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18 results on '"PAMPA PLAIN"'

1. Covariation patterns of phytoplankton and bacterioplankton in hypertrophic shallow lakes.

Author

Schiaffino, M. R., Huber, P., Sagua, M., Sabio y García, C. A., and Reissig, M.

Abstract

The aim of this work was to assess the temporal patterns in the community composition of phytoplankton (PCC) and bacterioplankton (BCC) in two interconnected and hypertrophic Pampean shallow lakes in Argentina. Factors shaping their community dynamics and community temporal covariations were also analysed. We performed 4 years of seasonal samplings (2012–2016) and communities were studied by the Uterm¨ ohl approach (PCC) and Illumina MiSeq sequencing (BCC). We found marked seasonal variations in both communities and inter-annual variations with decreasing microbial community similarities during the study. We also observed covariation in community-level dynamics among PCC and BCC within and between shallow lakes. The within-lake covariations remained positive and significant, while controlling for the effects of intrinsic (environmental) and extrinsic (temporal and meteorological) factors, suggesting a community coupling mediated by intrinsic biotic interactions. Algal-bacterial associations between different taxa of phytoplankton and bacterioplankton within each lake were also found. PCC was mainly explained by pure regional extrinsic (17–21%) and intrinsic environmental (8–9%) factors, while BCC was explained by environmental (8–10%) and biotic interactions with phytoplankton (7–8%). Our results reveal that the influence of extrinsic regional factors can be channeled to bacterioplankton through both environmental (i.e. water temperature) and phytoplankton effects. [ABSTRACT FROM AUTHOR]

Published
2020
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5. Spatial distribution of electrical conductivity and stable isotopes in groundwater in large catchments: a geostatistical approach in the Quequén Grande River catchment, Argentina.

Author

Quiroz Londoño, Orlando Mauricio, Martínez, Daniel Emilio, Massone, Hector Enrique, Londoño Ciro, Libardo Antonio, and Dapeña, Cristina

Subjects
*NUCLIDES, *ISOTOPES, *GROUNDWATER remediation, *ENVIRONMENTAL physics, *ELECTRIC conductivity
Abstract

Stable isotopes and electrical conductivity in groundwater were used as natural tracers to adjust the hydrogeological conceptual model in one of the largest catchments within the inter-mountainous Pampa plain, Argentina. Geostatistical tools were used to define the model that best fitted the spatial distribution of each tracer, and information was obtained in areas where there was a lack of data. The conventional isotopic analysis allowed the identification of three groundwater groups with different isotopic fingerprints. One group containing 56 % of the total groundwater samples suggested a well-mixed system and soil infiltration precipitation as the main recharge source to the aquifer. The other two groups included samples with depleted (25.5 %) and enriched (18.5 %) isotopic compositions, respectively. The combination ofδ18O,δ2H and electrical conductivities maps suggested ascending regional flows and water transfer from the Quequén Grande River catchment to the Moro creek. The spatial interpretation of these tracers modified the conceptual hydrogeological model of the Quequén Grande River. [ABSTRACT FROM AUTHOR]

Published
2015
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6. Which environmental factors trigger the dominance of phytoplankton species across a moisture gradient of shallow lakes?

Author

Izaguirre, Irina, Sánchez, María, Schiaffino, M., O'Farrell, Inés, Huber, Paula, Ferrer, Nora, Zunino, Josefina, Lagomarsino, Leonardo, and Mancini, Miguel

Subjects
*PHYTOPLANKTON populations, *ALGAL blooms, *SPECIES diversity, *CYANOBACTERIAL blooms, *EFFECT of moisture on plants, *EFFECT of environment on plants, *LAKES
Abstract

