Trophic ecology of Brycon henni (Pisces: Bryconidae) in Nare and Guatapé Rivers, Magdalena River basin, Colombia / Ecología trófica de Brycon henni (Pisces: Bryconidae) en afluentes de los Ríos Nare y Guatapé, cuenca del río Magdalena, Colombia

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.

Influence of ecoregion and river type on neotropical Chironomidae (Diptera) from humid mountain to semiarid lowland

Introduction: Chironomidae (Diptera) is the most widespread and abundant aquatic insect family in freshwater ecosystems. Chironomids are considered good indicators of water quality but are seldom identified at the genus level in broad spatial scale studies. Objective: To identify environmental conditions associated with chironomids in an altitudinal gradient. Methods: We compared ecoregions, river types, and seasons, for chironomids in neotropical streams and rivers (18 river sites; 2014-2018; Yungas rainforest and Western Chaco dry forest, Argentina). We used non-metric multidimensional scaling, dissimilarity, envfit analysis and rank-abundance curves. Results: Chironomid "assemblages''matched both ecoregions and river types. However, ecoregions presented a better fit with species composition. The stenothermal taxa of Orthocladiinae were dominant at high elevations and the eurythermal Chironominae in lowland rivers. Altitude, water temperature and conductivity were important. Seasonal differences were smaller than ecoregional differences. Conclusions: Ecoregions, altitude, water temperature and conductivity correlated with chironomid communities. Orthocladiinae were dominant at high elevations and Chironominae in lowland rivers.

Introducción: Chironomidae (Diptera) es la familia de insectos acuáticos más extendida y abundante en los ecosistemas dulceacuícolas. Los quironómidos se consideran buenos indicadores de la calidad del agua, pero rara vez se identifican a nivel de género en estudios de amplia escala espacial. Objetivo: Identificar las condiciones ambientales asociadas a los quironómidos en un gradiente altitudinal. Métodos: Comparamos ecorregiones, tipos de ríos y estaciones para quironómidos en arroyos y ríos neotropicales (18 sitios en ríos; 2014-2018; en un bosque tropical de Yungas y un bosque seco del Chaco Occidental, Argentina). Utilizamos escalamiento no métrico multidimensional, disimilitud, análisis de envfit y curvas de rango-abundancia. Resultados: Los "ensamblajes''de quironómidos coincidieron tanto con las ecorregiones como con los tipos de ríos. Sin embargo, las ecorregiones presentaron un mejor ajuste con la composición de especies. Los taxones estenotérmicos de Orthocladiinae fueron dominantes en las elevaciones altas y los euritermales de Chironominae en los ríos de las tierras bajas. La altitud, la temperatura del agua y la conductividad fueron importantes. Las diferencias estacionales fueron menores que las diferencias ecorregionales. Conclusiones: las ecorregiones, la altitud, la temperatura del agua y la conductividad se correlacionaron con las comunidades de quironómidos. Orthocladiinae fue dominante en los sitios altos y Chironominae en los ríos de tierras bajas.

Impacto de la movilidad poblacional en el comportamiento de virus respiratorios durante la pandemia COVID-19 / Impact of population mobility on the behavior of respira tory viruses during the COVID-19 pandemic

Resumen Introducción : Durante la pandemia de SARS-CoV-2 en Argentina se implementaron intervenciones no farma cológicas que produjeron cambios en la movilidad de la población. El objetivo de este estudio fue relacionar los porcentajes de positividad y la diversidad viral con la movi lidad poblacional durante parte del período de restricciones. Métodos : Estudio retrospectivo analítico realizado en el Instituto Médico Platense durante los años 2020 a 2022 que incluyó 458 pacientes a los que se les tomó un hisopado nasofaríngeo para la búsqueda de patóge nos respiratorios por PCR multiplex. Se analizaron los cambios en la movilidad de la población utilizando los "Informes de Movilidad Local", herramienta desarrollada por Google, cuyos datos son de público acceso. Resultados : La movilidad poblacional se correlacionó significativamente con el porcentaje de positividad de las muestras (p = <0.01; R2 = 0.89) y la diversidad viral (p = 0.04; R2 = 0.78). Discusión : Las intervenciones no farmacológicas destinadas a limitar la propagación del SARS-CoV-2 tuvieron efecto en la circulación de otros virus respi ratorios, hallándose mayor porcentaje de positividad y diversidad a medida que las mismas disminuyeron su grado de restricción.

Abstract Introduction : During the SARS-CoV-2 pandemic, Ar gentina population suffered from significant changes in population mobility due to non-pharmaceutical interventions. The aim of this study was to describe the impact of the mobility restrictions to the rates of positivity and diversity among different respiratory viruses. Methods : Retrospective analytical study per formed at Instituto Médico Platense in La Plata that included 458 patients with nasopharyngeal swab to search for respiratory pathogens by multiplex PCR. Changes in mobility were studied using "Community Mobility Reports", data set developed by Google and publicly available. Results : Community mobility had significant cor relation with the percentages of viral test positiv ity (p = < 0.01; R2=0.89) and viral diversity (p = 0.04; R2 = 0.78). Discussion : Non-pharmaceutical interventions estab lished to contain SARS-CoV-2 spread had a significant impact in the circulation patterns of other respiratory viruses.

Evaluation of the ecological status of the Ánimas River through multimetric indexes in Cerinza, Boyacá / Evaluación del estado ecológico del río ánimas mediante índices multimétricos en cerinza, boyacá

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.

Effect of Seasonality on the Assembly of Macrobenthos in a High Andean River / Efecto de la estacionalidad sobre el ensamble del macrobentos en un río altoandino

RESUMEN El estudio del funcionamiento de los ecosistemas altoandinos es de gran importancia pues cualquier modificación influirá en toda la cuenca; sin embargo, el conocimiento de estos ambientes aún es limitado. Por ello, se buscó determinar el efecto de la estacionalidad sobre el ensamble del macrobentos de un río altoandino y determinar las variables limnológicas, geomorfológicas e hidrológico-hidráulicas que más lo influencian. En el río El Salto, ubicado por encima de los 4500 msnm, en ambientes altoandinos al sur del Perú, se colectó macrobentos en el año 2020 en 11 unidades hidromorfológicas, registrándose variables limnológicas (oxígeno disuelto, porcentaje de saturación, conductividad, TSD, temperatura, pH, turbidez y SS), geomorfológicas (granulometría) e hidrológico-hidráulicas (caudal, velocidad, profundidad, ancho de cauce) en temporadas seca y húmeda. El análisis de componentes principales (ACP) de las variables fisicoquímicas evidenció que el caudal, la conductividad, el pH y los sólidos totales disueltos explicaron la mayor variabilidad de los datos (70 %). En cuanto a la granulometría, se encontró la predominancia de canto rodado y limo. El número de especies y la densidad fueron mayores en temporada seca que en la húmeda. Sin embargo, la diversidad, riqueza y equidad fueron mayores en temporada húmeda. El análisis de ordenación (nMDS, stress=0,09) mostró estructura diferente del ensamble macrobentónico entre ambas temporadas. Se concluye que la estacionalidad, dada por diversos factores, principalmente el caudal y la velocidad de flujo determinan variaciones en el ensamble del macrobentos, confirmando los cambios drásticos a los que están sometidos estos ecosistemas altoandinos con climas extremos.

