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Iron Formations (IF) are threatened by mining, particularly the Mesovoid Shallow Substratum (MSS), an understudied subterranean environment. We evaluate the spatiotemporal patterns of subterranean fauna in MSS of iron duricrust (canga) in the Iron Quadrangle and Southern Espinhaço Range, southeastern Brazil. Samplings took place between July 2014 and June 2022 using five trap types. We sampled 108,005 individuals, 1,054 morphospecies, and seven phyla, globally the largest dataset on MSS in IF. Arthropoda represented 97% of all invertebrates sampled. We identified 31 troglomorphic organisms, primarily Arthropoda and Platyhelminthes. MSS traps were the most efficient method, capturing 80% of all invertebrates. Morphospecies were more prevalent in each locality than shared among localities. Species replacement was the main processes to spatial differences. Over time, we found a decrease of total dissimilarity and importance of species replacement for troglomorphic organisms. A positive correlation between spatial distance and compositional dissimilarity of invertebrates was found. Iron Quadrangle and Southern Espinhaço Range showed marked differences in the spatiotemporal patterns of subterranean fauna. Brazilian IF are threatened, with their biological significance not fully understood but highly endangered due their limited distribution. Conservation efforts require a comprehensive understanding of both biotic and abiotic factors shaping the entire IF ecosystem.

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Over two decades, the area with sugarcane has more than doubled, from 4.8 million hectares in 2000 to 10 million in 2018, in Brazil. São Paulo State is mostly responsible for the sugarcane production in the country, accounting for 51% of the national production. In 2008, a study was conducted analysing the relationship between sugarcane cultivation and the aquatic macroinvertebrate community, showing the impacts of sugarcane on the macroinvertebrate aquatic fauna. The present study aims to gather actual information on the aquatic macroinvertebrate community in the same streams studied in 2008, to make a historical comparison with studies previously carried out. Eight streams were selected; four located in areas of sugarcane cultivation and four located in preserved areas. Three samples were carried out between 2018 and 2020. The aquatic macroinvertebrates were collected using a D-frame aquatic net (250 µm) including riffle and pools areas and identified using specific identification keys. The results of the historical assessment showed better ecological conditions of the streams in 2008 when compared to 2018 in areas of sugarcane cultivation, suggesting that the environmental impact was maintained and increased after ten years.

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Introduction: The Andes are characterized by an abundance of water resources and flows are frequently regulated by reservoirs for the generation of energy. The effects of regulation on aquatic macroinvertebrate communities are not well known in Colombia. Objective: To test the hypothesis that regulated currents have less macroinvertebrate diversity. Methods: We collected water and organism samples before, and after, the regulation of the Tafetanes, Calderas and Arenosa rivers, in Antioquia, Colombia, during various hydrological cycles (rain, transition and drought) and climatic phenomena (ENSO/El Niño Phenomenon) between 2016 and 2018. Results: We collected 53 214 individuals, from 165 taxa, mostly from the orders Ephemeroptera, Plecoptera, Trichoptera and Diptera (90 % of captures). Changes in diversity responded to spatial differences rather than to physicochemical variables: diversity was higher in non-regulated sites, regardless of the hydrological period or associated ENSO. Most species were found in all sampling sites, but abundance was higher in the site with the best habitat conservation status. Conclusion: The results support the hypothesis that physical barriers have effects on macroinvertebrate diversity at the local scale, however, the condition of adjacent habitats also seems to play an important role in preserving richness and abundance. The conservation of forest adjacent to the riverbed could mitigate the impacts of regulation.

Introducción: Los Andes se caracterizan por tener gran abundancia de recursos hídricos y las corrientes son frecuentemente reguladas por embalses para la generación de energía. Los efectos de la regulación en las comunidades de macroinvertebrados acuáticos no se conocen bien en Colombia. Objetivo: Probar la hipótesis de que las corrientes reguladas presentan menor diversidad de macroinvertebrados. Métodos: Recolectamos muestras de agua y organismos, antes y después de la regulación de los ríos Tafetanes, Calderas y La Arenosa, en Antioquia, Colombia, durante varios ciclos hidrológicos (lluvia, transición y sequía) y fenómenos climáticos (ENSO/Fenómeno de El Niño) entre 2016 y 2018. Resultados: Recolectamos 53 214 individuos, de 165 táxones, en su mayoría de los órdenes Ephemeroptera, Plecoptera, Trichoptera y Diptera (90 % de las capturas). Los cambios en la diversidad respondieron a las diferencias espaciales más que a las variables fisicoquímicas: la diversidad fue mayor en sitios no regulados, independientemente del periodo hidrológico o del ENSO. La mayoría de las especies se encontraron en todos los sitios de muestreo, pero su abundancia fue mayor en el sitio de mejor estado de conservación del hábitat. Conclusiones: Los resultados apoyan la hipótesis de que las barreras físicas tienen efectos sobre la diversidad de macroinvertebrados a escala local, sin embargo, el estado de los hábitats adyacentes también parece jugar un papel importante en la preservación de la riqueza y abundancia. La conservación del bosque adyacente podría mitigar los impactos generados por la regulación.