We investigated nine Pampean shallow lakes (Argentina) across a moisture gradient (mean annual precipitation 1,000-500 mm), under the framework of a network project of lake monitoring whose main objective was to analyse the responses of ecosystems to different stressors associated with human activities. We postulate that species bloom in different shallow lakes will be determined mainly by local optical features, nutrients and salinity. We analysed the phytoplankton structure during the warm season 2012-2013, identifying those species and functional groups that proliferate in the lakes. Most lakes showed high phytoplankton biomass, except a saline lake located in the driest part of the gradient and an inorganic turbid lake. In some lakes, cyanobacteria blooms occurred in summer, persisting until autumn. Small colonial cyanobacteria and small fast-growing chlorophytes were abundant in most turbid enriched and anthropogenically impacted systems. Lowest species and functional diversity occurred in the saline lake. Multivariate analysis indicated that the phytoplankton structure was mainly defined by conductivity, transparency and variables associated with the trophic state, also reflecting the importance of the geographical location. Our results evidenced the vulnerability of most shallow lakes in the region to water level fluctuations, eutrophication and canalization. [ABSTRACT FROM AUTHOR]

Published
2015
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8. Holocene changes in trophic states of shallow lakes from the Pampa plain of Argentina.

Author

Stutz, Silvina, Borel, C Marcela, Fontana, Sonia L, and Tonello, Marcela S

Subjects
*HOLOCENE paleoclimatology, *VEGETATION & climate, *PLAINS, *MACROPHYTES, *PHYTOPLANKTON, *REPRODUCTION
Abstract

Changes in trophic status of shallow lakes from the southeastern Pampa plain of Argentina are evaluated based on the relative presence of submerged macrophytes and phytoplankton. The evolution of lake Lonkoy is reconstructed for the last 5000 years, using pollen, non-pollen palynomorphs (NPPs) and macrofossil remain analyses, revealing three main lake stages. A macrophyte-dominated clear lake prevailed until 670 cal yr BP. Afterwards, the lake changed to a turbid phytoplankton-dominated state. Recently, the lake has turned to a turbid phase, caused by resuspended sediment. These results are compared with two other paleolimnological records from the region, lakes Hinojales and Nahuel Rucá, revealing a similar late-Holocene evolution, with a shift from a macrophyte- to phytoplankton-dominated lake, occurring at broadly the same time. The shift of states may be attributed to a shift in climate after 1000 cal. yr BP towards wetter conditions during the Medieval Climate Anomaly. [ABSTRACT FROM AUTHOR]

Published
2012
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9. A Gis-Based Assessment of Groundwater Suitability for Irrigation Purposes in Flat Areas of the Wet Pampa Plain, Argentina.

Author

Romanelli, Asunción, Lima, María, Quiroz Londoño, Orlando, Martínez, Daniel, and Massone, Héctor

Subjects
AGRICULTURE, GROUNDWATER, IRRIGATION water, WATER supply
Abstract

The Pampa in Argentina is a large plain with a quite obvious dependence on agriculture, water availability and its quality. It is a sensitive environment due to weather changes and slope variations. Supplementary irrigation is a useful practice for compensating the production in the zone. However, potential negative impacts of this type of irrigation in salinization and sodification of soils are evident. Most conventional methodologies for assessing water irrigation quality have difficulties in their application in the region because they do not adjust to the defined assumptions for them. Consequently, a new GIS-based methodology integrating multiparametric data was proposed for evaluating and delineating groundwater suitability zones for irrigation purposes in flat areas. Hydrogeological surveys including water level measurements, groundwater samples for chemical analysis and electrical conductivity (EC) measurements were performed. The combination of EC, sodium adsorption ratio, residual sodium carbonate, slopes and hydraulic gradient parameters generated an irrigation water index (IWI). With the integration of the IWI 1 to 3 classes (categories of suitable waters for irrigation) and the aquifer thickness the restricted irrigation water index (RIWI) was obtained. The IWI′s index application showed that 61.3 % of the area has 'Very high' to 'Moderate' potential for irrigation, while the 31.4 % of it has unsuitable waters. Approximately, 46 % of the tested area has high suitability for irrigation and moderate groundwater availability. This proposed methodology has advantages over traditional methods because it allows for better discrimination in homogeneous areas. [ABSTRACT FROM AUTHOR]

Published
2012
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10. Quaternary deformation around the Palo Negro area, Pampa Norte, Argentina

Author

Brunetto, E., Iriondo, M., Zamboni, L., and Gottardi, G.

