Neuquen River Research Articles

Influencia de ENOS en la hidrometeorología de la Cuenca Alta del Río Neuquén

La interacción océano-atmósfera actúa como forzante de los sistemas hidrológicos en diferentes escalas temporales, siendo El Niño-Oscilación Sur (ENOS) uno de ellos. Este trabajo presenta el análisis de variables hidrometeorológicas y su asociación con el Índice Oceánico del Niño (ONI), representativo de ENOS, en la Cuenca Alta del Río Neuquén para el período 2000-2014. Se ha detectado una débil correlación (r de 0,35). La precipitación, la temperatura, el caudal, el Equivalente de Agua en Nieve y el Área Cubierta de Nieve (ACN) presentaron una débil asociación con el ONI, con un coeficiente de correlación medio de 0,35 y un nivel de significación del 5% en la Cuenca Alta del Río Neuquén (CARN) para el período 2000-2014. El ACN presentó una correlación muy débil, entre -0,07 para El Niño y 0,14 para La Niña, mientras que las correlaciones entre el caudal y el ONI fueron de 0,51 para la totalidad del período y 0,31 para las fases de El Niño al 5% de significación, sin ser significativas para períodos de La Niña

Grabados imperceptibles. Pisadas y paralelas del sitio Piedra Auque, Departamento Minas, noroeste de la Provincia de Neuquén

En este trabajo se presenta un nuevo sitio con grabados rupestres localizado en el valle del arroyo Auque, en el noroeste de la provincia de Neuquén. Se trata de grabados efectuados sobre un afloramiento de pirofilita, roca similar a la esteatita o comúnmente denominada piedra sapo o jabón. Debido a la notable excepcionalidad de su uso como soporte efectuamos una caracterización del mismo, como también de los motivos presentes, las técnicas empleadas, su localización espacial y visibilidad arqueológica. De este modo, discutimos la particularidad de los diseños grabados dentro del contexto de producción rupestre de la cuenca del río Neuquén y el norte neuquino en general.

First record of the invasive tapeworm, Schyzocotyle acheilognathi (Pseudophyllidea; Bothriocephalidae) in native freshwater fish, Brazil.

Schyzocotyle acheilognathi is a tapeworm cestode commonly found in native freshwater fishes from Asia. This cestode has low host specificity and for that reason it has been registered parasitizing more than 200 cultured and wild fish species, besides amphibians, reptiles and birds from different regions of the world. With a high pathogenic potential, S. acheilognathi may cause mortalities in highly infected fish. In South America, Schyzocotyle was reported in Cyprinus carpio from a Brazilian fish farm at the municipality of Cornélio Procópio, northern Paraná State and from the natural environment in C. carpio from Neuquen River, Patagonia, Argentina. So far, there has been no report of this parasite in South American native fishes. Herein we report the first occurrence of the invasive tapeworm S. acheilognathi in Rineloricaria pentamaculata (Siluriformes, Loricariidae), a native armored freshwater catfish from southern Brazil.

Diseño y aplicación en SIG de un indicador de obstrucción al escurrimiento superficial en planicies aluviales reguladas: el caso del Río Neuquén (Argentina)

La construcción de presas y embalses en una planicie de inundación fluvial ocasiona modificaciones al funcionamiento natural de este sistema, regulando la erogación de caudales. Uno de los principales efectos inmediatos de esta situación es la ocupación antrópica no planificada, con la consiguiente alteración positiva o negativa, de las variables ambientales, y específicamente de los usos del suelo dentro de la planicie.La evaluación de estos cambios resulta entonces una prioridad para lograr un conocimiento más objetivo de sus consecuencias. En esta aportación se aborda la construcción de un indicador del grado de obstrucción al escurrimiento superficial, aplicándolo en un tramo del río Neuquén (Argentina), el cual se ubica aguas abajo de la presa Portezuelo Grande hasta el embalse San Patricio del Chañar; como resultado relevante se ha producido una cartografía final que destaca las zonas problemáticas. Con ello se busca analizar implicancias y avanzar hacia una herramienta idónea de diagnóstico de posibles cambios ambientales que deriven en situaciones de vulnerabilidad hídrica, y que deban ser considerados en futuros planes de manejo del tramo en cuestión.