ABSTRACT The study of the functioning of the high Andean ecosystems is of great importance since any change will influence the entire basin. However, knowledge of these environments is still limited. Therefore, we sought to determine the effect of seasonality on the macrobenthos assemblage of a high Andean River and to determine the limnological, geomorphological, and hydrological-hydraulic variables that most influence it. In the El Salto River, located 4,500 meters above sea level, in high Andean environments in southern Peru, macrobenthos was collected in 2020 in 11 hydro morphological units, recording limnological variables (dissolved oxygen, saturation percentage, conductivity, TSD, temperature, pH, turbidity and SS), geomorphological (granulometry) and hydrological-hydraulic (flow, velocity, depth, channel width) in dry and wet seasons. The principal component analysis (PCA) of the physicochemical variables showed that the flow rate, conductivity, pH, and total dissolved solids explained the greatest variability of the data (70 %). The predominance of boulders and silt was found. The number of species and density were higher in the dry season than in the wet season. However, the diversity, richness, and equity were higher in the wet season. The ordination analysis (nMDS, stress=0.09) showed a different structure of the macrobenthic assemblage between both seasons. It is concluded that seasonality, given by various factors, mainly flow rate and flow velocity, determine variations in the macrobenthos assemblage, confirming the drastic changes to which these high Andean ecosystems with extreme climates are subjected.

Taxonomic study and local environmental conditions of occurrence of Chlorophyceae (Chlorophyta) from subtropical lotic environments, Paraná, Brazil / Estudo taxonômico e condições ambientais locais da ocorrência de Chlorophyceae (Chlorophyta) de ambientes lóticos subtropicais, Paraná, Brasil

Abstract Lotic environments are subjected to the impacts of human activities in an intense way in urban regions and one of the ways to assist in the environmental diagnosis is through the knowledge of the composition of bioindicator organisms, including microalgae. The objective of this work was to qualitatively characterize the Chlorophyceae Class Wille, providing descriptions and meristic data of the specimens as well as the environmental conditions in which the taxa were recorded. Water and phytoplankton samplings were carried out quarterly in 2020, in nine supply rivers, distributed in three river basins in the western region of Paraná (Paraná III basin, Piquiri basin and Baixo Iguaçu basin). The studied rivers were classified as oligotrophic or mesotrophic and the taxa were mostly rare. Thirty-six taxa belonging to the Chlorophyceae class were recorded, distributed in five families: Hydrodictyaceae Dumortier, Neochloridaceae Ettl & Komárek, Radiococcaceae Fott ex P.C.Silva, Scenedesmaceae Oltmanns, Selenastraceae Blackman & Tansley. These taxa have mainly cenobial representatives, with about 70% of the individuals in this thallus configuration, followed by 22% colonies and 8% unicellular thallus. Among the identified species, five occurred only in mesotrophic sites, warning for environments with tendencies to elevate their trophic, since they are genera previously associated with these conditions. Ten new citations were recorded for the State of Paraná, namely: Pseudopediastrum boryanum var. longicorne (Reinsch) P.M.Tsarenko, Radiococcus skujae I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann, Desmodesmus perforatus (Lemmermann) E.Hegewald, Desmodesmus subspicatus (Chodat) E.Hegewald & A.W.F.Schmidt, Scenedesmus indicus Philipose ex Hegewald, Engelberg & Paschma, Ankistrodesmus bernardii Komárek, Monoraphidium capricornutum (Printz) Nygaard, Monoraphidium caribeum Hindák, Raphidocelis danubiana var. elegans (Playfair) Taşkin & Alp, Selenastrum rinoi Komárek & Comas. Taxonomic studies, such as this one, are an important tool for understanding the flora, and in addition to contributing to the registration of species in aquatic ecosystems, they serve as a basis for ecological studies and other approaches used to preserve biodiversity in these places.

Resumo Ambientes lóticos são ecossistemas muito vulneráveis aos impactos das atividades humanas, especialmente em regiões urbanas, e uma das formas para auxiliar no diagnóstico ambiental é utilizando o conhecimento da composição dos organismos bioindicadores, dentre eles as microalgas. O objetivo foi caracterizar qualitativamente as microalgas enquadradas na Classe Chlorophyceae Wille, fornecendo descrições e dados merísticos dos espécimes bem como as condições ambientais em que os táxons foram registrados. Foram realizadas amostragens de água e de fitoplâncton trimestralmente no ano de 2020, em nove rios de abastecimento, distribuídos em três bacias hidrográficas da região oeste do Paraná (bacia do Paraná III, bacia do Piquiri e bacia do Baixo Iguaçu). Os rios estudados foram enquadrados como oligotróficos ou mesotróficos e os táxons apresentaram em sua maioria ocorrência rara. Foram registrados 36 táxons pertencentes a classe Chlorophyceae distribuídos em cinco famílias: Hydrodictyaceae Dumortier, Neochloridaceae Ettl & Komárek, Radiococcaceae Fott ex P.C.Silva, Scenedesmaceae Oltmanns, Selenastraceae Blackman & Tansley. Esses táxons possuem representantes principalmente cenobiais, apresentando cerca de 70% dos indivíduos nessa configuração de talo, seguido por 22% de colônias e 8% de talos unicelulares. Entre as espécies identificadas, cinco ocorreram somente em locais mesotróficos, advertindo para ambientes com tendências a elevar sua trofia, visto que são gêneros já associados anteriormente a essas condições. Foram registradas 10 novas citações para o Estado do Paraná, sendo estas: Pseudopediastrum boryanum var. longicorne (Reinsch) P.M.Tsarenko, Radiococcus skujae I.Kostikov, T.Darienko, A.Lukesová & L.Hoffmann, Desmodesmus perforatus (Lemmermann) E.Hegewald, Desmodesmus subspicatus (Chodat) E.Hegewald & A.W.F.Schmidt, Scenedesmus indicus Philipose ex Hegewald, Engelberg & Paschma, Ankistrodesmus bernardii Komárek, Monoraphidium capricornutum (Printz) Nygaard, Monoraphidium caribeum Hindák, Raphidocelis danubiana var. elegans (Playfair) Taşkin & Alp, Selenastrum rinoi Komárek & Comas. Trabalhos taxonômicos, como este, são uma importante ferramenta para o conhecimento da flora, e além de contribuir no registro das espécies nos ecossitemas aquáticos, servem como base para estudos ecológicos e demais abordagens utilizadas na preservação da biodiversidade nesses locais.

