Recursos de colección

Universidad Nacional de La Plata (74.783 recursos)

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Número 30

Mostrando recursos 1 - 20 de 28

  1. En memoria de Víctor H. Conzonno

    Fernández Cirelli, Alicia; Volpedo, Alejandra
    Víctor H. Conzonno falleció el 3 de febrero de 2014. Cursó sus estudios universitarios en la Facultad de Ciencias Exactas y Naturales de la Universidad de Buenos Aires (UBA), de donde egresó como Licenciado y posteriormente como Doctor en Ciencias Químicas (1996). Su tesis se basó en “Sustancias húmicas solubles presentes en ambientes acuáticos” e inició de esta manera el estudio de la importancia de los ácidos húmicos en los cuerpos de agua pampeanos en nuestro país, siendo un pionero en la temática.

  2. Biotransferencia de flúor de agua a diferentes tejidos de pejerrey (Odontotesthes bonariensis)

    Puntoriero, María Laura; Volpedo, Alejandra; Fernández Cirelli, Alicia
    The presence of fluorine (F), toxic trace element, has relevance in the trophic chain because it can biotrasfer to different levels. It can come from water as food, being chronic ingestion harmful to human beings. Fluorine was found in different water bodies of southwest of Buenos Aires. Chasicó Lake has the highest fluorine concentration. This water body is the most important for commercial and recreational fishing silverside (Odontesthes bonariensis) of the area. The aim of this paper is to analyze the biotransfer of F from water to different silverside tissues in Chasicó Lake. Fish organs were subjected to an alkaline...

  3. La vegetación de ribera como indicadora de calidad ambiental en ríos serranos de la provincia de San Luis (Argentina)

    Nievas, R. P.; Moglia, M. M.
    The quality of the rivers can be analyzed using the characteristics of the vegetation of its banks. Nowadays, these habitats are being degraded at an accelerated rate by human disturbance. The aim of this study was to use the riparian vegetation of three rivers of the Sierra de San Luis (Argentina) as an indicator of the quality of aquatic environments. Fourteen phytosociological inventories were conducted in randomly selected sites on the banks of Potrero, El Volcán and El Trapiche rivers. In addition to the inventories, an anthropization index was calculated and a total of 23 alterations were identified. Each of...

  4. Estudio del fitoplancton aguas arriba y aguas abajo del embalse Casa de Piedra, río Colorado (La Pampa, Argentina)

    Galea, M. J.; Bazán, G. I.; Álvarez, S. B.; Martínez de Fabricius, A. L.
    In order to study the phytoplankton composition of the Colorado river, seasonal samples were taken during the period between May 2010 and April 2011. The study area is a natural border basin of the provinces of La Pampa and Río Negro and a transitional basin of Patagonia Argentina without records of previous studies. Selected sampling points are located upstream and downstream of the dam reservoir Casa de Piedra. In this study are presented preliminary results of phytoplankton composition analized in emplaced sites at 38º01’58”S-67º52’90”W to 288 msnm and 38°14’55’’ S-67º11’49’’W to 232 msnm. Samples were collected with plankton net of...

  5. Evaluación de la capacidad de auto-depuración de un arroyo urbano y el uso de macrófitas nativas como estrategia de restauración

    Efron, S. T.; Aquino, J.; De Cabo, L.; Dos Santos Afonso, M.; Graziano, M.
    Environmental degradation is one of the most serious problems in the metropolitan area of Buenos Aires, especially water pollution. The main aim of this work was to study mechanisms of self-purifying of a segment of San Francisco stream (located in Almirante Brown district), evaluating it in situ capacity of self-purifying downstream of a tubing and, in addition, by static bioassays in a greenhouse with native macrophytes. A stream section of 1500m was sampled twice during autumn 2013. The stream was generally hypoxic throughout the section (DO<2 mg/l), presenting low velocity (0.084 ± 0.008 m/s), moderate organic load (COD=72 ± 3...

