RESUMEN. La valoración ambiental de las riberas es una tarea necesaria para conocer el estado eco... more RESUMEN. La valoración ambiental de las riberas es una tarea necesaria para conocer el estado ecológico de los cursos de agua, lo cual permite evaluar los méritos de eventuales experiencias de manejo, impactos antropogénicos o bien detectar problemas ambientales de forma temprana. En tal sentido, el objetivo de este estudio fue desarrollar una metodología para evaluar la calidad del hábitat de la Franja Costera Sur del Río de la Plata. La información obtenida de 21 sitios de muestreo, visitados entre los años 2005 y 2008, fue resumida y simplificada en un índice, denominado Índice del Hábitat para el Río de la Plata (IHRPlata). Para obtener el índice se requiere evaluar cuatro descriptores: 1) sucesión espacial de la vegetación costera, 2) modificaciones costeras por introducción de infraestructuras, 3) ocurrencia de residuos en la línea de costa, y 4) indicadores biológicos de déficit de oxígeno. Según los valores del IHRPlata obtenidos, 32% de los casos analizados revelaron una calidad del hábitat muy buena, 20% buena, 24% moderada, 18% mala y 6% muy mala. Los valores del índice alcanzaron correlaciones significativas con parámetros relacionados con la calidad del agua y con indicadores de la calidad biótica, lo que fortalece su utilidad para evaluar la calidad del hábitat costero.
Extracellular recordings have elucidated spatial neural representations without identifying under... more Extracellular recordings have elucidated spatial neural representations without identifying underlying microcircuits. We labeled neurons juxtacellularly in medial entorhinal cortex of freely moving rats with a friction-based, pipette-stabilization system. In a linear maze novel to the animals, spatial firing of superficial layer neurons was reminiscent of grid cell activity. Layer 2 stellate cells showed stronger theta modulation than layer 3 neurons, and both fired during the ascending phase of field potential theta. Deep-layer neurons showed little or no activity. Layer 2 stellate cells resided in hundreds of small patches. At the dorsomedial entorhinal border, we identified larger (putative parasubicular) patches, which contained polarized head-direction selective neurons firing during the descending theta phase. Three axon systems interconnected patches: centrifugal axons from superficial cells to single large patches, centripetal axons from large-patch cells to single small patches, and circumcurrent axons interconnecting large patches. Our microcircuit analysis during behavior reveals modularity of entorhinal processing.
The aim of this study was to describe the colonization of the biofilm during its early stages und... more The aim of this study was to describe the colonization of the biofilm during its early stages under different concentrations of nutrients and organic matter, specifically in urban streams influenced by agriculture and urbanization. We hypothesized that in a stream with higher concentrations of nutrients and organic matter, the initial biomass growth would be faster, and the changes in the structure of the community would be greater. Sterile glass substrates were placed in 2 urban streams that differed in nutrient and organic matter concentrations; samples were collected during their first week of colonization to measure total biomass, bacterial biomass, chlorophyll a, activity of the electron transfer system, and the community composition. Results show that biofilm development in both streams began within a few hours and differed under different conditions of nutrients; in the stream with a better water quality, the colonization dynamics consisted of 2 increments of bacterial biomass linked with an increase of algal biomass. In the urban stream with higher nutrient and organic matter concentrations, biofilm development was slower and consisted of a simultaneous increase of bacteria and algae, consistent with a lower electron transfer system activity. Therefore, the dynamics of the colonization process in addition to those characteristics of the fully developed biofilm could have potential applications in water monitoring of urban streams.