Efecto de variables abióticas en la fauna hiporreica del río Dagua, Colombia / Effect of abiotic variables on the hyporheic fauna of Dagua River, Colombia

Introducción: La fauna de sedimentos del subsuelo, donde se da el intercambio entre aguas subterráneas y superficiales, llamada "fauna hiporreica", cumple funciones ecológicas importantes en los ríos; sin embargo, no ha sido estudiada suficientemente en Colombia. Objetivo: Identificar las relaciones entre los invertebrados hiporreicos y variables fisicoquímicas en el río Dagua, Colombia. Métodos: En tres giras a campo (entre octubre 2017 y diciembre 2018) en cinco estaciones de muestreo a lo largo de la cuenca del río, realizamos perforaciones implementando el método de Karaman-Chappuis (sedimento, agua e invertebrados), y registramos la granulometría y materia orgánica en los sedimentos; además, medimos nutrientes, iones y metales en el agua. Resultados: Las estaciones en la zona de cabecera tuvieron sustratos con sedimentos gruesos (grava y piedra), mayores niveles de oxígeno, y menor temperatura del agua. La riqueza y diversidad de especies fueron mayores en estaciones en la zona cabecera, donde predominaron Copepoda e Insecta, mientras que en sitios de cuenca baja predominaron Arachnida (Hydrachnidiae), Clitellata (Oligochaeta) y Nematoda. Conclusiones: La distribución y abundancia de la fauna hiporreica fueron principalmente influenciadas por cambios en la granulometría del sustrato hiporreico y sus contenidos de materia orgánica.

Introduction: The fauna from the subsurface sediments where groundwaters and surface waters are exchanged, called "hyporheic fauna", fulfills important ecological functions in rivers, but has not been sufficiently studied in Colombia. Objective: To identify relationships between hyporheic invertebrates and physicochemical variables in the Dagua River, Colombia. Methods: In three field trips (between October 2017 and December 2018) to five sites along the river basin, we drilled with the Karaman-Chappuis method (sediment, water, and invertebrates), and recorded granulometry and organic matter in sediments; and nutrients, ions, and metals in water. Results: The headwater stations had substrates with coarser sediments (gravel and stone), higher oxygen levels, and lower water temperature. Both richness and species diversity were higher at the headwater stations, dominated by Copepoda and Insecta, while the lower basin was dominated by Arachnida (Hydrachnidiae), Clitellata (Oligochaeta), and Nematoda. Conclusions: The distribution and abundance of the hyporheic fauna were principally influenced by changes in the granulometry of the hyporheic substrate and its content of organic matter.

Diferencias en el tamaño corporal y la abundancia de peces altoandinos, arriba y abajo de la represa Neusa, Colombia / Differences in body size and abundance of high Andean fishes, above and below the Neusa dam, Colombia

Resumen Introducción: Los ríos tropicales se ven cada vez más afectados por la fragmentación y la regulación; y, en Colombia, se sabe que las represas ponen en peligro a los peces endémicos debido, entre otros, a la migración limitada y la disponibilidad reducida de redes alimenticias basadas en el detrito. Sin embargo, el conocimiento de la ictiofauna nativa afectada por represas en ríos altoandinos es aún incipiente. Objetivo: Evaluar los efectos de la represa del Neusa sobre la ictiofauna. Métodos: Comparamos dos secciones del río, una aguas arriba y otra aguas abajo de la represa con el Sistema Richter IHA, muestreamos tres transectos de 100 m de largo en cada sección, cada dos meses, entre 2017 y 2019. Los peces fueron devueltos al río después de efectuadas las mediciones corporales. Resultados: Recolectamos 729 individuos de cinco familias; los Trichomycterus bogotense eran más pequeños aguas abajo de la represa; Oncorhynchus mykiss fue más pequeño y menos abundante; y no hubo diferencias para Grundulus bogotensis y Eremophilus mutisii. Independientemente de los factores climáticos, O. mykiss y G. bogotensis fueron más abundantes aguas arriba, y E. mutisii y T. bogotense aguas abajo de la represa. Conclusión: Las cinco especies de peces diferían en cómo las poblaciones se diferencian aguas arriba y aguas abajo de la represa, lo que sugiere que algunas se benefician de la represa, mientras que otras se vuelven más pequeñas y menos abundantes.

Abstract Introduction: Tropical rivers are increasingly being affected by fragmentation and regulation; and, in Colombia, dams are known to endanger endemic fishes through, among others, limited migration and reduced availability of sediment-based feeding networks. However, knowledge of native ichthyofauna affected by dams in high Andean rivers is still incipient. Objective: To assess the effects of the Neusa dam on the ichthyofauna. Methods: We compared two rivers' sections, one above and one below the dam with the Richter IHA System, we sampled three 100 m long transects in each section, every two months, between 2017 and 2019. The fishes were returned to the river after body measurements. Results: We collected 729 individuals from five families; Trichomycterus bogotense were smaller under the dam; Oncorhynchus mykiss was smaller and less abundant; and there were no differences for Grundulus bogotensis and Eremophilus mutisii. Independently of climatic factors, O. mykiss and G. bogotensis were more abundant above the dam, and E. mutisii and T. bogotense under the dam. Conclusion: The five fish species differed in how the populations differed above and under the dam, suggesting that some are benefited by the dam, while others become smaller and less abundant.

Peces de la cuenca del río Chira, Piura, Perú / Peces de la cuenca del río Chira, Piura, Perú

Abstract Chira River is located on the north coast of Peru. The scant information of the ichthyofauna from coastal drainages from Peru is noteworthy. The aim of this study is to characterize the ichthyofauna along the Chira River basin in terms of diversity and altitudinal range distribution. The material examined belongs to the Ichthyological collection of the Natural History Museum (MUSM). The diversity of fishes is composed of 27 species belonging to 19 families and ten orders. Siluriformes and Characiformes were the most diverse, consisting of 22% (six species) for each one. Five species are new records for the Chira River (three natives and two non-natives). Six marine species and seven exotic species were recorded as well. The altitudinal distribution patterns for all species were registered. This study increases the known diversity of freshwater fishes from Pacific Drainage Rivers in Peru, and it could be used for management and conservation plans.

