Tierra Del Fuego Research Articles

Variation in Alpine Plant Diversity and Soil Temperatures in Two Mountain Landscapes of South Patagonia

Alpine environments and their temporal changes are rarely studied at high latitudes in the southern hemisphere. We analyzed alpine plants, soil temperatures, and growing-season length in mountains of two landscapes of South Patagonia (46° to 56° SL): three summits (814–1085 m a.s.l) surrounded by foothill grasslands in Santa Cruz province (SC), and four summits (634–864 m a.s.l.) in sub-Antarctic forests of Tierra del Fuego province (TF). Sampling followed the protocolized methodology of the Global Observational Research Initiative in Alpine Environments (GLORIA). Factors were topography (elevation and cardinal aspect) and time (baseline vs. re-sampling for plants, five annual periods for temperatures), assessed by univariate and multivariate tests. Plant composition reflected the lowland surrounding landscapes, with only 9 mountain species on 52 totals in SC and 3 on 30 in TF. Richness was higher in re-sampling than baseline, being assemblages more influenced by aspect than elevation. Mean annual soil temperature and growing-season length, which varied with topography, were related to the Multivariate El Niño Southern Oscillation Index (MEI) but did not show clear warming trends over time. We highlight the importance of long-term studies in mountainous regions of extreme southern latitudes, where factors other than warming (e.g., extreme climate events) explain variations.

Landscape Variables Influence over Active Restoration Strategies of Nothofagus Forests Degraded by Invasive Castor canadensis in Tierra del Fuego

North American beavers (Castor canadensis) are responsible for the major changes in the Tierra del Fuego Archipelago, altering riparian forests for the long-term. Passive restoration of the areas affected was ineffective in the medium-term (up to 20 years), being necessary active strategies. Plantations in abandoned ponds were made with Nothofagus pumilio and N. antarctica tree species across Tierra del Fuego island (Argentina). In the first experiment, we analysed the influence of biotic and abiotic factors in three micro-habitats in the impacted areas: front and tail of ponds, and cut not-flooded forest areas. Five-years-old N. pumilio seedlings had 39% survival in front, 21% in tails, and 46% in cut areas at year-3 of the restoration experiments, being negatively influenced by plant cover and soil moisture. Lower growth was recorded during year-1 (0.7–0.9 cm yr−1), but increased on time (1.9 cm yr−1 front, 1.6 cm yr−1 tail, 4.3 cm yr−1 cut areas). A second experiment explores the alternative to substitute the tree species to face the harder conditions of the impact and climate change. For this, we conducted a new plantation at four locations across the main bioclimatic zones, where 10–40 cm N. antarctica plants attained 17% survival in meadows (front and tail) and 30% in cut areas, being higher with larger than smaller plants (25% vs. 18%), and where they are mainly influenced by rainfall (4% in sites <400 mm yr−1 and 41% in >400 mm yr−1). The main damage was detected in the above-ground biomass due to dryness, but root survival allowed the emergence of new shoots in the following growing season. It is necessary to monitor different Nothofagus species across natural environments in the landscape to determine the feasibility and effectiveness of different strategies in restoration plans, considering the selection of climate-resilient tree species.

Fuegian diaspora: The itinerary and agents involved in the construction of Fuegian ethnographic collections carried out by Martin Gusinde through South America and Europe, 1918–1924

ABSTRACT In this paper, we examine the itinerary of the objects and the agencies involved in the construction of the collections of ethnographic artefacts gathered by German ethnographer and priest Martin Gusinde during his fieldtrips to Tierra del Fuego (Argentina and Chile), carried out between 1918 and 1924. In order to study the formation processes of these collections, we will trace the agencies of the Selk´nam, Yagan and Kawésqar Indigenous people in the making, selling, trading or withholding of their material culture, showing the differential impact these had on the collections. We retrace the dispersal of these Fuegian collections into five museums located in Chile, Austria and the Vatican, presenting a reservoir unknown until now. Our exploration of the complex networks of social and material interactions involved in the dynamic biography of these Fuegian ethnographic collections sheds light on the active role of the Indigenous people in their construction.

