Southern Tierra Del Fuego Research Articles

Morphological and molecular data reveal the presence of exotic land snail species in Tierra del Fuego

In the present study, we report for the first time the presence of Vitrina pellucida and Arion silvaticus as invasive species in Isla Grande of Tierra del Fuego, Argentina. Additionally, our research confirmed the presence in the same region of Deroceras reticulatum a previously reported invasive species from continental Patagonia. Taxonomic identification was achieved through morphological and molecular analyses (ribosomal 5.8S-ITS2-28S region and 16S rRNAgene). The finding of V. pellucida constitutes the first record of Vitrinidae for South America. This species is already naturalized in southern Tierra del Fuego and invaded natural areas of the National Park but still with small populations. In the case of Arion silvaticus, we observed a comparable situation, as this species has not only been collected from urban areas but also from within the forests of the protected area. These exotic species of land snails are exclusively cold-adapted Pulmonates. Their feeding types and diets range from herbivores on fresh plant material to omnivorous, occasionally on dead animals. The native micro snail species, coexisting in the same habitats, due to their minimal dispersal capacity and probable dependence on particular microhabitats, are particularly vulnerable not only to anthropogenic disturbances but also to the impacts and activities of these exotic species. Given the tourist impact in the region, the introduction of V. pellucida and Arion silvaticus in Tierra del Fuego has most likely occurred through accidental transport in soil by tourists arriving on the island. Another possible pathway of introduction is plant transportation.

Distribution, Nesting Records, and Notes on the Ecology of the White-Throated Caracara (Phalcoboenus albogularis)

ABSTRACT Endemic to Patagonia, the White-throated Caracara (Phalcoboenus albogularis) is one of the least studied caracara species, with several aspects of its ecology, such as breeding biology and diet, largely unexplored. Using citizen science records and opportunistic observations, we obtained data on the breeding biology, nest sites, and diet of the species in Chile and Argentina. Nests were in rocky outcrops and cliffs, and aspects of diet corroborated others’ observations that this species feeds on live prey as well as carrion. The species’ nesting season apparently begins in September and ends in March, with some regional variation. The modal brood size is two, and many nests apparently are used across multiple years. Using citizen science data, we created the first distribution models for the White-throated Caracara, one for the breeding season and one for the winter season. The species predominantly occupies the highland plateaus of western Santa Cruz Province, Argentina, and the Andes Range from around 40° south to southern Tierra del Fuego. The models indicate a mostly consistent distribution without significant latitudinal changes between seasons and, apparently, only a limited transition to lower-elevation areas east of the Andes in winter. In both seasons, this caracara is associated primarily with barren rocky areas and Andean and sub-Andean herbaceous steppe—all open environments—rather than forested areas as has been thought previously. This study provides new knowledge of this regional endemic yet the species remains a poorly known raptor in southern South America. Additional and on-the-ground field research would likely produce benefits when addressing species-related conservation issues.

Mapping Soil Organic Carbon Content in Patagonian Forests Based on Climate, Topography and Vegetation Metrics from Satellite Imagery

Soil organic carbon (SOC) content supports several ecosystem services. Quantifying SOC requires: (i) accurate C estimates of forest components, and (ii) soil estimates. However, SOC is difficult to measure, so predictive models are needed. Our objective was to model SOC stocks within 30 cm depth in Patagonian forests based on climatic, topographic and vegetation productivity measures from satellite images, including Dynamic Habitat Indices and Land Surface Temperature derived from Landsat-8. We used data from 1320 stands of different forest types in Patagonia, and random forest regression to map SOC. The model captured SOC variability well (R² = 0.60, RMSE = 22.1%), considering the huge latitudinal extension (36.4° to 55.1° SL) and the great diversity of forest types. Mean SOC was 134.4 ton C ha−1 ± 25.2, totaling 404.2 million ton C across Patagonia. Overall, SOC values were highest in valleys of the Andes mountains and in southern Tierra del Fuego, ranging from 53.5 to 277.8 ton C ha−1 for the whole Patagonia region. Soil organic carbon is a metric relevant to many applications, connecting major issues such as forest management, conservation, and livestock production, and having spatially explicit estimates of SOC enables managers to fulfil the international agreements that Argentina has joined.

