Plancton conservation and water basins protection. The case of the Rio Salado Lower Basin, Province of Buenos Aires, Argentina

A diferencia de los principios para la conservación de recursos bióticos terrestres o marinos, en la conservación de recursos hídricos no se asigna importancia a los componentes bióticos y ninguna al plancton. Pocas de las miles de especies identificadas en esta comunidad figuran en una lista de especies en peligro o amenazadas de la Unión Internacional para la Conservación de la Naturaleza (UICN). Por ende, a nivel mundial no se les concede ningún tipo de protección. Desde la década del 1990, en ecología y biogeografía diferentes autores, han enfatizado la necesidad de reconocer la biodiversidad en relación al funcionamiento de los ecosistemas. En este sentido cabe plantearse los siguientes cuestionamientos: ¿Los organismos acuáticos, principalmente del plancton, merecen ser considerados objetos de conservación? ¿Mantener la integridad ecológica de los cuerpos de agua es suficiente para su conservación? La Cuenca del Río Salado, localizada en la provincia de Buenos Aires, transporta excesos de agua y nutrientes durante inundaciones hacia la Bahía Samborombón (un Sitio Ramsar). A pesar de períodos de sequía e inundación, los cambios de la salinidad producto de la influencia marina y el aporte de efluentes agropecuarios, los ambientes acuáticos mantienen un aceptable grado de conservación y biodiversidad. La estructura del plancton se mantiene dominada por clorofitas unicelulares, rotíferos Brachionidae y ciliados tintínidos en la cuenca inferior y crustáceos en sectores vinculados a ambientes lénticos. La comunidad planctónica es compleja, resiliente y está integrada por más de 300 especies. Las especies clave permitirían que el río mantenga su rol como ecosistema de servicio. Proponemos para ríos de llanura la visión territorial, multiescala, dentro del concepto de riverine landscape, que incluye tanto la conservación composicional (Biodiversidad) como funcional (Integridad Ecológica).Fil: Gabellone, Nestor Adrian. 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: Solari, Lía Cristina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Casco, Maria Adela. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Division Ficologia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Claps, Maria Cristina. 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

Fitoplancton, epipelon, materia orgánica y fósforo de una laguna arreica en relación con fases claras y oscuras

The Alternative Stable States Hypothesis has been revised over the last years, owing to the differences found between shallow lakes from temperate zones and those from other latitudes and climates. Studies performed in shallow lakes of the Pam-pean region showed that the temporal and spatial changes and the interactions between algal communities are very complex. In these shallow lakes the epiphyton and epipelon may play significant roles that can be as or ever more important as the roles described for phytoplankton. In Lacombe Lake, three different phases of equilibrium were defined, one of them with intermediate characteristics between clear and turbid phases. The aim of this paper was to analyze the individual fit of some estimators of system dynamics of in-frequently used application in the equilibrium state definition to this conceptual scheme. The differences between phases were mainly identified in water variables, whereas sedi-ment variables did not show great variations although changes in system?s state were be-ing recorded. Chlorophyll a, phytoplankton density and water organic matter were the best indicators of the phases. With respect to sediment variables, the three phases were only differentiated on the basis of variations in the settled planktonic algae.Fil: Mac Donagh, María Elicia. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Division Ficología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casco, Maria Adela. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Division Ficología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cano, Maria Gabriela. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Division Ficología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Solari, Lía Cristina. 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: Claps, Maria Cristina. 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: Gabellone, Nestor Adrian. 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

Feedback from the Therapeutic Alliance in Anxious Patients treated with Cognitive Behavioral Therapy in Argentina: pilot study