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One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H'≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.(AU)

Um dos indicadores biológicos mais utilizados para determinar a saúde de um ecossistema fluvial são os macroinvertebrados bentônicos. A presença de espécies recorrentes em um amplo gradiente de latitudes domina o padrão biogeográfico dos macroinvertebrados bentônicos nas águas doces do Chile; no entanto, o conhecimento sobre a ecologia comunitária destes nos rios chilenos continua escasso. Os modelos nulos se tornaram uma poderosa ferramenta estatística para descrever os mecanismos ecológicos que orientam a estrutura de uma comunidade ecológica e os padrões subjacentes da diversidade. O objetivo deste estudo foi determinar a estrutura da comunidade de invertebrados bentônicos no rio Allipén, descrevendo sua composição, riqueza e abundância de espécies através de modelos de riqueza e modelos nulos baseados na presença / ausência. Os resultados revelam alta riqueza de espécies e baixa diversidade, sendo identificados três filos, cinco classes, 11 ordens e 28 famílias na área de estudo durante as quatro estações do ano. O filo de Arthropoda foi o mais representativo em abundância e riqueza. Em relação à riqueza, Trichoptera (7) e Diptera (6) seguidos por Ephemeroptera (3) foram as ordens que mostraram a maior diversidade de famílias, no entanto, uma baixa diversidade com H'≤ 1,5 nit foi registrada na área de estudo. Demonstramos através dos modelos nulos, a randomização nas associações de espécies correspondentes aos três locais analisados. As informações aqui fornecidas contribuem para a compreensão dos padrões ecológicos das comunidades de invertebrados no rio Allipén, estabelecendo a base para estudos ecológicos mais complexos.(AU)

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One of the biological indicators most used to determine the health of a fluvial ecosystem are the benthic macroinvertebrates. The presence of recurrent species in a wide gradient of latitudes, dominates the biogeographic pattern of the benthic macroinvertebrates in Chilean fresh waters, nevertheless the knowledge on the communitarian ecology of these in the Chilean rivers continues to be scarce. Null models became a powerful statistical tool for describing the ecological mechanisms that drive the structure of an ecological community and the underlying patterns of diversity. The objective of this study was to determine the community structure of benthic invertebrates in the Allipén River by describing their composition, richness and abundance of species through richness models and null models based on presence/absence. The results reveal a high family richness and low diversity, three phyla, five classes, 11 orders and 28 families were identified in the study area during the four seasons of the year. The Arthropoda phylum was the most representative in abundance and richness. Regarding to richness, Trichoptera (7 families) and Diptera (6 families) followed by Ephemeroptera (3 families) were the orders that showed the greatest diversity of families, however, a low diversity with a H'≤ 1.5 nit was registered in the study area. We demonstrated through the null models, the randomization in the species associations corresponding to the three analyzed sites. The information provided here contributes to the understanding of the ecological patterns of the invertebrate communities in the Allipén River, establishing the basis for more complex ecological studies.

Um dos indicadores biológicos mais utilizados para determinar a saúde de um ecossistema fluvial são os macroinvertebrados bentônicos. A presença de espécies recorrentes em um amplo gradiente de latitudes domina o padrão biogeográfico dos macroinvertebrados bentônicos nas águas doces do Chile; no entanto, o conhecimento sobre a ecologia comunitária destes nos rios chilenos continua escasso. Os modelos nulos se tornaram uma poderosa ferramenta estatística para descrever os mecanismos ecológicos que orientam a estrutura de uma comunidade ecológica e os padrões subjacentes da diversidade. O objetivo deste estudo foi determinar a estrutura da comunidade de invertebrados bentônicos no rio Allipén, descrevendo sua composição, riqueza e abundância de espécies através de modelos de riqueza e modelos nulos baseados na presença / ausência. Os resultados revelam alta riqueza de espécies e baixa diversidade, sendo identificados três filos, cinco classes, 11 ordens e 28 famílias na área de estudo durante as quatro estações do ano. O filo de Arthropoda foi o mais representativo em abundância e riqueza. Em relação à riqueza, Trichoptera (7) e Diptera (6) seguidos por Ephemeroptera (3) foram as ordens que mostraram a maior diversidade de famílias, no entanto, uma baixa diversidade com H'≤ 1,5 nit foi registrada na área de estudo. Demonstramos através dos modelos nulos, a randomização nas associações de espécies correspondentes aos três locais analisados. As informações aqui fornecidas contribuem para a compreensão dos padrões ecológicos das comunidades de invertebrados no rio Allipén, estabelecendo a base para estudos ecológicos mais complexos.

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Introduction: The marine biodiversity is well known in some areas and for some marine ecosystems of the Pacific coast of Costa Rica. The marine sector of Área de Conservación Guanacaste, in the North Pacific of the country, is a priority area for conservation of marine and coastal biodiversity. Objective: Our aim was to increase the knowledge of marine biodiversity in a conservation priority site in Costa Rica and in poorly or scarcely studied marine ecosystems, such as rocky reefs and Sargassum beds, respectively. Methods: The study was conducted in Bahía Salinas and Golfo de Santa Elena in 2013. In January, four rocky reefs were visited; while in February three rocky reefs and one Sargassum bed were visited. We identified the macroinvertebrates and conspicuous fish species through underwater visual census methods (timed swim and band transects). The mean density of each species was estimated through band transects method. Results: A total of 25 invertebrates and 34 fish species were identified. We found a high number of species of invertebrates (23) and fish species (33) in rocky reefs, but few species on Sargassum beds (eight invertebrates and ten fish species). Species composition differed between marine ecosystems. Conclusions: Our study further evidence the limited knowledge of invertebrates and fish communities in these marine ecosystems in the North Pacific of Costa Rica. Considerably more surveys and field work are required to support management decisions that are backed by sound scientific knowledge.

