Nahuel Huapi Research Articles

Distribution of backswimmers in shallow ponds of Patagonia and their predatory role on a common tadpole–copepod assemblage

In this study, the distribution and occurrence of backswimmers in 21 fishless ponds was analysed in the Nahuel Huapi National Park (Patagonia, Argentina). We performed laboratory experiments to study the impact of different developmental stages of the endemic backswimmer Notonecta vereertbruggheni on typical co-occurring prey. We recorded three species of backswimmers N. vereertbruggheni, Notonecta virescens and Notonecta fazi. A seasonal study in Fantasma pond showed that adults of N. vereertbruggheni colonise and reproduce in the pond in spring and summer, co-occurring with other macroinvertebrates and endemic tadpoles. Predation experiments explored the impact of N. vereertbruggheni on two large co-occurring prey, the calanoid copepod Parabroteas sarsi and the tadpoles of Pleurodema thaul. The backswimmer consumed more copepods than tadpoles when prey was offered separately. Selectivity experiments demonstrated that the copepods were preferred over the tadpoles. Backswimmers may impact the typical assemblages of organisms found in fishless ponds of Patagonia during spring and summer.

A recently established Kelp Gull colony in a freshwater environment supported by an inland refuse dump in Patagonia

Populations of several species of gull are increasing worldwide as a result of a plentiful supply of anthropogenic food in urbanised environments. In light of this, we decided to examine the importance of anthropogenic food in the diet of a recently established colony of Kelp Gulls (Larus dominicanus). We collected 241 regurgitated pellets of the Kelp Gull during the 2008–09 breeding season at the colony in the De La Guardia Islands, Nahuel Huapi Lake, Argentina. In terms of percentage frequency of occurrence in pellets, human refuse (65.6%) was the most frequently recorded item, followed by insects (42.3%; mostly coleopterans) and fish (21.2%). In terms of the percentage number of total prey items, insects (62.1%) and human refuse (21.3%) were the most abundant items. The consumption of insects decreased and that of human refuse increased during chick-rearing. Human refuse was recorded in samples from most nests (97.3%). We compare our results with those obtained for other localities and discuss the consequences of the management of urban refuse. Our results suggest that the Kelp Gull breeding colony in the De La Guardia Islands is sustained by the availability of food from the rubbish tip of Villa la Angostura. This is the first dietary study of the Kelp Gull in a continental freshwater ecosystem and one more example of a gull colony supported by anthropogenic sources of food.

Three‐Component Coupling of Aldehydes, Amines, and Alkynes Catalyzed by Oxidized Copper Nanoparticles on Titania (Eur. J. Org. Chem. 16/2012)

AbstractThe cover picture shows an example of diastereoselective aldehyde/amine/alkyne coupling catalyzed by copper nanoparticles supported on titania under solvent‐free conditions. The background picture depicts a panoramic view from Cerro Campanario (1052 m) in Bariloche (Río Negro, Argentina). This is one of the most beautiful and fascinating views in the region including: the East Perito Moreno's lake (aldehyde), West Perito Moreno's lake (amine), Trebol's pool (alkyne), Nahuel Huapi's lake (background), Llao Llao's peninsula and hotel, and the surrounding hills (López and Capilla in the foreground). Details are discussed in the article by F. Alonso et al. on p. 3093 ff. magnified image

A New Microphallid (Digenea) Species from Lontra provocax (Mammalia: Mustelidae) from Freshwater Environments of Northwestern Patagonia (Argentina)

A new microphallid species of Maritrema is described from the native southern river otter, Lontra provocax (Thomas). A naturally infected otter was found dead in the Nahuel Huapi National Park, Argentina. Ovigerous adult worms were recovered from the anterior portion of the intestine. Specimens of Maritrema huillini n. sp. have an unarmed genital pore and glabrous cirrus. They can be distinguished from all other species in the genus by having a long intestinal ceca extending up to three-quarters of the testes length to the level of the posterior border of the testes and a metraterm composed of a proximal sphincter, a non-muscular sac, and a distal muscular portion. This microphallid is the first species recovered from a South American eutherian host and the first digenean recorded for L. provocax.