Resumen El río Chira está ubicado en la costa norte del Perú. La escasa información de la ictiofauna de las cuencas costeras del Perú es notable. El objetivo de este estudio es caracterizar la ictiofauna en la cuenca del río Chira en términos de diversidad y rango de distribución altitudinal. El material examinado pertenece a la colección ictiológica del Museo de Historia Natural (MUSM). La diversidad de peces está compuesta por 27 especies pertenecientes a 19 familias y 10 órdenes. Cinco especies son nuevos registros para el río Chira (tres nativas y dos no nativas). Fueron registradas seis especies marinas y siete especies exóticas. Este estudio incrementa el conocimiento de la diversidad de peces de las cuencas costeras en Perú, y puede ser usado para planes de manejo y conservación.

CONCENTRACIONES DE METILMERCURIO EN Prochilodus magdalenae (TELEOSTEI: CURIMATIDAE) Y Hoplias malabaricus (TELEOSTEI: ERYTHRINIDAE) EN LA CUENCA BAJA DEL RÍO CAUCA-MAGDALENA, NORTE DE COLOMBIA / Methylmercury concentrations in Prochilodus magdalenae (Teleostei: Curimatidae) and Hoplias malabaricus (Teleostei: Erythrinidae) in the lower Cauca-Magdalena river system, northern Colombia

RESUMEN Las emisiones de mercurio (Hg) a partir de actividades de minería afectan los recursos pesqueros, los cuales son importantes en la alimentación proteínica de las poblaciones humanas. El objetivo de este estudio fue analizar las concentraciones de MeHg (metilmercurio) en Prochilodus magdalenae (Bocachico) y Hoplias malabaricus (Moncholo) en hábitats continentales de la región de La Mojana y en la parte baja del río Cauca (Norte de Colombia), sitios que han sido afectados por actividades de minería aurífera. Un total de 160 ejemplares fueron colectados para su respectivo análisis, 130 en el grupo expuesto: Mojana 1 (n=36), Mojana 2 (n=56) y El Bajo Cauca (n=38), y n=30 en el grupo control. Se realizaron las determinaciones de MeHg mediante análisis directo con un Analizador Directo de Mercurio DMA 80, cromatografía líquida y espectrometría de absorción atómica. Las concentraciones de MeHg encontradas en muestras de tejido del músculo dorsal de los peces procedentes de los lugares expuestos, fueron significativamente mayores comparados con el grupo control (p < 0.05), siendo la región del Bajo Cauca la más afectada por altas concentraciones de MeHg. Los resultados indican que la presencia de MeHg en los peces es consecuencia de las actividades de minería aurífera ampliamente desarrolladas en la zona. Estas concentraciones MeHg representan un riesgo mortal para la salud humana y animal.

ABSTRACT Mercury (Hg) pollution from mining activities influence fishing resources, which are important for human populations' nutrition. The aim of this research was to explore MeHg (methylmercury) concentrations in Prochilodus magdalenae (bocachico) and Hoplias malabaricus (moncholo) in freshwater habitats of the Mojana region and in the Bajo Cauca river (Northern Colombia), which have been affected by gold mining activities. A total of 160 individuals were collected, 130 in the exposed group: Mojana 1 (36), Mojana 2 (56) and El Bajo Cauca (38); and 30 individuals in the control group (Cereté). After fish sampling, MeHg determinations were done by direct analysis with a Direct Mercury Analyser DMA 80, liquid chromatography, and atomic absorption spectrometry. The results show that MeHg found in the dorsal muscle tissue is significantly higher than in the control group (p < 0.05), the Bajo Cauca region being the most affected due to the high concentrations of MeHg. The results show that the presence of MeHg in fish may be related to gold mining activities, which are widely developed in the area. The toxic concentrations found represent a risk to human health.

Os modos de fazer saúde na Amazônia das Águas / Health care delivery in the Amazon of the Waters / Los modos de hacer salud en la Amazonia de las Aguas

Descrevemos como a organização do sistema de saúde é afetada pelas características da várzea amazônica. Elegemos uma região a oeste do estado do Amazonas que bem caracteriza esse cenário. Entrevistamos gestores de saúde e mapeamos os trajetos percorridos pelos usuários para acessar a rede sanitária. Municípios menores são extremamente dependentes da rede de serviço do polo regional e da capital estadual. O transporte de usuários, à exceção de emergências, é feito por via fluvial com maior tempo e maior custo em relação à via terrestre. O ciclo vazante-cheia também interfere no tempo, no custo e nos agravos prevalentes. Identificamos alguns pontos de tensão entre o instituído normativamente para conformação das regiões de saúde e a realidade regional. Promover saúde na Amazônia passa inevitavelmente pela adaptação e pela resiliência do sistema de saúde no diálogo com as características do território e dos fluxos dos usuários.(AU)

This article describes how the characteristics of the Amazon floodplain affect the organization of local health systems. We chose a region in the west of the state of Amazonas which is characteristic of this situation. We interviewed local health managers and mapped the routes taken by users to access health services. Smaller municipalities are extremely dependent on services in the regional hub and capital of the state. Patients, except emergency patients, are transported via waterways, resulting in longer travel times and higher costs than land routes. The seasonal flooding cycle also affects travel times, costs and prevalent health problems. We identified some points of tension between the rules and regulations governing the configuration of local health regions and the regional reality. Promoting health in the Amazon inevitably requires the health system to adapt and be resilient to local geographical characteristics and patient flows.(AU)

Describimos cómo la organización del sistema de salud se ve afectada por las características de la vega amazónica. Elegimos una región del oeste del Estado de Amazonas que caracteriza bien ese escenario. Entrevistamos a gestores de salud y mapeamos los trayectos recorridos por los usuarios para tener acceso a la red sanitaria. Los municipios menores son extremadamente dependientes de la red de servicio del polo regional y de la capital del estado. El transporte de usuarios, a no ser en casos de emergencia, se realiza por vía fluvial con mayor tiempo y costo con relación a la vía terrestre. El ciclo subida y bajada de las aguas también interfiere en el tiempo, costos y problemas prevalentes. Identificamos algunos puntos de tensión entre lo instituido normativamente para conformación de las regiones de salud y la realidad regional. La promoción de la salud en la Amazonia pasa inevitablemente por la adaptación y resiliencia del sistema de salud en el diálogo con las características del territorio y de los flujos de los usuarios.(AU)