Introducción: La biodiversidad marina es bien conocida en algunas áreas y para algunos ecosistemas marinos de la costa Pacífica de Costa Rica. El sector marino del Área de Conservación Guanacaste, en el Pacífico norte del país, es un área prioritaria para la conservación de la biodiversidad marina y costera. Objetivo: Nuestro objetivo fue el de incrementar el conocimiento de la biodiversidad marina en un sitio prioritario de conservación de Costa Rica y en ecosistemas marinos poco o nulamente estudiados, como son los arrecifes rocosos y mantos de Sargassum, respectivamente. Métodos: El estudio se realizó en Bahía Salinas y Golfo de Santa Elena en el 2013. En enero, cuatro arrecifes rocosos fueron visitados; mientras que en febrero tres arrecifes rocosos y un manto de Sargassum fueron visitados. Identificamos las especies de invertebrados y peces conspicuos a través métodos de censos visuales submarinos (buceos cronometrados y transectos de banda). La densidad promedio de cada especie se estimó mediante el método de transectos de banda. Resultados: Se registró un total de 25 invertebrados y 34 especies de peces. Encontramos un mayor número de especies de invertebrados (23) y peces (33) en los arrecifes rocosos, pero pocas especies en el manto de Sargassum (ocho especies de invertebrados y diez de peces). La composición de especies difirió entre ecosistemas marinos. Conclusiones: Nuestro estudio evidencia el limitado conocimiento de las comunidades de invertebrados y peces en estos ecosistemas marinos en el Pacífico Norte de Costa Rica. Considerablemente más encuestas y trabajo de campo son requeridos para apoyar decisiones de manejo que sean respaldados por conocimientos científicos solidos.

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Echinoderms are a major group of marine invertebrates that often play integral roles within the marine ecosystem. Studies about their occurrence, abundance, and distribution in Venezuela are focused in the central-eastern coasts; hence the aim of this study is to describe the echinoderm community in the north-western coast of the Gulf of Venezuela. Samples were collected from three sites in the Venezuelan Guajira Peninsula (Castilletes, Porshoure, and Kazuzain) where patchy coral reefs and seagrass meadows are abundant. According to the substrate, two methods were performed using quantitative (1 m² quadrates), and qualitative free-diving observations. All organisms were counted and identified to the lowest possible taxonomic level; finally, diversity (Shannon diversity index), richness (number of species), and dominance in the different sampled substrates were recorded. The updated list of echinoderms of the Gulf of Venezuela reported in this research, includes 20 genera, 15 families, 10 orders, four classes, and 28 species. The richest class was Ophiuroidea, with 18 species, followed by Asteroidea, Echinoidea and Holothuroidea, with three species each. Castilletes was the sampling site with the higher number of species (18 species), followed by Porshoure (15 species), and lastly Kazuzain (12 species). Our observations indicate that the number of species and abundance were higher when found in coral reefs (21 species, 80.69% of the total collected individuals) in contrast to the species found in seagrass beds (16 species, 19.31% of the total of individuals collected). This updated list of echinoderms represents 11.54% of the total diversity of the phylum in the marine areas from the coast of Venezuela; it is suggested that this percentage is greatly influenced by the differences of habitats and substrates alongside the north-western coast in the Gulf of Venezuela.(AU)

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Ornamentula Kisielewski, 1991 is a monospecific genus in Order Chaetonotida. The sole species, O. paraensis Kisielewsk, 1991, is a semiplanktonic gastrotrich found in a single pond in the Amazon region of Brazil. Herein we describe a new species of the genus Ornamentula, collected in a small urban lagoon in the Atlantic Forest of southeast Brazil. Ornamentula miyazakii sp. nov. resembles O. paraensis, but it shows differences in the ornamented trunk scales and spinal spines distribution, sufficient to proposte it as it’s a new species.

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Ornamentula Kisielewski, 1991 is a monospecific genus in Order Chaetonotida. The sole species, O. paraensis Kisielewsk, 1991, is a semiplanktonic gastrotrich found in a single pond in the Amazon region of Brazil. Herein we describe a new species of the genus Ornamentula, collected in a small urban lagoon in the Atlantic Forest of southeast Brazil. Ornamentula miyazakii sp. nov. resembles O. paraensis, but it shows differences in the ornamented trunk scales and spinal spines distribution, sufficient to proposte it as its a new species.(AU)

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The Southeast Pacific comprises two Large Marine Ecosystems, the Pacific Central-American Coastal and the Humboldt Current System; and is one of the less well known in the tropical subregions in terms of biodiversity. To address this, we compared DNA barcoding repositories with the marine biodiversity species for the Southeast Pacific. We obtained a checklist of marine species in the Southeast Pacific (i.e. Colombia, Ecuador, Chile, and Peru) from the Ocean Biodiversity Information System (OBIS) database and compared it with species available at the Barcoding of Life Data System (BOLD) repository. Of the 5504 species records retrieved from OBIS, 42% of them had at least one registered specimen in BOLD (including specimens around the world); however, only 4.5% of records corresponded to publicly available DNA barcodes including specimens collected from a Southeast Pacific country. The low representation of barcoded species does not vary much across the different taxonomic groups or within countries, but we observed an asymmetric distribution of DNA barcoding records for taxonomic groups along the coast, being more abundant for the Humboldt Current System than the Pacific Central-American Coastal. We observed high-level of barcode records with Barcode Index Number (BIN) incongruences, particularly for fishes (Actinopterygii = 30.27% and Elasmobranchii = 24.71%), reflecting taxonomic uncertainties for fishes, whereas for Invertebrates and Mammalia more than 85% of records were classified as data deficient or inadequate procedure for DNA barcoding. DNA barcoding is a powerful tool to study biodiversity, with a great potential to increase the knowledge of the Southeast Pacific marine biodiversity. Our results highlight the critical need for increasing taxonomic sampling effort, the number of trained taxonomic specialists, laboratory facilities, scientific collections, and genetic reference libraries.

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Domesticator-domesticate relationships are specialized mutualisms where one species provides multigenerational support to another in exchange for a resource or service, and through which both partners gain an advantage over individuals outside the relationship. While this ecological innovation has profoundly reshaped the world's landscapes and biodiversity, the ecological circumstances that facilitate domestication remain uncertain. Here, we show that longfin damselfish (Stegastes diencaeus) aggressively defend algae farms on which they feed, and this protective refuge selects a domesticator-domesticate relationship with planktonic mysid shrimps (Mysidium integrum). Mysids passively excrete nutrients onto farms, which is associated with enriched algal composition, and damselfish that host mysids exhibit better body condition compared to those without. Our results suggest that the refuge damselfish create as a byproduct of algal tending and the mutual habituation that damselfish and mysids exhibit towards one another were instrumental in subsequent mysid domestication. These results are consistent with domestication via the commensal pathway, by which many common examples of animal domestication are hypothesized to have evolved.