“This is the way”: Knowledge networks and toolkit specialization in the circumpolar coastal landscapes of western Alaska and Tierra del Fuego

One relevant dimension through which human populations articulate their occupation of the landscape involves the accumulation and interpersonal transmission of information pertaining to the spatio-temporal distribution, accessibility, and desirability of resources. The high productivity and resource diversity of coastal circumpolar landscapes enables them to sustain larger hunter-gatherer populations throughout the year. In circumpolar landscapes, marine mammals are a particularly highly ranked resource, as major sources of essential fats, proteins, and other nutrients. The adoption of specialized toolkits for marine mammal exploitation in open waters, encompassing watercraft and detachable harpoons, would have ensured that marine mammal hunting was a particularly rewarding and predictable endeavor. The first consistent adoption of toggling harpoons in southwestern Alaska is documented primarily at the height of the cold Neoglacial (ca. 4500–2500 BP), mirroring trends along the western Bering Sea coast. While maritime resource exploitation in northwestern Alaska also appears to have begun during the Neoglacial—particularly in the Kotzebue Sound area—specialized technological adaptations reflecting full-time maritime adaptations became more prominent in the wider region during the subsequent warmer period, in the context of population growth and increasing social connectivity. In contrast, the appearance of detachable harpoons at sites in the Beagle Channel (southern Tierra del Fuego) does not appear to be associated with any significant climatic changes, developing locally around 6500 BP after an initial period of human settlement in the region which lacked such adaptations. Therefore, we argue that the pathways toward the adoption of specialized toolkits enabling a maritime-oriented subsistence strategy in circumpolar coastal environments emerged primarily as the outcome of the consolidation of knowledge networks derived from the habituation of hunter-gatherer-fisher communities to predictable ecological conditions during periods in which the coastal landscapes they inhabited had become relatively stable.

Roosting ecology of the southernmost bats, Myotis chiloensis and Histiotus magellanicus, in southern Tierra del Fuego, Chile

AbstractThere are few studies of day‐roosting ecology of bats inhabiting the southernmost forests of South America, where cool summer temperatures and land management practices pose several challenges. The goal of the present study was to describe day‐roosting habitats and patterns of thermoregulation in two bat species occurring on Tierra del Fuego, Myotis chiloensis (Chilean myotis) and Histiotus magellanicus (southern big‐eared brown bat), during late austral spring. To do so, we tagged 17 bats with temperature‐sensitive radio‐transmitters, located 17 day‐roosts, and collected 81 days of skin temperature data. We concurrently recorded ambient air temperature to determine its effect on torpor use. Both species were found roosting in large diameter (77.8 ± 6 cm), typically live, Nothofagus pumilio trees (lenga) located on the edges of forest gaps or within stands primarily composed of smaller, younger trees. Bats of both species frequently used torpor, with skin temperatures dropping below a torpor threshold on 89% of days (n = 72) and daily minimum skin temperatures averaging 16.5°C over the course of our study. Average daily air temperature was a significant predictor of torpor use, with lower skin temperatures and more time spent in torpor observed on colder days. Minimum skin temperature and time spent torpid did not vary between bat species, nor did the characteristics of day‐roosts. These data show that spring ambient temperatures in Tierra del Fuego pose an energetic challenge that bats meet through frequent use of torpor and, likely, habitat selection. We recommend local conservation efforts keep these thermal challenges in mind by retaining large trees, which may provide warmer microclimates or room for social groups.Abstract in Spanish is available with online material.

Distribution of maternal lineages in hunter-gatherer societies of the southern coast of Tierra del Fuego, Argentina.

