Ecos de la tormenta de Comodoro Rivadavia en el valle inferior del Río Chubut. Aporte de sedimentos al Río Chubut desde la cuenca del Río Chico

El evento de abril de 2017 produjo en las comunidades del noreste de Chubut una crisis inusitada en la provisión de agua potable. Los sistemas de potabilización del agua, capaces de manejar los frecuentes eventos de turbiedad elevada producidos por precipitaciones torrenciales de corta duración sobre el Valle Inferior del Río Chubut, se vieron desbordados por un evento de características nuevas. La ?tormenta de Comodoro Rivadavia? fue de carácter extraordinario: 330 mm entre el 29 de marzo y el 4 de abril, con un máximo de 232 mm en 24 horas. La lluvia se extendió más allá de Comodoro Rivadavia abarcando el extremo sur de la cuenca del Río Chico. La conjunción de la lluvia y de la falta de vegetación en la cuenca (cerca del 62% de la superficie está desprovista de vegetación) produjo una crecida con caudal máximo estimado en 667 m3/s. El Río Chico es un afluente no permanente del DiqueFlorentino Ameghino. La crecida elevó el embalse en 12 m aproximadamente y aportó una cantidad ingente de sedimentos. La turbiedad alta en el embalse y en el Río Chubut se mantuvo por casi 60 días, lo que provocó cortes y restricciones al suministro de agua potable por tres meses, una duración y picos máximos de turbiedad nunca imaginados. El evento de abril de 2017 revela por sí mismo la complejidad y la fragilidad de la realidad hídrica de la comarca del VIRCH. Sequías, inundaciones, y problemas con la calidad del agua son problemas intrínsecos de las características biofísicas de este sistema, y sólo pueden ser agravados por el cambio climático y las actividades humanas no planificadas.Fil: Kaless, Gabriel. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Flaherty, Silvia. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Liberoff, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Brandizi, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Pessacg, Natalia Liz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentin

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

Age and growth differences in two populations of the edible marine gastropod Buccinanops globulosus

Buccinanops globulosus is an edible marine gastropod that is being captured by artisanal fishermen without management regulations. As basic knowledge on population features is required in case a sustained commercial exploitation of this species is established, we estimated and compared the age and growth of B. globulosus in two populations separated by 16 km, inhabiting similar physical environments but different anthropic influence. Our results, based on stable oxygen isotope analysis and best fitted models by likelihood ratio tests, detected differences in age and growth between both samplings. Maximum shell marks suggest one year difference between populations. Richards was chosen as the best fitting model for both sampling sites and significant differences were observed between them. Human activities could be causing the age reduction among other irreversible effects on the population under anthropic influence. This should be considered when developing sustainable management regulations for this fishery resource, especially those based on shell/age size.Fil: Bökenhans, Verena Diana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Bigatti, Gregorio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentin

Conflicting objectives in trophy trout recreational fisheries: evaluating trade-offs using an individual-based model

Standard fisheries models, based on average populations metrics are inadequate for analyzing recreational fisheries where fishing is size-selective and management objectives are related to preserving population size structure. Using data from the steelhead (Oncorhynchus mykiss) fishery in the Santa Cruz River (Patagonia, Argentina) we developed an individual-based harvest model to characterize the relationship between growth, mortality and size structure under different size-based harvest strategies. We evaluated fishery performance with indicators associated to catch-related components of anglers? satisfaction: yield (kg), population size, and availability of trophy-size fish. Large declines in trophy-size fish are to be expected at fishing mortalities much too light to cause a sizeable decline in recruitment from virgin values. When somatic growth is density independent, fish harvest occurs at the expense of other indicators associated to the quality of fishing experienced by individual anglers. Our results clearly expose such trade-offs, providing the kind of quantitative information managers need to decide where to operate. Size limits provide some tools to better accommodate harvest without compromising fishing quality. When preserving population size is favored over preserving trophy-size fish, minimum size limits constitute the best policies overall, whereas maximum size limits are best when the emphasis is on preserving trophy-size fish.Fil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Escati Peñaloza, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Parma, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentin

Assessing land use and land cover influence on surface water quality using a parametric weighted distance function

Stream water quality is directly influenced by land use and human practices in the surrounding environment. Understanding such effects and the spatial extent of impacts is essential to generate reliable information for ecosystem-based management of water resources. We identified sources of impact on water quality and characterized indicator-specific landscape influence on samples collected during base flow along the Chubut River (43 °S, 69 °W). We modeled Total Nitrogen (TN), Total Phosphorous (TP), Soluble Reactive Phosphorous (SRP) concentrations and δ15N of particulate organic matter along the river, as a function of effective contribution areas (AEC) of Land Use/Land Cover (LULC). AECs were calculated by assuming that landscape influence decays exponentially with the Euclidean distance between a given LULC parcel and the sampling point. We calibrated the model to the observations by estimating an indicator-specific decay rate. Agriculture and barren lands were the main sources of phosphate nutrients whereas urban areas were the main source of TN. Radius of landscape influence for SRP (100–180 km) was larger than for TP (10–25 km), reflecting different patterns of mobilization and delivery in the catchment. δ15N variation was explained by vegetation cover but the influence rapidly decreased (1–4 km) reflecting a mostly autochthonous source of organic matter.Fil: Liberoff, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Flaherty, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Hualde, Pablo. Centro de Ecología Aplicada del Neuquén; ArgentinaFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Fogel, Marilyn. University of California; Estados UnidosFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentin

Análisis espacial para la estimación de impactos humanos sobre la calidad del agua del Río Chubut

Se plantea un marco conceptual espacialmente explícito para (i) identificar las actividades humanas que afectan la calidad del agua del Río Chubut y ii) estimar el alcance espacial de los impactos. Como indicadores de calidad de agua se relevaron: nitratos (NO3), fósforo reactivo soluble (PRS), fósforo y nitrógeno totales (PT y NT) e isótopos en materia orgánica particulada (15N-MOP) en 20 sitios a lo largo del Río Chubut.Fil: Liberoff, Ana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Flaherty, Silvia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Hualde, P.. Provincia del Neuquén. Subsecretaría de Producción y Recursos Naturales. Centro de Ecología Aplicada del Neuquén; ArgentinaFil: Fogel, Marilyn. University of California; Estados UnidosFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaVII Congreso Argentino de LimnologíaSan Miguel de TucumánArgentinaInstituto de Biodiversidad Neotropica

Scale, connectivity, and incentives in the introduction and management of non-native species: The case of exotic salmonids in Patagonia

Many introduced species have become established throughout large areas of the world, causing millions of dollars in damages. The introduction of such pest species is universally condemned, and science and management efforts are geared toward eradication, containment, or prevention of future infestations. Meanwhile, other organisms are actively traded around the world for consumption, as well as recreational and aesthetic purposes, providing examples of the conflict between human development and conservation. When dealing with such species, are there ways to balance the competing goals of economic production and protection of nature? How can science help to identify suitable compromises? We address these questions by analyzing three case studies dealing with exotic salmonids in Patagonia: trout aquaculture in shallow, fishless lakes; trout recreational fisheries; and marine net-pen salmon aquaculture. We propose that three interrelated properties of these case studies (scale, connectivity, and incentives for conservation) determine our ability to identify and promote situations that balance production and the integrity of nature.Fil: Pascual, Miguel Alberto. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Lancelotti, Julio Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Ernst, Billy. Universidad de Concepción; Chile. Centro de Investigación en Ecosistemas de la Patagonia; ChileFil: Ciancio Blanc, Javier Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Aedo, Eduardo. Centro de Investigación en Ecosistemas de la Patagonia; Chile. Universidad Austral de Chile; ChileFil: Garcia Asorey, Martin Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin