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Chile is the second largest producer of farmed salmon in the world. After reaching a peak harvest of 631 000 tonnes in 2008, a severe sanitary and production crisis triggered a major legal and operational reorganization, and an imminent expansion of the industry into the Aysén Fjords System ( AFS). This expansion has caused increasing national and international concern about its potential negative impact upon this pristine area, which holds a mosaic of unique ecosystems and three World Biosphere Reserves. This paper reviews and provides some upper bounds to potential impacts under two feasible production scenarios. It is concluded that severe but highly localized mid-term damage to the sea-floor bottom may affect up to 6200 ha. Although this surface area represents only 0.5% of the AFS, the high heterogeneity and limited scientific knowledge of local ecosystems increase the risks of damaging sensitive habitats, communities or populations. While additional inputs of up to 60 000 t of nitrogen and 8000 t of phosphorus can be predicted, the estimation of carrying capacities is a pendant and urgent task to be accomplished in this area. If current escape rates are not reduced, the average number of escaped salmon may exceed 4.4 million individuals each year, able to consume up to 6600 t of pelagic prey from local ecosystems. We recommend following a strict precautionary approach, not granting new farming leases until sufficient information about the risk and magnitude of these impacts is obtained and transformed into effective management actions. [ABSTRACT FROM AUTHOR]

Abstract: Chilean Patagonia is one of the most extended fjord regions in the world that covers nearly 240,000km2 with an extremely complex coastline and topography in one of the least densely populated areas of the country (1–8 inhabitants every 10km2). In recent years, the area has been undergoing somewhat intense pressure since several commercial projects in hydroelectricity, tourism, and commercial salmon and mytilid cultures have been developed, or are in progress. Concomitantly, several large research programs have been devised to study the physical, chemical, and biological environment of Patagonia, such as the CIMAR FIORDO, and recently COPAS Sur-Austral based at Universidad de Concepcion, that attempts to close the bridge between oceanographic knowledge and its use by society. In this introductory article we summarize the collection of papers comprising this Special Issue of Continental Shelf Research. These papers deal with aspects of regional oceanography and geology, inorganic and organic geochemistry, ecology of pelagic and benthic organisms, and past changes in productivity. [Copyright &y& Elsevier]

We often wonder how many of the pristine places left on Earth we can protect from deterioration before it is too late. The assumption that remote regions remain pristine plays a key role in directing policies for regional environmental management and conservation, and affects the local and global financial impetus to do so. In this paper, we use Argentinean Patagonia and the SW Atlantic as examples to argue that the assumption 'remote region = pristine region' is unjustified and based on a lack of information rather than on scientific evidence. We also discuss the major existing environmental threats to this supposedly 'pristine' region, and use emblematic examples to provide a more realistic picture of the regional environmental integrity and to set recommendations directed to improve environmental management and conservation within this context. [ABSTRACT FROM AUTHOR]

Abstract: The management and conservation of animal species should be based upon a long-term analysis that considers its geographical distribution and feeding patterns. The study of carbon and nitrogen stable isotopes on skeletal remains provides a quantitative approach to the paleodietary reconstructions and constitutes a potent tool for comparing behavioral aspects of the fauna. In this paper we present the first set of isotopic values for modern and archaeological samples of Huemul (Hippocamelus bisulcus) from the forests of Central-western Patagonia, Chile. Contrary to initial expectations, our analysis indicates that there is no evidence of an important incidence of the canopy effect on the δ13Ccollagen values, which we suggest is due to an ecological selection that drives the huemul to focus its predation on open sectors within the forest. On the other hand, a wide range of δ15Ncollagen values for huemul was verified. This could reflect the N impoverishment of the forest soils and provide an interesting ecological indicator. The long-term information offered by the archaeological record provides the necessary context for decision-making conducive towards the preservation of Hippocamelus bisulcus in Patagonia. [Copyright &y& Elsevier]

