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Environmental impacts related to arsenic (As) contamination are a persistent issue of particular interest in Latin American countries with increasing mining activities. In Ecuador, the redefinition of public policies to promote the increase in mining since 2008 has led to a significant rise in the presence of this heavy metal in rivers and effluents, sometimes exceeding the 0.1 mg L-1, limit recommended by Ecuadorian Environmental Regulations. This study aimed to evaluate the sublethal effects through the detection of biochemical biomarker changes (Catalase, Antioxidant capacity by FRAP, and Glutathione S-transferase) generated in larvae of Nectopsyche sp following prolonged exposure to different concentrations of As (C1 = 0.05 mg L-1, C2 = 0.1 mg L-1, C3 = 0.8 mg L-1) in a controlled environment, emulating the maximum limits allowed by current Ecuadorian legislation. While As concentration levels in water increased, so did levels in the tissue of Nectopsyche sp specimens. On the other hand, behavioral parameters (mortality and mobility) did not show differences in either time or As concentrations. However, both Catalase and Antioxidant capacity by FRAP levels tended to decrease with increasing As concentration, and in both cases, the differences were significant. Additionally, Glutathione S-transferase activity did not increase significantly. These results preliminarily demonstrate that biochemical responses change with varying As concentrations in Nectopsyche sp and are affected at behavioral and biochemical levels produced by the As at chronic levels.

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ABSTRACT Understanding the trophic ecology of fish and how they use resources in space and time is important to support conservation and management actions. The trophic ecology of Brycon henni in the Nare and Guatapé rivers, Magdalena river basin, Colombia was determined. Five field samplings were carried out between October 2007 and January 2010, in rainy, dry, and dry-to-rainy transition periods. Stomachs of 262 specimens were collected. A Kruskall-Wallis analysis and a Mann-Whitney pairwise comparison test was performed to detect differences in the alimentary importance index of each food category between sex, size class, hydrological period and basins (Nare vs Guatapé). The Levin's Measure of Niche Breadth and the Morisita's Diet Overlapping Index were calculated to establish differences between size class in the different hydrological periods. Vegetable material was the most important food item, followed by Insecta, and fish. Individuals from Guatapé basin consumed more plant material and fish and fewer insects. We observed increased consumption of plant material and fish in ontogeny. Levin's niche breadth was lower and diet overlapping between individuals of length classes was higher during rainy period because the diet was mainly based on plant material. The diet of B. henni was composed mainly of plant material and Insects, and to a lesser extent from other groups such as fish, crustaceans and arachnids.

RESUMEN La comprensión de la ecología trófica de los peces y la forma en que utilizan los recursos en el espacio y en el tiempo es importante para la toma de acciones para su conservación y manejo. Se determinó la ecología trófica de Brycon henni en los ríos Nare y Guatapé, cuenca del río Magdalena, Colombia. Se realizaron cinco muestreos entre octubre de 2007 y enero de 2010, en periodos de lluvia, seca y transición de seca a lluvia. Se recolectaron estómagos de 262 ejemplares. Para detectar diferencias en el índice de importancia alimentaria de cada categoría de alimentos entre sexo, clase de talla, período hidrológico y cuencas se realizó un análisis de Kruskall-Wallis y una prueba de Mann-Whitney. Se calculó la amplitud del nicho de Levin y el Índice de superposición de dieta de Morisita para establecer diferencias entre clases de talla en diferentes períodos hidrológicos. El material vegetal fue el alimento más importante, seguido de Insecta y peces. Los individuos de la cuenca del Guatapé consumieron más material vegetal y peces, y menos insectos. Se detectó mayor consumo de material vegetal y de peces en individuos de mayor tamaño. La amplitud de nicho fue menor y la superposición entre clases de talla fue mayor en temporada de lluvias porque la dieta se basó principalmente en material vegetal. La dieta de B. henni estuvo compuesta principalmente por material vegetal e insectos y en menor proporción de otros grupos como peces, crustáceos y arácnidos.

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Water is a resource that influences sustainable development in different ways in social, economic, and environmental aspects, being the Andes the major provider of this resource. However, they have been affected mainly by anthropogenic activities due to the proximity of settlements in the watersheds, so they tend to have more significant contamination, and their evaluation is essential to mitigate problems for those who consume them. However, despite being a fundamental resource and one of the main contributors of water, it is not so studied, so the present study aims to determine the studies based on the water quality of the high mountain rivers of the Andes by using a PRISMA methodology with the scoping review extension, based on search techniques, inclusion and exclusion criteria, and monitoring tables, in order to maintain a line of research attached to the objective of the study. After using the methodology, ten articles were obtained, which were analyzed after a bibliometric analysis to determine features of interest, such as countries in which the studies were carried out, years of publication, methodologies used, and authors' consensus. High Andean rivers' importance, the need for more studies within these areas, and the lack of suitable indexes for these unique ecosystems are highlighted.

