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Historical records of trace elements in lake sediments provide source-to-sink information about potentially toxic pollutants across space and time. We investigated two lakes located at different elevations in the Ecuadorian Andes to understand how trace element fluxes are related to (i) geology, (ii) erosion in the watersheds, and (iii) local point sources and atmospheric loads. In remote Lake Fondococha (4150 m a.s.l.), total Hg fluxes stay constant between ca. 1760 and 1950 and show an approximately 4.4-fold increase between pre-1950 and post-1950 values. The post-1950 increase in fluxes of other trace elements (V, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb) is lower (2.1–3.0-fold) than for Hg. Mostly lithogenic sources and enhanced soil erosion contribute to their post-1950 increase (lithogenic contribution: > 85%, Hg: ~ 58%). Average post-1950 Hg fluxes are approximately 4.3 times higher in peri-urban Lake Llaviucu (3150 m a.s.l.) than in the remote Lake Fondococha. Post-1950 fluxes of the other trace elements showed larger differences between Lakes Fondococha and Llaviucu (5.2 < 25– 29.5-fold increase; Ni < Pb–Cd). The comparison of the post-1950 average trace element fluxes that are derived from point and airborne sources revealed 5–687 (Hg–Pb) times higher values in Lake Llaviucu than in Lake Fondococha suggesting that Lake Llaviucu’s proximity to the city of Cuenca strongly influences its deposition record (industrial emissions, traffic, caged fishery). Both lakes responded with temporary drops in trace element accumulations to park regulations in the 1970s and 1990s, but show again increasing trends in recent times, most likely caused by increase in vehicular traffic and openings of copper and gold mines around Cajas National Park.

Water chemistry and its ecological implications have been extensively investigated in temperate high-mountain lakes because of their role as sentinels of global change. However, few studies have considered the drivers of water chemistry in tropical mountain lakes underlain by volcanic bedrock. A survey of 165 páramo lakes in the Cajas Massif of the Southern Ecuador Andes identified 4 independent chemical variation gradients, primarily characterized by divalent cations (hardness), organic carbon, silica, and iron levels. Hardness and silica factors showed contrasting relationships with parent rock type and age, vegetation, aquatic ecosystems in the watershed, and lake and watershed size. Geochemical considerations suggest that divalent cations (and related alkalinity, conductivity, and pH) mainly respond to the cumulative partial dissolution of primary aluminosilicates distributed throughout the subsurface of watersheds, and silica and monovalent cations are associated with the congruent dissolution of large amounts of secondary aluminosilicates localized in former hydrothermal or tectonic spots. Dissolved organic carbon was much higher than in temperate high-mountain lakes, causing extra acidity in water. The smaller the lakes and their watersheds, the higher the likelihood of elevated organic carbon and metals and low hardness. The watershed wetland cover favored metal levels in the lakes but not organic carbon. Phosphorus, positively, and nitrate, negatively, weakly correlated with the metal gradient, indicating common influence by in-lake processes. Overall, the study revealed that relatively small tropical lake districts on volcanic basins can show chemical variation equivalent to that in large mountain ranges with a combination of plutonic, metamorphic, and carbonate rock areas

Monitoring water level changes is necessary to manage, conserve and restore natural, and anthropogenic lake systems. However, the in-situ monitoring of lake systems is unfeasible due to limitations of costs and access. Furthermore, current remote sensing methods are restricted to large lakes and low spatial resolutions. We develop a novel approach using subsequential pixel-wise observations of the Sentinel-1B sensor based on interferometric synthetic aperture radar to detect water level changes in small lakes. We used 24 small ungauged lakes of the Cajas Massif lake system in Ecuador for development and validation. We found Differential Interferometric Synthetic Aperture Radar (DInSAR)-derived water level changes across lakes to be consistent with precipitation, capturing the peak of the wet seasons. Furthermore, accumulated water level changes could be explained by differences in lake area among lakes. Although with limitations, this study shows the underutilized potential of DInSAR to understand water level changes in small lakes with current radar data availability.

