The eutrophication of aquatic systems is a problem related to the contribution of excess nutrient... more The eutrophication of aquatic systems is a problem related to the contribution of excess nutrients—phosphorus (P) and nitrogen (N)—to water bodies, which produces an increase in cyanobacterial blooms. Under eutrophic conditions, P and N concentrations are sufficient for cyanobacteria growth, and some micronutrients are considered to become limiting for population growth. This work aimed to assess the effect of iron on cyanobacteria growth and the content of MCs in natural populations of Microcystis spp. Microcosm setting experiments were carried out with natural samples collected during two bloom events of Microcystis spp., kept under controlled light, temperature and pH conditions. The first bloom sample was exposed to different iron concentrations (400, 700 and 1100 µg Fe·L−1) to determine the optimum concentration for growth. The second was exposed to different iron addition modes (one: T1P, and two pulses: T2P) to imitate the iron increase produced by the downward migration of M...
The changes within and between seasons in phytoplankton composition and abundance determine the c... more The changes within and between seasons in phytoplankton composition and abundance determine the carbon biomass available for upper levels of the food web. Temporal changes in phytoplankton community and environmental parameters in a port in Puerto Madryn, Southwest Atlantic were analysed. During an annual period (2011–2012), samples of surface seawater were collected approximately monthly. We determined phytoplankton community structure (species composition and abundance) and biomass (determined by carbon content and chlorophyll <i>a</i> (Chl <i>a</i>)). Water temperature, salinity and transparency were measured when sampling the surface water and local meteorological data were considered. The main groups observed were diatoms (Bacillariophyta; the most abundant during the concentration peaks of Chl <i>a</i>), dinoflagellates (Dinophyta) and flagellates, which mainly included species of Cryptophyta and Chlorophyta. Diatoms exhibited blooms in March (summer–autumn) and September (spring), represented by <i>Skeletonema costatum</i> and <i>Pseudo-nitzschia</i> spp. respectively. Dinoflagellates contributed to the highest carbon biomass, with peaks in January (summer) and April (autumn), exemplified by <i>Prorocentrum micans</i> and <i>Scrippsiella acuminata</i>, respectively. Temporal differences in community composition were related to the seasonal changes in temperature, solar irradiance, precipitation, salinity and wind velocity. The environmental conditions seem not only to determine the species composition but also cell size distribution: nanoplanktonic (≤ 20 µm) species dominated mainly during late spring, summer and early winter while microplanktonic species (&gt; 20 µm) during late winter and early spring. Our results showed within-season changes and show that not only Chl <i>a</i>, but also carbon content can be considered, as the former is a biased estimator of phytoplankton biomass. This study provides the first seasonally resolved estimation in the area of the carbon biomass available for upper levels of [...]
Microbial plankton assemblages, composition and biomass, during two ice-free periods in a deep hi... more Microbial plankton assemblages, composition and biomass, during two ice-free periods in a deep high mountain lake (Estany Redó, Pyrenees)
El presente trabajo tuvo como objetivo evaluar la historia trófica del Embalse San Roque, vincula... more El presente trabajo tuvo como objetivo evaluar la historia trófica del Embalse San Roque, vinculada a la eutrofización y la variación hidroclimática. Para ello se analizaron indicadores físicos, químicos y biológicos (paleopigmentos) en un testigo sedimentario. Esta información fue correlacionada con datos hidroclimáticos- precipitaciones y nivel del embalse-. Los resultados indican que existen una asociación entre la productividad del sistema con períodos más húmedos. Además, se observó un incremento de la productividad en los últimos años debido al aumento de los aportes autóctonos. Sin embargo, se requieren más análisis que confirmen estas relaciones.Centro de Investigaciones Geológica