Wildland–Urban Interface Fires and Socioeconomic Conditions: A Case Study of a Northwestern Patagonia City

In many regions of the world, fires are primarily of anthropogenic origin. In northwestern Patagonia, the number of fires is not correlated with meteorological variables, but is concentrated in urban areas. This study was conducted in the wildland-urban interface (WUI) area of San Carlos de Bariloche (Patagonia, Argentina), within the Nahuel Huapi National Park. WUI fires are particularly problematic because, besides people and goods, they represent a danger to protected areas. We studied the relationship between fire records and socioeconomic indicators within the WUI of San Carlos de Bariloche. We conducted a Multiple Correspondence Factorial Analysis and an Ascendant Hierarchical Classification of the city neighborhoods. The results show that the neighborhoods in Bariloche can be divided into three classes: High Socioeconomic Fire Risk neighborhoods, including neighborhoods with the highest fire rates, where people have low instruction level, high levels of unsatisfied basic needs and high unemployment levels; Low Socioeconomic Fire Risk neighborhoods, that groups neighborhoods which present the opposite characterization, and Moderate Socioeconomic Fire Risk neighborhoods, which are more heterogeneous. Once neighborhoods were classified, a Socioeconomic Fire Risk map was generated, supplementing the existing WUI Fire Danger map. Our results emphasize the relevance of socioeconomic variables to fire policies.

Patagonia, de margen exótico a periferia turística: Una mirada sobre un área natural protegida de frontera

During the fi rst half of the twentieth century, National Parks in Argentina were located in peripheral border spaces. This confi guration responded to previous territorial organization logics de- veloped in the country. In order to analyze the impact and infl uence of these Natural Protected Areas, the Nahuel Huapi National Park (Andean Patagonia, Argentina) case study was considered. It was concluded that, in the region of the Nahuel Huapi, the centralization in the national territorial adminis- tration was consolidated through the institutionalization of a Natural Protected Area. Moreover, this process allowed the identifi cation of different approaches from which local planning development and tourism were thought over time, affecting the way Natural Protected Areas were conceived.

Comparison of vocalisations of introduced European red deer stags (Cervus elaphus) in north-western Patagonia (Argentina) with native European populations

Polygynous deer are very vocal species, producing calls in various contexts. Male rutting calls in red deer (Cervus elaphus) have been most studied in captive and/or free-ranging European populations. The recent application of ‘source-filter theory’ has identified the independent roles of fundamental frequency (F0) and formants in the production of deer calls and demonstrated the relation between formant spacing and anatomical characteristics such as body size. The present paper describes and characterises the acoustical properties of male rutting vocalisations for a free-ranging red deer population located in the ecotone of the eastern Andean cordillera within the Nahuel Huapi National Reserve (Neuquén, Argentina), and is the first acoustic study of free-ranging red deer stags outside their historic distribution. Recordings were made of seven identified and several unidentified stags at the peak of the rut in 2007. Calculated F0 was found to be higher for these identified stags than for Scottish red deer on the island of Rhum. The analysis of formant spacing was used to calculate the length of the vocal tract (VTL) for the seven males studied; values were comparable to those found in stags from Rhum. The longest calculated VTLs within these males corresponded to those of the four stags with the largest antler racks and the only stags holding harems. Previous studies have shown that VTL correlates with body size, age and reproductive success and that these deer have the ability to lower their larynx and extend their vocal tracts to a maximum, which is probably under sexual selection. Our data fit with this explanation. The higher F0s recorded in this population may result from the influence of wapiti genes, known to be present in these deer, because wapiti have a much higher-frequency rutting call, namely, the bugle. Alternatively, they may be related to the mating strategy, which differs substantially from the northern European populations.