Partial migration, where migrant and resident organisms coexist within the same population, has been found in many fishes. Although it seems obvious that different life cycles exploit habitats and food webs differently, few assessments about the trophic consequences of partial migration are available. To unveil part of this complexity, we combined otolith chemistry with stable isotope analyses data for hind-casting Merluccius australis habitat use and diet composition at age. By providing detailed information about lifetime variability in diet, trophic position, and prey demand of four M. australis life-cycle types, we show that these groups feed differentially in estuarine and oceanic habitats throughout their ontogeny. Although trophic positions were similar between habitats for juvenile and subadults, substantial differences between life-cycle types were found regarding lifetime diet and trophic demand. Thus, the more abundant and heavily exploited oceanic stock of M. australis was heavily dependent of estuarine habitats within the Patagonian Fjords System, where it consumes large biomasses of Macruronus magellanicus , Pasiphaea , Sprattus fuegensis , and Euphausiidae at earlier stages. We show ignoring trophic consequences of partial migration and life-cycle diversity may produce highly biased results, both in terms of prey and habitat use, which appears critical for multispecies and ecosystem management approaches. [ABSTRACT FROM AUTHOR]

Wetlands are ecosystems that play a key role in maintaining biodiversity and associated economies (e.g. agriculture and livestock) because they are reservoirs of water and carbon. Globally, these environments have been largely deteriorated, so their sustainable use takes on special importance. This study examined the effect on water recharge of the replacement of natural grassland by pine afforestation on hillsides adjacent to two Patagonian wetlands with contrasting rainfall. Results showed that independently of the rainfall at the site considered, canopies with high coverage values (90%) intercept 40% of the precipitation. This percentage is significantly reduced when canopy coverage is near 70%. Considering forested and grassland hillsides, groundwater drainage showed different patterns, consisting of only a few millimetres in the seasons recorded. Surface runoff was not a significant source of recharge for these systems in spring and summer, showing similar values in forested and grassland hillsides. Differences found in the recharge water variables between afforestation and grassland conditions cannot be directly associated with the vegetation in areas surrounding the wetlands. These systems showed high complexity, requiring site-specific analysis to determine what the impact of afforestation will be on their hydrology. [ABSTRACT FROM AUTHOR]

For large herbivores, predation-risk, habitat structure and population density are often reported as major determinants of group size variation within and between species. However, whether the underlying causes of these relationships imply an ecological adaptation or are the result of a purely mechanistic process in which fusion and fragmentation events only depend on the rate of group meeting, is still under debate. The aim of this study was to model guanaco family and bachelor group sizes in contrasting ecological settings in order to test hypotheses regarding the adaptive significance of group-size variation. We surveyed guanaco group sizes within three wildlife reserves located in eastern Patagonia where guanacos occupy a mosaic of grasslands and shrublands. Two of these reserves have been free from predators for decades while in the third, pumas often prey on guanacos. All locations have experienced important changes in guanaco abundance throughout the study offering the opportunity to test for density effects. We found that bachelor group size increased with increasing density, as expected by the mechanistic approach, but was independent of habitat structure or predation risk. In contrast, the smaller and territorial family groups were larger in the predator-exposed than in the predator-free locations, and were larger in open grasslands than in shrublands. However, the influence of population density on these social units was very weak. Therefore, family group data supported the adaptive significance of group-size variation but did not support the mechanistic idea. Yet, the magnitude of the effects was small and between-population variation in family group size after controlling for habitat and predation was negligible, suggesting that plasticity of these social units is considerably low. Our results showed that different social units might respond differentially to local ecological conditions, supporting two contrasting hypotheses in a single species, and highlight the importance of taking into account the proximate interests and constraints to which group members may be exposed to when deriving predictions about group-size variation. [ABSTRACT FROM AUTHOR]

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

Background: Central Patagonia, Argentina, preserves an abundant and rich fossil record. Among vertebrate fossils from the Upper Cretaceous Bajo Barreal Formation of Patagonia, five individuals of the small, non-avian theropod dinosaur Aniksosaurus darwini were recovered. Group behavior is an important aspect of dinosaur paleoecology, but it is not well-documented and is poorly understood among non-avian Theropoda. Methods/Principal Findings: The taphonomic association of individuals from the Bajo Barreal Formation and aspects of their bone histology suggest gregarious behavior for Aniksosaurus, during at least a portion of the life history of this species. Histology indicates that the specimens were juvenile to sub-adult individuals. In addition, morphological differences between individuals, particularly proportions of the appendicular bones, are probably related to body-size dimorphism rather than ontogenetic stage. Conclusions/Significance: Gregarious behaviour may have conferred a selective advantage on Aniksosaurus individuals, contributing to their successful exploitation of the Cretaceous paleoenvironment preserved in the Bajo Barreal Formation. The monospecific assemblage of Aniksosaurus specimens constitutes only the second body fossil association of small, coelurosaurian theropods in South America and adds valuable information about the paleoecologies of non-avian theropod dinosaurs, particularly in the early Late Cretaceous of Patagonia. [ABSTRACT FROM AUTHOR]

Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19th century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displaced. We investigated spatial overlap and habitat selection by coexisting sheep and guanaco in winter and in summer. Additionally, we studied habitat selection of the guanaco in a control situation free from sheep, both in summer and winter. We also determined overlap between species in areas with different intensity of use (named preferred and marginal areas) in order to further detect the potential level of competition in the case of overlapping. Guanaco and sheep showed significantly different habitat preferences through all seasons, in spite of their spatial overlap at landscape scale. Additionally, the habitat used by guanaco was similar regardless of the presence or absence of livestock, which further indicates that sheep is not displacing guanaco where they coexist. These results suggest that habitat segregation between guanaco and sheep is due to a differential habitat selection and not to a competitive displacement process. Therefore, the potential for competition is considered low, contrary to what has been previously observed, although this could be a density-dependent result. [ABSTRACT FROM AUTHOR]

Sheep rearing is the main productive activity in Patagonian rangelands, where guanacos are the only native ungulate. Ranchers perceive a decrease in range carrying capacity as guanaco numbers increase, therefore guanaco conservation within private lands becomes a considerable challenge. This issue is particularly evident in the World Natural Heritage Península Valdés (PV), where there is a need to harmonize livestock production and biodiversity conservation. While sheep rearing prevails as the primary land use in the area, some ecotourism initiatives have been implemented to complement livestock production. In order to study how land use affected guanaco distribution, we characterized PV's ranches in terms of land subdivision, primary productivity, stocking-rate and management type, and assess how these variables affected guanaco encounter rates. Smaller ranches were composed of smaller paddocks (mean size 4.8 km2), which showed higher values of the remote-sensing derived Enhance Vegetation Index (EVI) (mean 0.14) and held higher sheep densities (mean 108.0 sheep/km2), while larger management units (mean size 23.8 km2), showed lower EVI values (mean 0.12) and lower stocking-rates (mean 36.7 sheep/km2). This pattern suggests that primary productivity has been a decisive factor to determine the minimal paddock size set by ranchers in PV, apparently precluding excessive land-subdivision in less productive areas. Guanaco encounter rate, expressed as number of guanacos per travelled kilometre, was inversely related to EVI and stocking-rate. However, land subdivision was the better predictor of guanaco encounter-rate within only sheep ranches, finding more guanacos per kilometre as paddock size increased. In contrast, in ranches where ecotourism was implemented as a complementary activity, guanaco encounter-rates were greater, regardless of paddock size. Our results suggest that the implementation of an additional activity by which landowners derive benefits from wildlife has prompted a beneficial outcome for guanacos, presumably through a decrease in harassment intensity. Finally, we propose possible mechanisms by which land subdivision may affect guanaco distribution and potential alternatives for the inclusion of wildlife conservation in a context of extensive livestock production. [ABSTRACT FROM AUTHOR]

Different precipitation regimes across Patagonia generate an environmental gradient that is expected to reflect upon the solute composition and concentration of lake water through the ensuing differences in water balance. In turn, this hydrochemical gradient could influence the occurrence and distribution of ostracods in the area. A cluster analysis on hydrochemical data of 36 Southern Patagonian waterbodies shows that low salinity, bicarbonate-dominated waters characterize Andean and ecotonal lakes, located in the wetter part of the precipitation gradient, while their steppe counterparts, which receive a much lower precipitation input, are more saline, enriched in all major anions and sodium-dominated. Kruskal-Wallis tests followed by Mann-Whitney pairwise comparisons show statistically significant differences in the ostracod species each water type hosts, with L. patagonica, E. cecryphalium, P. smaragdina and P. incae being found in the more dilute waters characteristic of Andean and ecotonal lakes and Limnocythere rionegroensis in the mesohaline, evaporatively evolved waters typical of steppe lakes. Other species studied do not appear to have such distinct distributions, having been found throughout the range of conditions studied. These findings promote the use of the aforementioned ostracods as semi-quantitative paleohydrological indicators, which could improve paleoclimatic reconstructions in Patagonia. [ABSTRACT FROM AUTHOR]

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

Lists a number of books related to conservation biology. "Act III in Patagonia: People and Wildlife," by W. Conway; "Alaska Wilderness: Exploring the Central Brooks Range"; "Chasing Neotropical Birds," by B. Thornton; "Dancing at the Dead Sea: Tracking the World's Environmental Hotspots," by A. Mitchell; "The Encyclopedia of Animals: A Complete Visual Guide," by S. Goodwin and A. Handley.