Abstract Reservoirs hold a detailed record of the changes in the input of sediments and nutrients... more Abstract Reservoirs hold a detailed record of the changes in the input of sediments and nutrients over decades to centuries. Paleolimnological multi-proxy analysis makes it possible to reconstruct baseline conditions to infer early evidence of environmental change. Our study aims to reconstruct historical human impacts derived from urban development on the San Roque reservoir (Cordoba, Argentina) related to the centennial dynamics of sedimentary and eutrophication processes. A paleolimnological record, dated by 210Pb and 137Cs, made it possible to identify two stages during the environmental evolution of the San Roque reservoir. Physical processes, such as fluvial discharge and water level variation, dominantly ruled stage 1 (Unit C) during the initial infilling of the reservoir. Nutrient load and eutrophication processes controlled stage 2 (Units B and A). Stage 1 (77-55 cm; AD 1921 to 1965) occurred before and after the second dam was built and while the level of water increased by ≈ + 8 m; it displayed a high variation in mean grain size and maximum values of magnetic susceptibility. Stage 2 (AD 1965–2017) records a new reservoir base level and the maintenance of high water levels and comparatively more stable conditions. Regarding the eutrophication process throughout stage 2, three sub-stages were defined: a) Sub-stage I (AD 1965–1985) is a period of incipient eutrophication; b) Sub-stage II (AD 1985–2005) is an interval of increase of eutrophication as shown by the increase in several organic proxies related to the abundance of phytoplankton. Echinenone, zeaxanthin and myxoxanthophyll indicate that cyanobacteria increased concentration by three-to four-fold in comparison with the previous sub-stage. c) Sub-stage III (AD 2005–2017) shows the transition to a hypereutrophic state. Diatomea (fuco and diato), dinophyceae (diadino), chlorophyta (lut) and cryptophyta (allo) groups show a comparatively higher contribution. Our results mostly highlight that during the last century the main drivers of changes in the environmental state of the San Roque reservoir were trophic, fluvial and hydrometeorological. These results might provide tools for anticipating future scenarios for water management plans under increasing anthropic pressure.
RESUMEN: El embalse San Roque y Los Molinos localizados en la provincia de Córdoba son la fuente ... more RESUMEN: El embalse San Roque y Los Molinos localizados en la provincia de Córdoba son la fuente de provisión de agua para una población de más de 1 millón de habitantes. Ambos embalses, presentan en distinto grado un deterioro en la calidad de sus aguas. El primero posee un avanzado estado de eutrofia producto de la descarga de efluentes y el segundo manifiesta una condición mesotrófica con serios riesgos de eutroficación debido al desarrollo agropecuario y urbanístico que presenta su cuenca de aporte. Uno de los principales síntomas de esta problemática son las floraciones algales, particularmente de cianobacterias. Las floraciones de estas algas y su posible presencia de cianotoxinas, puede representar un problema para los organismos en contacto con el medio acuático incluyendo al ser humano. Existe información dispersa de las principales especies de cianobacterias presentes en el embalse San Roque y Los Molinos y dada la importancia sanitaria de sus floraciones, se planteó la ne...
La eutrofización representa una importante problemática ambiental que ocasiona un deterioro en lo... more La eutrofización representa una importante problemática ambiental que ocasiona un deterioro en los sistemas acuáticos. El estudio del registro sedimentario de un cuerpo de agua eutrófico, el embalse San Roque (Córdoba, Argentina), constituye una importante fuente de información en el entendimiento de dicho proceso y del papel que cumplen los sedimentos en la eutrofización. Con este propósito se caracterizó la distribución espacial de la granulometría y composición geoquímica de los sedimentos de fondo obtenidos en dos muestreos llevados a cabo en junio y agosto de 2018. Los resultados indican que la distribución granulométrica responde principalmente al aporte fluvial del ESR. Las fracciones gruesas predominan en proximidades a las desembocaduras y las fracciones finas en las zonas profundas del embalse. Adicionalmente los mayores contenidos de fósforo inorgánico, hierro, manganeso y carbono orgánico total se hallaron en la zona de la garganta, probablemente asociados en el sediment...
El analisis de indicadores paleolimnologicos fisicos, quimicos y biologicos del registro sediment... more El analisis de indicadores paleolimnologicos fisicos, quimicos y biologicos del registro sedimentario de Laguna del Plata (LdP), sistema de la Laguna Mar Chiquita (LMC) (Cordoba, Argentina), permitio reconstruir la variabilidad ambiental ocurrida en los ultimos ca. 70 anos y relacionarla con la variabilidad hidroclimatica del sistema y con el impacto de las actividades antropicas en la region. Se identificaron 4 escenarios con caracteristicas ambientales diferentes. El incremento en las concentraciones de nutrientes determinado a partir del ano 1984 en el registro sedimentario es sincronico con el avance de la frontera agricola en la region, la cual se expandio en la decada de 1980. Ademas, los resultados muestran el control que ejerce la variabilidad hidroclimatica sobre el ingreso de nutrientes a LdP permitiendo relacionar forzantes antropicos y naturales. Asimismo, se observo que, durante periodos de alto impacto antropico, la mayor disponibilidad de nutrientes es el factor que p...
