Spatial pattern and habitat requirements of Galaxias maculatus in the last un-interrupted large river of Patagonia: a baseline for management

The relationship between the native Galaxias maculatus and environmental variables was studied in 52 sites located along 306 km of the main stemof the Santa Cruz River, the second largest river in Argentinean Patagonia. The abundance varied along the river, with three general sections clearly defined: upstream with minimum abundance increasing towards midstream and downstream areas. Distance to the sea and river wet width which were negatively significantly associated with abundance,and maximum depth explained the abundance in a polynomial shape - achieving a total explanation of 41.1%. The best predictive model also combined the river sinuosity. Our results suggested that the construction of two proposed hydroelectric dams will modify these variables, which might generate changes in G. maculatus distribution. The information obtainedduring the present study represents valuable information for conservation management of this species.Fil: Tagliaferro, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Quiroga, Analía. 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

Presencia y abundancia de aves acuáticas en la Meseta Strobel, Patagonia, Argentina

La meseta Strobel, ubicada en la estepa patagónica, alberga más de 1500 lagunas que son utilizadas regularmente por aves acuáticas, incluyendo una de las principales poblaciones reproductivas del Macá Tobiano (Podiceps gallardoi), una especie endémica de la Patagonia austral. Se registró la presencia y abundancia de aves acuáticas en 41 lagunas, cubriendo el amplio espectro de la variabilidad ambiental de la región. Se llevaron a cabo seis campañas de campo desde fines de primavera a principios de otoño en el período 2004–2006. Se registraron un total de 18 especies de aves acuáticas correspondientes a cinco familias. La familia Anatidae fue la más representada con 12 especies, constituyendo el 85% de las aves acuáticas observadas. La distribución de las aves entre las lagunas fue variable, desde un 2.4% de lagunas ocupadas por el Falaropo Común (Steganopus tricolor) y el Pato Zambullidor Grande (Oxyura jamaicensis) hasta un 80% ocupadas por el Cisne Cuello Negro (Cygnus melanocorypha), y la abundancia varió mucho entre especies y estaciones. El Macá Tobiano, en particular, fue observado en 14 lagunas (1–81 individuos). Seis especies fueron detectadas reproduciéndose en la meseta: el Macá Tobiano, el Macá Plateado (Podiceps occipitalis), el Quetro Volador (Tachyeres patachonicus), el Pato Crestón (Anas specularioides), el Cauquén Común (Chloephaga picta) y la Gallareta Chica (Fulica leucoptera). El Macá Tobiano nidificó en cuatro lagunas, tres de las cuales no habían sido reportadas previamente como sitio de reproducción. Los resultados evidencian la necesidad de generar estudios futuros basados en la dinámica de uso de las lagunas para determinar adecuadamente la importancia de la meseta Strobel como hábitat para la avifauna acuática.The Strobel Plateau is a conspicuous and representative basaltic plateau (“meseta”) in the Patagonian steppe, Argentina. This plateau is dotted with more than 1500 shallow lakes, which are regularly used by waterbirds and support one of the main breeding populations of the near threatened Hooded Grebe (Podiceps gallardoi). We collected data on bird presence and abundance in 41 shallow lakes, covering a wide spectrum of the wetland environmental variability found in the area. We conducted six surveys from spring to fall between 2004 and 2006. We recorded a total of 18 waterbird species, which represent 5 different families. Anatidae was the family most represented with 12 species, accounting for 85% of the observed waterbirds. Waterbird distribution among lakes was variable, from 2.4% occupied lakes for Wilson’s Phalarope (Steganopus tricolor) and Andean Ruddy-Duck (Oxyura jamaicensis) to 80% for Black-necked Swan (Cygnus melanocorypha), and abundance varied greatly both between species and seasons. The Hooded Grebe, in particular, was recorded in 14 lakes (1–81 individuals). Six species were detected breeding in the area: Hooded Grebe, Silvery Grebe (Podiceps occipitalis), Flying Steamer-Duck (Tachyeres patachonicus), Crested Duck (Anas specularioides), Upland Goose (Chloephaga picta), and White-winged Coot (Fulica leucoptera). The Hooded Grebe nested at four lakes, three of them not previously known to hold breeding birds. Results point to the need of further studies on the dynamic nature of waterbird lake use to adequately assess the importance of the Strobel Plateau as waterbird habitat.Fil: Lancelotti, Julio Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Pozzi, Luciana Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Marquez, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados UnidosFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentin

First study of food webs in a large glacial river: the trophic role of invasive trout