Argumentative discourse has a complexity that is not entirely captured by purely structural analyses. In arguments about socio-scientific issues (SSI), a range of dimensions, besides scientific knowledge, including values, ethical concerns, cultural habits, or emotions, are mobilized. The relationship between argumentation and emotions is now drawing attention of researchers. Our focus is on the dynamic interactions among emotions and scientific evidence. We draw from Plantin, who proposed that emotions are mobilized as argumentative resources alongside knowledge. The goal of our study is to examine in which ways emotional tension frames the construction of arguments about vegetarian vs. omnivorous diets (ODs) with a group of four preservice teachers. The results suggest that the interactions between the group emotional tension and the evaluation of evidence drive a change toward a decision that would be emotionally acceptable for all participants. Participants attended to the epistemic dimension, weighing evidence, and values about the choices, but the emotional framing took priority. We suggest that the analysis of this emotive framing may be a fruitful approach for sophisticated studies of argumentation beyond structural issues

La alimentación se percibe solo en términos nutricionales o casi, sin prestar atención al impacto ambiental de las distintas dietas. Este estudio aborda cómo se perciben cinco dimensiones de las dietas (nutricional, ambiental, económica, ética y cultural-personal) por parte del profesorado en formación y alumnado de Bachillerato, centrándose en la dimensión ambiental. Las preguntas son: 1) ¿cómo evolucionan sus valoraciones sobre el impacto ambiental de la alimentación al participar en una secuencia didáctica de argumentación?, y 2) ¿qué datos utilizan y cómo para argumentar la adecuación de distintas dietas a criterios ambientales? Las percepciones evolucionan desde la invisibilidad del impacto ambiental hasta considerar su relevancia y una mayor presencia en sus argumentos. Sugerimos la necesidad de problematizar la alimentación y su sustentabilidad, visibilizando su impacto en el ambiente., Human diet is almost solely considered in nutritional terms, without paying attention to its impact on the environment. This study examines how pre-service teachers and high school students perceive five dimensions of diet (nutritional, environmental, economic, ethical and cultural-personal), particularly focusing on environment. The research questions are: 1) how does their assessment of the environmental impact of diet change in the context of an argumentative teaching sequence? 2) Which data do they use and how do they use them in their arguments about the appropriateness of different diets according to environmental criteria? Their perceptions change from an initial invisibility of the environmental impact of diets to a full consideration of its relevance and an increased presence of the environment in their arguments. We suggest a need for problematizing diet and its sustainability, making its environmental impact more visible.

En esta tesis se investiga el desarrollo de criterios en la argumentación sobre alimentación sustentable y saludable a través de dos estudios de caso, con profesorado en formación y alumnado de bachillerato. El objetivo es contribuir al estudio de aspectos no estructurales de la argumentación en el contexto de toma de decisiones sobre cuestiones socio-científicas, al desarrollo de criterios sobre dietas adecuadas y a la promoción de conductas alimentarias más sustentables y saludables. Los resultados indican que la participación en este tipo de actividades favorece tanto el reconocimiento del impacto ambiental de la alimentación como la adopción de objetivos epistémicos, relacionados con la construcción del conocimiento.

Aim: Lakes in the Ecuadorean Andes span different altitudinal and climatic regions, from inter Andean plateau to the high-elevation páramo, which differ in their historical evolution in the several centuries since the pioneering Humboldt expeditions. Here, we evaluate temporal and spatial patterns of change in diatom assemblages between historical (palaeolimnological) and modern times. Location: Ecuadorean Andes Methods: We compared historical (pre-1850) and modern (2017) diatom assemblages from 21 lakes and determined the relative role of environmental (water chemistry and climate) and spatial factors (distance-based Moran's eigenvectors maps) on both assemblages using non-metric multidimensional scaling (NMDS) with environmental fitting. In addition, we used redundancy analysis (RDA) with variance partitioning to estimate the historical (measured using downcore assemblage composition) effects on modern diatom assemblages and identified diatom species that contributed most to dissimilarity between the two times. Results: Diatom changes between the two time points were limited across the group of lakes, as indicated by the NMDS ordination. Variance partitioning indicated that modern diatom assemblages were affected by environmental and spatial effects, but with non-significant effects of past diatom species composition. Ordination results showed that variables related to elevation and water chemistry affected both modern and historical diatom assemblages. Diatom species with the best fit on NMDS axes (i.e. >70%) were influenced by elevation and climatic variables. The most distinctive change between the two time periods was the higher relative abundance of planktic diatom species in top-core assemblages of some lakes, but in a highly variable fashion across gradients of increased elevation and water depth. Main conclusions: Landscape palaeolimnological analyses of varied Ecuadorean Andean lakes demonstrate both environmental and spatial controls on diatom metacommun