The aim of this work is to explore the maternal genetic diversity of hunter-gatherers of the southern Tierra del Fuego, specifically the north coast of Beagle Channel, the Península Mitre, and Isla de los Estados through ancient mitochondrial DNA analysis. The hypervariable regions 1 and 2 of the mitochondrial genome of five individuals from the north coast of Beagle Channel, six individuals from Península Mitre, and one individual from Isla de los Estados were analyzed. Through diversity statistics, Analysis of Molecular Variance (AMOVA), and Median Joining networks analyses, maternal relationships in the region were evaluated and phylogenetic similarities between ancient and contemporary populations of Tierra del Fuego were determined. The mitochondrial DNA lineages from the ancient individuals analyzed reveals the presence of subclades C1b and D1g. Pattern of decreasing genetic diversity toward the South is observed. The AMOVAs performed found no statistically significant differences between individuals of the north coast of Beagle Channel and Península Mitre-Isla de los Estados, and modern Yámana populations. Median joining network of haplotypes of clades C1 and D1g, show the same results. Ethnohistoric and ethnographic records of Península Mitre show that this region was occupied during the 19th century by Haush or Manekenk populations, although their biological, cultural, and subsistence characterization is unclear. We explore their maternal lineages and encounter low levels of genetic diversity and the absence of population differentiation with modern Yámana groups. We suggest that Península Mitre-Isla de los Estado was part of the same hunting and gathering populations as those of the Beagle Channel.

<p><strong>Studies in Austral Bryaceae (Bryopsida) I. New Combinations in <em>Ptychostomum</em> Hornsch. from southern South America</strong></p>

The genus Ptychostomum (Bryaceae, Bryopsida) is examined from southern South America including southern Patagonia and Tierra del Fuego regions of Argentina and Chile south of 50o S latitude. Five new combinations transferred from Bryum are made; Ptychostomum dicarpum (E.B. Bartram) J.R. Spence, Ptychostomum chorizodontum (Card. & Broth.) J.R. Spence, Ptychostomum lamprochaete (Dusén) J.R. Spence, Ptychostomum pauperculum (E.B. Bartram) J.R. Spence, and Ptychostomum vernicosum (Dusén) J.R. Spence. Bryum coelophyllum is placed into synonymy under P. nivale. Bryum macrosporum is placed into synonymy under P. chorizodontum. The type of B. pallidoviride represented undetermined material that could not be assigned to any species. A preliminary key to the 20 species of Ptychostomum currently recognized for the region is presented.

Micromamíferos, tafonomía y paleoambientes del cuaternario tardío en Tierra del Fuego: Los roedores de tres arroyos 1

We studied the micromammal remains recovered from the stratigraphic sequence of the archaeological site Tres Arroyos 1 (53o 23’ S, 68o 47’ W, Tierra del Fuego, Chile). The samples obtained from Late Pleistocene levels (ca. 12.5-10 ky) are mainly composed by Euneomys chinchilloides and Ctenomys magellanicus, with the unique occurrence of Eligmodontia sp., a sigmodontine today extinct in the Isla Grande de Tierra del Fuego but with populations in the southernmost mainland. These assemblages suggest very hard paleoenvironments with a general rocky and bare landscape under deep cold and windy conditions. The Late Holocene samples (ca. 1.7 ky-present), by the contrary, are composed basically by Reithrodon auritus, C. magellanicus, some sigmodontine species typically from southern Tierra del Fuego forests (e.g. Oligoryzomys magellanicus, Abrothrix lanosa), and show a declination of E. chinchilloides. These assemblages indicate amelioration in the environmental conditions surely coupled with the regional development of shrub and herbaceous steppes and perhaps a north displacement of the forest line. Taphonomically, pleistocenic assemblages seem to be mainly produced by the trophic activity of carnivore mammals, while those holocenic suggest a mixed origin with participation of owl pellets (especially for sigmodontine remains) and human consumption (responsible for a part of the Ctenomys remains). In overall, the micromammal evidence is in agreetment with the results obtained from other paleoclimatic records (e.g. polen).