RESUMEN: Córdoba posee numerosos embalses en los que se desarrollan actividades recreativas y muc... more RESUMEN: Córdoba posee numerosos embalses en los que se desarrollan actividades recreativas y muchos de ellos presentan tendencia a la eutrofización. En materia de gestión de recursos hídricos, se reconoce la falta de instrumentos locales para valorar las condiciones de uso recreativo en estos cuerpos de agua. Los aspectos de mayor relevancia relacionados con este uso tienen que ver con la estética del recurso y los posibles riesgos a la salud. La presencia de cianobacterias y el grado de toxicidad de sus floraciones, no son contemplados en los estándares locales y tampoco en los índices de calidad de agua (ICA) más comúnmente utilizados en la actualidad. Por esta razón se propone un índice que considere este aspecto, sumando el menor número de variables necesarias. La construcción del ICA se basó en datos de playas de los Embalse San Roque (ESR) y Los Molinos (ELM). El ICA propuesto, de tipo sumatorio, incluyó las variables transparencia, temperatura, bacterias coliformes termotole...
Journal of Photochemistry and Photobiology B Biology
We carried out experiments using long-term (5–7 days) exposure of marine phytoplankton species to... more We carried out experiments using long-term (5–7 days) exposure of marine phytoplankton species to solar radiation, in order to assess the joint effects of ultraviolet radiation (UVR) and temperature on the photochemical responses and photoprotective mechanisms. In the experiments, carried out at Atlantic coast of Patagonia (43°18.7′S; 65°2.5′W) in spring-summer 2011, we used three species as model organisms: the dinoflagellate Prorocentrum micans, the chlorophyte Dunaliella salina and the haptophyte Isochrysis galbana. They were exposed under: (1) two radiation quality treatments (by using different filters): P (PAR, >400 nm) and PAB (PAR + UV-A + UV-B, >280 nm); (2) two radiation intensities (100% and 50%) and (3) two experimental temperatures: 18 °C and 23 °C during summer and 15 °C and 20 °C in spring experiments, simulating a 5 °C increase under a scenario of climate change. In addition, short-term (4 h) artificial radiation exposure experiments were implemented to study v...
The eutrophication of aquatic systems is a problem related to the contribution of excess nutrient... more The eutrophication of aquatic systems is a problem related to the contribution of excess nutrients—phosphorus (P) and nitrogen (N)—to water bodies, which produces an increase in cyanobacterial blooms. Under eutrophic conditions, P and N concentrations are sufficient for cyanobacteria growth, and some micronutrients are considered to become limiting for population growth. This work aimed to assess the effect of iron on cyanobacteria growth and the content of MCs in natural populations of Microcystis spp. Microcosm setting experiments were carried out with natural samples collected during two bloom events of Microcystis spp., kept under controlled light, temperature and pH conditions. The first bloom sample was exposed to different iron concentrations (400, 700 and 1100 µg Fe·L−1) to determine the optimum concentration for growth. The second was exposed to different iron addition modes (one: T1P, and two pulses: T2P) to imitate the iron increase produced by the downward migration of M...
The changes within and between seasons in phytoplankton composition and abundance determine the c... more The changes within and between seasons in phytoplankton composition and abundance determine the carbon biomass available for upper levels of the food web. Temporal changes in phytoplankton community and environmental parameters in a port in Puerto Madryn, Southwest Atlantic were analysed. During an annual period (2011–2012), samples of surface seawater were collected approximately monthly. We determined phytoplankton community structure (species composition and abundance) and biomass (determined by carbon content and chlorophyll <i>a</i> (Chl <i>a</i>)). Water temperature, salinity and transparency were measured when sampling the surface water and local meteorological data were considered. The main groups observed were diatoms (Bacillariophyta; the most abundant during the concentration peaks of Chl <i>a</i>), dinoflagellates (Dinophyta) and flagellates, which mainly included species of Cryptophyta and Chlorophyta. Diatoms exhibited blooms in March (summer–autumn) and September (spring), represented by <i>Skeletonema costatum</i> and <i>Pseudo-nitzschia</i> spp. respectively. Dinoflagellates contributed to the highest carbon biomass, with peaks in January (summer) and April (autumn), exemplified by <i>Prorocentrum micans</i> and <i>Scrippsiella acuminata</i>, respectively. Temporal differences in community composition were related to the seasonal changes in temperature, solar irradiance, precipitation, salinity and wind velocity. The environmental conditions seem not only to determine the species composition but also cell size distribution: nanoplanktonic (≤ 20 µm) species dominated mainly during late spring, summer and early winter while microplanktonic species (&gt; 20 µm) during late winter and early spring. Our results showed within-season changes and show that not only Chl <i>a</i>, but also carbon content can be considered, as the former is a biased estimator of phytoplankton biomass. This study provides the first seasonally resolved estimation in the area of the carbon biomass available for upper levels of [...]