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The nemertean Malacobdella arrokeana is a commensal of the edible giant bivalve Panopea abbreviata; both species have a restricted geographic distribution, high specificity and populations settled along distinct biogeographic provinces. This supposes a high genetic structuring among populations and low intra-populational variability; nevertheless, a lack of genetic structure was detected previously between M. arrokeana populations from the Atlantic Northern Patagonia Gulfs System (NPGS) by means of mitochondrial and nuclear markers. Here, we present a model that explains this lack of genetic structure, integrating larval development and behavior, as well as bio-oceanographical model simulations. We observed in cultured larvae a maximum 30 days of planktonic life before settlement. Planuliform larval morphology and behavior of M. arrokeana suggested that the dispersion is more influenced by passive transport rather than active swimming. Modeling larvae as particles indicated that the limit of biogeographical provinces along the NPGS is not a barrier for dispersal, corroborating that larval dispersion is strictly related to season and to hydrodynamic diffusion patterns present in the area. These results explain the lack of genetic population structure recorded before in the NPGS. Our results provide novel baseline data regarding larval connectivity and oceanographic circulation patterns on the southwestern Atlantic. This information can be used as a reference for the implementation of management plans of invertebrate species with pelagic larvae to ensure the long-term viability of fishery resources shared by different government districts.

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Introducción: Los arroyos asociados a bofedales se hallan en ambientes donde las condiciones son extremas con temperaturas muy variables, baja presión atmosférica e intensa radiación solar. Sin embargo, existen ensamblajes de macroinvertebrados asociados a estos ambientes, cuya información es escasa. A escala global y regional, las características de los macroinvertebrados cambian con el aumento de la latitud y altitud (disminución de la riqueza y variación de la composición). A nivel local, también se puede agregar el efecto de las aguas ácidas y de elevada conductividad proveniente de manantiales que se unen a los arroyos, que generan heterogeneidad en la calidad de agua y consecuentemente en las características de los macroinvertebrados. Objetivo: Comparar la diversidad, composición y abundancia de macroinvertebrados y las características fisicoquímicas del agua de arroyos asociados a dos bofedales altoandinos, ubicados en el departamento de Ayacucho, Perú. Metodología: Se estudiaron once estaciones ubicados en arroyos de dos bofedales: 7 en Guitarrachayocc (G) de 43 ha (n = 28) y 4 en Pichccahuasi (P) de 28 ha (n = 8). Se empleó una red de Surber (0.3 mm de malla, área de muestreo de 1 200 cm2), para realizar muestreos mensuales de octubre de 2016 a abril de 2017. Análisis de componentes principales (PCA) y análisis de varianza multivariante no paramétrico (NP-MANOVA) se aplicaron para comparar las características del agua. Además, se utilizó un análisis de coordenadas principales (PCoA) y NP-MANOVA para comparar el ensamblaje. La prueba no paramétrica de Kruskal-Wallis (α = 0.05) se utilizó para comparar las abundancias absolutas de los taxa principales. Resultados: Las características del agua fueron heterogéneas, con pH de 3.2 (± 0.4) a 7.6 (± 0.1), conductividad de 168.9 (± 91) µS/cm a 1 117 (± 159.3) µS/cm; diferencias que fueron significativas (p < 0.05) al comparar las estaciones de muestreo, donde el agua de G6 presenta los mínimos valores de pH y los máximos de conductividad, al igual que cloruros. Se recolectaron un total de 8 126 individuos, distribuidos en 26 taxa de 20 familias, 11 órdenes y cinco clases. Los insectos fueron el grupo más diverso y abundante. A pesar a la cercanía de los arroyos de los bofedales, presentaron diferencias: en G, se registró 25 taxa, con dominancia de Macrelmis sp., Dicrotendipes sp., Claudioperla sp., Meridialaris sp. y en P, 9, con dominancia de Pedrowygomya sp., Hyalella sp. y Dicrotendipes sp. La densidad fue de 475 ind./m2 y de 31 ind./m2 para el bofedal G y P respectivamente, estos valores fueron estadísticamente diferentes (p < 0.05). El PCoA y el PCA confirmados por NP-MANOVA mostraron que G6 es diferente (p < 0.05) dentro de G porque recibe el aporte de agua de un manantial. Conclusiones: La riqueza, composición y densidad de los macroinvertebrados son diferentes en los arroyos según el bofedal al cual se halla asociado. La contribución de los manantiales a los arroyos genera cambios drásticos en la calidad del agua y los macroinvertebrados, determinando la formación de ensamblajes con diferente riqueza y estructura.