Environmental Monitoring and Assessment, Mar 17, 2018
We examined the responses of the phytoplankton and the bacterioplankton of the freshwater zone of... more We examined the responses of the phytoplankton and the bacterioplankton of the freshwater zone of the Río de la Plata estuary when exposed to an addition of hexavalent chromium (Cr +6). The planktonic community from a coastal site was exposed to a chromium increase of 80 μg L −1 for 72 h in laboratory conditions. The results showed a decrease in the concentration of Cr +6 by 33% in the treatments, along with significant decreases in chlorophyll-a (63%), the chlorophyll-a:pheophytin-a ratio (33%), oxygen production (37%), and in the total density of the phytoplankton (15%). The relative abundance of chlorophytes and diatoms decreased, while the cyanobacteria thrived. Finally, the total bacterial density and the density of viable bacteria decreased. These results show that even small increments in Cr +6 can cause significant effects on the phytoplankton and bacterioplankton, which could potentially affect other trophic levels of the community, risking alterations of the entire ecosystem. Keywords Chlorophyll-a. Pheophytin. Phytoplankton assemblage. Oxygen production. Bacterioplankton. Toxicology mulate heavy metals (De Rore et al. 1994; Wang and Dei 2001). References of the effects of chromium on certain species of planktonic algae and bacterial strains are abundant and usually include changes in cellular density, in cell size, in reproduction (sexual-asexual), in pigment concentration, in photosynthetic capacity, and intracellular damages (
A�������. Droughts reduce habitat and fragment the continuity of running water systems producing ... more A�������. Droughts reduce habitat and fragment the continuity of running water systems producing lasting effects on sediment biota and affecting density and biomass of algae. When droughts occur, the survival of algae and cyanobacteria of the biofilm depends on different alternatives to overcome the stress. In Pampean streams, periods of low flow causing desiccation stress in the biofilm may be linked to El Niño/Southern Oscillation phenomenon, and to water management practices (irrigation and extraction), that can reduce stream base flows for prolonged periods, reducing we�ed area and dewatering the stream bed. The aim of this study was to determine the response of epipelic algae (analyzed by greater algal groups Cyanobacteria, Euglenophyta, Dinoflagellates, Green Algae, Diatoms) to desiccation as a disturbance, in streams without frequent periods of drought. First, we studied the in situ vertical distribution of epipelic algae in stream sediment during the drought period as a refuge strategy, along with the vertical distribution of sediment humidity in 10 cm sediment corers divided in 6 segments at depths 0-1 cm (uppermost layer), 1-2 cm, 2-3 cm, 3-4 cm, 4-5 cm and 5-10 cm. Secondly, we analyzed the recolonization pa�erns of the epipelic algal assemblage after the drought by studying the succession of autotrophic organisms, in order to be�er understand the role of sediments as a source of algae populations. For this, 2 cm deep corers were placed with water in microcosms and monitored during 2 weeks. Our results indicate that when the streams are affected by a severe drought, algae and cyanobacteria survive; this could be related with the moisture content of the sediment. Besides, after hydratation of the sediment, the community rapidly increased its density. Cyanobacteria were the most resistant group to desiccation and the one who had the faster reaction to hydratation.
Biología Acuática 35 aborda distintos temas vinculados con los bañados de desborde fluvial. Estos... more Biología Acuática 35 aborda distintos temas vinculados con los bañados de desborde fluvial. Estos humedales asociados a los cursos de agua en la llanura pampeana están sometidos al permanente avance de las prácticas agropecuarias y la urbanización. El número aborda aspectos vinculados a la legislación, planificación del territorio, hidrología, calidad del agua y biota y pretende brindar información para la conservación y gestión de los mismos.
El agua es fundamental para la existencia de la vida, forma parte del territorio, define paisajes... more El agua es fundamental para la existencia de la vida, forma parte del territorio, define paisajes y promueve el desarrollo cultural y económico de los pueblos. Los múltiples usos del agua requieren que sea tratada como un bien común y un patrimonio universal compartido por los pueblos. Por lo tanto para lograr una gestión del agua responsable y sostenible a largo plazo es necesario preservar los ecosistemas acuáticos a partir de un fuerte compromiso de los diferentes sectores de la sociedad. El objetivo del VI Congreso Argentino de Limnología: Agua, Ambiente y Sociedad es generar un espacio de reunión para que especialistas, relacionados con las distintas temáticas de la ecología acuática, puedan exponer los avances en las investigaciones limnológicas y su potencial transferencia a la sociedad. Su principal propósito es abrir un ámbito de debate sobre temas relevantes como los relacionados con la calidad del agua y del hábitat de lagos, lagunas, embalses, ríos y estuarios, la conser...
Biocorredores nativos: basados en servicios ecosistémicos que contribuyen al saneamiento de la Cuenca Matanza Riachuelo, 2020
Para el servicio ecosistémico aportado por el Biocorredor que refiere a la calidad del agua y sed... more Para el servicio ecosistémico aportado por el Biocorredor que refiere a la calidad del agua y sedimento se puede recurrir al empleo de biomonitores que pueden comprender desde un organismo, una parte de un organismo o bien a la comunidad de organismos, brindando información sobre los aspectos cuantitativos de la calidad del medio ambiente; es decir nos permite cuantificar el daño como una medida del estrés ambiental. Una de las cualidades del empleo de la biota es que son sensores finos de los cambios que operan en el medio acuático de tal forma que pueden acumular información que en algunos casos no son advertidos por los análisis químicos de rutina. Pero aún existe un concepto más integrador que es el de la calidad ecológica en donde además de considerar la evaluación la calidad biológica se tiene en cuenta al hábitat como eje o centro que interactúa y condiciona la calidad ecológica, ya que los factores ambientales lo pueden modificar y por lo tanto la flora y fauna se pueden ver afectadas. 3.3.2 Objetivos Los estudios realizados permiten establecer una línea de base para que cuando se incluya un nuevo punto de monitoreo en el área de intervención del Biocorredor Marcos Paz, se pueda establecer el grado de influencia y mejora de las acciones de intervención con biorrollos fijando las riberas y disminuyendo la erosión. También reconocer el efecto de la plantación de especies nativas que bioacumulan contaminantes y los retiran del ecosistema, así como poder cuantificar la mejora en la riqueza y diversidad de especies de la biota local y poder comparar con el estado anterior a la misma en los distintos indicadores y parámetros biológicos de agua superficial y sedimentos, en el punto de intervención y en sitios de monitoreo aguas arriba y aguas debajo de la intervención.