Subjects
*QUATERNARY stratigraphic geology, *NEOTECTONICS, *DEFORMATIONS (Mechanics), *WAVELENGTHS, *KINEMATICS, *GEOLOGIC faults, *SEDIMENTOLOGY
Abstract

Abstract: The Pampa Norte region is a great plain characterized by low slopes and accumulation of hundreds of meters of thick loose sediments. A high morphostructure denominated San Guillermo block stands out in the central plain, the Tostado–Selva scarp forming its western boundary. It is located in an intraplate setting characterized by low tectonic activity. However recent uplift can be inferred by means of terrain analysis and the sedimentology of the Palo Negro Fm. Pond deposits (Palo Negro Fm.) observed in the scarp suggest topographic inversion during the Late Quaternary in the Palo Negro area. The morphology indicates that the deformation was widely distributed, forming a gentle (ca. 5 m amplitude and 13 km wavelength) asymmetric fold. Low sinuosity lineaments located in the base of the scarp, coincident with knick points in the topographic profile, can be interpreted as the projection of tip-lines by high-angle fault-propagation. This geometry is compatible with reverse kinematics on blind faults. A deformation style with reactivation of pre-existing faults is consistent with structural observations. Seismic reflectors suggest the presence of Cretaceous high-angle normal faults, and the orientation of lineaments is similar to the orientation of the graben systems and transverse accommodation zones originated during the opening of the South Atlantic Ocean. One OSL dating of 67.4±5.1 kyr B.P (from Palo Negro Fm. supposed as deposited on a flat plain floor) and a height difference of 9.5 m measured in the Tostado–Selva scarp account for an averaged uplift rate of 0.14 mm/year. [Copyright &y& Elsevier]

Published
2010
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11. Incorporating taphonomy into community-based paleoenvironmental reconstructions: Can diatom preservation discriminate among shallow lake sub-environments?

Author

Gabriela S. Hassan, Luciana A. Rojas, and Claudio German de Francesco

Subjects
0106 biological sciences, 010506 paleontology, Taphonomy, SHALLOW LAKES, 01 natural sciences, Paleontología, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Water column, DIATOMS, Littoral zone, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences, biology, 010604 marine biology & hydrobiology, Fragmentation (computing), Paleontology, Plankton, biology.organism_classification, PAMPA PLAIN, Macrophyte, TAPHONOMY, Oceanography, Diatom, Habitat, Geology, CIENCIAS NATURALES Y EXACTAS
Abstract

The value of taphonomic signatures as a source of paleoenvironmental information has been recognized at local and regional environmental scales. In environmentally heterogeneous shallow lakes, the habitat complexity provides an opportunity to evaluate the potential use of taphonomy to uncover environmental differences among within-lake sub-environments. In this contribution, the composition and preservation of diatom assemblages from five sub-environments (free-floating and attached macrophytes, water column, open waters, and littoral sediments) were analyzed in a Pampean shallow lake (Nahuel Rucá, Argentina). Sub-environments differed in depth, macrophyte coverage, and water composition, being these differences reflected both by the composition and preservation of diatom assemblages. Diversity, fragmentation, and dissolution were higher in planktonic and open-waters sedimentary assemblages, whereas fragmentation dominated in littoral sediments. Epiphytic assemblages were the least diverse and showed the best preservation. Compositional and taphonomic indices were significantly correlated, suggesting common environmental controls on the species composition and preservation at local scales. The joint analysis of compositional and taphonomic variations in the recent sedimentary record of Nahuel Rucá demonstrated the usefulness of taphonomic analyses to uncover subtle paleoenvironmental variations, which could be overlooked if only traditional compositional analyses are performed. We concluded that both taphonomic analyses and a holistic consideration of ecologically meaningful taxa should be considered in order to improve paleoenvironmental reconstructions in environmentally heterogeneous shallow lakes. Fil: Hassan, Gabriela Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Paredes Rojas, Yesica Luciana. Universidad Nacional de Mar del Plata; Argentina Fil: de Francesco, Claudio German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Published
2018