Produção de existências em ato na Amazônia, Brasil: "território líquido" que se mostra à pesquisa como travessia de fronteiras / Producing existences in action in the Amazon, Brazil: "liquid territory" that shows itself to research as a crossing of borders / Producción de existencias en acto en la Amazonia, Brasil: "territorio líquido" que se muestra a la investigación como travesía de fronteras

O objetivo do artigo é compartilhar a aprendizagem em pesquisa, fruto da vivência das pesquisadoras e dos pesquisadores na rede de cuidado à saúde de urgência e emergência na Amazônia, Brasil. Propomos pensar no conceito de pesquisa como travessia de fronteiras para falar da interculturalidade, da singularidade do território, mas também do diálogo tenso entre racionalidades da Ciência e das práticas de saúde e de pensamento. O texto está constituído de três eixos: a apresentação da categoria "território líquido", seguida da discussão epistemológica sobre o método e a apresentação dos recursos utilizados na pesquisa para propor uma episteme "emergente e insurgente". Traçamos linhas decolonizadoras do pensamento por entendermos que a função da pesquisa é descrever e produzir visibilidades como existência e não apenas como representação do que está vigente. (AU)

The aim of this article is to share research lessons learnt from the experiences of researchers in the urgent and emergency care network in the Amazon, Brazil. We propose to think about the concept of research as a crossing of boundaries to talk about interculturality, the uniqueness of territories, as well as the tense dialogue between the rationality of science and health practices and thinking. This article is structured into three core sections: presentation of the category "fluid territory", followed by an epistemological discussion of the method and presentation of the resources used in the study to propose an "emergent and insurgent" episteme. We outline decolonizing lines of thought based on the understanding that the function of research is to describe and produce visibility as existence and not just as a representation of what is current. (AU)

El objetivo del artículo es compartir el aprendizaje en investigación, fruto de la vivencia de las investigadoras e investigadores en la red de cuidados de la salud de Urgencias y Emergencias en la Amazonia, Brasil. Proponemos pensar en el concepto de investigación como travesía de fronteras, para hablar de la interculturalidad, de la singularidad del territorio, pero también del diálogo tenso entre racionalidades de la ciencia y de las prácticas de salud y de pensamiento. El texto está formado por tres ejes: la presentación de la categoría "territorio líquido", seguida de la discusión epistemológica sobre el método y presentación de los recursos utilizados en la investigación para proponer una episteme "emergente e insurgente". Trazamos líneas descolonizadoras del pensamiento por entender que la función de la investigación es describir y producir visibilidades como existencia y no solo como representación de lo vigente. (AU)

Structure of the aquatic Diptera community in the upper basins of the Fucha and Bogotá rivers / Estructura de la comunidad de dípteros acuáticos en tramos de los cursos altos de los ríos fucha y bogotá

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.

Avaliação da influência da estação de tratamento de efluente de Catanduva (SP) na qualidade da água do rio São Domingos / Evaluation of influence of the Catanduva (SP) Wastewater Treatment Plant (WWTP) in São Domingos river water quality

RESUMO O efluente sanitário bruto é um dos responsáveis pela poluição de rios urbanos, e a instalação de estações de tratamento de efluentes (ETE) exige uma avaliação comparativa do comportamento desses rios antes e depois da ETE. Este trabalho objetivou avaliar a qualidade da água do rio São Domingos (RSD) após o início da operação da ETE Catanduva (SP), cujas eficiências médias de remoção foram: demanda bioquímica de oxigênio (93,71%), nitrogênio amoniacal (73,12%), fósforo total (25,70%), turbidez (85,16%) e ST (31,75%). Foram utilizados 768 dados coletados pela Companhia Ambiental do Estado de São Paulo a montante e a jusante de Catanduva (SP). Obras de dragagem realizadas durante o período avaliado foram responsáveis por um significativo decréscimo temporário na qualidade da água do RSD em Catanduva. Após dois anos do início da operação da ETE, houve significativa melhoria na qualidade do RSD, com redução das concentrações médias de DBO (de 20,97 para 5,73 mg.L−1), nitrogênio amoniacal (de 3,84 para 0,99 mg.L−1) e Escherichia coli (de 105 para 104 UFC.100 mL−1) e aumento da concentração de oxigênio dissolvido (de 0,90 para 3,12 mg.L−1). A análise de componentes principais indicou que a qualidade do rio a jusante de Catanduva está-se aproximando da boa qualidade verificada a montante da cidade. Esses dados sugerem que o RSD pode futuramente ser classificado como Classe 3 (Resolução do Conselho Nacional do Meio Ambiente — CONAMA n° 357/05) e até ser utilizado para abastecimento humano, reduzindo a elevada demanda de água subterrânea na região.

ABSTRACT Non-treated wastewater is responsible for the pollution of urban rivers, and it is mandatory to evaluate the behavior of these rivers before and after the construction of a Wastewater Treatment Plant (WWTP). The aim of this study was to evaluate the water quality of São Domingos River (SDR) after the start of the Catanduva/SP WWTP operation, whose average removal efficiencies were: biochemical oxygen demand (BOD; 93.71%), ammonia nitrogen (73.12%), total phosphorus (25.70%), turbidity (85.16%), and total solids (31.75%). We used 768 data collected upstream and downstream of the city of Catanduva/SP, previously analyzed by CETESB (state environmental agency). Dredging works carried out during the evaluated period were responsible for a significant temporary worsening in the water quality of the SDR in Catanduva. Two years after the beginning of the Catanduva WWTP, there was a significant improvement in SDR water quality, with a reduction in the average concentrations of BOD (20.97 to 5.73 mg.L−1), ammonia nitrogen (3.84 for 0.99 mg.L−1), and Escherichia coli (105 to 104 CFU.100 mL−1) were reduced; and DO concentration (0.90 to 3.12 mg.L−1) increased. The Principal Component Analysis (PCA) indicated that the water quality of the river downstream of Catanduva is approaching the same quality verified upstream of the city. These data suggest that SDR may be considered a Class 3 river (Resolution CONAMA 357/05) in the future and may even be used for human supply, reducing the high demand for groundwater in the region.