La alianza terapéutica (AT) se ha establecido como un predictor robusto de mejoría en psicoterapia. Mantener un monitoreo de la percepción que el paciente tiene de la AT podría ser una herramienta de utilidad en la clínica. En este contexto, el presente trabajo presenta un estudio que tiene como objetivos: (i) analizar la viabilidad de implementar un dispositivo de feedback a terapeutas de orientación cognitivo-conductual respecto de la alianza de sus pacientes y (ii) obtener resultados preliminares sobre la relación entre el feedback de la AT desde el punto de vista del paciente, la evolución de la AT y los resultados del tratamiento. Fueron incluidos 21 pacientes diagnosticados con Trastornos de Ansiedad y atendidos en Buenos Aires (Argentina) con Terapia Cognitiva Conductual por siete terapeutas. Se concluye como viable desarrollar un proyecto de esta naturaleza a mayor escala y se hallaron resultados prometedores respecto a la relación entre las variables estudiadas.The Therapeutic Alliance (TA) has been established as a robust predictor of improvement in psychotherapy. In clinical practice, keeping track of the patient’s perception of TA could be a useful tool. Therefore, the present study aims to: (i) analyze the feasibility of implementing a feedback device for cognitive-behavioural therapists regarding the TA with their patients and (ii) to obtain preliminary results on the relationship between TA feedback from the patient point of view, development of TA across the treatment timeline and, finally, therapeutic outcome. The sample included 21 patients diagnosed with Anxiety Disorders receiving cognitive-behavioural therapy in Buenos Aires (Argentina) by seven therapists. In conclusion, it is considered viable to develop a project of this nature on a larger scale and promising results were found between the variables of interest.Fil: Solari, Adrian Amilcar. Universidad Argentina de la Empresa. Secretaria Academica y de Investigacion. Instituto de Ciencias Sociales y Disciplinas Proyectuales.; ArgentinaFil: Gómez Penedo, Juan Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Psicología. Instituto de Investigaciones; ArgentinaFil: Roussos, Andres Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Psicología. Instituto de Investigaciones; ArgentinaFil: Bogiaizian, Ricardo Daniel. Universidad Argentina de la Empresa. Secretaria Academica y de Investigacion. Instituto de Ciencias Sociales y Disciplinas Proyectuales.; Argentina. Asociación Civil Ayuda; Argentin

Prevalence of human cystic echinococcosis in the towns of Ñorquinco and Ramos Mexia in Rio Negro Province, Argentina, and direct risk factors for infection

Fil: Uchiumi, Leonardo. Ministerio de Salud de Rio Negro, Hospital Zatti,, Rio NegroFil: Mugica, Guillermo. Ministerio de Salud de Rio Negro, Salud Ambiental, Rio NegroFil: Araya, Daniel. Ministerio de Salud de Rio Negro, Ssluf Ambiental, Rio NegroFil: Salvitti, Juan. Ministerio de Salud de Rio Negro, Hospital Bariloche, Rio NegroFil: Sobrino, Mariano. Ministerio de Salud de Rio Negro, Hospital Bariloiche, Rio NegroFil: Moguilansky, Sergio. Universidad Nacional del Comahue, Catedra de Imagenes, Rio NegroFil: Solari, Santiago. Ministerio de Salud de Rio Negro, Hospital Valcheta, Rio NegroFil: Blanco, Patricia. Ministerio de Salud de Rio Negro, Salud Ambiental, Rio NedgroFil: Lamounier, Janette. Ministerio de Salud de Rio Negro, Hospital Ñorquinco, Rio NegroFil: Barrera, Federica. Ministerio de Salud de Rio Negro, Hospital Ramos Mexia, Rio NegroFil: Arezo, Marcos. Ministerio de Salud de Rio Negro, Salud Ambiental, Rio NegroFil: Seleiman, Marcos. Ministerio de Salud de Rio Negro, Salud Ambiental, Rio NegroFil: Yadon, Zaida. Academia Nacional de Medicina, Instituto investigaciones Epidemiologicas. Buenos AiresFil: Tamarozzi, Feamcesca. Universidad de La Sapienzia, Roma, ItaliaFil: Casulli, Adriano. Universidad de Las Sapienza, FRoma, ItaliaFil: Larrieu, Edmundo. Universidad Nacional de Rio Negro, Escuela de Veterinaria. Rio Negro. Argentina.Background: Cystic echinococcosis (CE) is a parasitic zoonosis caused by infection with the larval stage of Echinococcus granulosus (s.l.). This study investigated the prevalence and potential risk factors associated with human CE in the towns and rural areas of Ñorquinco and Ramos Mexia, Rio Negro province, Argentina. Methods: To detect abdominal CE cysts, we screened 892 volunteers by ultrasound and investigated potential risk factors for CE using a standardized questionnaire. Prevalence ratio (PR) with 95% confidence intervals (CI) was used to measure the association between CE and the factors investigated, applying bivariate and multivariate analyses. Results: Abdominal CE was detected in 42/892 screened volunteers (4.7%, 95% CI 3.2–6.1), only two of whom were under 15 years of age. Thirteen (30.9%) CE cases had 25 cysts in active stages (CE1, CE2, CE3a, according to the WHO Informal Working Group on Echinococcosis [WHO-IWGE] classification). The most relevant risk factors identified in the bivariate analysis included: living in rural areas (P = 0.003), age > 40 years (P = 0.000), always drinking water from natural sources (P = 0.007), residing in rural areas during the first 5 years of life (P = 0.000) and having lived more than 20 years at the current address (P = 0.013). In the multivariate final model, the statistically significant risk factors were: frequently touching dogs (P = 0.012), residing in rural areas during the first 5 years of life (P = 0.004), smoking (P = 0.000), age > 60 years (P = 0.002) and living in rural areas (P = 0.017). Conclusions: Our results point toward infection with CE being acquired since childhood and with constant exposure throughout life, especially in rural areas with a general environmental contamination. Keywords: Cystic echinococcosis, Echinococcus granulosus (s.l.), Ultrasound screening, Epidemiology, Risk factors

