Abstract: Aim Macroinvertebrates are extensively employed as bioindicators for evaluating how stream ecosystems respond to alterations in physical and chemical habitats caused by human activity. Although family-taxonomic level is usually used to identify macroinvertebrates in biomonitoring programs, coarser taxonomic resolution may provide similar information. We aim to evaluate taxonomic sufficiency by comparing macroinvertebrate communities at the order and family levels to differentiate the effects of different land uses. Methods We conducted colonization experiments using artificial substrates in streams representing three land use types: urban (U, n=3), intensive agriculture - dairy production (AD, n=4), and extensive cattle ranching (CR, n=4). Results We obtained similar results using both taxonomic levels, which effectively distinguished the impacts of different land uses. In the sites examined, the majority of indicator groups exhibited only one family per order, with the exception of Ephemeroptera (Leptophlebiidae, Baetidae, and Caenidae). Notably, Baetidae and Caenidae were more prevalent in streams associated with extensive cattle ranching (CR). Conclusions Although this study provides a clear precedent, further investigation of these systems and other land uses (e.g., afforestation) is needed to validate this pattern. Coarser taxonomic assessment holds potential as a cost-effective method for stream monitoring and assessment in Uruguay. Abstract activity familytaxonomic programs information types U, U (U n=3, n3 n n=3 , 3 n=3) AD, AD (AD n=4, n4 n=4 4 n=4) CR, CR (CR n=4. . examined Leptophlebiidae, Leptophlebiidae (Leptophlebiidae Caenidae. Caenidae) Notably CR. (CR) precedent e.g., eg e g (e.g. afforestation pattern costeffective cost effective Uruguay n= e.g. (e.g e.g

Resumo: Objetivo Os macroinvertebrados são amplamente utilizados como bioindicadores para avaliar a forma como os ecossistemas de riachos respondem às alterações dos habitats físicos e químicos causadas pela atividade humana. Embora o nível taxonômico de família seja normalmente utilizado para identificar macroinvertebrados em programas de biomonitoramento, uma resolução taxonômica mais grosseira pode fornecer informações semelhantes. O objetivo é avaliar a suficiência taxonómica, comparando as comunidades de macroinvertebrados ao nível da ordem e da família, para diferenciar os efeitos de diferentes usos do solo. Métodos Realizamos experimentos de colonização utilizando substratos artificiais em cursos de água representativos de três tipos de uso do solo: urbano (U, n=3), agricultura intensiva - produção de leite (AD, n=4), e pecuária extensiva (CR, n=4). Resultados Obtivemos resultados semelhantes utilizando ambos os níveis taxonômicos, o que permitiu distinguir eficazmente os impactos dos diferentes usos do solo. Nos locais examinados, a maioria dos grupos indicadores apresentava apenas uma família por ordem, com exceção dos Ephemeroptera (Leptophlebiidae, Baetidae e Caenidae). Notavelmente, Baetidae e Caenidae foram mais predominantes em riachos associados à criação extensiva de gado (CR). Conclusões Embora este estudo forneça um precedente claro, é necessária uma investigação mais aprofundada destes sistemas e de outras utilizações do solo (por exemplo, reflorestamento) para validar este padrão. A avaliação taxonômica mais grosseira tem potencial para ser um método económico de monitoramento e avaliação de cursos de água no Uruguai. Resumo humana biomonitoramento taxonómica U, U (U n=3, n3 n n=3 , 3 n=3) AD, AD (AD n=4, n4 n=4 4 n=4) CR, CR (CR n=4. . taxonômicos examinados Leptophlebiidae, Leptophlebiidae (Leptophlebiidae Caenidae. Caenidae) Notavelmente CR. (CR) claro exemplo reflorestamento padrão Uruguai n=