LA FLORA ALTOANDINA DE LOS SECTORES ESTE Y OESTE DEL PARQUE NACIONAL NAHUEL HUAPI, ARGENTINA

The floristic composition and species richness of the western (moister) and eastern (dryer) areas of the high Andean region of Nahuel Huapi National Park (Argentina) were compared. Species lists were compiled for the two sectors from collections in the alpine area of 20 mountains of the Park (10 from each sector) from 1993 to 1997. A total of 232 species, 111 genera and 48 families were recorded. Asteraceae (with 70 species), Poaceae (17), Apiaceae (12), Fabaceae (11) and Scrophulariaceae (11) are the predominant families in the area, and Senecio (with 22 species), Nassauvia (12), Acaena (7), and Perezia (7) are the best represented genera. There are six endemic species in this protected area. The most frequent life forms are perennial herbs and subshrubs, followed by shrubs, and annual species are nearly inexistent. Species richness was found to increase in relation to the precipitation decrease from west to east: 149 species were found in the moister westem sector and 220 in the dryer eastern sector. Some families and genera are more represented or appear exclusively in one of the two sectors. We discuss current ecological and past historical factor s that could explain this variation in spedes diversity and composition.

Yeast communities associated with the bulk-soil, rhizosphere and ectomycorrhizosphere of a Nothofagus pumilio forest in northwestern Patagonia, Argentina

Soil microorganisms play an important role in soil quality and they interact closely with vegetation. Little is known about yeast diversity and function in forest soil ecosystems and their interactions with other biotic soil components, particularly in the mycorrhizosphere. We studied the diversity of yeasts inhabiting the bulk-soil, rhizosphere and ectomycorrhizosphere of a Nothofagus pumilio forest in Nahuel Huapi National Park (Bariloche, Argentina). Ectomycorrhizal infection was observed in all N. pumilio trees studied. A total of 126 yeast isolates were obtained, including 18 known and three possibly new species. Basidiomycetous yeasts were predominant in all soil fractions, and the most frequently isolated species was Cryptococcus podzolicus. Diversity indices and multivariate analyses were used to study and compare yeast communities in the bulk-soil, rhizosphere and ectomycorrhizosphere. Yeasts able to ferment glucose were found associated with the rhizosphere. Many of the recovered yeast species were associated with lignocelluloses compound degradation, which suggest that yeast plays an important role as a decomposer in these forest soils. Each soil fraction has a distinct yeast assemblage related to their physiologic capacities and soil nutrient availability.

Estimating habitat suitability for potential hantavirus reservoirs in north-western Patagonia using satellite imagery: Searching for the best predictive tools

We modelled potential distribution maps for four species of rodents known to be reservoirs of the hantavirus disease. These models provide general distribution hypotheses based on a 14-year period and 274 field capture sites. Satellite remote sensing were used to extrapolate climatic and environmental features of potentially suitable habitats for these rodents in Nahuel Huapi National Park and surrounding areas. We tested the accuracy of different satellite sensors for the geographic distribution of Oligoryzomys longicaudatus, Abrothrix longipilis, Abrothrix olivaceus and Loxodontomys micropus. When looking for the best method to predict the presence of potential hantavirus reservoir species assemblages, the best prediction levels were obtained using supervised parallelepiped classifications of the SAC-C Normalized Difference Vegetation Index (NDVI) combined with the Digital Elevation Model (DEM) (91.71% for A. longipilis, 95.35% for A. olivaceus, 91.92% for L. micropus and 90.82% for O. longicaudatus). These results show that upper components of the landscape structure (e.g. climate and topography) determine the spatial distribution of hantavirus reservoirs independently of the floristic composition of the vegetation patches.