Discrimination of species and populations of the genus Cichla (Cichliformes: Cichlidae) in rivers of the Amazon basin using otolithic morphometry

ABSTRACT The genus Cichla is a highly diverse group, with 16 species already described. Externally, some species are very similar and discriminating between them may be very difficult. Nevertheless, discrimination of fish stocks is essential for management purposes. Morphometric analyses of otoliths have been successfully used to distinguish species and fish stocks, especially in marine environments. This study evaluated whether sagittal otolith shape can be used to discriminate among the species Cichla temensis, C. monoculus, and C. orinocensis, as well as within populations of C. temensis in rivers of the Amazon. Shape indices and Fourier coefficients were used to describe the shape of the otoliths. Among the groups of species, the morphology of the sagittal otolith of C. temensis was totally distinct from the species C. monoculus and C. orinocensis. While among populations of C. temensis, individuals from the Negro and Jatapú Rivers were different, regardless of the methods used. These results confirm the ability to differentiate species and populations by using the morphology of otoliths. However, more research is needed to verify the role of genetic versus environmental and biotic effects, and thus be able to explain the discrimination observed in otoliths.

RESUMO O gênero Cichla é bastante diverso, com 16 espécies descritas. Algumas espécies são externamente muito similares e sua discriminação pode ser bastante difícil. Ao mesmo tempo, a discriminação de estoques pesqueiros é essencial para propostas de manejo. Análises morfométricas em otólitos têm sido utilizadas com sucesso para a distinção de espécies e estoques pesqueiros, principalmente em ambientes marinhos. Este estudo avaliou se o formato do otólito sagittal pode ser utilizado para discriminar entre espécies Cichla temensis, C. monoculus e C. orinocensis, bem como dentro de populações de C. temensis em diferentes rios amazônicos. Índices de forma e coeficientes de Fourier foram utilizados para descrever a forma dos otólitos. Dentre as espécies, a morfologia do otólito sagittal do C. temensis mostrou ser totalmente distinta das espécies C. monoculus e C. orinocensis. Enquanto no grupo das populações de C. temensis, os indivíduos dos rios Negro e Jatapú mostraram-se diferentes independente dos métodos utilizados. Esses resultados confirmam a capacidade de diferenciação de espécies e populações através da morfologia dos otólitos. No entanto, são necessárias mais pesquisas para verificar o papel dos efeitos genéticos em comparação aos efeitos ambientais e bióticos para explicar a discriminação observada nos otólitos.

A cascade of dams affects fish spatial distributions and functional groups of local assemblages in a subtropical river

Dams reduce the longitudinal connectivity of rivers and thereby disrupt fish migration and the spatial distribution of species, impacts that remain poorly studied for some Neotropical rivers from mega-diverse basins. We investigated the spatial distribution of fish species with different trophic and movement/reproductive/size characteristics to assess how functional groups have responded to a cascade of dams on the Uruguai River in southern Brazil. Fish abundance, biomass, and species composition were evaluated at eight locations along the longitudinal gradient. The fish assemblage in the upper stretch was mainly characterized by small and medium-sized species at higher trophic levels, whereas the sites located furthest downstream displayed more medium and large-sized species, including many carnivorous species. Species with high fecundity, seasonal migrants, and catfishes with internal fertilization were common in the river´s middle and lower reaches. Detritivorous species dominated areas distant from the dams. Overall, functional diversity of local fish assemblages was greater in lower reaches. The cascade of dams has impacted the distribution of functional groups of local fish assemblages of Uruguai River. The alteration of functional groups in upper reaches of the river has potential consequences for ecosystem processes and services, such as nutrient cycling and fisheries.(AU)

As barragens reduzem a conectividade longitudinal dos rios e interrompem a migração e a distribuição espacial das espécies, configurando impactos pouco estudados para alguns rios Neotropicais megadiversos. Investigamos a distribuição espacial de espécies de peixes com diferentes características tróficas e reprodutivas para avaliar como grupos funcionais responderam a uma cascata de reservatórios no rio Uruguai, sul do Brasil. Abundância de peixes, biomassa e composição de espécies foram avaliadas em oito locais ao longo do gradiente longitudinal. A assembleia de peixes no trecho superior foi caracterizada principalmente por espécies de pequeno e médio porte em níveis tróficos mais elevados, enquanto que os ambientes localizados mais a jusante apresentaram mais espécies de médio e grande porte, incluindo muitas espécies carnívoras. Espécies com alta fecundidade, migradores sazonais e bagres com fertilização interna foram comuns no curso médio e inferior. Espécies detritívoras dominaram áreas distantes das barragens. A diversidade funcional das assembleias de peixes locais foi maior nas partes inferiores. A cascata de barragens impactou a distribuição dos grupos funcionais das assembleias de peixes locais no rio Uruguai. A alteração da diversidade funcional no curso superior do rio tem consequências potenciais para a dinâmica e serviços do ecossistema, como ciclagem de nutrientes e pesca.(AU)

Anthropogenic river fragmentation reduces long-term viability of the migratory fish Salminus brasiliensis (Characiformes: Bryconidae) populations

Life-history, geographical barriers, and damming can shape the genetic diversity of freshwater migratory fish, which are particularly vulnerable to anthropogenic impacts. We investigated the genetic diversity of Salminus brasiliensis, a long-distance migratory species that is recognized as an important provider of ecosystem services. We implemented microsatellite analyses to assess genetic diversity and simulate future scenarios for evaluating the long-term viability of dammed and non-dammed populations from the Uruguay River. High levels of genetic diversity were detected for all sampled populations. However, effective population sizes were lower in the uppermost river stretches, where the landscape is highly fragmented. Population structure analysis indicated two spatial genetic populations. It is suggested that this genetic structure preserves populations partially isolated by an ancient natural barrier, instead of being a result of the presence of dams. The simulated genetic scenarios indicated that genetic variability of S. brasiliensis populations from upstream dams could collapse over the years, mainly due to the reduction in the number of alleles. Therefore, besides helping to better understand issues related to the influence of dams on the genetic diversity of migratory fish, our results are especially relevant for driving local fishery policies and management actions for the species conservation.'