Vulnerabilidad urbana en asentamientos informales: diseño y aplicación de una propuesta metodológica de abordaje en ciudades de Tierra del Fuego. El caso de Río Grande

Informal settlements show various situations of vulnerability, associated with problems at multiple levels. This research aims to develop a methodology for measuring urban vulnerability in informal settlements in Tierra del Fuego cities, in order to recognize the comprehensiveness of the problems associated with living conditions there, from a right to the city perspective. To do this, an Urban Vulnerability Index is designed, taking into account specific dimensions and indicators of the context, agreed with actors from the State, academia and civil society. The application in a study case (Rio Grande) allows identifying situations of vulnerability with different degrees and characteristics, leading to the definition and prioritization of interventions.

The low-grade basement at Península La Carmela, Chilean Patagonia: new data for unraveling the pre-Permian basin nature of the Eastern Andean Metamorphic Complex

The Eastern Andean Metamorphic Complex at Península La Carmela (48°50’S) consists of quartz-rich metaturbiditic sequences with tectonic slices of pillow metabasalt bodies deformed under low-grade metamorphic conditions. Previous and new detrital zircon U–Pb geochronological data from metasandstones indicate a preferred early Carboniferous maximum depositional age of the protolith, interpreted from the youngest single zircon grains of several metasedimentary rocks in the area. The wide spectrum of zircon ages from Península La Carmela, includes Neoproterozoic-early Paleozoic components and subordinate ancient zircon grains (> 2200 Ma). They were sourced from cratonic regions and/or reworked material from older metasedimentary successions and plutonic belts in southwestern Gondwana (e.g., North Patagonian and Deseado massifs or from the Tierra del Fuego Igneous and Metamorphic Complex). The pillow metabasalts have geochemical affinities of normal mid-oceanic ridge basalts and island-arc tholeiites with Nb–Ta negative anomalies, derived from a depleted mantle source (εNdt of + 6 and + 7.5). In consideration that pillow metabasalts with ocean island basalt affinities are reported, we propose that metaturbiditic successions and metabasalts were tectonically juxtaposed within a pre-Permian accretionary wedge of an active continental margin, after the development of island arcs and back-arc marginal basins.

Efectos del crecimiento urbano sobre humedales costero-continentales del ambiente semiárido de Tierra del Fuego, Argentina

La conjunción de humedales costeros y continentales en zonas semiáridas y en adyacencias urbanas, representa un valioso patrimonio socio-ambiental, sujeto a las tensiones que la expansión urbana genera, especialmente si se manifiesta con altas tasas de crecimiento. El presente artículo aborda el problema de los cambios físicos sobre humedales provocados por la expansión urbana acelerada en el contexto mencionado, identificando factores agravantes. Se estudió el caso de Río Grande, ciudad costera de la estepa de Tierra del Fuego, Argentina, cuyo crecimiento fue impulsado desde 1972 por políticas de promoción industrial. Los humedales fueron identificados, clasificados y cartografiados mediante análisis multiespectral de imágenes de satélite. La expansión urbana se delimitó según tres períodos vinculados a variantes en las políticas de promoción. El análisis espacio-temporal evidencia correspondencia entre pulsos de fluctuación de las políticas, con la dinámica de la expansión urbana y ocupación de áreas naturales. Un tercio de la expansión urbana fue a expensas de la desaparición de humedales, con saldo adicional de unidades fragmentadas. Se analizan externalidades, no siempre evidentes, resultantes de la urbanización de estos ecosistemas y se concluye en la significación de los asentamientos informales, así como la falta de planificación como factores que incrementan la pérdida de humedales.

