were determined upon prior proofs tests and space availability. Generally array extension ranged among 25m and 100m, being 5m the geophone gap, allowing thus a great survey detail. The amount and distribution of shootings had for objective to calculate with utmost precision apparent velocities and their true ones derived; refractor inclinations and rock basement; assuring at least a 15m depth investigation. At the processing stage, first picking were determined, which were displayed versus geophones distances, i.e. time-distance or 'dromocrone' graphs. After calculating critical distances, apparent velocities, were estimated. Then, two interpretation methods were carried through: Intercept Time Method (ITM; and Generalized Reciprocal Method (GRM. With the latter, true velocities and depths beneath each geophone were calculated, and with the former, beneath each shot-point, extending so the determinations. The correlation with geologic data was performed using visual inspection and very scarce geologic information available. At last, seismic profiles were developed in separate form according to trace outreaching showing lateral and in-depth variations of compression wave velocity. In both survey areas, two well different layers were detected, being the first a thin sand-muddy alluvial fill-up and the inferior, altered rock (basalt (Zone 1; or compact alluvial terrain, wet to saturated. Information supported by geoseismic refraction method using GRM with 5 emission