Mercury in the biotic compartments of Northwest Patagonia lakes, Argentina

We report on total mercury (THg) concentrations in the principal components of food webs of selected Northern Patagonia Andean Range ultraoligotrophic lakes, Argentina. The THg contents were determined using Instrumental Neutron Activation Analysis in muscle and liver of four fish species occupying the higher trophic positions (the introduced Salmo trutta, Oncorhynchus mykiss and Salvelinus fontinalis, and the native Percichthys trucha) accounted for eight lakes belonging to Nahuel Huapi and Los Alerces National Parks. We studied the food web components of both the West and East branches of Lake Moreno, including benthic primary producers such as biofilm, mosses, and macrophytes, three plankton fractions, fish, riparian tree leaves, and benthic invertebrates, namely decapods, molluscs, insect larvae, leeches, oligochaetes, and amphipods.Mercury concentrations in fish muscle varied in a wide range, from less than 0.05 to 4μgg−1 dry weight (DW), without a distribution pattern among species but showing higher values for P. trucha and S. fontinalis, particularly in Lake Moreno.The THg contents of the food web components of Lake Moreno varied within 4 orders of magnitude, with the lower values ranging from 0.01 to 0.5μgg−1 DW in tree leaves, some macrophytes, juvenile salmonids or benthic macroinvertebrates, and reaching concentrations over 200μgg−1 DW in the plankton. Juvenile Galaxias maculatus caught in the pelagic area presented the highest THg contents of all fish sampled, reaching 10μgg−1 DW, contents that could be associated with the high THg concentrations in plankton since it is their main food source. Although Lake Moreno is a system without local point sources of contamination, situated in a protected area, some benthic organisms presented high THg contents when compared with those from polluted ecosystems.

Propagule pressure hypothesis not supported by an 80‐year experiment on woody species invasion

Ecological filters and availability of propagules play key roles structuring natural communities. Propagule pressure has recently been suggested to be a fundamental factor explaining the success or failure of biological introductions. We tested this hypothesis with a remarkable data set on trees introduced to Isla Victoria, Nahuel Huapi National Park, Argentina. More than 130 species of woody plants, many known to be highly invasive elsewhere, were introduced to this island early in the 20th century, as part of an experiment to test their suitability as commercial forestry trees for this region. We obtained detailed data on three estimates of propagule pressure (number of introduced individuals, number of areas where introduced, and number of years during which the species was planted) for 18 exotic woody species. We matched these data with a survey of the species and number of individuals currently invading the island. None of the three estimates of propagule pressure predicted the current pattern of invasion. We suggest that other factors, such as biotic resistance, may be operating to determine the observed pattern of invasion, and that propagule pressure may play a relatively minor role in explaining at least some observed patterns of invasion success and failure.

Yeasts from an oligotrophic lake in Patagonia (Argentina): diversity, distribution and synthesis of photoprotective compounds and extracellular enzymes

Nahuel Huapi (NH) Lake is an oligotrophic temperate lake of glacial origin with high transparency, surrounded by well-developed forests and located at San Carlos de Bariloche, Nahuel Huapi National Park, in Patagonia, Argentina. In this lake, we characterized yeast distribution and diversity along a south-to-north transect and established a relationship between the ability to produce photoprotective compounds (PPCs) (carotenoid pigments and mycosporines) and the occurrence of yeast at different collection points. Subsurface water samples were filtered for yeast isolation. Total yeast counts ranged between 22 and 141 CFU L(-1) , and the highest values corresponded to the most impacted sites. Littoral sites had a low proportion of yeast-producing PPCs and this group prevailed in pelagic sites. This is probably a result of the high transparency of the water and the increased UV exposure. The yeast community from NH Lake showed a high species richness and a uniform distribution of taxa between pelagic and border collection points. Yeasts were identified as belonging to 14 genera and 34 species. Rhodotorula mucilaginosa and Cryptococcus victoriae were the most frequently found species, representing 14.4% and 13.6% of the total yeast isolates, respectively. Most of the yeast isolates demonstrated at least one extracellular enzymatic activity (mainly cellulase and lipase activities), which suggested that these microorganisms are metabolically active in the lake.

El Sistema de Refúgios de Montaña en el Parque Nacional Nahuel Huapi: aportes para el desarrollo sustentable de Bariloche [Argentina