Exceptional foraging plasticity in King Penguins (Aptenodytes patagonicus) from a recently established breeding site in Tierra del Fuego, Chile

Animals constantly test the borders of their own ecological niche and tend to expand their range, which is now additionally challenged by global climate change. Following human exploitation throughout the Southern Ocean in the 19th and the beginning of the 20th century, numbers of King Penguin breeding pairs have increased and former breeding sites have been re-colonized. Since 2010 a breeding colony became (re-)established at Bahía Inútil, Strait of Magellan, Tierra del Fuego, Chile. The aims of this study were to study the foraging ecology of King Penguins at this new breeding site, which is characterized by a set of different environmental variables as it is located within the confined environment of the Magellan Strait, more than 300 km from the open ocean. During the course of this study, thirty-two birds were successfully equipped with external devices that recorded 206 foraging trips by breeding and non-breeding birds. With one exception, all birds foraged throughout the year exclusively in the Magellan Strait with the main foraging areas located within 100 km from the colony. The diving activities of 15 King Penguins were recorded during 59 foraging trips, the deepest dive was 160 m and the longest dive lasted 6.75 mins. Based on a representative subsample of 3000 dives, mean dive depth was 32 ± 34 m and mean dive duration 117 ± 84 s. Accordingly, foraging trip durations throughout the year were significantly shorter than those recorded for conspecifics elsewhere. In accordance with these changes in foraging behavior, stomach contents from seven birds showed a mix of fish and squid, with Falkland sprats Sprattus fuegensis as the main prey item present in all samples. The implications of these behavioral adaptations are discussed with regard to this unusual confined foraging environment and predicted changes in the performance of King Penguins breeding elsewhere following global change.

A reassessment of testate amoebae diversity in Tierra del Fuego peatlands: Implications for large scale inferences

Testate amoebae are a diverse group of shelled protists frequently used as model organisms in microbial biogeography. Relatively few species have been reported for the Southern Hemisphere, however, it remains unclear whether this lower diversity is real or an artifact of under-sampling or misidentifications, which would reduce their potential to address macroecological questions. We evaluated testate amoebae diversity from the full range of habitats occurring within two Tierra del Fuego peatlands and compared it with the reported diversity for the area and from the Northern Hemisphere peatlands. We recorded 87 species, of which 69 are new for the region and 45 of them probably new to science and likely to have restricted geographical distributions. Combined with previous studies, the total diversity of testate amoebae only from Tierra del Fuego peatlands now reaches 119, as compared with 183 reported from all Northern Hemisphere peatlands. Our results demonstrate that the number of Gondwanian and Neotropical endemic testate amoeba may be substantially higher than currently known. Previous reports of Holarctic taxa in Tierra del Fuego may result from forcing the identification of morphotypes to the descriptions in the most common literature (force-fitting) South American species into species common in literature from other regions.

Phylogeography of Otaria flavescens (Carnivora: Pinnipedia): unravelling genetic connectivity at the southernmost limit of its distribution

Abstract The Pleistocene glacial period shaped the current genetic structure of numerous species. The last glacial dynamics has been proposed to have split the South American sea lion, Otaria flavescens, into two Evolutionarily Significant Units (ESUs), one on each side of the continent. However, previous studies have not provided genetic information on colonies found along 3000 km of coastline of the southernmost limit of the species distribution, where gene flow could occur. We conducted an exhaustive phylogeographical analysis of O. flavescens using a mtDNA marker, including, for the first time, data from colonies living south of latitude 45° S, in the Argentinian provinces of Santa Cruz and Tierra del Fuego. Our results indicated the presence of five Conservation Units across the distribution range of O. flavescens and suggest that the Patagonian population must have expanded about 150 000 BP. We found evidence for gene flow across the entire species range, supporting a scenario of secondary contact in Tierra del Fuego where representatives of the oldest lineages coexist. The presence of gene flow between oceans leads us to reject the assumption of complete reciprocal monophyly for mtDNA between the presumed ESUs, suggesting that the species constitutes a single Evolutionarily Significant Unit.