Microbial plankton assemblages, composition and biomass, during two ice-free periods in a deep hi... more Microbial plankton assemblages, composition and biomass, during two ice-free periods in a deep high mountain lake (Estany Redó, Pyrenees)
El presente trabajo tuvo como objetivo evaluar la historia trófica del Embalse San Roque, vincula... more El presente trabajo tuvo como objetivo evaluar la historia trófica del Embalse San Roque, vinculada a la eutrofización y la variación hidroclimática. Para ello se analizaron indicadores físicos, químicos y biológicos (paleopigmentos) en un testigo sedimentario. Esta información fue correlacionada con datos hidroclimáticos- precipitaciones y nivel del embalse-. Los resultados indican que existen una asociación entre la productividad del sistema con períodos más húmedos. Además, se observó un incremento de la productividad en los últimos años debido al aumento de los aportes autóctonos. Sin embargo, se requieren más análisis que confirmen estas relaciones.Centro de Investigaciones Geológica
Abstract Reservoirs hold a detailed record of the changes in the input of sediments and nutrients... more Abstract Reservoirs hold a detailed record of the changes in the input of sediments and nutrients over decades to centuries. Paleolimnological multi-proxy analysis makes it possible to reconstruct baseline conditions to infer early evidence of environmental change. Our study aims to reconstruct historical human impacts derived from urban development on the San Roque reservoir (Cordoba, Argentina) related to the centennial dynamics of sedimentary and eutrophication processes. A paleolimnological record, dated by 210Pb and 137Cs, made it possible to identify two stages during the environmental evolution of the San Roque reservoir. Physical processes, such as fluvial discharge and water level variation, dominantly ruled stage 1 (Unit C) during the initial infilling of the reservoir. Nutrient load and eutrophication processes controlled stage 2 (Units B and A). Stage 1 (77-55 cm; AD 1921 to 1965) occurred before and after the second dam was built and while the level of water increased by ≈ + 8 m; it displayed a high variation in mean grain size and maximum values of magnetic susceptibility. Stage 2 (AD 1965–2017) records a new reservoir base level and the maintenance of high water levels and comparatively more stable conditions. Regarding the eutrophication process throughout stage 2, three sub-stages were defined: a) Sub-stage I (AD 1965–1985) is a period of incipient eutrophication; b) Sub-stage II (AD 1985–2005) is an interval of increase of eutrophication as shown by the increase in several organic proxies related to the abundance of phytoplankton. Echinenone, zeaxanthin and myxoxanthophyll indicate that cyanobacteria increased concentration by three-to four-fold in comparison with the previous sub-stage. c) Sub-stage III (AD 2005–2017) shows the transition to a hypereutrophic state. Diatomea (fuco and diato), dinophyceae (diadino), chlorophyta (lut) and cryptophyta (allo) groups show a comparatively higher contribution. Our results mostly highlight that during the last century the main drivers of changes in the environmental state of the San Roque reservoir were trophic, fluvial and hydrometeorological. These results might provide tools for anticipating future scenarios for water management plans under increasing anthropic pressure.
RESUMEN: El embalse San Roque y Los Molinos localizados en la provincia de Córdoba son la fuente ... more RESUMEN: El embalse San Roque y Los Molinos localizados en la provincia de Córdoba son la fuente de provisión de agua para una población de más de 1 millón de habitantes. Ambos embalses, presentan en distinto grado un deterioro en la calidad de sus aguas. El primero posee un avanzado estado de eutrofia producto de la descarga de efluentes y el segundo manifiesta una condición mesotrófica con serios riesgos de eutroficación debido al desarrollo agropecuario y urbanístico que presenta su cuenca de aporte. Uno de los principales síntomas de esta problemática son las floraciones algales, particularmente de cianobacterias. Las floraciones de estas algas y su posible presencia de cianotoxinas, puede representar un problema para los organismos en contacto con el medio acuático incluyendo al ser humano. Existe información dispersa de las principales especies de cianobacterias presentes en el embalse San Roque y Los Molinos y dada la importancia sanitaria de sus floraciones, se planteó la ne...