El Parque Nacional Nahuel Huapi, ubicado al noroeste de la Patagonia andina argentina, posee un Sistema de Refugios de Montaña, conformado por bienes patrimoniales naturales y culturales, de alto valor inmaterial y paisajístico. Se analiza como referente de la identidad socio-territorial, a fin de reflexionar sobre su valorización como bien patrimonial. Se enuncian una serie de acciones de participación ciudadana para su puesta en valor como patrimonio local en común y como recurso turístico, para la generación de un compromiso ético que promueva una gestión equilibrada. Con el fin de realizar recomendaciones de uso como recurso para el desarrollo local, se analiza el perfil productivo de la ciudad y los enunciados del Desarrollo sustentable y de la Carta del Turismo Sostenible. Según los marcos actuales, se analizan los factores endógenos y se propicia la implementación de un Plan de Gestión, –a considerarse en un Plan de Desarrollo Local Territorial–, que atienda a la apropiación de ese patrimonio, y que brinde herramientas de transferencia ambiental a través de la educación y la arquitectura, ponderando su difusión a todos los usuarios de la información. Este Sistema y en particular el Circuito de los Cuatro Refugios, se propicia como modelo vivo de transferencia de buenas prácticas en materia de turismo sustentable y como factor de desarrollo local, planteándose como el mecanismo para gestionar racionalmente el capital natural y el acervo local, a fin que la comunidad pueda seguir continuar beneficiándose de los bienes y servicios de este ecosistema de forma racional y perdurable.

Synergistic influences of introduced herbivores and fire on vegetation change in northern Patagonia, Argentina

Question: We investigated how cattle and European hares, the two most widespread exotic herbivores in Patagonia, affect species composition, life-form composition and community structure during the first 6 years of vegetation recovery following severe burning of fire-resistant subalpine forests and fireprone tall shrublands. We asked how the effects of introduced herbivores on post-fire plant community attributes affect flammability of the vegetation. Location: Nahuel Huapi National Park, northwest Patagonia, Argentina Methods: We installed fenced plots to exclude livestock and European hares from severely burned subalpine forests of Nothofagus pumilio and adjacent tall shrublands of N. antarctica. The former is an obligate seed reproducer, whereas the latter and all other woody dominants of the shrubland vigorously resprout after burning. Results: Repeated measures ANOVA of annual measurements over the 20012006 period indicate that cattle and hare exclusion had significant but complex effects on the cover of graminoids, forbs, climber species and woody species in the two burned community types. Significant interactions between the effects of cattle and hares varied by plant life forms between the two communities, which implies that their synergistic effects are community dependent. Conclusions: Following severe fires, the combined effects of cattle and hares inhibit forest recovery and favour transition to shrublands dominated by resprouting woody species. This herbivore-induced trend in vegetation structure is consistent with the hypothesis that the effects of exotic herbivores at recently burned sites contribute to an increase in the overall flammability of the Patagonian landscape.

The Imperial Shag (Phalacrocorax atriceps) in the Nahuel Huapi Lake (northwestern Patagonia, Argentina): distribution, abundance, and potential threats from scavenging birds

We describe the distribution and breeding abundance of the Imperial Shag (Phalacrocorax atriceps) in the northern portion of the Nahuel Huapi Lake (northwestern Patagonia, Argentina) during the 2006-2007 and 2007-2008 reproductive seasons. We recorded low population numbers and null breeding success in both seasons. Attacks from several scavenging birds were recorded, and breeding activities were interrupted abruptly. Future studies should consider the potential threats from scavenging birds, subsidized by urban garbage dumps, over this freshwater shag.

The Relationship Between Fish Assemblages and the Helminth Communities of a Prey Fish, in a Group of Small Shallow Lakes

Galaxias maculatus (small puyen) is an abundant native fish distributed in lakes and rivers of the Patagonia, and it is the frequent prey of other fishes, fish-eating birds, and mammals. Previous studies have shown that it is parasitized by 33 metazoan species and that the richness and composition of the parasite communities vary between lakes. The aim of the present work was to analyze the relationship between the composition of fish assemblages and the helminth component community structure of G. maculatus . Ten environmentally similar, small, shallow lakes, belonging to the Nahuel Huapi Lake basin, were chosen because of the differences in the native fish assemblages. Parasite community structure in G. maculatus varied according to the fish assemblage of each lake. The presence of the piscivorous fish Percichthys trucha regularly produced variations in the composition and richness at the component and infracommunity levels, as well as the percentage of autogenic parasite species in G. maculatus .