Ontogeny versus environmental forcing off the Southwest Atlantic Ocean: Nutritional condition of Fuegian sprat (Sprattus fuegensis) early stages

AbstractThe Fuegian sprat, Sprattus fuegensis, plays a key trophic role in the Southwest Atlantic Ocean. Growth and survival of small pelagic fishes like sprat are strongly affected by environmental variability and can determine recruitment success. We estimated the nucleic acid composition and assessed with a standardized RNA/DNA index (sRD) the nutritional condition of 273 larvae, metamorphosing, and juvenile Fuegian sprat from two environmentally distinct habitats: the waters off Tierra del Fuego (TDF) and the Marine Protected Area Namuncurá/Burdwood Bank (MPAN/BB). A similar ontogenetic pattern, in which nucleic acid concentrations decreased and sRD increased with increasing standard length (SL) among larval stages was observed in both habitats. A higher percentage of preflexion larvae were under the sRD threshold for growth and optimal growth performance, with sRD values being significantly higher in TDF. Postflexion larvae in both habitats showed maximum sRD values, suggesting that both habitats are suitable nursery grounds. In contrast, metamorphosing and juvenile sprat (only captured in TDF) had consistently low nucleic acid concentrations and sRD values despite increasing SL. Environmental forcing (temperature, salinity, and station depth) was assessed over size‐corrected larval sRD. The best model included a negative response to station depth, and the effect of processes associated with this factor are discussed. Although further analyses are needed to reveal underlying dynamics determining early development, these results comprise a baseline for future monitoring approaches on Fuegian sprat life traits and factors affecting their recruitment in this region.

Southern High-Latitude Plant-Insect Interactions from the Miocene of Tierra del Fuego, Argentina

Premise of research. The Miocene Punta Basílica Beds (northeast of Tierra del Fuego, Patagonia, Argentina) preserved a flora rich in insect herbivory traces. Here we document its insect damage and compare it with three Miocene floras from northwestern Argentina (low-latitude San José and Palo Pintado) and New Zealand (high-latitude Hindon Maar). In addition, comparisons are established for insect damage observed on Miocene Nothofagus in the Punta Basílica flora and the New Zealand Hindon Maar, Double Hill, and Kaikorai floras.Methodology. Plant-insect interactions were photographed and determined for 209 fossil leaves collected at the Punta Basílica locality. Leaves were censused for the presence/absence of functional feeding types.Pivotal results. Six functional feeding groups and 26 damage types (DTs) were recognized: hole (seven DTs) and margin (five DTs) feeding, skeletonization (six DTs), piercing and sucking (two DTs), mining (three DTs), and galling (three DTs). Nothofagus spp. are the most affected members of the paleoflora. Both of the low-latitude paleofloras compared have lower percentages of damaged leaves than the high-latitude ones; hole and margin feeding, mining, and skeletonization are recognized at all floras. Hole and margin feeding and skeletonization are recognized on Nothofagus leaves and are the most common functional feeding groups; hole feeding on Nothofagus is more prominent at Hindon Maar and Kaikorai than at Double Hill and Punta Basilíca. Additionally, Nothofagus specimens from Hindon Maar and Punta Basílica have evidence of mining, whereas galling is observed only on the New Zealand leaves. The Punta Basílica Nothofagus specimens are the only ones with piercing and sucking.Conclusions. Southernmost Miocene records of leaf herbivory worldwide and the first record from Argentine Patagonia are rich and comprise several functional feeding groups also observed in other Miocene paleofloras from the Southern Hemisphere. Clearly, multiple biotic and abiotic factors explain differences in the intensity of folivory. This report evidences the need for additional studies on herbivory at high-latitude floras.