Stream biofi lms are among the fi rst to react to environmental degradation, since their structur... more Stream biofi lms are among the fi rst to react to environmental degradation, since their structural and functional characteristics are tightly linked to the physicochemical variables in the water and sediment. The objectives of this research were to study the differences in chlorophyll-a, bacterial density and metabolism endpoints of epipelic biofi lms in nutrient-rich streams under different physical-chemical conditions in the stream water in relation to changes in urbanization, and to measure the short-term responses (up to 72 h) in the biofi lm when translocated to more urbanized sites. For these purposes, chlorophyll-a, bacterial density, biofi lm respiration (electron transfer activity) and O 2 consumption were measured in epipelic biofi lms in nutrient-rich streams exposed to different levels of urbanization after a 30 day colonization. Afterward, biofi lms were translocated downstream to more polluted sites, and sampled to identify any fast occurring changes to be considered as potential indicators of environmental degradation. Results show that in the nutrient-rich streams studied, the structural characteristics of the biofi lm were linked to urbanization, and even after a short time following the translocation, chlorophyll-a and bacterial density varied, refl ecting the environmental degradation. On the other hand, metabolic variables were highly variable and produced inconsistent results when representing an increase in urbanization.
The objective of this study was to assess the effects of dredging on the structure and compositio... more The objective of this study was to assess the effects of dredging on the structure and composition of diatom assemblages from a lowland stream and to investigate whether the response of diatom assemblages to the dredging is also influenced by different water quality. Three sampling sites were established in Rodríguez Stream (Argentina); physico-chemical variables and benthic diatom assemblages were sampled weekly in spring 2001. Species composition, cell density, diversity and evenness were estimated. Diatom tolerance to organic pollution and eutrophication were also analyzed. Differences in physico-chemical variables and changes in benthic diatom assemblages were compared between the pre-and post-dredging periods using a t-test. Data were analyzed using Principal Components Analysis (PCA), non-metric multidimensional scaling (MDS) ordination and cluster analysis. The effects of dredging in the stream involve two types of disturbances: (i) in the stream bed, by the removal and destabilization of the substrate and (ii) in the water column, by generating chemical changes and an alteration of the light environment of the stream. Suspended solids, soluble reactive phosphorus and dissolved inorganic nitrogen were significantly higher in post-dredging periods. Physical and chemical modifications in the habitat of benthic diatoms produced changes in the assemblage; diversity and species numbers showed an immediate increase after dredging, decreasing at the end of the study period. Changes in the tolerance of the diatom assemblage to organic pollution and eutrophication were also observed as a consequence of dredging; in the post-dredging period sensitive species were replaced by either tolerant or most tolerant species. These changes were particularly noticeable in site 1 (characterized by its lower amount of nutrients and organic matter previous to dredging), which showed an increase in the amount of nutrients and oxygen demand as a consequence of sediment removal. However, these changes were not so conspicuous in sites 2 and 3, which already presented a marked water quality deterioration before the execution of the dredging works.