Environment and anthropogenic impacts as main drivers of plant assemblages in forest mountain landscapes of Southern Patagonia

Management of natural areas generated multiple trade-offs, and changes in the plant assemblages was identified as one of the most critical ones. In this context, understanding the drivers of change of exotic plant diversity is critically important for biodiversity conservation and land planning. The aim of this work was to evaluate the relationships between environmental gradients in mountain landscapes and anthropogenic impacts related to human uses as drivers for plant assemblages (native and exotic species) in Southern Patagonian forests. The study was located in the Andorra Valley basin (12,934 ha) in the southern Tierra del Fuego Island (Argentina), where mountain landscape units (land-cover and land-use) were identified according to their vegetation types (forests and open-lands), elevational effects (<400 and >400 m.a.s.l.) and anthropogenic impacts derived from economic activities (harvesting and cattle grazing). Classification was based on Landsat 8 OLI images with fieldwork samplings, relevating a total of 101 landscape units. In each unit, forest structure and floristic surveys (dicots, monocots, pteridophytas and bryophytes) were conducted. Data were evaluated using ANOVAs and multivariate analyses (cluster, detrended and canonical correspondence analysis). A total of 104 plant species were surveyed (88% natives and 12% exotics), where managed deciduous forests (Nothofagus pumilio) had the highest values of exotic species occurrence frequency (20%). Multivariate analyses showed that environmental gradients and anthropogenic impacts highly affected the distribution of exotic species. Native species had higher cover values at upper elevations, while exotic plants had a higher cover at lower elevations, where the N-S aspects were strongly correlated with plant preferences for shaded/lighted aspects. The occurrence of exotic species can be specifically related to human activities (e.g., Agrostis stolonifera and Rumex acetosella with cattle grazing; and Poa nemoralis, Ranunculus repens and Stellaria media with harvesting), however one of them (P. trivialis) was related with unharvested forests. We conclude that environmental gradients and anthropogenic impacts define the plant assemblages at landscape level, and they also influence the occurrence of the exotic species, where the main driver was the harvesting. We propose that land-sharing conservation strategy in these mountain landscapes could be the better approach towards sustainability ensuring the preservation of the land-cover and the land-use at the low and upper elevations.

Early migration and estuary stopover of introduced chinook salmon population in the Lapataia River Basin, southern Tierra del Fuego Island

Established populations of chinook salmon (Oncorhynchus tshawytscha) have recently been reported in South America, at both Atlantic and Pacific basins. Several studies have evaluated different aspects of their life histories; however, little is known about the use of the estuaries by the juveniles of these populations. We examined spawning time, seaward migration timing, growth rate, scale patterns, diet, and geometric morphometric, contrasting the early life history during freshwater and estuary residence of a chinook population established in Lapataia Basin. Fall run spawning took place in March–April and the parr emerged in September. Two distinct seaward migration patterns were identified from sein net fishing records: one population segment migrating earlier to the estuary in October and a second group migrating later in February. The growth rate of fish captured at the estuary was significantly higher than the fish captured in freshwater. In addition, higher scale intercirculi distances were observed in estuary fish showing differences in growth rate. The feeding habitat in fish captured in both environments changed through time from bottom feeding to surface feeding and from significant diet overlap to no overlap. The morphology of the fish captured at the estuary was associated with the elongation of the caudal peduncle and a decrease in the condition factor index, both changes related to smolt transformation. The earlier migration and the higher growth rate of juveniles in the estuary together with fish of 1 + yo captured in this environment reveal that the estuary of Lapataia Basin is not only a stopover for the chinook salmon, but also a key habitat to reside and feed previous to the final seaward migration.

First approximation to paleodemography through age-at-death profiles in hunter-gatherers from Southern Patagonia during middle-late Holocene