The taxonomic composition of the litoral benthic limnetic crustacean communities, (branchiopods, copepods and ostracods) and macrophytes of the lacustrine water bodies of the Cajas National Park located in the Southern Andes of Ecuador have been studied in order to identify the most suitable taxa to be used as indicators of the ecological status of lakes. Among the crustaceans (22 taxa) three groups were differentiated. A first group with taxa of higher indicator value including Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra and Alona sp. gr. manueli. A second group with medium indicator value including Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. and Paracyclops sp. The third group was formed by taxa of the lower indicator value, either because of its eurioic and / or cosmopolitan character or because of its rarity. Macrophytes have been evaluated as good indicators of the ecological and conservation status of the lakes. The taxa which were submerged, floating and rooted in the sediment were identified to be a good indicator for the water body, and helophytes and hygrophytes for the limnetic litoral zone., Se ha estudiado la composición taxonómica de las comunidades de crustáceos litoral-bentónicos (branquiópodos, copépodos y ostrácodos) y macrófitos de las masas de agua lacustre del Parque Nacional Cajas situado en los Andes Australes de Ecuador, con objeto de identificar los taxones más adecuados para ser utilizados como indicadores del estado ecológico de los lagos. De los crustáceos (22 taxones) se diferencian tres grupos. Un primer grupo con taxones de alto valor indicador formado por Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra y Alona sp. gr. manueli. Un segundo grupo con taxones de valor indicador medio formado por Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. y Paracyclops sp. El tercer grupo estaría formado por taxones de escaso valor indicador, bien por su carácter eurioico y/o cosmopolita o por su rareza. De los macrófitos se han valorado como buenos indicadores del estado ecológico y de conservación de los lagos, los taxones enraizados sumergidos y flotantes para la masa de agua, y los helófitos e higrófitos para los litorales.

Extensive sampling of 202 lentic water bodies (lakes, lagoons and ponds) located between 3150 and 4460 m a.s.l. in the Cajas National Park (South Ecuadorian Andes) has revealed the high interest of these mountain enclaves in tropical latitudes for the investigation of faunal and ecological aspects of the branchiopod fauna. The first results allowed to recognize 21 species, 15 of them new to Ecuador, of which 2 are in process of description to be published as new to science. All species are characteristic of little mineralized and oligotrophic waters, 8 of them appear in the plankton and the rest in the limnetic littoral benthos., Un muestreo extensivo de 202 masas de agua leníticas (lagos, lagunas y charcas), ubicadas entre 3,150 y 4,460 m s.n.m. en el Parque Nacional Cajas (Andes Australes de Ecuador), ha puesto de manifiesto el elevado interés que tienen estos enclaves de alta montaña en latitudes tropicales para la investigación de aspectos faunísticos y ecológicos de la fauna de branquiópodos. Los primeros resultados han permitido reconocer 21 especies, 15 de ellas nuevas para Ecuador, de las cuales 2 están en proceso de descripción para ser publicadas como nuevas para la Ciencia. Todas las especies son propias de aguas poco mineralizadas y oligotróficas, 8 de ellas aparecen en el plancton y el resto en el bentos litoral.

The tropical Andes has a high density of glacial lakes that are situated in the high-altitude páramo (3500–4500 m). Ecological information about such lakes is scant despite the fact that these lakes are an important source of water for drinking, irrigation and electricity generation and feed several major tributaries of the Amazon. In this study, we provide data on a survey of 31 lakes in Cajas National Park (Ecuador). Two of the lakes were monitored monthly during one year. In situ nutrient addition experiments were carried out in three of the lakes. Seasonal monitoring in two lakes revealed a thermal stratification of the water column between October and June, with a small temperature difference between epi- and hypolimnion (2–3 °C). Oxygen depletion of the hypolimnion towards the end of the stratification period indicated that no complete mixing of the water column occurred during stratification. There was no evidence of depletion of nutrients in the epilimnion or accumulation in the hypolimnion during stratification. There were also no clear seasonal changes in chlorophyll-a (Chl-a) concentration nor in phytoplankton community composition in the two lakes. Inputs of dissolved organic carbon (DOC) from the vegetated catchment resulted in high DOC concentrations (median 2.9 mg L−1) compared to temperate mountain lakes. Water transparency was relatively low, with a median extinction coefficient for photosynthetic active radiation of 0.50 m−1 and for UV-B radiation of 10.13 m−1. Although the thermocline was deep and water transparency was low, estimates of the critical depth for photosynthesis were deeper than the mean water depth in all lakes, suggesting that phytoplankton was not light limited. The phytoplankton community was dominated by chlorophytes (e.g. Oocystis), diatoms (small Cyclotella spp.) or small colonial cyanobacteria (Aphanocapsa, Merismopedia). The zooplankton community was either dominated by large cladocerans and cyclopoid copepods, or by the cala