  6. Composición taxonómica y variación estacional del zooplancton del embalse Piedras Moras (Córdoba, Argentina)

    Cabrera, Gabriela; Vignatti, A.; Echaniz, S.; Mancini, M.; Salinas, V.; Rodríguez, C.
    Reservoirs are water bodies relatively similar to natural lakes, differing in aspects such as the longitudinal gradient of certain environmental and biotic factors. In the mountainous region of Córdoba there are more than 15000 ha of reservoirs. Although aspects of these reservoirs have been studied, the zooplankton has generally not received much attention. The aim of this study was to determine the composition and seasonal variation of the zooplankton of Piedras Moras reservoir, a multipurpose reservoir built on the Ctalamochita River, in which this community had not been previously studied. Seasonal samples were taken (November 2009 - September 2010) at...

  7. Dieta de Pseudocorynopoma doriae (Characiformes: characidae) en el arroyo La Choza, Buenos Aires, Argentina

    Brancolini, Florencia; Maroñas, Miriam E.; Sendra, Eduardo Daniel
    In this paper the objective is to characterize the Pseudocorynopoma doriae diet of the La Choza stream, assessing the relative importance of the contribution of the terrestrial environment to it and compare it with mesopotamian lotic environments. In all environments studied this species presented an invertivorous feeding. In the case of La Choza stream, comparison of diet between sampling dates showed a low degree of similarity, nevertheless the food items were all related to the surface film of water. Latter also is found in mesopotamian streams. When comparing the results of the percentage composition of the diet of P.doriae, it...

  8. Variación estacional de la comunidad microfitoplanctónica del curso medio del río Colorado (La Pampa, Argentina)

    Biasotti, A. E.; Álvarez, S. B.; Bazán, G. I.; Martínez de Fabricius, A. L.
    We analyzed the seasonal variation of the phycoflora in the Colorado River alluvium with the aim of expanding knowledge of algal biodiversity in lotic environments of the province of La Pampa. The study area is located in the middle basin of the Colorado River (38º 49’ S and 64º 59’ W), Lihue Calel, which is the natural limit between La Pampa and Río Negro provinces. The site is located 122 meters above sea level with a channel width of 113 m. Samples were collected according to the standard methodology for lotic environments during autumn 2010 - autumn 2011. Physicochemical parameters...

  9. Efecto de la invasión de acacia negra (Gleditsia triacanthos L.) sobre arroyos pampeanos

    Vilches, C.; Torremorell, A.; Debandi, J.; Rodríguez Castro, M. C.; Rigacci, L.; Zunino, E.; Kravetz, S.; Giorgi, A.
    Pampean fluvial ecosystems of low order usually lack of riparian vegetation. In recent years the invasion of honey locust (Gleditsia triacanthos L.) has caused changes in landscape composition. The aim of this study was to evaluate the effect of honey locust invasion on pampean streams. Three reaches with different degree of invasion were selected and compared with three control reaches with no canopy. In order to evaluate the effect of invasion, nutrients (soluble reactive phosphorus, ammonium and nitrates), biomass of producers (seston, macrophytes, periphyton and phytobenthos) and net production in each reach were determined. Significant differences were observed for all...

  10. Crecimiento de juveniles de pejerrey (Odontotesthes bonaeriensis) bajo diferentes condiciones de cultivo

    Velasco, Claudia A. M.; Berasain, Gustavo E.; Padín, D. A.
    The aim of this work was to analyze the growth and survival of Odontesthes bonariensis juveniles using different densities and culture conditions. One assay (E1) was carried out with individuals from 67 to 295 day-old, with a density of 217.2 ind/m3 in a 20 m3 tank. Water salinity varied between 12 and 15 g/L and an open water circulation system was used. The other assay (E2) was carried out with individuals from 43 to 182 day-old, with a density of 121.2 ind/m3 in a 100 m3 previously fertilized pond. Water salinity varied between 4 and 5 g/L and partial water...