Abstract The aims of this paper is threefold: 1) to explore the spatial and temporal variations in age-at-death profiles of human remains from Southern Patagonia in order to test and discuss the hypothetical increasing demography during the late Holocene; 2) to evaluate probable biases in the skeletal samples derived from preservation issues, social organization features and/or mortuary behavior, and 3) to compare the results with those reported for other hunter-gatherer societies from Pampa and Patagonia regions, offering valuable insights about the age-at-death profiles and paleodemographic for other Southern South American hunter-gatherers with different social characteristics. Age-at-death profiles from Southern Patagonia below 50°S, corresponding to the middle-late Holocene (i.e., after ca. 5500 years before present -YBP-), were constructed from a skeletal series of 119 individuals. Sex and age distribution of the entire sample was firstly analyzed, and two other age-at-death profiles were thereafter built, dividing the sample by region (Santa Cruz/Magellan, Northern Tierra del Fuego and Southern Tierra del Fuego) and by chronology (5500–3500 YBP, 3500–1000 YBP, 1000–400 YBP and after 400 YBP). The results show an attritional profile with two peaks, the first one between 1.1 and 10 years-old and the other for the 20.1–35 age group. A low number of newborns younger than 1 year-old is observed. This could be the result of a low mortality rate for this age interval and a high parental care during the first period of childhood, although taphonomical and mortuary biases cannot be completely excluded. Adult males and females are similarly represented in each age category. Juvenile Index data are higher than 0.17 between 5500 and 400 YBP periods, suggesting population growth, with a particular demographic increase between 5500–3500 and 1000–400 YBP periods. During the contact period, fertility is dramatically reduced. The age-at-death profile is similar to other hunter-gatherer past populations from Pampa and Patagonia regions. Despite the differences regarding mobility strategies, social organization, demographic dynamics and mortuary behavior known for those societies, all profiles show a comparable bimodal attritional pattern, although some variation in the most represented age-groups and demographic growth is observed.

Porpidia navarina, a New Endemic Species from Isla Navarino (Southern Tierra del Fuego, Chile)

Abstract: Ruprecht, U., Sochting, U. & Turk, R. 2016. Porpidia navarina, a new endemic species from Isla Navarino (southern Tierra del Fuego, Chile). — Herzogia 29: 596–609. As part of a comprehensive taxon sampling in southern Patagonia, South America, along a latitudinal gradient from Isla Navarino (55°S) to Bariloche (41°S) saxicolous lecideoid lichen species were collected in 20 habitats, all within the subantarctic climate zone above tree line by increasing altitude to the north. Phylogenetic analyses of the closely related genera Lecidea and Porpidia revealed altogether more than ten well-supported new lineages. The most strongly supported group of 13 accessions, found at Isla Navarino solely at the ridge of Cerro Bandera is described as the new endemic species Porpidia navarina.

Genetic and morphological analysis of Berberis microphylla G. Forst. accessions in southern Tierra del Fuego

Calafate (Berberis microphylla G. Forst.) is a spontaneous shrub grown in the Patagonian region, from which berries are traditionally harvested for different purposes. This study aims to investigate on the spatial genetic structure of calafate populations grown in southern Tierra del Fuego and their morphological and genetic diversity. A first step of the research focused on 23 putative populations screened by a landscape genetic approach based on 82 geo-referenced and Random Amplified Polymorphic DNA marker characterized plants. The second phase regarded the analysis of the morphological characteristics of fruits, shoots and leaves observed on a subset of 39 plants. Taking into account multiple similarity between pairs and sub-sets of accessions, the observed differences have been associated to geographical and environmental conditions. The results allowed to postulate the existence of homogeneous populations within the studied plant sets and to formulate hypothesis on the evolution of B. microphylla in that area. No association between genetic and morphologic distances of the accessions has been observed.

First record of Palaeostomocystis subtilitheca in Holocene marine sediments from the Beagle Channel, southern Tierra del Fuego, Argentina

This study documents the occurrence of Palaeostomocystis subtilitheca in Holocene sediments from the Beagle Channel area, southern Argentina, and represents the first record of this acritarch in high latitudes of the Southern Hemisphere. P. subtilitheca is considered as an indicator for polar to subpolar environments with high planktonic productivity and nutrient-rich waters and can probably be associated with low-salinity stratified waters. The Beagle Channel presents environmental characteristics similar to those reported by other authors in Central West Greenland and the Faroe Islands, characterized by high concentrations of nutrients in the surface waters. The Beagle Channel constitutes a favourable environment for the development of this species in subpolar regions of the Southern Hemisphere.