Los primeros registros geológicos y paleontológicos del Neuquén: la expedición de Luis de la Cruz y Goyeneche en 1806

Luis de la Cruz y Goyeneche realizó en 1806 un viaje de reconocimiento comisionado por las autoridades de Chile y del Virreinato del Río de la Plata. A principios del siglo XIX se propiciaba la búsqueda de un camino más directo entre Buenos Aires y el centro-sur de Chile, con la finalidad de mejorar la actividad comercial, atravesando territorios desconocidos y habitados por los indios. Aquí se analiza el recorrido en el territorio de la actual provincia del Neuquén a la que ingresó por el paso Pichachén, también conocido como boquete de Antuco, y siguió el curso del río Reñileuvú por su margen sur hasta su desembocadura en el río Neuquén. Luego se dirigió hacia el sur, recorriendo Treuco, pasando por el cerro Caicayén y por Truquicó para llegar a la unión de los ríos Curi Leuvú y Neuquén. Siguió viaje hacia Auquinco y desde allí atravesó la vega de Tril, con rumbo norte hasta Coboleuvú. A lo largo del camino describió diferentes litologías y en varias localidades hizo referencia a diversos tipos de moluscos petrificados, así como también a troncos y restos fósiles de grandes vertebrados. Estas precisas observaciones corresponden a los primeros registros geológicos y paleontológicos del Neuquén, lo que modifica algunas afirmaciones previas en la literatura geológica de la cuenca Neuquina y remonta por muchos años hallazgos fosilíferos de esta región de lo que hoy es la Argentina, en aquellas épocas aún parte del Virreinato del Río de La Plata.

Hallazgo de restos de la serpiente <em>Dinilysia patagonica</em> Smith-Woodward 1901 en una nueva localidad del Santoniano de Patagonia, Argentina

In this study, we describe new remains of the cretaceous snake Dinilysia patagonica from beds of the locality Barreales Norte, Bajo de la Carpa Formation (Upper Santonian), Neuquen province, Argentina. The material comprises the back of a partially preserved skull, articulated with a fragment of the compound bone, atlas and axis. Additionally, six fragments of precloacal vertebrae have been preserved. The assignation to Dinilysia patagonica is based on: large skull, otooccipital with long paraoccipital process adjacent to an elongate supratemporal that extends farther the level of the occipital condyle; well developed sagital crest of parietal bone, continuously joined with the supraoccipital crest; italics I -like prootic; wide, short and robust vertebrae; prezygapophyses long and highly inclined above the horizontal; triangular section of vertebral centrum; reduced prezygapophyseal process; flattened neural arches with straight posterior edge. This material adds a new Upper Cretaceous location for the distribution of the species at the north of the Neuquen River.

Macroparasites of the Invasive Fish,Cyprinus carpio, in Patagonia, Argentina

The common carp (Cyprinus carpio L.) is probably the most widely distributed freshwater fish species and is cultured on almost all continents. In South America, studies on the parasites from C. carpio are limited. The aim of the present study was to report on the macroparasites from wild C. carpio populations inhabiting the Neuquen River, which is at the southernmost distribution of C. carpio in Argentina. From spring 2011 to winter 2012, four seasonal samples of C. carpio were collected from the Neuquen River at the Ingeniero Ballester dam using gill nets. Fish were dissected and all organs were examined using microscopy. All macroparasites were determined and counted and their prevalences and mean intensities calculated. In total, 33 fish were examined and the following six parasites were recorded: the monogeneans Dactylogyrus extensus (gills) and Pseudacolpenteron sp. (in the canals of the scales along the lateral line system); the cestode Bothriocephalus sp. (intestine); the nematode Contracaecum sp. (liver and visceral fat); and the acanthocephalans Pomphorhynchus patagonicus (intestine and liver) and Polymorphus sp. (liver and wall of intestine). The monogenean D. extensus was the most commonly encountered species and had the highest prevalence and mean intensity of all parasites detected. This study reports 6 new records of parasite species in C. carpio from Argentina.

Sources and distribution of aliphatic and polyaromatic hydrocarbons in sediments from the Neuquen River, Argentine Patagonia

Spatial distribution and probable sources of aliphatic and polyaromatic hydrocarbons (AHs, PAHs) were investigated in surface sediments collected along the bank of the Neuquen River, Argentina. Total concentrations of aliphatic hydrocarbons ranged between 0.41 and 125 μg/g dw. Six stations presented low values of resolved aliphatic hydrocarbons and the n–alkane distribution indexes applied suggested a clear biogenic source. These values can be considered the baseline levels of aliphatic hydrocarbons for the river sediments. This constitutes important information for the assessment of future impacts since a strong impulse in the exploitation of shale gas and shale oil in these zones is nowadays undergoing. For the other 11 stations, a mixture of aliphatic hydrocarbons of petrogenic and biogenic origin was observed. The spatial distribution reflects local inputs of these pollutants with a significant increase in concentrations in the lower course, where two major cities are located. The highest values of total aliphatic hydrocarbons were found in this sector which, in turn, was the only one where individual PAHs were detected.