Comment on the paper by Buono et al. “Dynamics of degassing in evolved alkaline magmas: Petrological, experimental and theoretical insights” (Earth Science Reviews, 211 (2020), 103402)

The mountainous, glaciated island of South Georgia is the crest of one of the most isolated fragments of continental crust on Earth. It is located approximately 1700 km east of the southern termination of the Andean Cordillera of South America. The island is primarily composed of Lower Cretaceous turbidites, the infill of a marginal basin floored by stretched continental and ophiolitic crust. Remnants of a volcanic arc are preserved on offshore islands to the southwest. The Pacific hinterland of the southernmost Andes is missing in Tierra del Fuego, terminating at a submarine escarpment forming the continental margin immediately east of Cape Horn. The arc and back-arc basin infill rocks of South Georgia correspond exactly to part of the missing Cordilleran hinterland.The mechanism of transport of the South Georgia microcontinent eastward relative to South America remains obscure, but likely involved some form of ‘escape tectonics’ during mid- to Late Cretaceous counterclockwise rotation of the arc that led to closure and inversion of the marginal basin.

The lichen genus Villophora (Teloschistaceae, Ascomycota)

AbstractThe Southern Hemisphere lichen genus Villophora in subfamily Teloschistoideae is analyzed based on DNA sequence data. Six species are described, five of which are new to science: V. darwiniana and V. wallaceana grow on lignum and bark in southern Patagonia and Tierra del Fuego; V. onas and V. patagonica are lichenicolous or saxicolous on rocks in southern Patagonia; V. rimicola is saxicolous in Antarctica. Based on a three-gene DNA analysis, Tayloriellina is shown to be closely related to Villophora, and Tayloriellina microphyllina is established as a new combination. A key is provided to all species of the two genera. Raesaeneniana maulensis is combined into Villophora.

Wind Variations in the Mesosphere and Lower Thermosphere Near 60°S Latitude During the 2019 Antarctic Sudden Stratospheric Warming

AbstractSudden stratospheric warmings (SSWs) could act as an important mediator in the vertical coupling of atmospheric regions and dramatic variations in the mesosphere and lower thermosphere (MLT) in response to SSWs have been documented. However, due to rare occurrences, SSWs in the Southern Hemisphere (SH) and their impacts on the MLT dynamics are not well understood. This study presents an analysis of MLT winds at ∼80–98 km altitudes measured by meteor radars located at Tierra del Fuego (53.7°S, 67.7°W), King Edward Point (54.3°S, 36.5°W) and King Sejong Station (62.2°S, 58.8°W) near 60°S latitude during the Antarctic winter. Eastward zonal winds from these stations are observed to decrease significantly near the peak date of the 2019 Antarctic SSW, and both zonal and meridional winds in 2019 exhibit considerable differences to the mean winds averaged over other non‐SSW years. A quasi 6‐day oscillation is observed at all three radar locations, being consistent with the presence of the westward propagating zonal wave‐1 planetary wave. The vertical wavelength of this wave is estimated to be ∼55 km, and the enhancement of the wave amplitude during this SSW is noticeable. Evidence of the interaction between the 6‐day wave and the semidiurnal diurnal tide is provided, which suggests a possible mechanism for SSWs to impact the upper atmosphere. This study reports the large‐scale variations in winds in the MLT region at SH midlatitudes to high latitudes in a key dynamic but largely unexplored latitudinal band in response to the 2019 Antarctic SSW.

Blooms of Alexandrium catenella in Coastal Waters of Chilean Patagonia: Is Subantarctic Surface Water Involved?

