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La cuenca del río Luján está sometida a inundaciones recurrentes que impactan negativamente a las urbanizaciones y actividades que se desarrollan en las cercanías de sus cauces. La determinación y el análisis de las características morfométricas de una cuenca en parámetros de forma, relieve y drenaje son elementales para explicar su dinámica hídrica. El objetivo del trabajo fue caracterizar morfométricamente a la cuenca del río Luján, Buenos Aires, Argentina. Dichos parámetros fueron determinados a partir de un MDE a través del empleo de un SIG de uso libre. El área de la cuenca fue de 2938,50 km2 , su longitud axial de 108,75 km y el ancho promedio de 27 km. Los valores obtenidos para los parámetros de forma indican que la misma es alargada y de forma oval-oblonga a rectangular-oblonga. La curva hipsométrica adimensional demostró que la cuenca está en equilibrio y en fase de madurez. La longitud del cauce principal fue de 135,7 km y su pendiente media de 0,043 %. Su drenaje fue de tercer orden, con baja densidad y escasa frecuencia, lo que hace que este sea pobre. El tiempo de concentración fue superior a las 50 horas. Todos los parámetros cuantificados son la base inicial para generar el modelado hidrológico de la cuenca del río Luján. The Luján river basin is subject to recurrent floods that negatively impact the urbanizations and activities near its channels. Determining and analyzing the morphometric characteristics of a basin in terms of shape, relief and drainage parameters is fundamental to explain its water dynamics. The aim of this study was to morphometrically characterize the Luján river basin, in Buenos Aires, Argentina. Parameters were determined based on a DEM using a free and open source GIS. It was determined that its area is 2938.50 km2 , its axial length is 108.75 km, and its mean width is 27 km. The values obtained for the shape parameters indicate that it is elongated and oval-oblong to rectangular-oblong. The dimensionless hypsometric curve showed that the basin is in equilibrium and in the mature phase. The river length was 135.7 km with a mean slope of 0,043 %. Its drainage was of third order, with low density and frequency, which makes it poor. The concentration time was greater than 50 hours. All quantified parameters serve as the initial basis to generate an hydrological model of the Luján river basin.

El objetivo general del presente trabajo fue identificar las especies de peces que capturan los pescadores y el uso que le dan a las mismas en la cuenca inferior del río Luján. Para tal fin, se realizaron entrevistas semiestructuradas durante la primavera de 2015, el verano y el otoño 2016, las cuales permitieron obtener información sobre el uso que les dan los pescadores a los peces capturados. Se analizaron a lo largo de este período dos escenarios: los días de semana y los fines de semana. En la cuenca inferior del río Luján coexiste una diversidad de contextos sociales manifestados a través de sus actores: los pobladores locales y los pobladores de partidos vecinos que visitan el área. Las especies más mencionadas a lo largo de todo el estudio fueron: Pimelodus maculatus, Pimelodus albicans, Astyanax sp., Megaleporinus obtusidens y Rhamdia quelen. Los resultados obtenidos permiten plantear la importancia que tiene este territorio en la ribera del río Luján para los pobladores de la zona y de las regiones cercanas dado que los días de semana es un sitio que ofrece un espacio para realizar pesca de subsistencia mientras que los fines de semana constituye un espacio para el esparcimiento familiar., The general objective of the present work was to identify the fish species that the fishermen capture and the use they give to them at the lower basin of the Luján River. To this purpose, semi-structured interviews were conducted, which allowed obtaining information on the use that fishers give to the captured fish during the spring of 2015, summer and autumn 2016. Throughout this period, two scenarios were analyzed: weekdays and weekends. At the lower basin of the Luján River, a diversity of social contexts manifested through its actors coexists: the local inhabitants and the inhabitants of neighboring municipalities that visit the area. The most mentioned species throughout the study were: Pimelodus maculatus, Pimelodus albicans, Astyanax sp., Megaleporinus obtusidens y Rhamdia quelen. The obtained results revealed the importance of this territory situated at banks of the Luján River for the inhabitants of the area and the nearby regions due to it is a location that on weekdays offers a space for subsistence fishing, and on weekends for family recreation., Instituto de Limnología "Dr. Raúl A. Ringuelet"

San Luis province presents arheic and endorheic basins that are poorly understood in terms of their ichthyological composition. The samples taken recently from the main basins of this province have yielded data of undisputed biogeographic value for the knowledge of the ichthyofauna of San Luis, as well as for drawing up lists of species for watersheds with poor or absent previous records. Here, we cite Jenynsia multidentata from the Desaguadero and Bebedero rivers, Cnesterodon decemmaculatus for Chorrillos River, and Oligosarcus jenynsii for Luján, Quines and Quinto rivers. We add five taxa to the Nogolí River that have not been previously reported. We also present for the first time a list of the fish fauna from the Conlara, Luján and Quines basins. Our results provide 34 new records of freshwater fish distribution., Facultad de Ciencias Naturales y Museo