Ecological aquaculture promotes the development of sustainable farming systems, focusing on a wid... more Ecological aquaculture promotes the development of sustainable farming systems, focusing on a wide range of ecosystem elements. The ecological aquaculture of the zooplanktivorous pejerrey (Odontesthes bonariensis) in floating cages in Pampean shallow lakes (Argentina) needs to be carried out considering the hydrological and chemical variations as modulators of plankton community and consequently of the pejerrey yield. To assess its performance in lakes with contrasting hydrological regimes, an experiment was carried out in two water bodies: La Salada de Monasterio Lake (Mon), an endorheic environment, and San Lorenzo Lake (Lor), connected to several lakes and the Salado River. During the experiment, regional rainfall generated high hydrological variability in Lor Lake changing its status of unconnected lake to a run-of-the-river lake. High standard deviation in Chlorophyll-a values in Lor indicated the significant effects of hydrological instability on the plankton community. Microcrustaceans abundance and biomass were higher in Mon, and almost disappeared in Lor when it turns into run-of-the-river. The final fish growth and survival were significantly higher in Mon, endorsing the importance of zooplankton of high nutritional quality and hydrological, physical–chemical and biological stability. The results indicate that productive and stable environments with a sustained offer of natural food are better for the zooplanktivorous fish production. Connectivity with other water bodies and hydrological dependence on rainfall regimes have defining effects on phytoplankton, zooplankton and fish production, thus emerging as key factors to be considered for achieving better results in the ecological aquaculture implementation.Fil: Garcia, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Yorojo Moreno, Vivian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Sathicq, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentina. Consiglio Nazionale delle Ricerche; ItaliaFil: Gomez, Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Sampietro, Susana. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Donadelli, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin
(Sari F em ando-M agdalena). AA-AGOSBA-ILPLA-SHN.Buenos Aires. 157pp +2 anexos. A r r a g a E., B... more (Sari F em ando-M agdalena). AA-AGOSBA-ILPLA-SHN.Buenos Aires. 157pp +2 anexos. A r r a g a E., B a z á n J., F io r a v a n t i O. y L ó pe z J. 1997a. Parámetros de campo, material en suspensión y turbiedad.
Pampean rivers run through a territory with intense urban and agricultural use, being exposed to ... more Pampean rivers run through a territory with intense urban and agricultural use, being exposed to point and diffuse sources of pollution, including from enrichment with organic matter and nutrients to a varied contamination by industrial and agricultural waste, some with toxic characteristics. The advance of urbanization, the expansion of the agricultural frontier together with the new practices in agriculture and livestock has not been accompanied by adequate planning and management. This situation has generated a progressive deterioration in the water quality and habitat whose diagnosis and monitoring requires the use of multiple indicators, including biomonitors. In this chapter we will discuss the development and application of biological indicators used in the monitoring of the basins located in the Buenos Aires province (Pampa Ecoregion).
segunda en im portancia en A m érica del Sur después de la amazónica. Este sistema fluvio-m aríti... more segunda en im portancia en A m érica del Sur después de la amazónica. Este sistema fluvio-m arítim o está form ado por la confluencia de los ríos Paraná y Uruguay, que le ap ortan un caudal entre 2 3 0 0 0 y 2 8 0 0 0 m 3 seg 1. Tiene un ancho de 1.7 km en su origen (Punta G orda) y 2 3 0 km en su desem bocadura. La longitud fue estim ada en 6 4 0 km pero actualm ente es de 3 2 3 km, debido a la
Boletin de la Sociedad Argentina de Botanica, Oct 1, 2003
Review about modalities of study using microalgae in the evaluation and monitoring of some lotic ... more Review about modalities of study using microalgae in the evaluation and monitoring of some lotic systems from the province of Buenos Aires. The pampean plain´s running waters are exposed to strong antropogenic activities (agriculture, cattle-raising and industry), showing different environmental problems such as enrichment with organic matter and nutrients and contamination with industrial wastes. The particular features of the pampean streams and rivers require the development of suitable methodology and indices for water quality monitoring. The purpose of this paper is to outline some possibilities offered by the planktonic and benthic algae for the diagnosis of water quality and their implementation in biomonitoring. The investigations were carried out in lotic ecosystems of the province of Buenos Aires and in the coast of the Río de la Plata (southern coastal fringe). Two different types of strategies are exposed, extensive and intensive studies, which differ in the temporal and spatial scales employed. The results of these investigations have contributed with a first approach to the diagnosis of the ecological status of the studied basins.
DOAJ (DOAJ: Directory of Open Access Journals), Apr 1, 2019
Diatoms are useful ecological indicators because they are found in abundance in most lotic ecosys... more Diatoms are useful ecological indicators because they are found in abundance in most lotic ecosystems. The use of diatoms as indicators of the quality of river waters is widely accepted based on the fact that all diatom species have optima with respect to their tolerance for environmental conditions such as nutrients, organic pollution, pH, etc. Moreover diatoms are indicators of pollution in short term compared with other groups eg. macroinvertebrates. The rivers and streams of the Pampean plain, in Buenos Aires Province, are subjected to different human impacts. The most important stresses on rivers and streams in the Pampean plain are organic enrichments (discharge of insufficiently treated sewage), nutrients, heavy metals, pathogenic agents, pesticides, herbicides and physical changes produced by dredging and canalisation. The bottom substrate is mostly composed of slime-clay with low proportions of gravel and sand; in consequence, the epipelon is the most represented benthic community and suitable for biomonitoring purposes because it allows for comparing similar substrates along the rivers and streams. The aim of this study is to summarise the most common methodologies used in biomonitoring with diatoms and the application of biotic indices (diversity and pollution indices) in the evaluation of water quality of rivers and streams from the Pampean plain.