CONOCIMIENTO, USO Y VALORACIÓN DE LA FLORA VASCULAR DE TIERRA DEL FUEGO: EL EJEMPLO DE KARUKINKA

Biodiversity conservation requires knowledge and valuation of the preserved entity. Wildlife Conservation Society (WCS) is leading a conservation program in southern Tierra del Fuego, in the private park Karukinka that expects to preserve globally important ecosystems for the benefit of the present and future, local and global community. The overall objective of this research is to know the current and potential use of plants contained in Karukinka, to determine the degree of knowledge among local people on this flora and their uses, as well as the level of valuation of the latter. Therefore, we expect to contribute to the valuation of the biota of the area, making suggestions for future environmental education programs, possible to be implemented by WCS. This work has evaluated the potential use for vascular plants of Karukinka through an exhaustive checking of botanical, ethnobotanical and others kinds of literature. Current use was estimated using specific surveys on the population of the area of Porvenir and Punta Arenas. The polls were conducted in two strata of the Magallanes region population: schoolchildren and professionals. These surveys dealt with the knowledge about vascular plants of Tierra del Fuego, its uses, and their valuation. They were analyzed combining qualitative and quantitative methods with general descriptive statistics. The survey results confirm the initial hypothesis of the existence of a large gap of knowledge about flora of Tierra del Fuego, especially alarming in the case of schoolchildren and adults of Porvenir.

Análisis de la regeneración natural de la vegetación en taludes de caminos de la Ruta Y-85, Parque Karukinka, Tierra del Fuego, Chile

in this study we analyzed the pattern of vegetal succession of 38 road slopes formed by the cons truction of the Route Y-85, which connects Estancia vicuna with Yendegaia (54° 20 ‘S, 68° 45’ W) in Chilean tierra del Fuego. Our results indicate that both coverage and species richness show significant differences between the degraded road slopes and the reference sites in the four studied ecosystems. Most of the species that established themselves on degraded road slopes came from the reference ecosystems, the most abundant species were Acaena magellanica, Deschampsia flexuosa and Nothofagus pumilio. the road slopes with greater vegetation cover of species were found in the forest ecosystem (less than 25%), followed by ecotone ecosystem. these results suggest that the natural restoration of road slopes in southern tierra del Fuego is an extremely slow process, making it necessary to start an “active” res

Art in time. Diachronic rates of change in the decoration of bone artefacts from the Beagle Channel region (Tierra del Fuego, Southern South America)

This paper explores the differential rates of diachronic change developed by diverse features of portable art in southern Tierra del Fuego. It is argued that decorative designs and techniques, which simultaneously constitute each decorated artefact, had asynchronic rates of change throughout the archaeological sequence. Results indicate that: (I) decorated harpoon points (1) had a broader and more complex design repertoire which entailed a higher labour investment and showed a faster rate of change than beads, due to a greater individual input in their decoration, (2) were richly decorated in spite of their high risk of loss/fracture, yet their decoration was concentrated in the early period of the archaeological sequence and then decreased in time due: a) to such loss/fracture risk, which jeopardised the labour invested in their decoration, (b) to a relative decrease in pinniped hunting which might have reduced the socio-economic and symbolic value of harpoons; (II) decorated beads (1) had a simpler and more standardised design repetoire which entailed a lower labour investment and showed a slower rate of change than harpoons, due to a stricter process of teaching/learning or imitation during their production and a collective way of ornamentation during their display, (2) increased with time and have been decorated during the three periods of the archaeological sequence due to: (a) their lower risk of loss/fracture, which did not endanger the labour invested in their decoration, (b) their social function as a shared form of ornamentation; (III) decorative techniques had a slower rate of change than decorative designs throughout the archaeological sequence due to their differential instrinsic variability potentials.

Palaeoenvironmental conditions during the Middle Holocene at Isla de los Estados (Staaten Island, Tierra del Fuego, 54° S, Argentina) and their influence on the possibilities for human exploration