História de vida, barreiras geográficas e barramento dos rios podem moldar a diversidade genética de grandes peixes migratórios de água doce, que são particularmente vulneráveis a impactos antrópicos. Nós investigamos a diversidade genética de Salminus brasiliensis, uma espécie migratória de longa distância que é reconhecida como um importante provedor de serviços ecossistêmicos. Realizamos análises de microssatélites para avaliar a diversidade genética e simular cenários futuros, possibilitando estimar a viabilidade em longo prazo de populações situadas em regiões com e sem represas do rio Uruguai. Altos níveis de diversidade genética foram detectados para todas as populações amostradas. Contudo, os tamanhos populacionais efetivos foram menores nos trechos superiores do rio, onde a paisagem é altamente fragmentada. A análise da estrutura populacional indicou duas populações genéticas espaciais. Sugere-se que esta estrutura genética preserva populações parcialmente isoladas por uma antiga barreira natural, ao invés de ser resultado da presença de barragens. Os cenários genéticos simulados indicaram que a variabilidade genética das populações de S. brasiliensis situadas a montante das barragens entraria em colapso ao longo dos anos, principalmente como resultado da redução do número de alelos. Portanto, além de ajudar a entender melhor questões relacionadas à influência de barragens na diversidade genética de peixes migradores, nossos resultados são especialmente relevantes para a condução de políticas pesqueiras locais e ações de manejo para a conservação das espécies.(AU)

Functional Feeding Group composition and attributes: evaluation of freshwater ecosystems in Atlantic Forest, Brazil / Composição e atributos de Grupos Funcionais Alimentares: avaliação de ecossistemas de água doce na Mata Atlântica, Brasil

Abstract: Benthic macroinvertebrates Functional Feeding Group (FFG) have been used to determine aquatic assemblage dynamics and as a biomonitoring tool. The main goals of this study were to assess the effects of stream variables on the abundance and richness of FFGs and evaluate ecosystem attributes (FFG ratios) as a tool to assess ecological conditions of Atlantic Rainforest streams. We sampled 146 sites with different impairment conditions in Rio de Janeiro, Brazil. Richness was significantly different among impairment conditions for all FFGs. Mixed-effect models show that aquatic macroinvertebrate FFGs differed in their responses to abiotic variables for abundance and richness. Also, they were reduced in the impaired sites when compared to intermediate and reference sites. The FFG ratio indicated significant differences along the impairment gradient. The FFG ratio analysis was shown to be a fast and cheap tool that can be used for monitoring aquatic ecosystems in the Atlantic Forest biome. However, further studies are required to calibrate the method specifically for the Atlantic Forest region.

Resumo: Os Grupos Funcionais de Alimentação (GFA) são utilizados para determinar a dinâmica da comunidade de macroinvertebrados bentônicos e como uma ferramenta de biomonitoramento. Os principais objetivos deste estudo foram: avaliar os efeitos de variáveis de riacho na abundância e riqueza de GFAs e os atributos do ecossistema (razão GFA) como uma ferramenta para avaliar as condições ecológicas dos córregos da Mata Atlântica. Foram amostrados 146 locais com diferentes condições de impacto no Rio de Janeiro, Brasil. A riqueza foi significativamente diferente com as condições de impacto entre todos os GFA. Os modelos de efeito misto mostraram que os GFA diferiam em suas respostas às variáveis abióticas quanto à abundância e riqueza. Além disso, eles diferem nas áreas impactadas quando comparados as áreas intermediária e de referência. A razão de GFA encontrou diferenças significativas ao longo do gradiente de impacto. A análise da razão de GFA evidenciou-se uma ferramenta rápida e barata, com potencial para ser utilizada no monitoramento de ecossistemas aquáticos no bioma Mata Atlântica. No entanto, mais estudos serão necessários para calibrar o método especificamente para a região da Mata Atlântica.

Macroinvertebrates of Eichhornia crassipes (Pontederiaceae) roots in the alluvial floodplain of large tropical rivers (Argentina) / Macroinvertebrados de Eichhornia crassipes (Pontederiaceae) raíces en la llanura aluvial aluvial de grandes ríos tropicales (Argentina)

Introduction: Eichhornia crassipes is a dominant aquatic plant of neotropical-river floodplains and is invasive in warm waters of different continents. Plants provide food and habitat for fish, especially Prochilodus lineatus and Gymnotus omarorum, which are relevant to subsistence fishing by local indigenous communities. Objective: In this study we describe the main traits of E. crassipes floating meadows, and analyze the abundance and composition of macroinvertebrate assemblages associated with their roots in two floodplain wetlands of the Paraná River (within the Ramsar site Wetlands Chaco) and of the Pilcomayo River (within the Pilcomayo River National Park). Methods: During spring and summer, the macroinvertebrates were collected in monospecific stands of E. crassipes with a net of 962 cm2 area and 500 µm mesh size. Leaf density, the biomass of leaves and roots, the length of leaves and roots, and the water quality were measured simultaneously. Results: Temperature, oxygen concentration, and nutrient content were significantly higher and electrical conductivity was lower in the Pilcomayo than in the Paraná floodplain. E. crassipes growing in the Pilcomayo floodplain had longer leaves and less root biomass than those found in the Paraná floodplain. The number of macroinvertebrates per 1 000 g root dry weight and per m2 was significantly different between both floodplains, but the taxon richness was similar. Non Metric Multidimensional Scaling analysis differentiated the abundance of 14 selected taxa between both floodplains, and showed a high correlation between the environmental variables and macroinvertebrate abundance. The most abundant taxonomic groups in the Paraná River floodplain were oligochaetes (Naididae), ostracods mainly Cytheridella ilosvayi and larvae of non-biting midges (Chironomidae). Two families, Hydrobiidae (Heleobia parchappii) and Chironomidae accounted for 49.3 % of the total abundance in the Pilcomayo floodplain. The prawns Macrobrachium jelskii and M. amazonicum, frequent in the Pilcomayo floodplain, were not found in the Paraná floodplain. Conclusions: The different environmental conditions in both floodplains affect the abundance, composition, and the dominance of macroinvertebrate assemblages; however, the total taxa richness was similar. The area occupied by E. crassipes in the floodplains of these rivers provides the habitat that contributes most to overall biotic diversity, which must be considered in management strategies.