Introduction: Streams associated with high Andean wetlands are found in environments where conditions are extreme, highly variable temperature, low atmospheric pressure, intense solar radiation. The macroinvertebrate assemblages have been poorly studied compared to streams located at lower altitudes. On a global and regional scale, the characteristics of macroinvertebrates change with the increase in latitude and altitude (decreasing in richness and variation in composition). At the local level, the effect of acidic waters with high conductivity from springs that join streams generate heterogeneity in water quality and consequently in the characteristics of macroinvertebrate structure. Objective: To compare the diversity, composition and abundance of macroinvertebrates and the physicochemical characteristics of stream water in two high Andean wetlands in Peru. Methodology: Eleven stations located in streams of two high Andean wetlands were studied: 7 in Guitarrachayocc (G) of 43 ha (n = 28) and 4 in Pichccahuasi (P) of 28 ha (n = 8). A Surber sampler (0.3 mm mesh, sampling area of 1 200 cm2) was used to carry out monthly samplings from October 2016 to April 2017. Principal Component Analysis (PCA) and Non-Parametric-Multivariate-Analysis-Of-Variance (NP-MANOVA) were applied to compare water characteristics. The macroinvertebrate assemblages from the two streams were compared by using a Principal coordinate analysis (PCoA), NP-MANOVA, and a non-parametric Kruskal-Wallis test (α = 0.05). Results: The characteristics of the water were heterogeneous, with significant differences in pH which ranged from 3.2 (± 0.4) to 7.6 (± 0.1) and conductivity ranging from 168.9 (± 91.0) µS / cm to 1 117.0 (± 159.3) µS / cm. In particular, G6 presented the lowest pH values and the highest electrical conductivity, as well as chlorides. A total of 8 126 individuals were collected, distributed in 26 taxa from 20 families, 11 orders and five classes. Insects were the most diverse and abundant group. Differences were found between the streams of the highland wetlands, despite their proximity: in G, 25 taxa were registered, with a dominance of Macrelmis sp., Dicrotendipes sp., Claudioperla sp. and Meridialaris sp. and in P, 9, with a dominance of Pedrowygomya sp., Hyalella sp. and Dicrotendipes sp. The density was 475 ind./m2 and 31 ind./m2 for G and P respectively, these values were statistically different (p < 0.05). The PCoA and PCA confirmed by NP-MANOVA showed that G6 was different (p < 0.05) within G because it receives water contribution from a spring. Conclusions: The richness, composition and density of macroinvertebrates were different in streams depending on the bofedal with which it is associated. The contribution of the springs to the streams generates drastic changes in the quality of the water and the macroinvertebrates, determining the formation of assemblages with different richness and structure.

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Introducción: La distribución de los macroinvertebrados acuáticos en los ríos puede estar determinada por el tipo del sustrato, la forma del canal del río, el régimen hidrológico y las interacciones con factores bióticos y abióticos. En Costa Rica se desconoce en gran parte de los ríos, las variaciones en la distribución de los macroinvertebrados acuáticos producto de las transiciones y consecuentes variaciones en características fisicoquímicas e hidrológicas. Objetivos : 1) Estudiar el cambio del ensamblaje de macroinvertebrados acuáticos en dos sitios dentro del cauce del Río Naranjo, durante los cuatro periodos hidrológicos del año; 2) determinar la relación entre las variables fisicoquímicas, sustrato y el caudal con el ensamblaje. Metodología: El estudio se realizó en el Río Naranjo, Costa Rica, en dos sitios de muestreo durante un año, evaluando los cuatro periodos hidrológicos del año. En cada sitio de muestreo se obtuvieron valores de velocidad y profundidad del agua, caudal, oxígeno disuelto, pH, conductividad, sulfatos, amonio, nitrato, silicatos, fosfatos y sustrato, y se obtuvo una muestra de macroinvertebrados acuáticos por cada tipo de microhábitat determinado por la velocidad del agua. Se realizó una prueba PERMANOVA de dos vías, para determinar si existe una diferencia entre la abundancia de macroinvertebrados acuáticos, por periodo y entre sitios. Se hizo un análisis de correspondencia canónica para observar la relación entre los macroinvertebrados acuáticos y los factores ambientales. Por último, se realizó una prueba de Spearman para determinar la relación positiva o negativa de las variables con los macroinvertebrados Resultados: Hubo una mayor abundancia durante la estación seca, mientras que durante la transición de la estación seca a la lluviosa se registró la menor abundancia de organismos. El ACC indicó que el primer eje presentó una relación positiva con el sustrato limo y arena, y una relación negativa para las variables velocidad de corriente y sustrato rocoso. El segundo eje presentó una relación positiva con el caudal y los nitratos, y negativa para el sustrato canto rodado. La mayoría de los organismos mostraron una respuesta negativa al aumento del flujo y los nitratos. Discusión: Conforme aumenta el caudal, aumenta la velocidad del agua y no todos los organismos registrados en el Río Naranjo cuentan con características para sobrevivir a estas condiciones. Además, la profundidad también aumenta junto con la fuerza de arrastre, provocando el movimiento de los sustratos de menor tamaño y una remoción de organismos. El aumento de nitratos puede generar una disminución de los organismos más sensibles como Plecoptera y Ephemeroptera. A pesar de las variaciones fisicoquímicas y de caudal registradas en el Río Naranjo, éstas no fueron lo suficientemente fuertes como para variar el ensamblaje de macroinvertebrados acuáticos, por lo que la cuenca por el momento no cuenta con factores estresantes que elimine organismos durante uno o varios meses del año.

Introduction: The distribution of aquatic macroinvertebrates in rivers may be determined by the type of substrate, the shape of the river channel, the hydrological regime, and interactions with biotic and abiotic factors. Variations in the distribution of aquatic macroinvertebrates due to transitions and variations in physicochemical and hydrological characteristics are unknown in most rivers. Objectives: 1) to study the change in the aquatic macroinvertebrates assemblages in two sites in Naranjo River, during the four hydrological seasons; 2) to determine the relationship between the physicochemical variables, substrate and flow with the assemblages. Methodology: The study was conducted in the Naranjo River, Costa Rica, at two sampling sites during one year, evaluating the four seasons of the year. In each station we measure, values of water velocity and depth, flow rate, dissolved oxygen, pH, conductivity, sulfates, ammonium, nitrate, silicates, phosphates, and substrate were obtained, and a sample of aquatic macroinvertebrates was obtained for each type of microhabitat determined by water velocity. Two-way PERMANOVA was made to determine if there is a difference among aquatic macroinvertebrate abundance, per period and between sites. Canonical correspondence analysis was used to observe the relationship between aquatic macroinvertebrates and environmental factors. Finally, a Spearman's rank correlation coefficient was performed to determine the positive or negative relationship of variables with macroinvertebrates. Results: There was a greater abundance during the dry season, while during the transition from dry to the rainy season, the lowest abundance of organisms was recorded. The CCA indicates that the first axis presented a positive relationship with the silt and sand substrate and a negative relationship for the current velocity and rock substrate variables. The second axis showed a positive relationship with flow and nitrates and negative for the pebble substrate. Most organisms showed a negative response to increased flow and nitrates. Discussion: As flow increases, current velocity increases, and not all organisms recorded in the Naranjo River have the characteristics to survive these conditions. In addition, the depth also increases along with the drag force, causing movement of smaller substrates and removal of organisms. Increased nitrates can lead to a decrease in more sensitive organisms, such as Plecoptera and Ephemeroptera. In spite of the physicochemical and flow variations registered in the Naranjo River, these were not strong enough to vary the assemblages of aquatic macroinvertebrates, so the basin does not have stressful factors that eliminate organisms during one or several months of the year.