Feeding Habits of Torrent Ducks (Merganetta Armata Armata) in Nahuel Huapi National Park, Argentina

The Torrent Duck (Merganetta armata) is a little-known species that feeds on benthic invertebrates in fast-flowing mountain rivers and streams from Venezuela to Tierra del Fuego. In Argentina the species is classified as Threatened but basic studies of its resource requirements are necessary for conservation. Prey selection by adult Torrent Ducks was investigated by comparing the proportion of prey species in duck faeces with the proportion available in the benthos. Faeces and benthos were sampled seasonally over one year, from four territories in the Manso River Basin, Nahuel Huapi National Park, northwestern Argentine Patagonia. Filter feeding Simuliidae larvae (Diptera, 41–76% number of total prey) were consumed in greater proportion than their abundance. In Arroyo Blanco, an oligotrophic stream, Simuliidae were absent and the most important prey were Gripopterygidae larvae (Plecoptera, 53%) and Blephariceridae larvae (Diptera, 23%). Simuliidae may be easy prey because, like other filter feeders, they feed in exposed places. However, where these filtering species are rare or absent (as in Arroyo Blanco), ducks consume other prey. The results show that Torrent Ducks exhibit a versatile feeding behavior, indicating that the species can adjust to changes in the benthos without disappearing in a given environment.

Early Eocene40Ar/39Ar Age for the Pampa de Jones plant, Frog, and Insect Biota (Huitrera Formation, Neuquén Province, Patagonia, Argentina)

The Pampa de Jones fossil site, a stratigraphically isolated roadcut near the northeastern shore of Nahuel Huapi Lake in Neuquén Province, Argentina, holds a rich fossil biota including a macroflora, a microflora, insects, and most famously, an ontogenetic series of pipid frogs. The site exposes tuffaceous mudstone and sandstone beds of probable lacustrine origin, considered to belong to the volcanic Huitrera Formation. However, there have been no reliable age constraints for the fossil assemblage. We undertook laser fusion analyses of sanidine and biotite crystals occurring in a tuff layer found 4.4 m above the main fossil horizon. Twenty-eight sanidine crystals yielded an 40Ar/39Ar age of 54.24 ± 0.45 Ma that is preferred over our biotite age of 53.64 ± 0.35 Ma. Pampa de Jones is thus the oldest well-dated Eocene fossil site in Patagonia, predating two other recently 40Ar/39Ar-dated sites: Laguna del Hunco (51.91 ± 0.22 Ma) and Río Pichileufú (47.46 ± 0.05 Ma). The improved age control makes possible a finer scale of evolutionary hypothesis testing and turnover analysis in the region. The age is concordant with the site's placement in the Huitrera Formation and a depositional origin related to Early Paleogene arc volcanism, and it correlates to an interval of significant climate fluctuations following the Paleocene-Eocene boundary.

Wide spread invasion without sexual reproduction? A case study on European willows in Patagonia, Argentina

Willows of the Salix alba–Salix fragilis complex, native to western Eurasia, represent typical invaders of floodplain ecosystems worldwide. Introduced to South America by European settlers probably at the end of the nineteenth century, their distribution has increased significantly along the rivers in Northern Patagonia. This case study carried out mainly in the area around Lake Nahuel Huapi aims to analyze clonal structures and their spatial distribution using molecular markers as well as to relate the observed patterns to settlement history and life history traits of this species complex. Leaf material from 171 trees was collected along selected river floodplains in Northern Patagonia and genotypes were determined at six microsatellite loci. Including 62 reference samples of the S. alba–S. fragilis complex from German rivers, Probability of Identity (P ID) was calculated and a Principal Coordinate Analysis (PCoA) conducted. From the altogether thirteen different genotypes detected, one dominant genotype (female) formed monoclonal stands along most of the studied river stretches. The maximum linear distance between the most remote ramets of this clone was 790 km. Evidence arose that the colonizing process so far is exclusively based on vegetative propagation in the focal study area and is obviously attributable to the pronounced brittleness of the hybrid parent S. fragilis. However, outside this area the occurrence of male trees and a diversity of genotypes indicate that evolutionary processes by recombination are involved within the willow complex. Therefore, an increase in genotypes can be assumed when male individuals and therefore sexual reproduction would appear in the area around Lake Nuhuel Huapi. This could be a crucial point for the long-term invasion success of the taxa when climatic and other environmental conditions will change in Southern Argentina.