The Middle Holocene is a particular time period in which there are uneven environmental dynamics all along the southern portion of the continent. Whereas in the Puna, extreme aridity and high temperatures (the so-called “Hypsithermal” period) have been recorded, a more humid and rainy phase dominated southern Tierra del Fuego. The present paper explores the palaeoenvironmental situation of Isla de los Estados (Staaten Island, 54°38′–54°55′ S; 63°48′–64°46′ W) and its relationship with the archaeological record left behind by ancient canoeing people. The considered period is characterized by exceptionally windy conditions. The palaeoenvironmental information could be used as an explanation for the absence of cultural remains and also for the scarce archaeological record for Península Mitre. At the beginning of the Middle Holocene, the diatom record shows a large amount of Aulacoseira sp that could indicate either windy conditions or higher water levels at the site core. The more distinctive changes in the diatom assemblages occurred at ca. 5000 cal B.P., suggesting a shallower water level and more acidic conditions. By 3000 cal B.P., the diatom species are strongly linked to peat and swampy environments. However, during the late Holocene, milder conditions might have favored seasonal travelling to the outer islands of the Fuegian Archipelago, though no definitive or permanent settlements have been found.

Atmospheric background trace elements deposition in Tierra del Fuego region (Patagonia, Argentina), using transplanted Usnea barbata lichens

Lichen, Usnea barbata, transplants taken from Tierra del Fuego (south Patagonia, Argentina) were tested as potential biomonitors of atmospheric airborne deposition in an apparently pristine environment. In 2005, lichens were sampled in a reference site (n = 31) and transplanted in the northern Region of Tierra del Fuego. After, respectively, 1month and 1year of exposure, we collected them. The aim of the study was to determine the bioaccumulation of 26 elements in order to evaluate the background levels in the selected area. Samples were analyzed by the sector field inductively coupled plasma mass spectrometry. Discriminant analysis on principal component analysis factors was applied in order to explore the relationship among the different elements as far as time and spatial variation in transplants regards. The analysis was tested by Monte Carlo test based on 999 replicates. The most important contamination source resulted to be the atmospheric soil particle deposition. Furthermore, the results were compared with those obtained from the lichens collected in central and southern Tierra del Fuego. This study confirms the ability of U. barbata to reflect the background levels of the 26 elements in that environment. Compared with other background sites in the world, we did confirm that Tierra del Fuego lichens have a low content of the studied elements. Tierra del Fuego turned out not to be a pristine environment as supposed, but it can be considered as a reference basal ecosystem for useful comparisons among different geographical areas. These findings can be very relevant and useful for environmental conservation programs.

A geochemical and sedimentary record of high southern latitude Holocene climate evolution from Lago Fagnano, Tierra del Fuego

Situated at the southern margin of the hemispheric westerly wind belt and immediately north of the Antarctic Polar Frontal zone, Tierra del Fuego is well-positioned to monitor coupled changes in the ocean–atmosphere system of the high southern latitudes. Here we describe a Holocene paleoclimate record from sediment cores obtained from Lago Fagnano, a large lake in southern Tierra del Fuego at 55°S, to investigate past changes in climate related to these two important features of the global climate system. We use an AMS radiocarbon chronology for the last 8000yr based on pollen concentrates, thereby avoiding contamination from bedrock-derived lignite. Our chronology is consistent with a tephrochronologic age date for deposits from the middle Holocene Volcán Hudson eruption. Combining bulk organic isotopic (δ13C and δ15N) and elemental (C and N) parameters with physical sediment properties allows us to better understand sediment provenance and transport mechanisms and to interpret Holocene climate and tectonic change during the last 8000yr. Co-variability and long-term trends in C/N ratio, carbon accumulation rate, and magnetic susceptibility reflect an overall Holocene increase in the delivery of terrestrial organic and lithogenic material to the deep eastern basin. We attribute this variability to westerly wind-derived precipitation. Increased wind strength and precipitation in the late Holocene drives the Nothofagus forest eastward and enhances run-off and terrigenous inputs to the lake. Superimposed on the long-term trend are a series of abrupt 9 negative departures in C/N ratio, which constrain the presence of seismically-driven mass flow events in the record. We identify an increase in bulk δ13C between 7000 and 5000calyr BP that we attribute to enhanced aquatic productivity driven by warmer summer temperatures. The Lago Fagnano δ13C record shows similarities with Holocene records of sea surface temperature from the mid-latitude Chilean continental shelf and Antarctic air temperatures from the Taylor Dome ice core record in East Antarctica. Mid-Holocene warming occurred simultaneously across the Antarctic Frontal Zone, and in particular, in locations currently influenced by the Antarctic Circumpolar Current.