12. Composición y estructura de los ensambles de peces en un arroyo pampeano con uso del suelo contrastante

Author

Bertora, Andrea, Grosman, Fabián, Sanzano, Pablo, and Rosso, Juan José

Subjects
Riparian index, Use of land, Región pampeana, Pampa plain, Fish community, Uso del suelo, Comunidad de peces, Índice de ribera
Abstract

La intensificación del uso del suelo en la región pampeana ha afectado negativamente sus ecosistemas acuáticos y las comunidades bióticas que en ellos habitan. En este escenario, los arroyos son particularmente vulnerables. Este trabajo caracteriza la comunidad de peces y las condiciones de ribera del arroyo del Azul en tramos con usos del suelo contrastantes: agrícola, urbano y ganadero. Para ello, se cuantificó la condición de ribera y se realizaron muestreos ictiológicos durante dos períodos estivales. Para caracterizar la ribera y las comunidades de peces se calcularon diversos índices y métricas. Además, se calculó el grado de asociación entre las métricas de peces y dos índices de riberas pampeanos. La condición de ribera bajo los distintos usos de suelo fue diferente, siendo menor en el tramo urbano. Se capturaron 1180 peces y 15 especies. La estructura de peces del tramo agrícola fue diametralmente diferente al resto. Sin embargo, la composición de especies fue semejante entre los sitios. El tramo ganadero presentó la mayor riqueza de peces y el tramo agrícola la máxima diversidad. La abundancia de Corydoras paleatus y la proporción de Siluriformes estuvieron asociadas inversamente a la condición de las riberas. La abundancia de Oligosarcus jenynsii manifestó el patrón opuesto. Los peces y las riberas respondieron a los diferentes usos del suelo. Se evidenció asociación entre algunos atributos de las comunidades de peces y la calidad de ribera. Estos resultados contribuyen al conocimiento de base necesario para una conservación y manejo eficientes de los recursos acuáticos continentales. Aquatic ecosystems and their biotic communities in the Pampa Plain have been negatively affected by the intensification of land use during the last years. In this scenario, streams are particularly vulnerable. This work characterizes the fish communities and riparian conditions of del Azul stream in different reaches with contrasting land uses: agricultural, urban and livestock. Riparian conditions and ichthyological samplings were conducted during two summers in the three studied sites. In order to characterize riparian conditions and fish communities different indices and metrics were calculated. The empirical relationships between fish metrics and two pampean riparian indices were calculated. The riparian condition differed among land uses, being lowest in the urban section. A total of 1180 fishes of 15 species were captured. The fish community structure of agricultural reach was diametrically different from the others. However, the species composition was similar between reaches. Fish richness was highest at the livestock reach whereas the agricultural reach showed the largest diversity. The abundance of Corydoras paleatus and the relative abundance of Siluriformes were inversely related with the riparian condition. Instead, the abundance of Oligosarcus jenynsii presented the opposite pattern. Fish communities and riparian conditions responded to different land uses and it also was evidenced an association between some fish community attributes and riparian condition. These results contribute to the basic knowledge needed for an efficient conservation and management of the freshwater resources.