A depositional unit called DU2 identified for the period MIS 3 (ca—30,000–60,000 year B.P.) formed by only one sedimentary facies (F3) was found in the Luján and Salto-Arrecifes rivers basins. F3 is a fluvio–lacustrine unit that overlies in erosive unconformity over eolian sediments with ages of 56,400 ± 6500 and 50,400 ± 10,200 years B.P. and is unconformably covered by another eolian vitroclastic sandy loess deposit, dated as 32,000 ± 4000 years (Infrared Stimulated Luminescence , IRSL) (Blasi et al. 2009a). It represents the recurrence of ephemeral fluvial streamlets and the development of temporary pools by subsequent damming of channels. It corresponds lithologically to sandy muddy gravel, gravelly muddy sand, gravelly mud olive to pale olive, feldspar and quartz sands, bearing extinct mollusks such as Heleobia ameghini and Diplodon lujanensis. Radiocarbon chronologies obtained on monospecific samples of Cyprideis salebrosa hartmanni and Heleobia ameghini yielded ages of 37,710 ± 840 years 14C B.P. and >40,000 years 14C B.P., respectively. Furthermore, the age obtained through the IRSL technique was of 44,000 ± 6500 years. Based upon the analyzed bioproxies (malacological, phytoliths and diatomological content) F3 accumulated under variable climatic conditions, ranging from temperate to colder and from subhumid to drier. According to the exhaustive stratigraphic identification, it is proposed that in N-E Buenos Aires Province, the so-called Undulated Pampa region, the sediments that were accumulated during MIS3 occur only in the central portion of the studied fluvial basins. This prompted two hypotheses related to the existence of a particular drainage pattern for the Late Pleistocene, different from the present one, and subsequent tectonic controls that allowed the identification of DU2 sediments only in some of the analyzed sections., Facultad de Ciencias Naturales y Museo

A 3-km reach of the Luján River was studied by establishing 6 sampling stations, which were from 300 to 500 m apart. The first station was the control reading for river nutrients and particulate material. The second station measured the continuous effluent from a wastewater treatment plant flow of the city of Luján and was, therefore, considered a continuous addition point of nutrients. The other 4 stations were used to evaluate whether the river captured phosphorus as phosphate, nitrogen as ammonium, nitrite or nitrates, and the suspended particulate material, both organic and inorganic. These data were used to calculate material uptake (U), uptake velocity (Vf), and net distance Snet under two different hydrological situations, during low and high flow, during the same season of the same year. Results indicate that phosphate ions as well as organic matter are retained for less than 2 km in both high and low flow situations. In the case of ammonium, the results appear similar to those of phosphate ions but it may be transformed into nitrates and transported in the latter form for greater distances. It is concluded that this river, in the reach under study, has a variable retention speed according to its flow but the retention capacity is no less than 900 m and as much as 2000 m. Therefore, a 2 km distance must be considered as the minimum distance before another effluent of nutrients or organic matter is added. Fil: Piccinini, Mauricio. Provincia de Buenos Aires. Municipalidad de Lujan; Argentina Fil: Sánchez Caro, Anibal. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina Fil: Gultermiriam, M.L.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Giorgi, Adonis David Nazareno. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

En el presente trabajo de tesis se evaluó la respuesta de una batería de parámetrosbiomarcadores fisiológicos, bioquímicos y moleculares en teleósteos dulceacuícolas, útiles yaplicables en la evaluación de la calidad de cuerpos de agua afectados por compuestosorgánicos persistentes (COPs) de origen antrópico. Se evaluaron biomarcadores decontaminación asociados a la biotransformación (actividad enzimática de glutatión-Stransferasa,inmunodetección de la proteína CYP1A y la actividad catalítica de la EROD,niveles de metabolitos biliares); al estrés oxidativo (actividad enzimática de la catalasa,superóxido dismutasa y niveles de TBARS) y asociado a la presencia de desorganizadoresendócrinos (inmunodetección de vitelogenina plasmática). También se determinaron losíndices fisiológicos factor de condición e índice hepatosomático. Se utilizaron comoorganismos prueba ejemplares juveniles de Cyprinus carpio y de diferentes especies nativasfrecuentadoras de fondo. Se evaluaron los efectos adversos por exposición de dichas especiesa diferentes tipos de COPs (hidrocarburos aromáticos policíclicos, bifenilos policlorados ycompuestos con efecto desorganizador endócrino) por medio de ensayos de laboratorio ymediante evaluaciones a campo por exposición en jaulas (Río de la Plata y río Luján) y derecolección de especies nativas. Los resultados obtenidos permitieron caracterizar y compararel efecto de los diferentes COPs sobre las respuestas de los biomarcadores en las especiesprueba. Se demostró que el confinamiento de peces en jaulas es una metodología de trabajoútil en la evaluación de la calidad ecotoxicológica de ríos periurbanos. Se utilizaron técnicasque permitieron realizar un análisis de los resultados comparando e integrando las respuestasde los biomarcadores en los ensayos de laboratorio y de campo in situ. Se elaboró una líneade base para cada parámetro biomarcador y se proporcionó información de referencia sobre lavariabilidad natural de los mismos que puede ser empleada en futuros ensayos de laboratorioy de evaluación de ambientes acuáticos afectados por COPs. In this thesis we evaluated the response of a battery of physiological, biochemical andmolecular biomarkers of freshwater teleost, useful and relevant in the evaluation of the qualityof water bodies affected by anthropogenic inputs of persistent organic compounds (POCs). Biomarkers of contamination associated with biotransformation (enzymatic activity ofglutathione-s transferase, immunodetection of CYP1A protein and catalytic activity of EROD,biliary metabolites levels), oxidative stress (enzymatic activity of catalase and superoxidedismutase, TBARS levels) and endocrine disruption (immunodetection of vitellogeninplasmatic protein) were assessed. Physiological indices, condition factor and liver somaticindex were also assessed. Cyprinus carpio and bottom dweller native species juveniles wereused as test organisms. Adverse effects were assessed by exposing those species to differentkind of POCs (polycyclic aromatic hydrocarbons, polychlorinated biphenyls and endocrine-disrupting chemicals) by means of laboratory and field evaluations by cage exposure (Rio dela Plata and Luján river) and native collected fish. Results allowed comparing andcharacterizing the effect of different POCs on the responses of biomarkers in the test species. Fish exposure in cages proved to be a useful ecotoxicological methodology when evaluatingthe condition of periurbans rivers. An integrated analysis of the results allowed comparinglaboratory assays and field in situ biomarker responses of test species. A baseline for eachbiomarker was developed and reference information was provided about their naturalvariability that can be used in future laboratory tests and in the assessment of aquaticenvironments affected by POCs. Fil: Scarcia, Paola Inés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.