RESUMEN. La valoración ambiental de las riberas es una tarea necesaria para conocer el estado eco... more RESUMEN. La valoración ambiental de las riberas es una tarea necesaria para conocer el estado ecológico de los cursos de agua, lo cual permite evaluar los méritos de eventuales experiencias de manejo, impactos antropogénicos o bien detectar problemas ambientales de forma temprana. En tal sentido, el objetivo de este estudio fue desarrollar una metodología para evaluar la calidad del hábitat de la Franja Costera Sur del Río de la Plata. La información obtenida de 21 sitios de muestreo, visitados entre los años 2005 y 2008, fue resumida y simplificada en un índice, denominado Índice del Hábitat para el Río de la Plata (IHRPlata). Para obtener el índice se requiere evaluar cuatro descriptores: 1) sucesión espacial de la vegetación costera, 2) modificaciones costeras por introducción de infraestructuras, 3) ocurrencia de residuos en la línea de costa, y 4) indicadores biológicos de déficit de oxígeno. Según los valores del IHRPlata obtenidos, 32% de los casos analizados revelaron una calidad del hábitat muy buena, 20% buena, 24% moderada, 18% mala y 6% muy mala. Los valores del índice alcanzaron correlaciones significativas con parámetros relacionados con la calidad del agua y con indicadores de la calidad biótica, lo que fortalece su utilidad para evaluar la calidad del hábitat costero.
Extracellular recordings have elucidated spatial neural representations without identifying under... more Extracellular recordings have elucidated spatial neural representations without identifying underlying microcircuits. We labeled neurons juxtacellularly in medial entorhinal cortex of freely moving rats with a friction-based, pipette-stabilization system. In a linear maze novel to the animals, spatial firing of superficial layer neurons was reminiscent of grid cell activity. Layer 2 stellate cells showed stronger theta modulation than layer 3 neurons, and both fired during the ascending phase of field potential theta. Deep-layer neurons showed little or no activity. Layer 2 stellate cells resided in hundreds of small patches. At the dorsomedial entorhinal border, we identified larger (putative parasubicular) patches, which contained polarized head-direction selective neurons firing during the descending theta phase. Three axon systems interconnected patches: centrifugal axons from superficial cells to single large patches, centripetal axons from large-patch cells to single small patches, and circumcurrent axons interconnecting large patches. Our microcircuit analysis during behavior reveals modularity of entorhinal processing.
The aim of this study was to describe the colonization of the biofilm during its early stages und... more The aim of this study was to describe the colonization of the biofilm during its early stages under different concentrations of nutrients and organic matter, specifically in urban streams influenced by agriculture and urbanization. We hypothesized that in a stream with higher concentrations of nutrients and organic matter, the initial biomass growth would be faster, and the changes in the structure of the community would be greater. Sterile glass substrates were placed in 2 urban streams that differed in nutrient and organic matter concentrations; samples were collected during their first week of colonization to measure total biomass, bacterial biomass, chlorophyll a, activity of the electron transfer system, and the community composition. Results show that biofilm development in both streams began within a few hours and differed under different conditions of nutrients; in the stream with a better water quality, the colonization dynamics consisted of 2 increments of bacterial biomass linked with an increase of algal biomass. In the urban stream with higher nutrient and organic matter concentrations, biofilm development was slower and consisted of a simultaneous increase of bacteria and algae, consistent with a lower electron transfer system activity. Therefore, the dynamics of the colonization process in addition to those characteristics of the fully developed biofilm could have potential applications in water monitoring of urban streams.