Hay consenso en caracterizar la argumentación como la evaluación de conocimientos u opciones en base a pruebas. Sin embargo esta caracterización no incluye un rasgo específico de la argumentación sobre cuestiones sociocientíficas: la articulación de pruebas y de valores. Este estudio examina una secuencia de actividades sobre argumentación y toma de decisiones acerca del dilema en-tre dietas vegetarianas y omnívoras. Se estudia: 1) cómo evalúa el profesorado en formación (N=101) la adecuación de cada dieta a criterios de distinto carácter; y 2) qué peso es asignado explícitamente en la toma de decisiones a cada criterio. Los resultados muestran la influencia de la reflexión explícita sobre el peso de los valores en decisiones sobre cuestiones de incidencia social.

The taxonomic composition of the litoral benthic limnetic crustacean communities, (branchiopods, copepods and ostracods) and macrophytes of the lacustrine water bodies of the Cajas National Park located in the Southern Andes of Ecuador have been studied in order to identify the most suitable taxa to be used as indicators of the ecological status of lakes. Among the crustaceans (22 taxa) three groups were differentiated. A first group with taxa of higher indicator value including Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra and Alona sp. gr. manueli. A second group with medium indicator value including Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. and Paracyclops sp. The third group was formed by taxa of the lower indicator value, either because of its eurioic and / or cosmopolitan character or because of its rarity. Macrophytes have been evaluated as good indicators of the ecological and conservation status of the lakes. The taxa which were submerged, floating and rooted in the sediment were identified to be a good indicator for the water body, and helophytes and hygrophytes for the limnetic litoral zone.

Extensive sampling of 202 lentic water bodies (lakes, lagoons and ponds) located between 3150 and 4460 m a.s.l. in the Cajas National Park (South Ecuadorian Andes) has revealed the high interest of these mountain enclaves in tropical latitudes for the investigation of faunal and ecological aspects of the branchiopod fauna. The first results allowed to recognize 21 species, 15 of them new to Ecuador, of which 2 are in process of description to be published as new to science. All species are characteristic of little mineralized and oligotrophic waters, 8 of them appear in the plankton and the rest in the limnetic littoral benthos.

Extensive sampling of 202 lentic water bodies (lakes, lagoons and ponds) located between 3150 and 4460 m a.s.l. in the Cajas National Park (South Ecuadorian Andes) has revealed the high interest of these mountain enclaves in tropical latitudes for the investigation of faunal and ecological aspects of the branchiopod fauna. The first results allowed to recognize 21 species, 15 of them new to Ecuador, of which 2 are in process of description to be published as new to science. All species are characteristic of little mineralized and oligotrophic waters, 8 of them appear in the plankton and the rest in the limnetic littoral benthos.

The taxonomic composition of the litoral benthic limnetic crustacean communities, (branchiopods, copepods and ostracods) and macrophytes of the lacustrine water bodies of the Cajas National Park located in the Southern Andes of Ecuador have been studied in order to identify the most suitable taxa to be used as indicators of the ecological status of lakes. Among the crustaceans (22 taxa) three groups were differentiated. A first group with taxa of higher indicator value including Branchinecta papillata, Ilyocryptus spinosus, Alonella sp, Pleuroxus sp. Paralona pigra and Alona sp. gr. manueli. A second group with medium indicator value including Alona glabra, Alona guttata, Microcyclops sp. Eucyclops sp. and Paracyclops sp. The third group was formed by taxa of the lower indicator value, either because of its eurioic and / or cosmopolitan character or because of its rarity. Macrophytes have been evaluated as good indicators of the ecological and conservation status of the lakes. The taxa which were submerged, floating and rooted in the sediment were identified to be a good indicator for the water body, and helophytes and hygrophytes for the limnetic litoral zone.