Published
2018

13. Síntesis emergética como herramienta de comparación entre dos sistemas de producción agrícola argentinos: chaco seco y pampa ondulada

Author

Totino, Mariana

Subjects
Emergy Synthesis, soybean, industrial agriculture, chaco plain, pampa plain, Llanura chaqueña, Emergy synthesis, Soja, Síntesis Emergética, Agricultura industrial, Ciencias de la Tierra y relacionadas con el Medio Ambiente, purl.org/becyt/ford/1 [https], purl.org/becyt/ford/1.5 [https], Industrial agriculture, Pampa plain, Llanura pampeana, Soybean, Chaco plain, Meteorología y Ciencias Atmosféricas, CIENCIAS NATURALES Y EXACTAS, soja, agricultura industrial, llanura chaqueña, llanura pampeana
Abstract

The agricultural system in Argentina was one of the main drivers of native ecosystems transformation, becoming an important economic activity. The Pampas region has an agricultural tradition of over a century, underpinned by the most fertile soil in the country. But from the 90s on, with the entrance of GM soybean and the very large number of its inputs, this model of industrial agriculture pushed the boundaries of the "core area" toward areas with different environmental characteristics. The proposal of this research is to track all the resources and energy used to produce soybean, transforming them to a common unit, which is solar energy. From this conversion soybean production at a location of the Rolling Pampa (Rojas) may be compared to one at the Chaco Seco (Charata). Indices that provide information on specific features of the process are also calculated. Despite the environmental differences between the two sites associated with greater environmental fragility of the Chaco plain, mainly related to reduced availability of water, high temperatures and slightly less fertile soils than those of the Pampas, virtually no difference was found in regarding the contributions of the environment in both locations. Possible causes of this result are discussed., El sistema agropecuario en Argentina fue uno de los principales motores de transformación de los ecosistemas nativos, constituyéndose en una importante actividad económica. La región pampeana posee una tradición agrícola de más de un siglo, sustentada por los suelos más fértiles del país. Pero a partir de la década de los 90, junto a la entrada de la soja transgénica de la mano de gran cantidad de insumos, este modelo de agricultura industrial fue superando los límites de la “zona núcleo” para avanzar hacia zonas con diversas características ambientales. La propuesta de esta investigación es rastrear todos los recursos y energía utilizados para producir soja, transformándolos a una unidad común que es laenergía solar. A partir de esta conversión es posible comparar la producción de soja en una localidad de la Pampa Ondulada (Rojas) con una en el Chaco Seco (Charata). También se calculan índices que informan sobre distintas características del proceso. A pesar de las diferencias ambientales entre ambos sitios asociadas a la mayor fragilidad ambiental de la llanura chaqueña, relacionadas principalmente con una menor disponibilidad de agua, altas temperaturas y suelos un poco menos fértiles que los de la llanura pampeana, prácticamente no se encontraron diferencias en cuanto a los aportes del ambiente en ambas localidades. Se analizan las posibles causas de dicho resultado.

Published
2016

14. Spatial distribution of electrical conductivity and stable isotopes in groundwater in large catchments: a geostatistical approach in the Quequén Grande River catchment, Argentina

Author

Cristina Dapeña, Libardo Antonio Londoño Ciro, Daniel Emilio Martinez, Hector Enrique Massone, and Orlando Mauricio Quiroz Londoño

Subjects
GROUNDWATER, δ18O, Otras Ciencias de la Tierra y relacionadas con el Medio Ambiente, Argentina, Aquifer, Soil science, Oxygen Isotopes, OXYGEN- 18, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Inorganic Chemistry, ISOTOPE HYDROLOGY, Environmental Chemistry, HYDROGEN-2, Groundwater, General Environmental Science, Isotope analysis, Hydrology, geography, Hydrogeology, geography.geographical_feature_category, Electric Conductivity, Groundwater recharge, Models, Theoretical, Deuterium, PAMPA PLAIN, ELECTRICAL CONDUCTIVITY, Isotope hydrology, Spatial variability, GEOSTATISTICS, Geology, CIENCIAS NATURALES Y EXACTAS, Environmental Monitoring
Abstract