  11. Evaluación de modelos de crecimiento de diferentes condiciones de cultivo de pejerrey (Odontotesthes bonariensis)

    Solimano, Patricio José; García de Souza, Javier Ricardo; Maiztegui, Tomás; Bazzani, J. L.; Baigún, Claudio R. M.; Colautti, Darío C.
    The pejerrey is one of the most important temperate native freshwater species of Argentina. Its culture is mainly done intensively and in recent years is being developed in floating cages in several Pampean lakes under semi-intensive and extensive conditions. To evaluate the growth of fish under different culture methodologies several models are used, most of which are based on the specific growth rate (SGR). The objective of this study is to compare how the SGR of pejerrey responds under different culture methods and generate a theoretical model to predict the growth that the species can reach. To carry out the...

  12. Ecología trófica del pejerrey (Odontotesthes bonariensis) en la laguna del Venado y Alsina, dos ambientes del sistema Encadenadas del Oeste, prov. de Buenos Aires

    Schwerdt, Marcelo; López Cazorla, Andrea C.
    The aim of the present study was to analyze the feeding of the silverside Odontesthes bonariensis in the Venado and Alsina lake. which are part of the Encadenadas del Oeste lake system. The stomach content of 206 individuals was analyzed. Total length ranged from 93 to 585 mm. The vacuity index (VI) and repletion index (RI) were estimated by season and site. Index of Relative Importance (IRI) for each food category and the trophic level (TL) of pejerrey were calculated by site. The diet of the silverside was composed of 68 prey items, most of which were occasional preys. Copepods...

  13. Estudio limnológico de Laguna Blanca Chica (Olavarría, provincia de Buenos Aires) durante un período de sequía

    Sanzano, Pablo; Grosman, Fabián; Colasurdo, Viviana
    The aquatic ecosystems of the Pampean plains usually have highly variable dynamics which affects the abundance of fish resources. We analyzed Blanca Chica shallow lake located in the central region of the province of Buenos Aires. It has neither tributaries nor effluents. It hosts sport fishing, water sports without engine, and its surroundings are used for recreation. Here we report the effects of drought in the structure and functioning of the shallow lake, with emphasis on the fish community. Limnological and ichthyologic analyses were carried out in 2007, 2008, 2011 (year characterized by extreme regional dry period) and 2014. In...

  14. La comunidad algal epilítica en hábitat de rabión en un arroyo serrano

    Rodríguez Catanzaro, L.; Luque, E.; Gari, N.
    In flowing water habitats areas of turbulent erosion, oxygenated waters and heterogeneity can be distinguished, which are called riffles. The objective of this study was to determine the composition and structure of the epilithic algal community in riffle habitat of Arroyo Achiras (Córdoba, Argentina). Two sampling sites were selected along the longitudinal gradient, one in mountainous zone (A) and another one in piedmont (B). In 2005 and 2006 epilithic samples were collected during periods of low and high waters and physico-chemical and hydraulic variables were measured. At each site algal abundance and frequency were determined. Similarity index, taxonomic richness, species...

  15. Estructura y dinámica del fitoepifiton en cuerpos de agua temporarios del Cinturón Hortícola Platense

    Medina, M.; Solari, Lía C.; Agostini, G.
    The horticultural belt of La Plata is a complex framework of lands with a marked urban influence. The unregulated use of agrochemicals is one of the most important sources of superficial and underground water contamination producing drastic changes in the biodiversity of natural communities. The shallowness of the temporary waters favors the macrophyte growth which, in turn, allows the colonization of the phytoepiphyton. Four samplings were carried out during spring 2011 and summer 2012 in four adjacent temporary waters of different agroecosystems, three of them with agricultural activity (site over 5 meters crops, CUL1 and CUL2; site within 5 meters...