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Introduction: The benthic fauna of the littoral zone in lakes is important in transferring energy to other trophic levels, habitat coupling, and helping to keep habitat stability. The study of this type of interactions in lentic systems is priority, since functional aspects about biological communities are unknown. Objective: Describing the trophic relations of aquatic invertebrates of the littoral zone in a tropical high mountain lake by characterizing gut content and stable isotope analysis of δ13C and δ15N. Methods: Samples of benthic invertebrates were collected in the littoral zone of the Lago de Tota where Egeria densa was present using a handheld net method. Samples were processed in the laboratory, organisms were identified, counted and weighed. Gut contents and δ13C and δ15N stable isotopes analysis were performed as well. Results: Records of the trophic relations of aquatic invertebrates, which live in the littoral in high mountain lentic ecosystem in the Neotropics are shown. The analysis of gut contents distinguished seven food items, microphytes and MOPF were the most frequent, and through the stable isotopes analysis (δ15N) we identified four trophic levels, among resources (macrophytes and POM), and consumers (detritivores, herbivores, and predators). The two upper trophic levels concentrated greater diversity and biomass. Conclusion: Most of the organisms studied were linked to omnivorous habits, evidenced in a wide spectrum of food items in their diet. The δ15N values show an enrichment, which occurs due to the effects of the tendency towards eutrophication of the system or due to unknown values of protozoa and bacteria that plays a fundamental role in the diet of these organisms, besides the δ13C values reported in organisms consumes, allows us to suggest an affinity with native resources of the littoral zone.

Introducción: La fauna béntica de la zona litoral de los lagos constituye un vínculo importante en el acoplamiento de hábitats, dinamizando los procesos de transferencia de materia y energía, y con ellos la estabilidad del sistema. El estudio de este tipo de interacciones en sistemas lénticos es prioritario, ya que existen vacíos de información sobre aspectos funcionales que involucran a las comunidades biológicas. Objetivo: Describir las relaciones tróficas de invertebrados acuáticos de la zona litoral de un lago de alta montaña tropical mediante caracterización de contenidos estomacales y análisis de isótopos estables de δ15N y δ13C. Métodos: Se colectaron muestras en la zona litoral del Lago de Tota, asociadas con la presencia de Egeria densa utilizando una red portátil. Las muestras se procesaron en el laboratorio donde los organismos se identificaron, contaron y pesaron. También se realizaron análisis de contenido estomacal e isótopos estables δ13C y δ15N. Resultados: Presentamos registros sobre hábitos tróficos de invertebrados acuáticos de litoral para ecosistemas lénticos de alta montaña del Neotrópico. El análisis de contenido estomacal permitió distinguir siete ítems alimenticios, donde los micrófitos y la MOPF fueron los recursos más frecuentes y el análisis de isótopos estables permitió identificar cuatro niveles tróficos, un nivel basal que hace referencia a los recursos (Macrófitos, MOP) y consumidores detritívoros, herbívoros y depredadores. Los dos niveles tróficos superiores concentraron mayor diversidad y biomasa. Conclusión: La mayor parte de los organismos estudiados fueron vinculados con hábitos omnívoros, evidenciado en un amplio espectro de ítems alimenticios en su dieta. Los valores de δ15N muestran un enriqueciendo que puede deberse a la tendencia del lago hacia la eutroficación o por valores desconocidos de protozoos y bacterias que pueden estar jugando un rol fundamental en la dieta de estos organismos, adicionalmente los valores de δ13C reportados en los organismos consumidores nos permiten sugerir una afinidad hacia recursos propios de la región litoral.

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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.

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Introduction: Glacierised catchments are remote and hostile environments, in which streams from different water sources (e.g., glacier melt, rain/snowmelt, groundwater) converge, creating a complex mosaic of stream sites with varying levels of glacial influence and environmental conditions. This environmental heterogeneity, in turn, influences the assemblage and composition of aquatic communities and produces complex patterns of species diversity at the catchment scale. Objectives: In this contribution, we assessed biodiversity and community composition of aquatic macroinvertebrate communities from 51 stream site types in a glacierised catchment in the tropical Andes. The aim of our study was to: (1) determine diversity, rarity, commonness and spatial distribution patterns of aquatic macroinvertebrate communities from sites with different water sources, and (2) identify which environmental variables influence the density and presence of macroinvertebrate taxa and, in particular, of the subfamilies of the ubiquitous chironomids. Methods: Our study sites were grouped according to their water source and to their percentage of glacier coverage in the catchment (GCC). At each site we sampled aquatic macroinvertebrates, measured environmental variables and assessed community differences and environmental influence with ordination analyses and generalized linear models. Results: Kryal and mixed sites had an important proportion of rare taxa. Mean richness was highest in the mixed sites and lowest in the sites with the highest glacier cover; while sites with an intermediate percentage of glacier cover, had the highest values of α and β diversity. We found that 13 taxa (15.9%) were common to all stream site types. SIMPER analysis showed that Orthocladiinae, Hyalella sp. and Andesiops sp. contributed the most to the dissimilarity between site types (˃ 45% of cumulative contribution). RDA showed that kryal sites were associated with high turbidity and density of Podonomids, and with low temperature, amount of CPOM and densities of both Anomalocosmoecus sp. and Andesiops sp. Orthocladinae was associated with high current velocity and chlorophyll a concentration, whereas Hyalella sp. had a positive relationship with higher pH and streambed stability. Generalized linear models showed that GCC was the main variable explaining all faunal metrics. Current velocity explained macroinvertebrate abundance, water temperature was related to chironomid density and chlorophyll a influenced Orthocladiinae presence-absence. Conclusions: Our results suggest that by favoring the presence of rare taxa and taxa turnover, glacier influence may increase biodiversity in glacierised catchments. In terms of biodiversity conservation, this study confirms an urgent need to increase knowledge of high-Andean stream biodiversity, especially in highly heterogenous glacierised catchments, to better describe regional biodiversity patterns and community composition of these highly vulnerable freshwater ecosystems. Detailed analyses of benthic communities and development of databases are key for conservation strategies. Water management municipalities and/or enterprises should consider water quality and stream types for more sustainable management of these important ecosystems.