At the southern tip of South America, evidence of shellfish toxicity has been recorded in the accounts of early explorers and shipwreck survivors since the late 16th Century. Blooms of the toxic dinoflagellate Alexandrium catenella were described in the western Magellan Strait in the early 1970s and have since shown a northward progression through Chilean Patagonia, culminating in a catastrophic toxic event around Chiloé Island in 2016. This shift has taken place through coastal areas of extremely sparse human population density, and anthropogenically driven eutrophication is therefore unlikely to be significantly involved, at least in the south. However, human activities – such as salmon cultivation – may play a role in the intensification of blooms in the more densely populated areas of northern Patagonia. In the fjords and channels of Chilean Patagonia, phytoplankton assemblages are shaped by complex interactions between freshwater (FW) run-off and intrusions of subantarctic surface water (SASW). In the context of blooms of A. catenella, we review the properties of SASW – transformed in coastal waters into modified subantarctic water (MSAW). FW input is characterized by very low concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP), but relatively high concentrations of silicic acid (DSi); DIN and DIP are instead supplied predominantly by SASW which is severely deficient in DSi. These waters therefore show strong vertical gradients in DIN, DIP and DSi, but also potentially in dissolved trace metals and CO2. Large scale shifts in the relative inputs of SASW or FW can modify these vertical gradients, potentially forcing competitive changes in phytoplankton assemblages with latitude, with implications for growth and toxicity of A. catenella and other harmful species. The northward shift of blooms of A. catenella could be associated with anomalies in the Southern Annular Mode (SAM) that modify the influence of MSAW through variations in FW input to coastal waters. The historical presence of blooms in southern Patagonia and Tierra del Fuego, combined with the strongly contrasting conditions with latitude and depth, mean that southern Chile represents an ideal natural laboratory to study climatic and oceanographic influences on dynamics of A. catenella populations.

Hyperbius joceliae a new species of Ditomotarsinae from Tierra del Fuego, <br />Argentina (Hemiptera: Acanthosomatidae)

Hyperbius joceliae sp. n., a new Patagonian Acanthosomatidae (Hemiptera) species is described from the north of Tierra del Fuego Island. Diagnostic characters such as color, dorsal pilosity, head and pronotal punctures, length of mandibular plates and antennae, shape and color of paratergite 9, shape and texture of gonocoxite I and II of the only known species of the genus, Hyperbius geniculatus (Signoret), are compared with the new species and discussed. Distributional patterns of the South American Acanthosomatidae and speciation of the Patagonian fauna of this family are also briefly discussed.

Revised chrono and lithostratigraphy for the Oligocene-Miocene Patagoniense marine deposits in Patagonia: Implications for stratigraphic cycles, paleogeography, and major drivers

Richly fossiliferous upper Oligocene to lower Miocene Patagoniense marine deposits constitute a conspicuous feature of the sedimentary record of most basins in Patagonia. Patagoniense meaning and subdivisions have been confusing, and correlation and elucidation of factors controlling sedimentation in a region as extensive as Patagonia are still highly debated. Our revision of the distribution, correlation, stratigraphic arrangement, and timing of deposition, allows redefining the Patagoniense as a succession of widely distributed marine sediments accumulated in Patagonia from ~25 to 15 Ma, showing different timing of accumulation for each basin. It can also be conceived as a higher rank stratigraphic cycle of relative sea-level fluctuation, which comprises two medium rank stratigraphic cycles spanning 2–4 Myr each, in turn enclosing several lower rank cycles of less than 1 Myr. The late Oligocene (~25-23 Ma) medium rank cycle shows deposits restricted mostly to the coastal area of Tierra del Fuego and Santa Cruz provinces in the Austral-Magallanes Basin, which respond to a combination of global sea-level fluctuations and flexural subsidence. The overlying early Miocene (~22-15 Ma) medium rank cycle comprises sediments deposited over extensive areas of Patagonia with a maximum flooding at 20-19 Ma suggesting, in addition to tectonic subsidence in the Austral-Magallanes Basin, regional long-wavelength subsidence and a global sea level component for this episode. The timing and thickness of the regressive part of this cycle show differences for each basin, suggesting the action of local sedimentary controls such as differential rates of sediment supply. Further geochronological and stratigraphic studies are necessary, especially for the northern exposures, which will allow improving time-constrained paleogeographic reconstructions.