  16. Cambios en la características limnológicas del embalse Río Tercero por efecto de la invasión de Limnoperma fortunei (Bivalvia: Mytilidae)

    Marileñarena, Alejandro Jorge; Donadelli, Jorge Andrés; Hechem, M.
    Since its introduction in South America around 1990, the freshwater Asian mussel Limnoperna fortunei has been shown to strongly interact with several components of the local biota, sometimes producing significant changes at the ecosystem-wide scale. The “golden mussel” is present prior to 2000 in Río Tercero reservoir, Córdoba, Argentina, most probably introduced overland by a fouled recreational or fishing boat from the Paraná River. Since 2003 massive growth on submerged solid structures (piles, moorings, boat hulls) was strongly noticeably. Data collected regularly since 1996 showed changes in several water-column properties after the invasion. From 2004 on, water transparency increased, and...

  17. Caracterización limnológica y fauna de peces de la laguna La Helvecia (Córdoba, Argentina)

    Mancini, M.; Biolé, Fernando; Salinas, V.; Morra, G.; Prieto, G.; Montenegro, H.
    La Helvecia shallow lake (33°25’16’’S, 62°53’26’’W, 90 ha) is one of the few permanent aquatic environments that still exist in the “Bañados del Saladillo” (Córdoba, Argentina). During November 2011, a study of fish and limnological characterization was performed. Different active and passive gears were used and water quality variables were measured. Average values pH, oxygen concentration, temperature and water transparency (Secchi disk) were 8.63, 9.05 mg/L, 23.8 °C and 39 cm respectively. The shallow lake was classified as “turbid” type. The water was hypohaline (4.74 g/L), sulfated sodium chlorinated and very hard (298 ppm CaCO3). The macrozooplankton abundance was 240,850...

  18. Efectos de la exclusión de ganado sobre la calidad ambiental de un arroyo pampeano

    Giorgi, A.; Rosso, J. J.; Zunino, E.
    For two years, records of channel morphology and quality of the bank on a section of a stream were made because the cattle farming have been excluded at a section of 500 meters of long near the bank and 10 meters at each bank. There were registered also changes in the aquatic vegetation and some physico-chemical parameters. Fish sampling was conducted annually to observe species presence and their relative abundance. It was detected a rapid improvement in the quality of banks and an increase of the richness of fishes in each sample. Contrary to expectations macrophyte richness was reduced and...

  19. Efecto del ganado sobre la estructura de la vegetación en las riberas de un arroyo pampeano

    Gantes, P.; Falco, L.; Sánchez Caro, A.
    Livestock is a main perturbation for the riparian zones of streams in the Buenos Aires province. Our goal is to compare the vegetation’s and soil’s characteristics of two almost contiguous reaches of the Nutrias stream, an affluent to the Reconquista river. One reach has been closed to cattle for 2 years, and the other -500m downstream- has kept livestock along the whole period. For each stream margin, six 10m transects were sampled for species cover and 3 soil samples were drawn for organic matter, phosphorus, pH, conductivity and apparent density determination. The vegetation’s canopy hight, cover, and the amphibious macrophytes’...

  20. Parámetros ambientales y pesqueros de un lago somero de La Pampa, luego de una mortandad masiva de Odontesthes bonariensis

    Del Ponti, O.; Marani, J. L.; Ganora, E.; Berguño, A.; Galea, J. L.; Pratts, P.
    The Bajo Giuliani Lagoon (36 ° 42 ‘20’’ S, 64 ° 16 ‘ 02 ‘’ W) is located south of the city of Santa Rosa, La Pampa, which was stocked with fish during the late 90’s. In this hypertrophic shallow lake, major environmental changes caused mass mortalities of silverside Odontesthes bonariensis, the last one occurred in 2010. In order to know the current state of the environment, in April 2013 surface water samples were collected, several points were georeferenced and major morphometric parameters were estimated. Fish were captured by trawls and gillnets. The lake has an area of 965 ha...

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