Environmental Monitoring and Assessment, Mar 17, 2018
We examined the responses of the phytoplankton and the bacterioplankton of the freshwater zone of... more We examined the responses of the phytoplankton and the bacterioplankton of the freshwater zone of the Río de la Plata estuary when exposed to an addition of hexavalent chromium (Cr +6). The planktonic community from a coastal site was exposed to a chromium increase of 80 μg L −1 for 72 h in laboratory conditions. The results showed a decrease in the concentration of Cr +6 by 33% in the treatments, along with significant decreases in chlorophyll-a (63%), the chlorophyll-a:pheophytin-a ratio (33%), oxygen production (37%), and in the total density of the phytoplankton (15%). The relative abundance of chlorophytes and diatoms decreased, while the cyanobacteria thrived. Finally, the total bacterial density and the density of viable bacteria decreased. These results show that even small increments in Cr +6 can cause significant effects on the phytoplankton and bacterioplankton, which could potentially affect other trophic levels of the community, risking alterations of the entire ecosystem. Keywords Chlorophyll-a. Pheophytin. Phytoplankton assemblage. Oxygen production. Bacterioplankton. Toxicology mulate heavy metals (De Rore et al. 1994; Wang and Dei 2001). References of the effects of chromium on certain species of planktonic algae and bacterial strains are abundant and usually include changes in cellular density, in cell size, in reproduction (sexual-asexual), in pigment concentration, in photosynthetic capacity, and intracellular damages (
A�������. Droughts reduce habitat and fragment the continuity of running water systems producing ... more A�������. Droughts reduce habitat and fragment the continuity of running water systems producing lasting effects on sediment biota and affecting density and biomass of algae. When droughts occur, the survival of algae and cyanobacteria of the biofilm depends on different alternatives to overcome the stress. In Pampean streams, periods of low flow causing desiccation stress in the biofilm may be linked to El Niño/Southern Oscillation phenomenon, and to water management practices (irrigation and extraction), that can reduce stream base flows for prolonged periods, reducing we�ed area and dewatering the stream bed. The aim of this study was to determine the response of epipelic algae (analyzed by greater algal groups Cyanobacteria, Euglenophyta, Dinoflagellates, Green Algae, Diatoms) to desiccation as a disturbance, in streams without frequent periods of drought. First, we studied the in situ vertical distribution of epipelic algae in stream sediment during the drought period as a refuge strategy, along with the vertical distribution of sediment humidity in 10 cm sediment corers divided in 6 segments at depths 0-1 cm (uppermost layer), 1-2 cm, 2-3 cm, 3-4 cm, 4-5 cm and 5-10 cm. Secondly, we analyzed the recolonization pa�erns of the epipelic algal assemblage after the drought by studying the succession of autotrophic organisms, in order to be�er understand the role of sediments as a source of algae populations. For this, 2 cm deep corers were placed with water in microcosms and monitored during 2 weeks. Our results indicate that when the streams are affected by a severe drought, algae and cyanobacteria survive; this could be related with the moisture content of the sediment. Besides, after hydratation of the sediment, the community rapidly increased its density. Cyanobacteria were the most resistant group to desiccation and the one who had the faster reaction to hydratation.
Biología Acuática 35 aborda distintos temas vinculados con los bañados de desborde fluvial. Estos... more Biología Acuática 35 aborda distintos temas vinculados con los bañados de desborde fluvial. Estos humedales asociados a los cursos de agua en la llanura pampeana están sometidos al permanente avance de las prácticas agropecuarias y la urbanización. El número aborda aspectos vinculados a la legislación, planificación del territorio, hidrología, calidad del agua y biota y pretende brindar información para la conservación y gestión de los mismos.
El agua es fundamental para la existencia de la vida, forma parte del territorio, define paisajes... more El agua es fundamental para la existencia de la vida, forma parte del territorio, define paisajes y promueve el desarrollo cultural y económico de los pueblos. Los múltiples usos del agua requieren que sea tratada como un bien común y un patrimonio universal compartido por los pueblos. Por lo tanto para lograr una gestión del agua responsable y sostenible a largo plazo es necesario preservar los ecosistemas acuáticos a partir de un fuerte compromiso de los diferentes sectores de la sociedad. El objetivo del VI Congreso Argentino de Limnología: Agua, Ambiente y Sociedad es generar un espacio de reunión para que especialistas, relacionados con las distintas temáticas de la ecología acuática, puedan exponer los avances en las investigaciones limnológicas y su potencial transferencia a la sociedad. Su principal propósito es abrir un ámbito de debate sobre temas relevantes como los relacionados con la calidad del agua y del hábitat de lagos, lagunas, embalses, ríos y estuarios, la conser...
Biocorredores nativos: basados en servicios ecosistémicos que contribuyen al saneamiento de la Cuenca Matanza Riachuelo, 2020
Para el servicio ecosistémico aportado por el Biocorredor que refiere a la calidad del agua y sed... more Para el servicio ecosistémico aportado por el Biocorredor que refiere a la calidad del agua y sedimento se puede recurrir al empleo de biomonitores que pueden comprender desde un organismo, una parte de un organismo o bien a la comunidad de organismos, brindando información sobre los aspectos cuantitativos de la calidad del medio ambiente; es decir nos permite cuantificar el daño como una medida del estrés ambiental. Una de las cualidades del empleo de la biota es que son sensores finos de los cambios que operan en el medio acuático de tal forma que pueden acumular información que en algunos casos no son advertidos por los análisis químicos de rutina. Pero aún existe un concepto más integrador que es el de la calidad ecológica en donde además de considerar la evaluación la calidad biológica se tiene en cuenta al hábitat como eje o centro que interactúa y condiciona la calidad ecológica, ya que los factores ambientales lo pueden modificar y por lo tanto la flora y fauna se pueden ver afectadas. 3.3.2 Objetivos Los estudios realizados permiten establecer una línea de base para que cuando se incluya un nuevo punto de monitoreo en el área de intervención del Biocorredor Marcos Paz, se pueda establecer el grado de influencia y mejora de las acciones de intervención con biorrollos fijando las riberas y disminuyendo la erosión. También reconocer el efecto de la plantación de especies nativas que bioacumulan contaminantes y los retiran del ecosistema, así como poder cuantificar la mejora en la riqueza y diversidad de especies de la biota local y poder comparar con el estado anterior a la misma en los distintos indicadores y parámetros biológicos de agua superficial y sedimentos, en el punto de intervención y en sitios de monitoreo aguas arriba y aguas debajo de la intervención.