La calidad ecotoxicológica de los ríos Luján y Reconquista fue monitoreada por un año, mediante parámetros químicos, bioquímicos, fisiológicos y genéticos; en larvas premetamorficas de Lithobates catesbeianus, en bioensayos semiestáticos de laboratorio. Ambos ecosistemas exhiben disturbios de distinto origen (industrial, doméstico, agrícola-ganadero). Las muestras ambientales de cada río fueron tomadas en dos sitios, uno de los cuales se consideró de referencia; otro grupo permaneció en agua potable como control. Se determinaron los biomarcadores de: a) neurotoxicidad: acetilcolinesterasa cerebral (AChE), b) estrés oxidativo en branquia e hígado: catalasa (CAT), glutation-S-transferasa (GST) y superóxido dismutasa (SOD), c) contenido de glutatión (GSH) y peroxidación lipídica (TBARS), d) microscopía electrónica de barrido (MEB) y factores de condición (FC) y hepatosomático (IHS) y e) genotoxicidad en eritrocitos (micronúcleos [MN]). Se determinaron 13 parámetros fisicoquímicos, concentración de 6 metales pesados y 27 pesticidas clorados y organofosforados. Con ellos se calcularon 3 Índices de Calidad, que indicaron alta contaminación. Se registraron bajas concentraciones de oxígeno y elevados niveles de DBO5, DQO, cloruros, amonio, nitritos y nitratos. Los pesticidas en ambos ríos estuvieron por debajo de los límites de detección y algunos metales pesados por encima de los niveles guía para protección de la vida acuática. El Análisis de Componentes Principales permitió discriminar diferencias entre los sitios monitoreados de los ríos y explicar cuál/es de los biomarcadores fue clave; en ambos cuerpos de agua se destacó la frecuencia de MN. El protocolo aplicado y la especie test elegida resultaron ser aptos para monitorear la calidad toxicológica en ambos ríos. Ecotoxicological quality of Luján and Reconquista rivers was monitored for one year using chemical, biochemical, physiological and genetic parameters. Both ecosystems are showing disturbances from different sources (industrial, domestic, agricultural and livestock). Semi-static laboratory bioassays were conducted exposing Lithobates catesbeianus larvae to environmental samples of each river. They were taken from two sites; one of them was considered the reference, while the other group remained in tap water as control. Biomarkers were determined: a) neurotoxicity: brain acetylcholinesterase (AChE), b) oxidative stress in gill and liver: catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD), c) glutathione content (GSH) and lipid peroxidation (TBARS), d) scanning electron microscopy (SEM) and condition factors (CF) and hepatosomatic index (IHS) and e) genotoxicity in erythrocytes (micronucleus [MN]). Thirteen physicochemical parameters, 6 heavy metals and 27 chlorinated and organophosphates pesticides were measured. Three water quality Indices were calculated, which indicated high pollution. There was low concentration of oxygen and high levels of BOD, COD, chlorides, ammonia, nitrites and nitrates. In both rivers, pesticides were below detection limits and some heavy metals exceeded the guideline levels for protection of aquatic life. The Analysis of Principal Component allowed to make a difference between the monitored places of the rivers and to explain which biomarker was key; on both water bodies the frequency of MN was highlighted. The protocol applied and the test species chosen were adequate to monitor the toxicological quality of the Luján and Reconquista rivers. Fil: Ossana, Natalia Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.