Statistical Prediction of Wet and Dry Periods in theComahue Region (Argentina)

General features of rainy season with excess or deficits are analyzed using standardized precipitation index (SPI) in Limay and Neuquen River basins. Results indicate that most of dry and wet periods persist less than three months in both basins. Furthermore, an increase of rainfall variability over time is observed in the Limay river basin but it is not detected in the Neuquen river basin. There is a tendency for wet (dry) periods to take place in El Ni?o (La Ni?a) years in both basins. Rainfall in both basins, have an important annual cycle with its maximum in winter. In addition, possible causes of extreme rainy seasons over the Limay River Basin are detailed. The main result is that the behavior of low level precipitation systems displacing over the Pacific Ocean in April influences the general hydric situation during the whole rainy season. In order to establish the existence of previous circulation patterns associated with interannual SPI variability, the composite fields of wet and dry years are compared. The result is that rainfall is related to El Ni?o- Southern Oscillation (ENSO) phenomenon and circulation over the Pacific Ocean. The prediction scheme, using multiple linear regressions, showed that 46% of the SPI variance can be explained by this model. The scheme was validated by using a cross-validation method, and significant correlations are detected between observed and forecast SPI. A polynomial model is used and it little improved the linear one, explaining the 49% of the SPI variance. The analysis shows that circulation indicators are useful to predict winter rainfall behavior.

Pesticide distribution in an agricultural environment in Argentina

An assessment of the off-site migration of pesticides from agricultural activity into the environment in the Neuquen River Valley was performed. The aim of this study was to evaluate the distribution of pesticides in several compartments of a small agricultural sub-catchment. Soil, surface water, shallow groundwater and drift deposition were analyzed for pesticide residues. Results showed the presence of some pesticide residues in soil, surface water and shallow groundwater compartments. The highest detection frequencies in water (surface and subsurface) were found for azinphos-methyl and chlorpyrifos (>70%). In terms of concentration, the highest levels were observed in shallow groundwater for azinphos methyl (22.5 μg/L) and carbaryl (45.7 μg/L). In the soil, even before the application period had started, accumulation of residues was present. These residues increased during the period studied. Spray drift during pesticide application was found to be a significant pathway for the migration of pesticide residues in surface water, while leaching and preferential flows were the main transport routes contributing to subsurface contamination.

Effect of Pesticide Use in Fruit Production Orchards on Shallow Ground Water

As a part of landscape‐scale study, ground water samples were collected from 30 wells located in fruit production farms belonging to the valley of Neuquen river during the period 1995–1998 and analyzed for organophosphate pesticides. As a consequence of the leaching process, ground water from the Valley of Neuquen River frequently contained concentrations of organophosphorus pesticides that exceeded acute toxicity risk ratios established to protect aquatic life. It was found that some pesticides, as azinphos methyl, had a high detection frequency, 66% of the samples, with concentrations varying from no detection to 48.9 ppb. Dimethoate, metidathion and phosmet were also detected with frequencies of 14.1, 13.6 and 10.8% and with concentration ranks from no detection to a maximum value of 10.9, 2.0 and 15.5 ppb, respectively. Seasonal variations and temporal trends were found for these compounds in ground water.

Groundwater contamination by azinphos methyl in the Northern Patagonic Region (Argentina)

Approximately 30 groundwater monitoring wells, under a fruit production field, in the Valley of the Neuquen River (Northern Patagonic, Argentina), to which different pesticides have been applied, were sampled eleven times between October 1995 and March 1997. Azinphos methyl was the main pesticide applied and it was detected with the highest frequency in groundwater wells during the period of intensive pesticide application in the Southern Hemisphere. Dimethoate, methidathion, fosmet, cipermethrin, carbaryl, propoxur, carbofuran, benomyl and carbendazim were also detected with lower frequency. The characteristic of the area under study was alkaline soil, with an organic matter content below 2.5% and texture sandy clay loam. The half life of azinphos methyl in soils was 166.2 days in the sun light for horizon A and 194.15 in the dark for horizon B. Leaching of azinphos methyl through the different soil horizons was minimum. On the basis of our lysimeter laboratory data, in which most of the pesticide was adsorbed into the soil column and only small quantities leachate, we inferred that the impact of azinphos methyl on groundwater would be minimal. However, field data indicates that there is a persistence of azinphos methyl in groundwater during the application season.