El objetivo de este estudio fue determinar la estructura trófica de un gran río de la Patagonia en dos secciones (río arriba y medio) y evaluar la superposición isotópica entre especies nativas e introducidas. Utilizamos análisis de isótopos estables δ15N y δ13C y contenido estomacal. La sección río arriba tuvo una estructura de trama trófica más compleja, con mayor riqueza de macroinvertebrados y peces respecto de la sección media. Los recursos basales dominantes río arriba fueron las algas filamentosas. En esta área, la trucha de lago tuvo la posición trófica más alta entre los peces, aunque, las especies de peces más abundantes fueron las truchas arcoiris. Dependiendo del estadio, la trucha arcoiris cambió su rol de presa a competidor/depredador. En la sección media del río, la base de la trama trófica estuvo dominada por materia orgánica particulada gruesa y la trucha arcoíris adulta fue el depredador tope. Los valores isotópicos variaron entre zonas para invertebrados y peces. Las dos especies nativas e invasoras más abundantes, Puyen y trucha arcoiris, mostraron una separación isotópica en la sección media, pero no en secciones de río arriba. La presencia de peces invasores que ocupan una posición tope en los niveles tróficos puede tener un impacto significativo sobre las poblaciones de peces nativos de gran importancia ecológica en la regiónThe aim of this study was to determine the food webs structure of a large Patagonian river in two river sections (Upstream and Midstream) and to evaluate isotopic overlap between native and introduced species. We used stable isotope analyses of δ15N and δ13C and stomach content. The Upstream section had a more complex food webs structure with a greater richness of macroinvertebrates and fish species than Midstream. Upstream basal resources were dominated by filamentous algae. Lake Trout were found to have a higher trophic position than all other fish species in that area although, the most abundant fish species, were Rainbow Trout. Depending on the life stage, Rainbow Trout shifted from prey to competitor/predator. In the Midstream section, the base of the food webs was dominated by coarse particulate organic matter, and adult Rainbow Trout had the highest trophic level. Isotopic values changed among macroinvertebrates and fish for both areas. The two most abundant native and invasive species — Puyen and Rainbow Trout — showed an isotopic separation in Midstream but did not in Upstream areas. The presence of invasive fish that occupy top trophic levels can have a significant impact on native fish populations that have great ecological importance in the region.Fil: Tagliaferro, Marina Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Kelly, Sean P.. Universidad de Puerto Rico; Puerto RicoFil: 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

Value, quality, purchasing habits and repurchase intention in B2C: differences between frequent and occasional purchasers

Este estudio propone un modelo integrador de la recompra en comercio electrónico (B2C), basado en la teoría de la confirmación de expectativas, tomando como partida el modelo de Bhattacherjee extendido con el modelo de satisfacción Cronin. El modelo de investigación se ha probado con 536 compradores españoles, usando análisis multigrupo. El modelo fue capaz de explicar más del setenta por ciento de la varianza de la intención de recompra. Como resultados, la relación entre la calidad y la satisfacción es no significativa para todos los tipos de consumidores y la relación entre la utilidad y la recompra es no significativa sólo para los compradores más frecuentes. Algunas ideas para llevar a la práctica son presentadas a modo de discusión

Population regulation in Magellanic penguins: what determines changes in colony size?

Seabirds are often studied at individual colonies, but the confounding effects of emigration and mortality processes in open populations may lead to inappropriate conclusions on the mechanisms underlying population changes. Magellanic penguin (Spheniscus magellanicus) colonies of variable population sizes are distributed along the Argentine coastline. In recent decades, several population and distributional changes have occurred, with some colonies declining and others newly established or increasing. We integrated data of eight colonies scattered along ~600 km in Northern Patagonia (from 41°26´S, 65°01´W to 45°11´S, 66°30´W, Rio Negro and Chubut provinces) and conducted analysis in terms of their growth rates, production of young and of the dependence of those vital rates on colony age, size, and location. We contrasted population trends estimated from abundance data with those derived from population modeling to understand if observed growth rates were attainable under closed population scenarios. Population trends were inversely related to colony size, suggesting a density dependent growth pattern. All colonies located in the north — which were established during the last decades — increased at high rates, with the smallest, recently established colonies growing at the fastest rate. In central-southern Chubut, where colonies are the oldest, the largest breeding aggregations declined, but smaller colonies remained relatively stable. Results provided strong evidence that dispersal played a major role in driving local trends. Breeding success was higher in northern colonies, likely mediated by favorable oceanographic conditions. However, mean foraging distance and body condition of chicks at fledging were influenced by colony size. Recruitment of penguins in the northern area may have been triggered by a combination of density dependence, likely exacerbated by less favorable oceanographic conditions in the southern sector. Our results reaffirm the idea that individual colony trends do not provide confident indicators of population health, highlighting the need to redefine the scale for the study of population changes.Fil: Pozzi, Luciana Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Garcia Borboroglu, Jorge Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Global Penguin Society. Washington; Estados Unidos. University of Washington; Estados UnidosFil: Boersma, P. Dee. Global Penguin Society. Washington; Estados Unidos. University of Washington; Estados UnidosFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia; Argentin