Stable isotopes and electrical conductivity in groundwater were used as natural tracers to adjust the hydrogeological conceptual model in one of the largest catchments within the inter-mountainous Pampa plain, Argentina. Geostatistical tools were used to define the model that best fitted the spatial distribution of each tracer, and information was obtained in areas where there was a lack of data. The conventional isotopic analysis allowed the identification of three groundwater groups with different isotopic fingerprints. One group containing 56 % of the total groundwater samples suggested a well-mixed system and soil infiltration precipitation as the main recharge source to the aquifer. The other two groups included samples with depleted (25.5 %) and enriched (18.5 %) isotopic compositions, respectively. The combination of δ18O, δ2H and electrical conductivities maps suggested ascending regional flows and water transfer from the Quequén Grande River catchment to the Moro creek. The spatial interpretation of these tracers modified the conceptual hydrogeological model of the Quequén Grande River. Fil: Quiroz Londoño, Orlando Mauricio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Martinez, Daniel Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Massone, Hector Enrique. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Geología de Costas y del Cuaternario. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Geología de Costas y del Cuaternario; Argentina Fil: Londoño Ciro, Libardo Antonio. Universidad de Antioquia; Colombia Fil: Dapeña, Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotópica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; Argentina

Published
2015

15. Length-weight relationships for nine fish species from shallow lakes of the Pampa plain, Argentina

Author

Gonzalez Sagrario, Maria de Los Angeles, Rodríguez Golpe, Daniela Carmen, la Sala, Luisina, and Seco Pon, Juan Pablo

Subjects
Ciencias Biológicas, FISH, LENGTH-WEIGHT RELATIONSHIPS, Bioquímica y Biología Molecular, SHALLOW LAKES, PAMPA PLAIN, CIENCIAS NATURALES Y EXACTAS
Abstract

This study presents length-weight relationships for nine neotropical fish species collected from four shallow lakes from the southeastern Pampean region, representing the first record for these species. Also, new sizes for six species are also provided. Fil: Gonzalez Sagrario, Maria de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina Fil: Rodríguez Golpe, Daniela Carmen. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: la Sala, Luisina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Seco Pon, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Published
2013

16. Holocene changes in trophic states of shallow lakes from the Pampa plain of Argentina

Author

Sonia L. Fontana, C. Marcela Borel, Marcela Sandra Tonello, and Silvina Stutz

Subjects
0106 biological sciences, 010506 paleontology, Archeology, alternative stable states, medicine.disease_cause, 01 natural sciences, Southern South America, Alternative stable state, Pollen, Phytoplankton, medicine, Holocene, 0105 earth and related environmental sciences, Earth-Surface Processes, Trophic level, Global and Planetary Change, Ecology, 010604 marine biology & hydrobiology, shallow lakes, Paleontology, Sediment, Macrofossil, palaeolimnology, Macrophyte, late Holocene, Pampa plain, 13. Climate action, Physical geography, Geology
Abstract

Changes in trophic status of shallow lakes from the southeastern Pampa plain of Argentina are evaluated based on the relative presence of submerged macrophytes and phytoplankton. The evolution of lake Lonkoy is reconstructed for the last 5000 years, using pollen, non-pollen palynomorphs (NPPs) and macrofossil remain analyses, revealing three main lake stages. A macrophyte-dominated clear lake prevailed until 670 cal yr BP. Afterwards, the lake changed to a turbid phytoplankton-dominated state. Recently, the lake has turned to a turbid phase, caused by resuspended sediment. These results are compared with two other paleolimnological records from the region, lakes Hinojales and Nahuel Rucá, revealing a similar late-Holocene evolution, with a shift from a macrophyte- to phytoplankton-dominated lake, occurring at broadly the same time. The shift of states may be attributed to a shift in climate after 1000 cal. yr BP towards wetter conditions during the Medieval Climate Anomaly.

