169 research outputs found
Fish assemblages as biological indicators of ecological quality in portuguese rivers
No full textNo contexto da aplicação da Directiva-Quadro da Água, a ictiofauna é considerada como um
relevante elemento biológico. Pela primeira vez foi desenvolvido um sistema de classificação
para avaliação do estado ecológico dos ecossistemas aquáticos em Portugal, apesar dos
constrangimentos impostos pela variedade e ubiquidade das pressões humanas e pelas
peculiaridades dos agrupamentos piscícolas. Foram definidos grupos piscícolas para posterior
estabelecimento de uma tipologia nacional de rios, foram seleccionadas métricas responsivas ás
pressões humanas e foi desenvolvido um índice biótico piscícola. Os resultados evidenciam a
necessidade de diferenciar correctamente a resposta da ictiofauna ás perturbações naturais e
antropogénicas, considerando quer a variabilidade espacial, quer temporal dos agrupamentos
piscícolas, típica dos cursos de tipo Mediterrânico. O uso de solo tem fortes consequências na
degradação dos rios e na integridade da ictiofauna, sendo importante que a avaliação dos
impactos considere a interacção entre diferentes pressões. A compreensão da influência relativa
dos factores ambientais e humanos na ocorrência e abundância das espécies não nativas
permitiu evidenciar o potencial papel das mesmas como indicadores biológicos. Esta tese
contribuiu para o desenvolvimento e aperfeiçoamento de ferramentas de avaliação ecológica em
Portugal, permitindo igualmente um aumento do conhecimento sobre a ecologia das
comunidades piscícolas e funcionamento dos ecossistemas em rios de tipo Mediterrânico, com
vista à sua conservação e reabilitação; ABSTRACT:Under the implementation of the Water Framework Directive fish fauna is considered a useful
biological element. For the first time a Portuguese classification system to assess the ecological
status of aquatic ecosystems was established, despite several constrains posed by the variety
and ubiquity of human pressures and by the peculiarities of the fish assemblages. It was possible
to define fish-based geographical groups for the subsequent establishment of a national river
typology, to select metrics responsive to human pressures and to develop a fish biotic index.
Results underline the needs for accurately differentiate between fish responses to natural and
anthropogenic disturbances by accounting for the spatial and temporal variability of fish
assemblages. Land use may lead to strong impacts on stream degradation and fish assemblages
integrity and this evaluation must consider the interaction of different pressures. Understanding
the influence of environmental and human factors in the occurrence and abundance of non-native
species enlightened their role as a reliable tool in the ecological assessment of rivers. This thesis
represents an important contribution to improve the ecological assessment tools in Portugal,
while increasing knowledge on the ecology of fish communities and ecosystem functioning in
Mediterranean climate rivers in view of their urgent conservation
Macroinvertebrate-based multimetric predictive models for evaluating the human impact on biotic condition of bolivian streams
No full textWe developed and validated a single multimetric index based on predictive models that could evaluate anthropogenic disturbances in streams of three disparate ecoregions of Bolivia. To do so, we examined 45 candidate metrics reflecting different aspects of macroinvertebrate assemblage structure and function gleaned from available literature and for their potential to indicate degradation. More importantly, we integrated functional trait metrics to improve the sensitivity of our index. To quantify possible deviation from reference conditions, we first established and validated statistical models describing metric responses to natural environmental differences in the absence of any significant anthropogenic disturbance. We considered that the residual distributions of these models described the response range of each metric, independently of natural environmental influence. After testing the sensitivity of these residuals to a gradient of anthropogenic disturbance, we retained eight metrics that were used in the final assemblage index, four metrics based on richness and composition and four metrics based on biological traits. Our index performed well in discriminating between reference and disturbed sites, giving a significant negative linear response to a gradient of physical and chemical anthropogenic disturbances. After employing a probability survey