On the role of entropy in the stabilization of α-Helixes

Protein folding evolves by exploring the conformational space with a subtle balance between enthalpy and entropy changes which eventually leads to a decrease of free energy upon reaching the folded structure. A complete understanding of this process requires, therefore, a deep insight into both contributions to free energy. In this work, we clarify the role of entropy in favoring the stabilization of folded structures in polyalanine peptides with up to 12 residues. We use a novel method referred to as K2V that allows us to obtain the potential-energy landscapes in terms of residue conformations extracted from molecular dynamics simulations at conformational equilibrium and yields folding thermodynamic magnitudes, which are in agreement with the experimental data available. Our results demonstrate that the folded structures of the larger polyalanine chains are stabilized with respect to the folded structures of the shorter chains by both an energetic contribution coming from the formation of the intramolecular hydrogen bonds and an entropic contribution coming from an increase of the entropy of the solvent with approximate weights of 60 and 40%, respectively, thus unveiling a key piece in the puzzle of protein folding. In addition, the ability of the K2V method to provide the enthalpic and entropic contributions for individual residues along the peptide chain makes it clear that the energetic and entropic stabilizations are basically governed by the nearest neighbor residue conformations, with the folding propensity being rationalized in terms of triads of residuesThis work was partially supported by the Spanish Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER, UE) under Project CTQ2016-79345-P and by the Fundación Séeneca under Project 20789/PI/18. We thank the computational assistance provided by J. F. Hidalgo of the Servicio de Infraestructuras TIC de ATICA

Fishless shallow lakes of Southern Patagonia as habitat for waterbirds at the onset of trout aquaculture

1. The Strobel Meseta, a basaltic plateau of Patagonia (Santa Cruz Province, Argentina), holds thousands of shallow fishless lakes that are prime habitat for many species of waterbirds, including some considered 'near threatened'. In recent years, several lakes have been stocked with trout which has created uncertainty about the potential effects on the recipient ecosystem. 2. Limnological and topographical analyses were performed in a group of 32 lakes of the Strobel Meseta in order to characterize and classify individual lakes of the meseta based on their limnological and topographic features, analyze the association between lake type and use by aquatic birds in general and by the endemic hooded grebe (Podiceps gallardoi) in particular, and evaluate the overlap between trout aquaculture and critical habitat for waterbirds. 3. The lakes were classified by multivariate analyses into four characteristic types: Turbid, high conductivity lakes (T), small vegetated lakes (SV) and larger lakes which were subdivided into either vegetated (LV) or unvegetated (LU). In general, macrophyte cover was the main classificatory variable, whereas conductivity, pH, surface, and depth contributed moderately. Large vegetated lakes were generally found to be important for waterbirds and provided critical habitat for the hooded grebe, whereas trout farmers largely favoured largeunvegetated lakes. However, since some large vegetated lakes have already been stocked, there is some level of geographical overlap between waterbird habitat and trout farming. 4. The existence of some level of spatial segregation between production and critical waterbird habitat affords opportunities for designing a spatially-based management system for trout aquaculture.Fil: Lancelotti, Julio Lucio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Pozzi, Luciana Melina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Wildlife Conservation Society; Estados UnidosFil: Dieguez, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Pascual, Miguel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; Argentin

Analysis of the Functionality of the Feed Chain in Olive Pitting, Slicing and Stuffing Machines by IoT, Computer Vision and Neural Network Diagnosis

Olive pitting, slicing and stuffing machines (DRR in Spanish) are characterized by the fact that their optimal functioning is based on appropriate adjustments. Traditional systems are not completely reliable because their minimum error rate is 1–2%, which can result in fruit loss, since the pitting process is not infallible, and food safety issues can arise. Such minimum errors are impossible to remove through mechanical adjustments. In order to achieve this objective, an innovative solution must be provided in order to remove errors at operating speed rates over 2500 olives/min. This work analyzes the appropriate placement of olives in the pockets of the feed chain by using the following items: (1) An IoT System to control the DRR machine and the data analysis. (2) A computer vision system with an external shot camera and a LED lighting system, which takes a picture of every pocket passing in front of the camera. (3) A chip with a neural network for classification that, once trained, classifies between four possible pocket cases: empty, normal, incorrectly de-stoned olives at any angles (also known as a “boat”), and an anomalous case (foreign elements such as leafs, small branches or stones, two olives or small parts of olives in the same pocket). The main objective of this paper is to illustrate how with the use of a system based on IoT and a physical chip (NeuroMem CM1K, General Vision Inc.) with neural networks for sorting purposes, it is possible to optimize the functionality of this type of machine by remotely analyzing the data obtained. The use of classifying hardware allows it to work at the nominal operating speed for these machines. This would be limited if other classifying techniques based on software were used

Maternal influence on early lipid content in an introduced partially anadromous population of rainbow trout Oncorhynchus mykiss

This study evaluated how the maternal migratory tactic in a partially anadromous population of Oncorhynchus mykiss may influence the early energetic status of their offspring. Total lipid content variation (% dry mass) of recently emerged fry caught in the Santa Cruz River, Argentina, was evaluated as a function of their maternal origin (anadromous v. resident) and fork length (LF ). Lipid content of fry decreased with LF and was higher for offspring of anadromous mothers.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: Leal Martínez, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; ArgentinaFil: Díaz de Vivar, María Enriqueta Adela. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Riva Rossi, Carla Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Diversidad y Evolución Austral; 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; Argentin