Published
2012

17. Relationships between fish species abundances and water transparency in hypertrophic turbid waters of temperate shallow lakes

Author

Juan José Rosso, Alejandro Sosnovsky, Rolando Quirós, and Armando M. Rennella

Subjects
Ecology, Species diversity, Aquatic animal, Aquatic Science, Biology, Ecología, PAMPA PLAIN, Freshwater ecosystem, SECCHI DISC, Fishery, Ciencias Biológicas, Temperate climate, SOUTH AMERICA, Species richness, Water quality, Turbidity, FRESHWATER ECOSYSTEMS, Water transparency, Ecology, Evolution, Behavior and Systematics, CIENCIAS NATURALES Y EXACTAS
Abstract

We explored the relationships between Secchi disc depth and the abundance of fish species in very shallow, hypertrophic, turbid waters of Pampa Plain lakes, Argentine. We tested whether the abundance of any of the species present was associated with water transparency for lakes where water transparency, as measured by Secchi disc depth, ranged from 0.1 to 0.4 m. Overall, the abundance of five species (Cnesterodon decemmaculatus, Jenynsia multidentata, Corydoras paleatus, Pimelodella laticeps and Odontesthes bonariensis) seemed to be affected by this narrow gradient in water transparency. These findings represent an interesting result for turbid hypertrophic environments where narrow ranges in water transparency are traditionally neglected as important factors for fishes. We show, however, how water transparency patterns may be still important for some species in highly turbid waters with extremely narrow gradients in Secchi disc depth. Fil: Rosso, Juan Jose. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Centro de Estudios Transdisciplinarios del Agua; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sosnovsky, Alejandro. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Grupo de Evaluación y Manejo de Recursos Icticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Rennella, A. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Sistemas de Producción Acuatica; Argentina Fil: Quiros, Rolando. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal. Cátedra de Sistemas de Producción Acuatica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Published
2010

18. Quaternary deformation around the Palo Negro area, Pampa Norte, Argentina

Author

Martín Iriondo, L. Zamboni, Ernesto Brunetto, and G. Gottardi

Subjects
Lineament, Inversion (geology), LATE QUATERNARY DEPOSITS, Geology, Fold (geology), Fault scarp, PAMPA PLAIN, Neotectonics, Ciencias de la Tierra y relacionadas con el Medio Ambiente, Graben, Tectonics, NEOTECTONICS, Intraplate earthquake, Geología, Geomorphology, CIENCIAS NATURALES Y EXACTAS, Earth-Surface Processes, TERRAIN ANALYSIS
Abstract

The Pampa Norte region is a great plain characterized by low slopes and accumulation of hundreds of meters of thick loose sediments. A high morphostructure denominated San Guillermo block stands out in the central plain, the Tostado-Selva scarp forming its western boundary. It is located in an intraplate setting characterized by low tectonic activity. However recent uplift can be inferred by means of terrain analysis and the sedimentology of the Palo Negro Fm. Pond deposits (Palo Negro Fm.) observed in the scarp suggest topographic inversion during the Late Quaternary in the Palo Negro area. The morphology indicates that the deformation was widely distributed, forming a gentle (ca. 5 m amplitude and 13 km wavelength) asymmetric fold. Low sinuosity lineaments located in the base of the scarp, coincident with knick points in the topographic profile, can be interpreted as the projection of tip-lines by high-angle fault-propagation. This geometry is compatible with reverse kinematics on blind faults.A deformation style with reactivation of pre-existing faults is consistent with structural observations. Seismic reflectors suggest the presence of Cretaceous high-angle normal faults, and the orientation of lineaments is similar to the orientation of the graben systems and transverse accommodation zones originated during the opening of the South Atlantic Ocean.One OSL dating of 67.4 ± 5.1 kyr B.P (from Palo Negro Fm. supposed as deposited on a flat plain floor) and a height difference of 9.5 m measured in the Tostado-Selva scarp account for an averaged uplift rate of 0.14 mm/year. Fil: Brunetto, Ernesto. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Iriondo, Martin Horacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Zamboni Galliusi, Luis Victorio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Gottardi, Maria Griselda. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina

Published
2010

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