Introducción: Las cuencas glaciares son entornos remotos y hostiles, en los que los arroyos de diferentes fuentes de agua (p.ej., deshielo de glaciares, lluvia/deshielo, agua subterránea) convergen, creando un mosaico complejo de tramos con diferentes niveles de influencia glacial y condiciones ambientales. Esta heterogeneidad ambiental influye, a su vez, en el ensamblaje y composición de las comunidades acuáticas y produce complejos patrones de diversidad a la escala de la cuenca. Objetivos: En esta contribución, evaluamos la biodiversidad y composición de comunidades de macroinvertebrados acuáticos en 51 sitios de una cuenca glaciar en los Andes tropicales. Los objetivos de nuestro estudio fueron: (1) determinar la diversidad, la contribución de taxones raros y comunes y los patrones de distribución espacial de las comunidades de macroinvertebrados acuáticos en sitios con diferentes fuentes de agua, y (2) identificar qué variables ambientales influyen en la densidad y presencia de taxones de macroinvertebrados y, en particular, de las subfamilias de los omnipresentes quironómidos. Métodos: Agrupamos a nuestros sitios de estudio según su fuente de agua y su porcentaje de cobertura de glaciar en la cuenca (GCC). En cada sitio donde muestreamos macroinvertebrados acuáticos, medimos variables ambientales y evaluamos las diferencias entre comunidades y la influencia ambiental con análisis de ordenación y modelos lineales generalizados. Resultados: Los sitios kryal y mixtos tuvieron una proporción importante de taxones raros. La riqueza media fue más alta en los sitios mixtos y más baja en los sitios con mayor cobertura glaciar; mientras que los sitios con un porcentaje intermedio de cobertura glaciar tuvieron los valores más altos de diversidad α y β. Encontramos que 13 taxones (15,9%) fueron comunes a todos los tipos de sitios de estudio. El análisis SIMPER mostró que Orthocladiinae, Hyalella sp. y Andesiops sp. contribuyeron más a la disimilitud entre tipos de sitios (˃ 45% de la contribución acumulada). El RDA mostró que los sitios kryal estaban asociados con alta turbidez y densidad de podonómidos, y con baja temperatura, cantidad de CPOM y densidad de Anomalocosmoecus sp. y Andesiops sp. Orthocladinae se asoció con una alta velocidad de corriente y concentración de clorofila a, mientras que Hyalella sp. tuvo una relación positiva con pH más alto y estabilidad del lecho del río. Los modelos lineales generalizados mostraron que GCC fue la variable principal para explicar todas las métricas de fauna. La velocidad de corriente explicó la abundancia de macroinvertebrados, la temperatura del agua estuvo relacionada con la densidad de los quironómidos y la clorofila influenció la presencia-ausencia de Orthocladiinae. Conclusiones: Nuestros resultados sugieren que, al favorecer la presencia de taxones raros y la rotación de taxones, la influencia de los glaciares puede aumentar la biodiversidad en cuencas con influencia glaciar. En términos de conservación de la biodiversidad, este estudio confirma la necesidad urgente de incrementar el conocimiento de la biodiversidad en arroyos de la región altoandina, especialmente en cuencas glaciares altamente heterogéneas, para describir mejor los patrones de biodiversidad regional y la composición de las comunidades en estos ecosistemas altamente vulnerables. Análisis detallados de las comunidades bentónicas y el desarrollo de bases de datos son claves para diseñar estrategias de conservación. Los municipios y/o empresas administradoras de agua deben considerar la calidad del agua y los tipos de arroyos para una gestión más sostenible de estos importantes ecosistemas.

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Introducción: Existen diferentes metodologías para la recolecta de macroinvertebrados acuáticos (p.e., la red D y Red Surber), sin embargo, algunas de estas no son efectivas en todos los cuerpos de agua o representa un riesgo para la persona que adquiere la muestra. Los sustratos artificiales pueden emplearse en ríos profundos, contaminados o con presencia de cocodrilos. En Costa Rica hay estudios donde se utilizó los sustratos artificiales, para determinar la riqueza y abundancia en humedales tipo lago y lagunas, no obstante se desconoce la efectividad de un tipo de sustrato sobre otro y en sistemas lóticos. El objetivo del estudio fue demostrar la efectividad de tres tipos de sustratos artificiales. Métodos: las muestras se obtuvieron de manera bimensual entre los años 2013 y 2017, en el Río Parismina, Costa Rica, en cuatro sitios a lo largo del río y se evaluó los sustratos piedra, madera y hojas. Se aplicó una prueba de Kruskal-Wallis para determinar las diferencias entre la abundancia y el tipo de sustrato, como también para determinar la diferencia entre la abundancia y el sitio de muestreo. Además, para determinar si existe una diferencia entre los sustratos por sitio, se aplicó una prueba Permanova de dos vías. Un análisis de correspondencia múltiple para determinar el grado de asociación de la comunidad con respecto al tipo de sustrato. Resultados: Un total de 1159 organismos fueron recolectados, siendo Diptera y Ephemeroptera los órdenes más abundantes. La madera y hojas fueron los sustratos con mayor biodiversidad, como también los sitios con mayor vegetación. Conclusiones: El uso en conjunto de los tres tipos de sustratos artificiales, es efectivo para obtener una mayor riqueza de organismos, ya que se observó afinidad por un sustrato según el género de macroinvertebrado acuático.