La mayoría de los ríos en las montañas andinas de Venezuela en la cuenca del Orinoco sufren variadas perturbaciones. A pesar de esto, sus comunidades de peces han sido poco evaluadas en términos de sus gradientes espaciales y temporales. La generación de información sobre estas comunidades es prioritaria, y puede impulsar la conservación de los recursos hidrobiológicos regionales. Con este fin, seis localidades fueron evaluadas mensualmente en tributarios de la cuenca alta del río Turbio en la Sierra de Portuguesa (770-1 305msnm) durante el período de sequía y el inicio del período de lluvias (enero-abril de 2012), se caracterizaron las dimensiones del cauce, el sustrato y las variables físico-químicas del agua. Se utilizó electropesca para determinar el número y abundancia de especies de peces. Las comunidades de peces y su estabilidad se evaluaron explorando los cambios en la riqueza y abundancia y por coeficientes de variación, clasificación jerárquica y análisis de escalamiento multidimensional no métrico. El estado de conservación de las localidades se estimó con un índice de integridad del hábitat. La riqueza de 12 especies varió según la elevación, los tributarios y el estado de conservación de las localidades. Chaetostoma dorsale, Creagrutus taphorni y Chaetostoma milesi comprendieron el 90.8% de la abundancia relativa y mantuvieron los primeros rangos durante el período. Las comunidades tuvieron poca variación espacio-temporal y esta se expresó en un gradiente asociado principalmente por las coberturas de sombra, rocas y grava, la temperatura del agua y la conductividad. La estabilidad fue moderada, variando con la elevación y el estado de conservación de las localidades. Los tributarios en la cuenca alta del río Turbio se encuentran bajo impactos severos y sus ictiofaunas son empobrecidas y en situación de riesgo.

Most Andean mountain streams of the Orinoco Basin in Venezuela, had been suffering various disturbances. in spite of this, fish communities have been poorly evaluated in terms of spatial and temporal gradients. Thus, the generation of information about these communities is a priority, since it may support conservation of regional hydrobiological resources. For this, six sites were monthly evaluated in tributaries of upper Turbio River in Sierra de Portuguesa (770-1 305msnm), during the dry season and the beginning of the rainy season (January-April 2012); we characterized stream dimensions, substrate and water physicochemical variables. Electrofishing was used to determine the number and abundance of fish species. The fish communities and their stability were evaluated by exploring the changes in richness and abundance, coefficients of variation, hierarchical classification and non-metrical multidimensional scaling analysis. The sites conservation status was estimated with a habitat integrity index. Our results showed that richness of the 12 species found varied according to the mountain elevation, the tributaries and the conservation status of the sites. Chaetostoma dorsale, Creagrutus taphorni and Chaetostoma milesi comprised 90.8% of the relative abundance, and maintained the first ranks during the study period. The communities had little spatio-temporal variation which was associated with a gradient signed principally by the amount of shadow, rocks and gravel cover, water temperature and conductivity. Stability was moderate but varied with elevation and according to site conservation status. The tributaries in upper Turbio River were found to be under severe impacts and their fishes were found impoverished and at risk.

Las fuertes perturbaciones en la cuenca del río Turbio (vertiente andina del río Orinoco en Venezuela) requieren la evaluación de sus afluentes para contribuir con el manejo adecuado de los recursos hidrobiológicos. Con este fin, durante el período de sequía de 2011 y en localidades de muestreo ubicadas en la cuenca alta se midieron los cauces, la cobertura del sustrato y las variables del agua; igualmente, se estimó el estado de conservación del ambiente ribereño según un índice de conservación fluvial (ICF) y se colectaron insectos acuáticos mediante protocolos estandarizados. Con base en la abundancia de familias de insectos se aplicaron índices para estimar la variación en su riqueza, dominancia y diversidad y el estado de la calidad de las aguas (índices bióticos de BMWP’ e IBF), los cuales fueron relacionados con variables sintéticas del hábitat fluvial generadas en un análisis de ordenación multivariada y con los valores del ICF. El gradiente en el hábitat fluvial y el ICF predijeron significativamente los atributos de las familias de insectos, así como en los índices bióticos. Gran parte de los afluentes en la cuenca alta del río Turbio tienen cauces y ambientes ribereños con perturbaciones evidentes que se expresan en pérdida de la riqueza y diversidad de los insectos acuáticos.

Significant negative impacts in the Turbio River watershed (located in the Andean versant of Orinoco River in Venezuela) require evaluation of the tributaries to achieve adequate management of the hydrobiological resources. During the dry season of 2011, measurements of dimensions, substrate types and coverage, and water quality parameters were taken at sample sites in the upper stream reaches of the drainage of riverbed. At the same time, estimates of the conservation status of the riverine environments were made using an index of fluvial conservation (ICF) and aquatic insects were collected using standard protocol methods. Based on the abundance of families of the insects found, indices were calculated to estimate their variation in richness, dominance and diversity, and water quality status (using biotic indices from BMWP’ and IBF); these were found to be correlated with synthetic variables of fluvial habitat generated using multivariate ordination techniques and the values of the ICF. The fluvial habitat gradient and the ICF significantly predicted the variation observed in attributes of the insect families, as well as the biotic indices. The great majority of the tributaries of the Turbio River have obvious negative impacts that are reflected in a notable decline of the richness and diversity of aquatic insects.