Stream biofi lms are among the fi rst to react to environmental degradation, since their structur... more Stream biofi lms are among the fi rst to react to environmental degradation, since their structural and functional characteristics are tightly linked to the physicochemical variables in the water and sediment. The objectives of this research were to study the differences in chlorophyll-a, bacterial density and metabolism endpoints of epipelic biofi lms in nutrient-rich streams under different physical-chemical conditions in the stream water in relation to changes in urbanization, and to measure the short-term responses (up to 72 h) in the biofi lm when translocated to more urbanized sites. For these purposes, chlorophyll-a, bacterial density, biofi lm respiration (electron transfer activity) and O 2 consumption were measured in epipelic biofi lms in nutrient-rich streams exposed to different levels of urbanization after a 30 day colonization. Afterward, biofi lms were translocated downstream to more polluted sites, and sampled to identify any fast occurring changes to be considered as potential indicators of environmental degradation. Results show that in the nutrient-rich streams studied, the structural characteristics of the biofi lm were linked to urbanization, and even after a short time following the translocation, chlorophyll-a and bacterial density varied, refl ecting the environmental degradation. On the other hand, metabolic variables were highly variable and produced inconsistent results when representing an increase in urbanization.
The objective of this study was to assess the effects of dredging on the structure and compositio... more The objective of this study was to assess the effects of dredging on the structure and composition of diatom assemblages from a lowland stream and to investigate whether the response of diatom assemblages to the dredging is also influenced by different water quality. Three sampling sites were established in Rodríguez Stream (Argentina); physico-chemical variables and benthic diatom assemblages were sampled weekly in spring 2001. Species composition, cell density, diversity and evenness were estimated. Diatom tolerance to organic pollution and eutrophication were also analyzed. Differences in physico-chemical variables and changes in benthic diatom assemblages were compared between the pre-and post-dredging periods using a t-test. Data were analyzed using Principal Components Analysis (PCA), non-metric multidimensional scaling (MDS) ordination and cluster analysis. The effects of dredging in the stream involve two types of disturbances: (i) in the stream bed, by the removal and destabilization of the substrate and (ii) in the water column, by generating chemical changes and an alteration of the light environment of the stream. Suspended solids, soluble reactive phosphorus and dissolved inorganic nitrogen were significantly higher in post-dredging periods. Physical and chemical modifications in the habitat of benthic diatoms produced changes in the assemblage; diversity and species numbers showed an immediate increase after dredging, decreasing at the end of the study period. Changes in the tolerance of the diatom assemblage to organic pollution and eutrophication were also observed as a consequence of dredging; in the post-dredging period sensitive species were replaced by either tolerant or most tolerant species. These changes were particularly noticeable in site 1 (characterized by its lower amount of nutrients and organic matter previous to dredging), which showed an increase in the amount of nutrients and oxygen demand as a consequence of sediment removal. However, these changes were not so conspicuous in sites 2 and 3, which already presented a marked water quality deterioration before the execution of the dredging works.
Ecological aquaculture promotes the development of sustainable farming systems, focusing on a wid... more Ecological aquaculture promotes the development of sustainable farming systems, focusing on a wide range of ecosystem elements. The ecological aquaculture of the zooplanktivorous pejerrey (Odontesthes bonariensis) in floating cages in Pampean shallow lakes (Argentina) needs to be carried out considering the hydrological and chemical variations as modulators of plankton community and consequently of the pejerrey yield. To assess its performance in lakes with contrasting hydrological regimes, an experiment was carried out in two water bodies: La Salada de Monasterio Lake (Mon), an endorheic environment, and San Lorenzo Lake (Lor), connected to several lakes and the Salado River. During the experiment, regional rainfall generated high hydrological variability in Lor Lake changing its status of unconnected lake to a run-of-the-river lake. High standard deviation in Chlorophyll-a values in Lor indicated the significant effects of hydrological instability on the plankton community. Microcrustaceans abundance and biomass were higher in Mon, and almost disappeared in Lor when it turns into run-of-the-river. The final fish growth and survival were significantly higher in Mon, endorsing the importance of zooplankton of high nutritional quality and hydrological, physical–chemical and biological stability. The results indicate that productive and stable environments with a sustained offer of natural food are better for the zooplanktivorous fish production. Connectivity with other water bodies and hydrological dependence on rainfall regimes have defining effects on phytoplankton, zooplankton and fish production, thus emerging as key factors to be considered for achieving better results in the ecological aquaculture implementation.Fil: Garcia, Javier Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Yorojo Moreno, Vivian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Sathicq, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentina. Consiglio Nazionale delle Ricerche; ItaliaFil: Gomez, Nora. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Sampietro, Susana. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Donadelli, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; ArgentinaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin
(Sari F em ando-M agdalena). AA-AGOSBA-ILPLA-SHN.Buenos Aires. 157pp +2 anexos. A r r a g a E., B... more (Sari F em ando-M agdalena). AA-AGOSBA-ILPLA-SHN.Buenos Aires. 157pp +2 anexos. A r r a g a E., B a z á n J., F io r a v a n t i O. y L ó pe z J. 1997a. Parámetros de campo, material en suspensión y turbiedad.