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RESUMEN El estado o calidad ecológica es un concepto integral que refleja el grado de deterioro de los ambientes acuáticos. Para medirlo se han diseñado protocolos que evidencian los cambios en la estructura y funcionamiento de las comunidades bióticas en respuesta a las presiones antropogénicas. Se evaluó el estado ecológico del río Ánimas a lo largo de su eje longitudinal, mediante los índices IMEERA, IMARBO y BMWP-Col. Se realizaron muestreos en épocas seca y lluviosa en cuatro tramos del eje longitudinal. Se tomaron datos fisicoquímicos del agua y datos hidromorfológicos. Se colectaron macroinvertebrados mediante una red Surber. Los iones disueltos en el agua fueron los factores más relevantes del conjunto de variables fisicoquímicas. El índice hidromorfológico indicó que los puntos a menor elevación en la cuenca presentaron una puntuación deficiente. En cuanto a la abundancia y composición de macroinvertebrados, se reflejó una mayor abundancia en época seca y una mayor riqueza en época de lluvias. Los índices IMEERA y BMWP-Col tuvieron un comportamiento similar con valores menores en la época seca, mientras que en la fase lluviosa alcanzaron los registros más altos, revelando diferencias claras en el estado ecológico de los puntos de muestreo. El índice IMARBO presentó un comportamiento distinto, según el cual los puntos de menor elevación (uno y dos) reflejaron una condición de mayor deterioro en comparación con los puntos más altos (tres y cuatro). Para los tres índices, este último punto presentó la mejor condición de calidad. Este estudio contribuye al conocimiento del comportamiento de ríos andinos frente a índices de calidad ecológica.

ABSTRACT Ecological or quality status is an integral concept that reflects the degree of deterioration of aquatic environments. To measure it, protocols have been designed that demonstrate changes in the structure and functioning of biotic communities in response to anthropogenic pressures. The ecological status of the Ánimas River was evaluated along its longitudinal axis, using the IMEERA, IMARBO, and BMWP-Col indices. The samplings were carried out in dry and rainy seasons, in four sections of the longitudinal axis. Physicochemical data of the water and hydromorphological data were taken. Macroinvertebrates were collected using a Surber net. The ions dissolved in the water were the most relevant factors of the set of physicochemical variables. The hydromorphological index indicated that the points at lower elevations in the basin presented a deficient score. Regarding the abundance and composition of macroinvertebrates, a greater abundance was reflected in the dry season and a greater richness in the rainy season. The IMEERA and BMWP-Col indices had a similar behavior with lower values in the dry season, while in the rainy phase they reached the highest records, revealing clear differences in the ecological status of the studied points. The IMARBO index presented a different behavior according to which the lowest elevation points (one and two) reflected a condition of greater deterioration compared to the highest points (three and four). In this last point, the three indices showed the best quality condition. This study contributes to the knowledge of the behavior of Andean rivers in relation to ecological quality indices.

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Andean streams are becoming increasingly impacted by agricultural activities. However, the potential effects of pesticides on their aquatic biodiversity remain unassessed. In order to address this knowledge gap, we conducted an experiment over 37 days in microcosms to assess the effect of two pesticides commonly used in Ecuador (Engeo and Chlorpyrifos) on the aquatic insect Nectopsyche sp. (Trichoptera: Leptoceridae) at 0, 0.10, 5 and 10 µg L-1 concentrations. The highest concentration corresponds to the maximum concentration allowed by the Equatorian legislation. We assessed insect mortality every 24 h, with leaf litter decomposition rates of organic matter determined by deploying Andean alder (Alnus acuminata) dry leaf packs in the microcosms. We found significant mortality of Nectopsyche sp. at high concentrations of Chlorpyrifos, whereas leaf litter was not significantly affected by any of the treatments. We conclude that the environmental legislation of Ecuador might not be fully protecting aquatic biodiversity from pesticide pollution. Further studies are needed, especially when considering that the maximum permitted concentration is very likely exceeded in many areas of the country. We also suggest that the maximum permissible values should be reviewed, considering each pesticide individually.