La eutrofización representa una importante problemática ambiental que ocasiona un deterioro en lo... more La eutrofización representa una importante problemática ambiental que ocasiona un deterioro en los sistemas acuáticos. El estudio del registro sedimentario de un cuerpo de agua eutrófico, el embalse San Roque (Córdoba, Argentina), constituye una importante fuente de información en el entendimiento de dicho proceso y del papel que cumplen los sedimentos en la eutrofización. Con este propósito se caracterizó la distribución espacial de la granulometría y composición geoquímica de los sedimentos de fondo obtenidos en dos muestreos llevados a cabo en junio y agosto de 2018. Los resultados indican que la distribución granulométrica responde principalmente al aporte fluvial del ESR. Las fracciones gruesas predominan en proximidades a las desembocaduras y las fracciones finas en las zonas profundas del embalse. Adicionalmente los mayores contenidos de fósforo inorgánico, hierro, manganeso y carbono orgánico total se hallaron en la zona de la garganta, probablemente asociados en el sediment...
El analisis de indicadores paleolimnologicos fisicos, quimicos y biologicos del registro sediment... more El analisis de indicadores paleolimnologicos fisicos, quimicos y biologicos del registro sedimentario de Laguna del Plata (LdP), sistema de la Laguna Mar Chiquita (LMC) (Cordoba, Argentina), permitio reconstruir la variabilidad ambiental ocurrida en los ultimos ca. 70 anos y relacionarla con la variabilidad hidroclimatica del sistema y con el impacto de las actividades antropicas en la region. Se identificaron 4 escenarios con caracteristicas ambientales diferentes. El incremento en las concentraciones de nutrientes determinado a partir del ano 1984 en el registro sedimentario es sincronico con el avance de la frontera agricola en la region, la cual se expandio en la decada de 1980. Ademas, los resultados muestran el control que ejerce la variabilidad hidroclimatica sobre el ingreso de nutrientes a LdP permitiendo relacionar forzantes antropicos y naturales. Asimismo, se observo que, durante periodos de alto impacto antropico, la mayor disponibilidad de nutrientes es el factor que p...
RESUMEN: Córdoba posee numerosos embalses en los que se desarrollan actividades recreativas y muc... more RESUMEN: Córdoba posee numerosos embalses en los que se desarrollan actividades recreativas y muchos de ellos presentan tendencia a la eutrofización. En materia de gestión de recursos hídricos, se reconoce la falta de instrumentos locales para valorar las condiciones de uso recreativo en estos cuerpos de agua. Los aspectos de mayor relevancia relacionados con este uso tienen que ver con la estética del recurso y los posibles riesgos a la salud. La presencia de cianobacterias y el grado de toxicidad de sus floraciones, no son contemplados en los estándares locales y tampoco en los índices de calidad de agua (ICA) más comúnmente utilizados en la actualidad. Por esta razón se propone un índice que considere este aspecto, sumando el menor número de variables necesarias. La construcción del ICA se basó en datos de playas de los Embalse San Roque (ESR) y Los Molinos (ELM). El ICA propuesto, de tipo sumatorio, incluyó las variables transparencia, temperatura, bacterias coliformes termotole...
Journal of Photochemistry and Photobiology B Biology
We carried out experiments using long-term (5–7 days) exposure of marine phytoplankton species to... more We carried out experiments using long-term (5–7 days) exposure of marine phytoplankton species to solar radiation, in order to assess the joint effects of ultraviolet radiation (UVR) and temperature on the photochemical responses and photoprotective mechanisms. In the experiments, carried out at Atlantic coast of Patagonia (43°18.7′S; 65°2.5′W) in spring-summer 2011, we used three species as model organisms: the dinoflagellate Prorocentrum micans, the chlorophyte Dunaliella salina and the haptophyte Isochrysis galbana. They were exposed under: (1) two radiation quality treatments (by using different filters): P (PAR, >400 nm) and PAB (PAR + UV-A + UV-B, >280 nm); (2) two radiation intensities (100% and 50%) and (3) two experimental temperatures: 18 °C and 23 °C during summer and 15 °C and 20 °C in spring experiments, simulating a 5 °C increase under a scenario of climate change. In addition, short-term (4 h) artificial radiation exposure experiments were implemented to study v...
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