Pampean rivers run through a territory with intense urban and agricultural use, being exposed to ... more Pampean rivers run through a territory with intense urban and agricultural use, being exposed to point and diffuse sources of pollution, including from enrichment with organic matter and nutrients to a varied contamination by industrial and agricultural waste, some with toxic characteristics. The advance of urbanization, the expansion of the agricultural frontier together with the new practices in agriculture and livestock has not been accompanied by adequate planning and management. This situation has generated a progressive deterioration in the water quality and habitat whose diagnosis and monitoring requires the use of multiple indicators, including biomonitors. In this chapter we will discuss the development and application of biological indicators used in the monitoring of the basins located in the Buenos Aires province (Pampa Ecoregion).
segunda en im portancia en A m érica del Sur después de la amazónica. Este sistema fluvio-m aríti... more segunda en im portancia en A m érica del Sur después de la amazónica. Este sistema fluvio-m arítim o está form ado por la confluencia de los ríos Paraná y Uruguay, que le ap ortan un caudal entre 2 3 0 0 0 y 2 8 0 0 0 m 3 seg 1. Tiene un ancho de 1.7 km en su origen (Punta G orda) y 2 3 0 km en su desem bocadura. La longitud fue estim ada en 6 4 0 km pero actualm ente es de 3 2 3 km, debido a la
Boletin de la Sociedad Argentina de Botanica, Oct 1, 2003
Review about modalities of study using microalgae in the evaluation and monitoring of some lotic ... more Review about modalities of study using microalgae in the evaluation and monitoring of some lotic systems from the province of Buenos Aires. The pampean plain´s running waters are exposed to strong antropogenic activities (agriculture, cattle-raising and industry), showing different environmental problems such as enrichment with organic matter and nutrients and contamination with industrial wastes. The particular features of the pampean streams and rivers require the development of suitable methodology and indices for water quality monitoring. The purpose of this paper is to outline some possibilities offered by the planktonic and benthic algae for the diagnosis of water quality and their implementation in biomonitoring. The investigations were carried out in lotic ecosystems of the province of Buenos Aires and in the coast of the Río de la Plata (southern coastal fringe). Two different types of strategies are exposed, extensive and intensive studies, which differ in the temporal and spatial scales employed. The results of these investigations have contributed with a first approach to the diagnosis of the ecological status of the studied basins.
DOAJ (DOAJ: Directory of Open Access Journals), Apr 1, 2019
Diatoms are useful ecological indicators because they are found in abundance in most lotic ecosys... more Diatoms are useful ecological indicators because they are found in abundance in most lotic ecosystems. The use of diatoms as indicators of the quality of river waters is widely accepted based on the fact that all diatom species have optima with respect to their tolerance for environmental conditions such as nutrients, organic pollution, pH, etc. Moreover diatoms are indicators of pollution in short term compared with other groups eg. macroinvertebrates. The rivers and streams of the Pampean plain, in Buenos Aires Province, are subjected to different human impacts. The most important stresses on rivers and streams in the Pampean plain are organic enrichments (discharge of insufficiently treated sewage), nutrients, heavy metals, pathogenic agents, pesticides, herbicides and physical changes produced by dredging and canalisation. The bottom substrate is mostly composed of slime-clay with low proportions of gravel and sand; in consequence, the epipelon is the most represented benthic community and suitable for biomonitoring purposes because it allows for comparing similar substrates along the rivers and streams. The aim of this study is to summarise the most common methodologies used in biomonitoring with diatoms and the application of biotic indices (diversity and pollution indices) in the evaluation of water quality of rivers and streams from the Pampean plain.
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Papers by Nora Gómez