Introduction: Different methodologies exist for sampling aquatic macroinvertebrates, however, some of these (e.g., kick-net, Surber) are not well suited for deep, contaminated rivers or rivers with presence of crocodiles, which represent a risk to the person who must take the sample. One alternative is to use artificial substrates. The use of artificial substrates to evaluate the aquatic macroinvertebrate biodiversity in wetlands has been studied previously in Costa Rica, but no research has been conducted to determine which types of substrates are most effective. The present study aimed to evaluate the effectiveness of three artificial substrates (i.e., stones, leaves and wood). Methods: Samples of the three substrates were taken bi-monthly between 2013 and 2017 in four sites of the Parismina River. A Kruskal-Wallis test was applied to determine differences between the macroinvertebrate abundance among substrate type. Beside to determine if there is a difference between substrates per site, a two-way PERMANOVA test was applied and a multiple correspondence analysis was used to correlate the substrate type with the macroinvertebrate community. Results: A total of 1 159 organisms were collected, with Diptera and Ephemeroptera being the most abundant. Wood and leaves were the substrates with greatest biodiversity and abundance of organisms; in addition the two sites with greatest vegetation were the most diverse. Conclusions: Most of the organisms were registered on any of the three types of artificial substrates, thus we recommend the joint use of the three types of substrates for biomonitoring or taxa richness studies.

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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.

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Introducción: Describir los patrones de biodiversidad y los mecanismos que los subyacen es indispensable para afrontar las desenfrenadas presiones sobre los ecosistemas de agua dulce en el trópico. Esto es particularmente relevante en regiones escasamente estudiadas como el escudo guayanés colombiano Objetivo: Describir la estructura taxonómica y funcional de las comunidades de macroinvertebrados, y evaluar su variación a lo largo de escalas espaciales y temporales Métodos: Las comunidades de macroinvertebrados de cuatro ríos fueron muestreadas durante la época seca del 2017 y 2018. Adicionalmente, se evaluaron los patrones de diversidad dentro y entre los ríos y entre diferentes meses de muestreo en uno de los cursos hídricos. Los patrones de diversidad fueron evaluados mediante la comparación de los patrones entre y dentro de los ríos de la diversidad alfa (diferencias en la riqueza y abundancia de taxones entre comunidades) y de la diversidad beta (diferencias en la composición de taxones entre comunidades). La diversidad alfa fue estimada usando los números de Hill, mientras que la diversidad beta se estimó usando los índices de Sørensen y Morisita-Horn y comparada usando un análisis de similaridad (ANOSIM). Resultados: La composición de taxones fue distinta dentro (escala de mesohábitat) y entre los ríos (escala regional). Sin embargo, la composición de FFG cambió entre, pero no dentro de los ríos. La comparación de los números de Hill y de la composición de taxones sugiere que el tipo de mesohábitat es un factor determinante de la diversidad taxonómica pero no de la diversidad de FFG en distintas escalas. En la escala temporal, la diversidad alfa fue baja para los meses con altas precipitaciones (febrero-abril) y alta para la temporada seca (enero). La diversidad beta temporal fue alta para los periodos muestreados y los procesos de anidamiento fueron el componente más notable de la diversidad beta a lo largo del año. Conclusión: Los ríos de la Serranía de la Lindosa albergan una alta diversidad de macroinvertebrados acuáticos. La estacionalidad y las diferencias en la heterogeneidad del hábitat dentro de los ríos parecen determinar los patrones de diversidad observados a diferentes escalas temporales y espaciales. Profundizar en su estudio es necesario para entender el funcionamiento de estos ecosistemas y mejorar la habilidad para generar estrategias de manejo y conservación.

Introduction: Describing biodiversity patterns and the underlying drivers is relevant for tackling the rampant pressures on tropical freshwaters. This is particularly relevant in scarcely studied regions, such as in the Colombian Guiana shield. Objective: To describe the taxonomic and functional structure of macroinvertebrate communities and assess their variability across spatial and temporal scales. Methods: We sampled the invertebrate communities in four streams during the dry seasons of 2017 and 2018. Additionally, we assessed diversity patterns within and among streams and between different sampling months in one stream. To assess diversity patterns, we compared alpha (differences in taxon richness and abundance within communities) and beta (differences in taxon composition among communities) diversity patterns among and within rivers. Alpha diversity was estimated using the numbers of Hill, while beta diversity was estimated using the Sørensen and Morisita-Horn indices and compared using a similarities analysis (ANOSIM). Results: The taxon composition of the communities was different within (mesohabitat scale) and among streams (regional scale). However, the composition of FFGs changed among but not within streams. The comparison of the numbers of Hill and the taxon composition suggested that the mesohabitat type is a determining factor of the taxonomic but not FFG diversity across scales. At the temporal scale, alpha diversity was low for months with high precipitation (February-April) and high for the dry season (January). The temporal beta diversity was high among sampling periods, being nestedness processes driving beta diversity among years and turnover processes driving beta diversity within years. Conclusion: Streams from Serranía de la Lindosa host a high diversity of freshwater macroinvertebrates. Seasonality and differences in the in-stream habitat heterogeneity seem to determine the diversity patterns observed at different temporal and spatial scales. A deeper study is needed to understand the functioning of these ecosystems and improve the ability to generate management and conservation strategies.

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