Off Patagonian coasts, Argentina, the dusky dolphin is one of the most common small cetaceans. This species is the aim of newly developed watching activities during summer in Golfo Nuevo. However, the real occurrence and movement pattern are unknown. The objectives of this work were to investigate the predictability of dusky dolphin distribution, group structure and behaviour in the western portion of Golfo Nuevo, with respect to environmental features (bottom depth, bottom slope, distance from shore and substrate). Random transects in the bay were searched by small boat during the summer and autumn of 2001–2004. When a group of dolphins was sighted, estimates of group size, composition (mothers with calves, adults and juveniles only, and mixed groups) and the predominant activity ( feeding, travelling, socialising, resting and milling) were recorded and thereafter at 2 min intervals. A grid of 1.5 × 1.5 km was constructed and each cell was characterised by environmental features, Area Use Index (percent of total annual search effort) and Activity Index (predominant behaviour of groups observed in that cell). Mothers with calves and smaller groups and resting behaviour occurred in shallowest waters supporting the idea/hypothesis that movement to shallower water is related to increased safety for individuals. Travelling occurred in the deepest areas with other behaviours observed in intermediate depths. Dolphin distribution within the bay differed significantly between years, but this was not related to any of the factors analysed in this study. Although there was considerable variation between years, in general, dolphins were found in deeper waters further from shore (except for mother–calf groups) and over areas with steeper seafloor gradient. The high variability in the distribution of the animals does not allow for the generation of a simple, area-specific management plan. [ABSTRACT FROM AUTHOR]

In this contribution, we describe latest Cretaceous aquatic plant communities from the La Colonia Formation, Patagonia, Argentina, based on their taxonomic components and paleoecological attributes. The La Colonia Formation is a geological unit deposited during a Maastrichtian-Danian transgressive episode of the South Atlantic Ocean. This event resulted in the deposition of a series of fine-grained sediments associated with lagoon systems occurring along irregular coastal plains in northern Patagonia. These deposits preserved a diverse biota, including aquatic and terrestrial plants and animals. The aquatic macrophytes can be broadly divided into two groups: free-floating and rooted, the latter with emergent or floating leaves. Free-floating macrophytes include ferns in Salviniaceae (Azolla and Paleoazolla) and a monocot (Araceae). Floating microphytes include green algae (Botryoccocus, Pediastrum and Zygnemataceae). Among the rooted components, marsileaceous water ferns (including Regnellidium and an extinct form) and the eudicot angiosperm Nelumbo (Nelumbonaceae) are the dominant groups. Terrestrial plants occurring in the vegetation surrounding the lagoons include monocots (palms and Typhaceae), ferns with affinities to Dicksoniaceae, conifers, and dicots. A reconstruction of the aquatic plant paleocommuniy is provided based on the distribution of the fossils along a freshwater horizon within the La Colonia Formation. This contribution constitutes the first reconstruction of a Cretaceous aquatic habitat for southern South America. [ABSTRACT FROM AUTHOR]

Native actinorhizal species Ochetophila trinervis (Gillies ex Hook. & Arn.) Poepp. ex Miers, also known as Discaria trinervis (Kellermann et al. 2005), grows along watercourses and distant from them, along a rainfall gradient in north-west Patagonia. We studied the reproductive ecology of this species under different macro- and micro-environmental conditions, in three zones in a rainfall gradient (western, intermediate and eastern) with two sites for each one, near and distant to a watercourse (riparian and dry-land). We performed field studies and germination trials. Plant size, reproductive effort (seed abundance per branch) and seed bank size of O. trinervis, were favoured by the proximity of streams in the drier environments of the gradient. The abundance of seedlings and saplings in the field was very low, which was in agreement with a lack of germination in the field, despite the good germination capacity of seeds. Sexual reproduction of O. trinervis was affected by the low abundance of seedlings. Lower rainfall, higher temperatures and a longer growing season along the gradient favour the potential regeneration of the species. Because of its nitrogen-fixing capacity and other features, O. trinervis has potential for reclamation of eroded lands in Patagonia. Patterns of seed biology and regeneration presented in this study will aid in the use of O. trinervis in the reclamation of disturbed lands. [ABSTRACT FROM AUTHOR]