Applying an extended theoretical framework for data collection mode to health services research

<p>Abstract</p> <p>Background</p> <p>Over the last 30 years options for collecting self-reported data in health surveys and questionnaires have increased with technological advances. However, mode of data collection such as face-to-face interview or telephone interview can affect how individuals respond to questionnaires. This paper adapts a framework for understanding mode effects on response quality and applies it to a health research context.</p> <p>Discussion</p> <p>Data collection modes are distinguished by key features (whether the survey is self- or interviewer-administered, whether or not it is conducted by telephone, whether or not it is computerised, whether it is presented visually or aurally). Psychological appraisal of the survey request will initially entail factors such as the cognitive burden upon the respondent as well as more general considerations about participation. Subsequent psychological response processes will further determine how features of the data collection mode impact upon the quality of response provided. Additional antecedent factors which may further interact with the response generation process are also discussed. These include features of the construct being measured such as sensitivity, and of the respondent themselves (e.g. their socio-demographic characteristics). How features of this framework relate to health research is illustrated by example.</p> <p>Summary</p> <p>Mode features can affect response quality. Much existing evidence has a broad social sciences research base but is of importance to health research. Approaches to managing mode feature effects are discussed. Greater consideration must be given to how features of different data collection approaches affect response from participants in studies. Study reports should better clarify such features rather than rely upon global descriptions of data collection mode.</p

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

The effects of hydraulic works and wetlands function in the Salado-River basin (Buenos Aires, Argentina)