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In June 2011 the Puyehue-Cordón Caulle volcanic complex (PCCVC) erupted, ejecting around 950 million metric tons of volcanic ash and pyroclastic rock, generating habitat destruction, environmental deterioration and devastation of ecological communities in rivers near the volcanic fissure. We evaluate the long-term effect of this eruptive event on the recovery of the diversity of aquatic macroinvertebrates, collecting biological and environmental information from 2011 to 2018 in visibly impacted Chilean rivers (Gol-Gol and Nilahue) and not visibly impacted rivers (Calcurrupe and Chanleufu). With the macroinvertebrate records we developed a recovery coefficient based on their diversity before and after the eruption. The results show that before the eruption (2009-2010), the accumulated family richness and mean diversity in the Gol-Gol River were higher than that observed post-eruption in rivers visibly impacted and not visibly impacted. Between 2013 and 2018, 17 families recolonized the Gol-Gol River, as well as 10 new families that were not recorded before the eruption. The richness of families post-eruption was negatively related to the increase in the concentration of total suspended solids, affecting the successional changes and recovery in the medium term. The recovery coefficient indicates that seven years after the eruption the diversity of macroinvertebrates still shows lower levels than those recorded before the eruptive event, with predominance of a slow recovery phase. Families of orders Ephemeroptera, Plecoptera and Trichoptera that were dominant before the eruption of the PCCVC began to recover the richness of taxa two years later, Plecoptera reaching 50% recolonization in 2018, Ephemeroptera 33.3% and Trichoptera 30%. In contrast, Diptera reached 100% recovery by 2018 and chironomids increased since 2015, becoming the dominant taxon during intermediate recovery in the Gol-Gol River. The recovery of macroinvertebrates in the Gol-Gol River is related to their modes of dispersal, feeding and the decrease in ash concentration.

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RESUMEN Los macroinvertebrados acuáticos son bien conocidos como bioindicadores de la calidad del agua. En Colombia, los estudios sobre este tema se han hecho principalmente a nivel taxonómico de familia. En este trabajo se analizan las respuestas en abundancia, riqueza y diversidad de los dípteros identificados a nivel de género en ríos altoandinos (río Bogotá y río Fucha), en épocas de aguas bajas y aguas altas. Los especímenes se recolectaron con tres métodos: red Surber, red de mano y lavado de rocas. La temperatura promedio fue de 12,9 °C y la saturación de oxígeno estuvo cerca del 100 % o más, con excepción del tramo bajo del río Bogotá antes de Villapinzón. Se colectaron 13 690 dípteros pertenecientes a diez familias y 40 géneros. La riqueza taxonómica fue alta, con una mayor variación en los tramos bajos de las dos corrientes. Las subfamilias de Chironomidae fueron las más abundantes. El análisis de correspondencia canónica (ACC) mostró que los Orthocladiinae se asociaron con la conductividad; el género Gigantodax (Simuliidae) no mostró una relación clara con ninguna variable; por el contrario, el género Simulium se vinculó con el caudal. En términos generales, la asociación entre taxones y variables ambientales fue más clara para los géneros que para las familias, pero no fue suficientemente robusta. Se sugiere que para encontrar un mayor grado de asociación biota-ambiente, es necesario realizar los análisis a nivel de especie, considerando las variaciones locales y temporales.

ABSTRACT Aquatic macroinvertebrates are recognized as bioindicators of water quality. In Colombia, the studies have mainly been addressed by the family taxonomic level. This work analyzes the responses in abundance, richness, and diversity of the Diptera at the genus level in high Andean rivers (Bogotá River and Fucha River), in periods of low and high waters. The specimens were collected with three methods: Surber net, hand net, and rock washing. The average temperature was 12.9 °C and oxygen saturation was close to 100 % or more, except for the lower section of the Bogotá River, before the Villapinzón town. 13 690 Diptera were collected from ten families and 40 genera. Taxonomic richness was high with the greatest variation in the lower sections of the two streams. The Chironomidae subfamilies were the most abundant. Canonical correspondence analysis (CCA) showed that Orthocladiinae were associated with water conductivity; the Gigantodax genus (Simuliidae) did not show a clear relationship with any variable; conversely, the genus Simulium was linked to the caudal. In general terms, the association between taxa and environmental variables was clearer for genera than for families, but it was not robust enough. It is suggested that to find a higher degree of biota-environment association, it is necessary to carry out analyzes at the species level, considering local and temporal variations.

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Since the beginning of COVID-19 pandemic studies on viral shedding have reported that this virus is excreted in feces in most patients. High viral loads are found at the sewage pipeline or at the entrance of wastewater treatment plants from cities where the number of COVID-19 cases are significant. In Quito (Ecuador) as in many other cities worldwide, wastewater is directly discharged into natural waters. The aim of this study was to evaluate SARS-CoV-2 presence in urban streams from a low sanitation context. Three river locations along the urban rivers of Quito were sampled on the 5th of June during a peak of COVID-19 cases. River samples were evaluated for water quality parameters and afterwards, concentrated for viral analysis using skimmed milk flocculation method. The viral concentrates were quantified for SARS-CoV-2 (N1 and N2 target regions) and Human Adenovirus as a human viral indicator. The results showed that SARS-CoV-2 was detected for both target regions in all samples analyzed in a range of 2,91E+05 to 3,19E+06 GC/L for N1 and from 2,07E+05 to 2,22E+06 GC/L for N2. The high values detected in natural waters from a low sanitation region have several implications in health and ecology that should be further assessed.

