Nutrient fluxes through boundaries in the hypolimnion of Sau reservoir : expected patterns and unanticipated processes

By contrast to many natural lakes, the summer hypolimnion in advection-dominated systems like canyon-shaped reservoirs is not isolated from direct inputs from the river. This has important implications in the evolution of limnological features of the hypolimnion through the stratified period, especially if the river water directly plunges as a density current into the hypolimnion as a consequence of temperature differences. Taking the Sau Reservoir (Spain) as a prototype for this kind of systems, we present data from 11 years of monitoring to show how the river water entering the reservoir during summer is the main factor determining hypolimnetic nutrient concentrations. The empirical regression approach used all through the paper also stressed the effect of the improvement in water quality experienced by the river during the studied period on the improvement of the water quality stored in the summer hypolimnion of the reservoir. Since the change in river water quality was the consequence of the implementation of remediation measures at the basin scale, we advocate these solutions to manage reservoir eutrophication problems in this type of systems, which, in addition, had other unexpected benefits for the hypolimnetic water quality in Sau Reservoir.A diferencia de muchos lagos naturales, el hipolimnion que se forma en verano en sistemas dominados por la advección, como los embalses que inundan valles profundos y estrechos, no está aislado de las entradas directas desde el río. Esto tiene importantes implicaciones en la evolución de las características limnológicas del hipolimnion durante el periodo de estratificación, especialmente si el agua del río entra al embalse como una corriente de densidad directamente en el hipolimnion debido a diferencias de temperatura. Tomando el Embalse de Sau (España) como prototipo de este tipo de sistemas, mostramos 11 años de datos de un programa de monitoreo para ejemplificar cómo el agua del río que entra en verano al embalse es el factor determinante de la concentración de nutrientes en el hipolimnion. La aproximación de regresión empírica utilizada en el artículo también puso de manifiesto el efecto de la mejora en la calidad del agua que sufrió el río durante el periodo de estudio en la mejora del agua del agua embalsada en el hipolimnion. Ya que esta mejora en el río fue consecuencia de la implementación de medidas de restauración a nivel de la cuenca, promovemos estas soluciones para la gestión de problemas de eutrofización en este tipo de sistemas, que por otra parte mostraron ventajas inesperadas en el caso del hipolimnion del Embalse de Sau

Scientific production profile of leading universities leading universities in Latin American countries

Scientific production in Latin America is mainly concentrated in Higher Education Institutions located in Brazil and Mexico, characterized by the high volume of papers published and citations received. However, universities in other countries of the region also stand out for their excellence in research. This paper describes the scientific production profile of leading universities in Latin American countries positioned in the top ten of the SCImago Journal & Country Rank. Using five indicators reported in the SIRiber 2020 Report, the profile of these leading universities is characterized with respect to Normalized Impact, Scientific Leadership, Open Access, International Collaboration and High-Quality Publications. As a result, the scientific production of this group of Latin American universities, leaders in their countries, is characterized by 50% international collaboration, especially of foreign main authors, 38% impact below the world average of citations, 45% of open access publications and 39% of Q1 publications.  &nbsp

Global pressures, specific responses: effects of nutrient enrichment in streams from different biomes

Fil: Artigas, Joan. Clermont Université. Université Blaise Pascal. Laboratoire Microorganismes: Génome et Environnement; FranceFil: García-Berthou, Emili. Institute of Aquatic Ecology. University of Girona. Girona; SpainFil: Bauer, Delia Elena. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Castro, Maria I.. Department of Biology. National University of Colombia. Bogotá DC; ColombiaFil: Cochero, Joaquín. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Colautti, Darío César. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Cortelezzi, Agustina. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La PlataFil: Donato, John C.. Department of Biology. National University of Colombia. Bogotá DC; ColombiaFil: Elosegi, Arturo. Faculty of Science and Technology. The University of the Basque Country. Bilbao; SpainFil: Feijoó, Claudia S.. INEDES. Department of Basic Sciences. National University of Luján. Luján; ArgentinaFil: Giorgi, Adonis. INEDES. Department of Basic Sciences. National University of Luján. Luján; ArgentinaFil: Gómez, Nora. Institute of Aquatic Ecology. University of Girona. Girona; SpainFil: Leggieri, Leonardo. Institute of Aquatic Ecology. University of Girona. Girona; SpainFil: Muñoz, Isabel. Department of Ecology. University of Barcelona. Barcelona; SpainFil: Rodrigues Capítulo, Alberto. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Romaní, Anna M.. Institute of Aquatic Ecology. University of Girona. Girona; SpainFil: Sabater, Sergi. Catalan Institute for Water Research (ICRA). Scientific and Technological Park of the University of Girona. Girona; Spai

Global pressures, specific responses: effects of nutrient enrichment in streams from different biomes

We assessed the effects of nutrient enrichment on three stream ecosystems running through distinct biomes (Mediterranean, Pampean and Andean). We increased the concentrations of N and P in the stream water 1.6–4-fold following a before–after control–impact paired series (BACIPS) design in each stream, and evaluated changes in the biomass of bacteria, primary producers, invertebrates and fish in the enriched (E) versus control (C) reaches after nutrient addition through a predictive-BACIPS approach. The treatment produced variable biomass responses (2–77% of explained variance) among biological communities and streams. The greatest biomass response was observed for algae in the Andean stream (77% of the variance), although fish also showed important biomass responses (about 9–48%). The strongest biomass response to enrichment (77% in all biological compartments) was found in the Andean stream. The magnitude and seasonality of biomass responses to enrichment were highly site specific, often depending on the basal nutrient concentration and on windows of ecological opportunity (periods when environmental constraints other than nutrients do not limit biomass growth). The Pampean stream, with high basal nutrient concentrations, showed a weak response to enrichment (except for invertebrates), whereas the greater responses of Andean stream communities were presumably favored by wider windows of ecological opportunity in comparison to those from the Mediterranean stream. Despite variation among sites, enrichment globally stimulated the algal-based food webs (algae and invertebrate grazers) but not the detritus-based food webs (bacteria and invertebrate shredders). This study shows that nutrient enrichment tends to globally enhance the biomass of stream biological assemblages, but that its magnitude and extent within the food web are complex and are strongly determined by environmental factors and ecosystem structure.Instituto de Limnología "Dr. Raúl A. Ringuelet