Man-made activities exert great influences on fluvial ecosystems, with lowland rivers being substantially modified through agricultural land use and populations. The recent construction of drainage canals in the upper stretch of the Salado-River basin caused the mobilization of huge amounts of salts formerly stored in the groundwater. The main aim of this work was to analyze the effect of the discharges of those canals into the Salado-River water, under different hydrologic conditions, and the role of the wetlands and shallow lakes placed along the canals’ system. Physicochemical variables were measured and water samples were taken during times of high water, mean flows, drought, and extreme drought. The environmental variables and the plankton development were related to the hydrologic regime and reached minimum values during floods because of low temperatures and dilution. Local effects on the water’s ionic composition became pronounced during droughts because of groundwater input. Nutrient concentrations were mainly associated with point wastewater discharges. Conductivity, ion concentrations, total plankton biomass, and species richness increased in the Salado-River downstream site, after the canals’ discharges. The artificial-drainage system definitely promotes the incorporation of salts into the Salado-River basin. In this scenario, a careful hydraulic management is needed to take into account this issue of secondary salinization that threatens the economic exploitation of the region. The wetlands present in this study acted as service environments not only helping to reduce salt, nutrient, and suspended-solid concentrations downstream but also contributing a plethora of species and plankton biomass into the Salado-River main course.Fil: Bazzuri, Maria Elisa. 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: Gabellone, Nestor Adrian. 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: Solari, Lía Cristina. 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

Succession of microconsumers in waterlogged pampean soils (Buenos aires, Argentina) and its significance for nearby wetlands

In floodplains, the passive dispersal by drift occurs when water bodies become connected, and is a key feature offering pathways for the recolonization of periodically flooded habitats. Mesocosms with experimental flooding were used to document the succession of small invertebrates under differing hydrologic regimes with the intent of identifying which animals were capable of moving among habitats. The mesocosm experiments were performed in soils in sandy areas of the Salado-River basin including a mixed-use plot, a plot for breeding livestock, and a plot currently without any use located in different topographic positions (upper, middle, lower). Forty-seven taxa were found including ciliates, amoebae, rotifers, and microcrustaceans. The maximum total specific richness was recorded in middle soil and the minimum in upper soil because of a shorter colonization time. Higher mean densities occurred in middle and lower topographies, while the upper exhibited lower values. The ciliates and rotifers were the dominant. During the intermediate stage of flooding, the high density and biomass of the primary producers resulted in high concentration of dissolved oxygen (photosynthesis exceeded respiration). In contrast, in the final stage, low densities of microalgae led to low concentrations of dissolved oxygen and a high density of consumers (preponderance of respiration over photosynthesis). These flooded areas are significant as sources of microorganism inocula into the river. An abundance of microbiota arising from temporary wetlands and floodplains is fundamental for a successful recruitment of native-fish species.Fil: Solari, Lía Cristina. 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: Quaini, Karina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Ambiente y Desarrollo Sustentable; ArgentinaFil: Gabellone, Nestor Adrian. 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

Zooplankton‑population dynamics in the Salado‑River basin (Buenos Aires, Argentina) in relation to hydraulic works and resulting wetland function

The construction of drainage canals in the upper stretch of the Salado River has caused the input of salty waters into the basin, with unexplored consequences on zooplankton dynamics and reproduction. To determine the consequences of thoseanthropic interventions, zooplankton samples were taken under four hydrologic conditions (high water, mean flows, low flows, very low flows) in the canals and the river watercourse. Environmental variables were measured in situ (pH, temperature,conductivity, turbidity, flow velocity, water level, dissolved-oxygen concentration) and in the laboratory (chlorophylla, nutrients). A total of 166 zooplankton taxa was identified, among which rotifers and ciliates were the most diverse and abundant. A redundancy analysis indicated temperature, conductivity, and water discharge to be the main constraints to zooplankton development. Accordingly, abundance peaks were recorded during mean and low flows in the spring and summer,and minimum values during high water (autumn?winter floodings). The dominant species, Brachionus plicatilis s.l.,recorded outstanding densities at ca. 34,800 ind L?1?that figure representing a worldwide novelty?during low flows in the canals and at the river downstream site. The wetlands and shallow lakes in the study area acted as sources of inocula for theriver, increasing the total abundance of zooplankton, gravid females, nauplii, copepodites, juveniles, and total number of eggs being carried at the second river site downstream from the canals? discharges. The presence of diverse habitats coupled with the alternation of hydrologic conditions have resulted in the development of a very rich, complex zooplankton community.Fil: Bazzuri, Maria Elisa. 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: Gabellone, Nestor Adrian. 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: Solari, Lía Cristina. 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