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The large spiny mouse Neacomys spinosus (Thomas, 1882) has been considered the widest ranging species of the genus, occurring in southern Colombia, eastern Peru, western Brazil and northern Bolivia. The morphological variation between subspecies and populations of N. spinosus has been noted; nonetheless, this variation has not been assessed in a morphological or molecular context. Here, we present a taxonomic revision of Neacomys spinosus s.l. using qualitative and quantitative morphological analyses. These analyses were complemented with molecular analysis to reconstruct the phylogenetic relationships among species of Neacomys, based on sequences of the cytochrome b gene. Our results reveal that N. spinosus s.l. is a monophyletic group, and morphological and molecular evidence to differentiate three taxa: N. spinosus s.s., an endemic species from mountain cloud forests in Peru; N. amoenus s.l. from the Cerrado between Bolivia and Brazil to the Amazonia between Ecuador and northern Peru, and Neacomys sp. nov. from mountain cloud forests from southern Peru to Bolivia. Also, our molecular results indicate that Neacomys is still far from being completely known. For instance, there are three candidate species pending of taxonomic revision. Finally, we propose three species groups within Neacomys: "paracou", "tenuipes" and "spinosus", and discuss biogeographical scenarios of the genus within South America.

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The remarkable fish diversity in the Caribbean rivers of north-western South America evolved under the influences of the dramatic environmental changes of neogene northern South America, including the Quechua Orogeny and Pleistocene climate oscillations. Although this region is not the richest in South America, endemism is very high. Fish assemblage structure is unique to each of the four aquatic systems identified (rivers, streams, floodplain lakes and reservoirs) and community dynamics are highly synchronized with the mono-modal or bi-modal flooding pulse of the rainy seasons. The highly seasonal multispecies fishery is based on migratory species. Freshwater fish conservation is a challenge for Colombian environmental institutions because the Caribbean trans-Andean basins are the focus of the economic development of Colombian society, so management measures must be directed to protect aquatic habitat and their connectivity. These two management strategies are the only way for helping fish species conservation and sustainable fisheries.

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Population status of insects of Plecoptera order in Sierra Nevada National Park in Venezuela and its implications for conservation planning. Longitudinal distribution of Plecoptera species were examined along the Sierra Nevada National Park in the Andean region of Merida State, Venezuela. PNSN is one of the largest protected areas and consists of two major sub-basins. Quantitative samples were collected in 7 river tributaries along the PNSN from February to May of 2009, and a total of 135 individuals and 4 species of the genus Anacroneuria were collected. Only three rivers (Nuestra Señora, La Picón y Corcovada) found the presence of stoneflies, the principal component analysis show that the characterization of habitat, current velocity, dissolved oxygen and the absence of human disturbance sources of influence in a suitable habitat for populations. Stoneflies are endangered or have become extinct throughout much of its range due to human activities. Conservation plans must be implemented urgently, in order to avoid recreational areas and/or economic in vicinity thereof. Rev. Biol. Trop. 58 (4): 1299-1310. Epub 2010 December 01.

La distribución longitudinal de las especies de plecópteros fue examinada a lo largo del Parque Nacional Sierra Nevada en la región Andina del estado Mérida, Venezuela. El PNSN es uno de las más grandes regiones protegidas y abarca dos subcuencas hidrográficas importantes. Muestras cuantitativas fueron recolectadas en 7 ríos tributarios de estas cuencas a lo largo del PNSN desde febrero a mayo del 2009, con un total de 135 individuos de 4 especies del género Anacroneuria. Sólo en tres ríos (Nuestra Señora, La Picón y Corcovada) se encontró la presencia de plecópteros, los análisis de componentes principales muestran que la caracterización del hábitat, la velocidad de la corriente, el oxígeno disuelto y la ausencia de fuentes de perturbación antrópica influyen en un hábitat idóneo para las poblaciones. Los plecópteros se hallan en peligro de desaparición o incluso se han llegado a extinguir en gran parte de su área de distribución como consecuencia de actividades humanas. Planes de conservación deben ser implementados con urgencia, como evitar zonas recreacionales y/o económicas en las cercanías de los mismos.

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