Assessing Socio-ecological Systems Using Social Media Data: An Approach for Forested Landscapes in Tierra del Fuego, Argentina

The purpose of this study was to analyse how visitors valued a socio-ecological system through the use of social media data. We gathered YouTube´s videos of Ushuaia city and its surrounding forested landscapes (Tierra del Fuego, Argentina) posted between 2010 and 2020. We used the screen time (seconds) of each video to compare the value of visitors on biophysical, cultural, and biodiversity attributes of the studied socio-ecological system. Each of the visitors registered differently the same attribute (e.g. mountains, forests, signposts, fauna, among others), therefore we assessed the time each visitor spend on any attribute, that was calculated considering the focus and scale through which it was observed. Based on our analyses, we found a diversity of attributes with different valuation data for each visitor. Attributes were classified as biophysical, cultural, and biodiversity variables, and the origin of the visitors (e.g. regions of the world) was also evaluated, with descriptive and multivariate analyses. Results indicated that visitors give more value to biophysical and cultural attributes compared to local biodiversity. These outputs highlight the need to explore and implement alternative methods to assess the socio-ecological values to achieve management objectives, and to include socio-ecological attributes in the study area as key indicators to create better tools and solutions for conservation issues. In this context, we provide a new insight into how visitors can appreciate different socio-ecological values.

Water quality index including periphyton chlorophyll-a in forested urban watersheds from Tierra del Fuego (Argentina)

The city of Ushuaia, Argentina, has experienced a rapid and unorganized population growth with possible consequences on the dynamics and functioning of urban lotic ecosystems. Urban expansion was not largely accompanied by the development of infrastructure for the provision of services such as drinking water and sewers to all the population. Currently, only 65% of the population is connected to the main sewage system (pre-treatment) and the city does not have a secondary wastewater treatment plant yet. We evaluated the impact of wastewater discharges and non-point contamination on the water quality of the three main water courses that cross the city of Ushuaia: Pipo river (PR), Buena Esperanza stream (BES) and Arroyo Grande river (AGR). We sampled four sites per watershed from spring to autumn in two consecutive years (2018 and 2019): S1 (not urbanized at the upper section), S2 (transitional section), S3 (urbanized at the middle-low section), and S4 (urbanized, close to the outlet). We developed the Fuegian Water Quality Index (F_WQI) as a tool for environmental monitoring in forest streams which includes several indicators of organic inputs (dissolved oxygen, nitrogen-ammonium, total phosphorus, fecal coliform bacteria) and periphyton chlorophyll-a (Peri Chl-a). The variables were ranked and weighed, and the index was constructed using a mathematical formula. Urbanization negatively impacted the water quality of these ecosystems; the F_WQI showed “very bad” and “bad” water quality categories at S4 in BES and AGR, both sites impacted by wastewater discharges and large percentage of urbanized area. Likewise, in the PR watershed, with less urbanization and sewage discharges, the F_WQI indicated “very good” water quality. The F_WQI summarizes the water quality of forested watersheds in a simple numerical scale, resulting in a useful tool for monitoring studies in temperate rivers and streams. We encourage the inclusion of Peri Chl-a in water quality indices, due to its ubiquity in these ecosystems and the fact that it increased the sensitivity of the index.

Genetic Diversity and Demographic History of the Shaggy Soft-Haired Mouse Abrothrix hirta (Cricetidae; Abrotrichini).

Genetic information on species can inform decision making regarding conservation of biodiversity since the response of organisms to changing environments depend, in part, on their genetic makeup. Territories of central-southern Chile and Argentina have undergone a varying degree of impact during the Quaternary, where the response of local fauna and flora was rather species-specific. Here, we focus on the sigmodontine rodent Abrothrix hirta, distributed from 35° S in Chile and Argentina to northern Tierra del Fuego. Based on 119,226 transcriptome-derived SNP loci from 46 individuals of A. hirta, we described the geographic distribution of the genetic diversity of this species using a maximum likelihood tree, principal component and admixture analyses. We also addressed the demographic history of the main intraspecific lineages of A. hirta using GADMA. We found that A. hirta exhibited four allopatric intraspecific lineages. Three main genetic groups were identified by a Principal Component Analysis and by Ancestry analysis. The demographic history of A. hirta was characterized by recent population stability for populations at the northernmost part of the range, while southern populations experienced a recent population expansion.