Introduccion: Eichhornia crassipes es la planta acuática dominante en la planicie de inundación de los ríos tropicales y ha invadido las aguas cálidas de diferentes continentes. Las plantas proveen alimento y hábitat para los peces, especialmente Prochilodus linneatus y Gymnotus omarorum, que son relevantes para la pesca de subsistencia de las comunidades indígenas locales. Objetivo: En el presente trabajo nosotros describimos las principales características de las formaciones flotantes de E. crassipes, y analizamos la abundancia y composición de los ensambles de macroinvertebrados asociados a sus raíces en dos humedales de las planicies de inundación de los ríos Paraná (dentro del sitio Ramsar Humedales Chaco) y Pilcomayo (dentro del Parque Nacional Río Pilcomayo). Métodos: Durante la primavera y el verano, los macroinvertebrados se recolectaron en formaciones monoespecíficas de E. crassipes con una red de 962 cm2 y 500 µm de tamaño de malla. La densidad de hojas, la biomasa de hojas y raíces, la longitud de las hojas y raíces y la calidad del agua se midieron simultáneamente. Resultados: La temperatura, la concentración de oxígeno disuelto y el contenido de nutrientes fueron significativamente mayores y la conductividad eléctrica fue significativamente menor en la planicie de inundación del Pilcomayo que en la del Paraná. Las plantas de E. crassipes que crecen en la planicie de inundación del Pilcomayo tuvieron hojas más largas y menos biomasa de raíces que las encontradas en la planicie del Paraná. El número de macroinvertebrados por 1 000 g. de peso seco de la raíz y por m2 fueron significativamente diferentes entre ambas planicies de inundación, pero la riqueza de taxa fue similar. El análisis de Escalamiento Multidimensional No Métrico diferenció la abundancia de los 14 taxa seleccionados entre ambas planicies de inundación, y mostró alta correlación entre las variables ambientales y la abundancia de los macroinvetebrados. Los grupos taxonómicos más abundantes en la planicie de inundación del río Paraná fueron los oligoquetos (Naididae), los ostrácodos, principalmente Cytheridella ilosvayi y las larvas de mosquitos no picadores (Chironomidae). Dos familias, Hydrobiidae (Heleobia parchappii) y Chironomidae representaron el 49,3 % de la abundancia total en la planicie de inundación del Pilcomayo. Los camarones Macrobrachium jelskii y M. amazonicum, frecuentes en la planicie de inundación del Pilcomayo, no se encontraron en la planicie de inundación del Paraná. Conclusiones: Las diferentes condiciones ambientales en ambas planicies de inundación afectan la abundancia, composición y la dominancia de los ensambles de macroinvertebrados; sin embargo, la riqueza total de taxa fue similar. El área ocupada por E. crassipes en la planicie de inundación de estos ríos proporciona el hábitat que más contribuye a la diversidad biótica, lo que debe ser considerado en las estrategias de manejo.

Estudio de la diversidad taxonómica y funcional de los macroinvertebrados en un río de montaña Andino / Study of the taxonomic and functional diversity of the macroinvertebrate assemblages in an Andean mountain river

Introducción: La estructura, diversidad taxonómica y diversidad funcional del ensamblaje de macroinvertebrados acuáticos son estimadores sensibles a las variaciones del medio circundante. El ambiente físico es un factor fundamental, donde el sustrato y la dinámica hidráulica modifican la disponibilidad de recursos, la estructuración, el funcionamiento de la comunidad y del ecosistema. Objetivo: Determinar la estructura, diversidad taxonómica y diversidad funcional del ensamblaje de macroinvertebrados bajo diferentes condiciones abióticas en el río Hato Laguna, tributario del Lago de Tota. Métodos: Se recolectaron 120 muestras biológicas en cuatro momentos de muestreos en dos tramos en el río. Se midieron in situ profundidad, velocidad del flujo, ancho de canal y rugosidad del sustrato. Los rasgos funcionales evaluados fueron: longitud corporal, forma corporal, tipo de respiración, movilidad, gremio trófico y grupos funcionales alimenticios. Resultados: Se identificaron un total de 38 taxones; los órdenes Diptera, Coleoptera y Trichoptera presentaron la mayor riqueza de familias y géneros. Hubo mayor abundancia de Orthocladiinae, Andesiops sp. y Simulium sp. en condiciones de alta velocidad del flujo en los tramos altos; Nectopsyche sp. fue abundante en los tramos bajos relacionados con menores velocidades y mayor ancho del canal. Según los índices de diversidad taxonómica se presentó variación por tramos y muestreos sin observarse tendencias. En los tramos altos, el gremio trófico MOPF (colectores), respiración por tegumento y tamaño del cuerpo pequeño fueron característicos. En los tramos bajos, el ensamblaje fue de tipo raspador con respiración por branquias y forma del cuerpo aplanada. La riqueza, divergencia y equidad funcional fueron mayores en el tramo alto. En el Análisis de Correspondencia Canónica, los mayores valores de ancho y velocidad se relacionaron con categorías adherido al sustrato y endobentónico, mientras que valores bajos de ancho y rugosidad se relacionaron con las categorías de forma del cuerpo aplanado, recurso alimentario micrófitas y tamaño del cuerpo máximo. Conclusiones: El sistema presentó variación en las condiciones abióticas, en la estructura, diversidad taxonómica y funcional de los macroinvertebrados. Se resalta el papel de la velocidad del flujo como una variable determinante de la estructura y función del ensamblaje de macroinvertebrados. Asimismo, se destaca la diversidad funcional como una expresión de los rasgos descritos, por lo cual se relaciona en los tramos altos con la dominancia de taxones como Orthocladiinae, Chironominae, Simulium sp.y Andesiops sp.

Introduction: The structure, taxonomic diversity and functional diversity of the aquatic macroinvertebrate assemblages are estimators sensitive to variations in the surrounding environment. The physical environment is a key factor, where the substrate and hydraulic dynamics modify the availability of resources, the structuring, the functioning of the community and the ecosystem. Objective: Determine the structure, taxonomic diversity and functional diversity of the macroinvertebrate assemblages under different abiotic conditions in the Hato Laguna river, a tributary of Lake Tota. Methods: 120 biological samples were collected in four sampling events in two reaches in the river. Depth, flow velocity, channel width and roughness of the substrate were measured in situ. The functional traits evaluated were: body length, body shape, type of breathing, type of locomotion, trophic guild and functional feeding groups. Results: A total of 38 taxa were identified; Diptera, Coleoptera and Trichoptera orders presented the highest abundance of families and genera. Orthocladiinae, Andesiops sp. and Simulium sp. were more abundant groups under high-velocity conditions in the upper reaches. Nectopsyche sp. was abundant in the lower sections related to lower velocity and greater channel width. According to the taxonomic diversity indices, variation by reaches and samplings was presented without observing trends. In the upper reaches, the MOPF trophic guild (collectors), in tegument respiration, and small body size were characteristic. In the lower reaches, the assembly was of the scraper type with gill breathing and flattened body shape. The richness, divergence and functional evenness were higher in the upper reaches. In the Canonical Correspondence Analysis, the highest values of width and speed were related to categories attached to the substrate and endobenthic, while low width and roughness were related to the categories of flattened body shape, microphytes food resource, and maximum body size. Conclusions: The system presented a variation in the abiotic conditions, in the structure, taxonomic and functional diversity of the macroinvertebrates. The role of the flow velocity as a determining variable of the structure and function of the community is highlighted. Likewise, functional diversity stands out as an expression of the described traits, which is why it is related in the upper reaches with the dominance of taxa such as Orthocladiinae, Chironominae, Simulium sp. and Andesiops sp.