design and sampling a relatively small number of sites throughout all major ecoregions of Bolivia, we believe our methodology can be used to develop a monitoring tool to evaluate status and trends in biological condition for streams of the entire country despite its complex and heterogeneous geology and climate.Fil: Moya, Nabor. Universidad Mayor de San Simón; Bolivia. Universite Pierre et Marie Curie; FranciaFil: Hugues, Robert M.. State University of Oregon; Estados UnidosFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Gibon, François Marie. Muséum National d'Histoire Naturelle; Francia. Universite Pierre et Marie Curie; FranciaFil: Goitia, Edgar. Universidad Mayor de San Simón; BoliviaFil: Oberdorff, Thierry. Muséum National d'Histoire Naturelle; Francia. Universite Pierre et Marie Curie; Franci
Development of a multimetric index based on aquatic macroinvertebrates to assess the biological integrity in streams of the Bolivian inter-Andean valleys
No full textSe presenta un índice multimétrico que permite discriminar la variabilidad ambiental natural de la antropogénica en 91 sitios (63 sitios de referencia y 28 sitios perturbados) distribuidos de manera uniforme a lo largo de la cuenca alta del Río Grande (Bolivia). En este procedimiento se utilizaron inicialmente 12 métricas que reflejan distintos atributos de la estructura y el funcionamiento de la comunidad de macroinvertebrados acuáticos, por su potencial como indicadoras de alteración de ambientes acuáticos. En principio, usando los sitios de referencia, se desarrollaron modelos estadísticos que describen la respuesta de las distintas métricas a la variabilidad ambiental natural. Luego se utilizaron estos modelos para predecir la respuesta de las métricas en condiciones alteradas, para lo cual se usaron los sitios que presentaban distintos tipos de perturbación antropogénica (i.e., perturbación por actividad agrícola, urbana y minera). De las 12 métricas iniciales se conservaron sólo cinco para elaborar el índice final (riqueza total, abundancia total, riqueza de Ephemeroptera, Plecoptera y Trichoptera (EPT), porcentaje en abundancia de EPT y porcentaje en abundancia de raspadores). Estas métricas resultaron las más efectivas al responder de manera significativa al gradiente de perturbación. Este índice distinguió con claridad los sitios de referencia de los perturbados, y mostró una relación lineal negativa significativa frente a un gradiente de perturbaciones físicas y químicas. Esta aproximación puede servir como herramienta de biomonitoreo para evaluar la integridad biótica y la biodiversidad acuática en los ríos de la región de los valles interandinos de Bolivia.We developed a multimetric index that could discriminate natural from anthropogenic variability in 91 sites (63 reference sites and 28 disturbed sites) fairly evenly distributed across the upper Grande River Basin (Bolivia). To do so, we examined 12 candidate metrics for their potential to indicate degradation and reflecting different aspects of macroinvertebrate assemblage structure and function. Initially, using the reference sites, we developed statistical models describing the response of the different metrics to the natural environmental variability. In a second step, using sites experiencing three types of anthropogenic disturbances (i.e., agriculture, urban and mining activities), we quantified the deviation in the response of each metric model between reference and disturbed conditions. From the initial 12 metrics, we retained only 5 metrics in the final index (total richness, total abundance, richness of Ephemeroptera, Plecoptera and Trichoptera (EPT), percentage of EPT abundance and percentage of scrapers abundance). These metrics were the most effective ones in responding to anthropogenic disturbances. Our final index performed well in discriminating between reference and disturbed sites, giving a significant negative linear response to a gradient of physical and chemical anthropogenic disturbances. This index can be used as a monitoring tool to evaluate the biological integrity and aquatic biodiversity of the Bolivian inter-Andean valleys streams.Fil: Moya, Nabor. Universidad Mayor de San Simón; BoliviaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Goitia, Edgar. Universidad Mayor de San Simón; BoliviaFil: Oberdorff, Thierry. Muséum National d'Histoire Naturelle; Franci
Fish communities in the Amazon basin : aquatic habitats, diversity gradients, drivers and processes involved, and conservation options
No full textLa biodiversité aquatique du bassin versant de l'Amazone, le plus grand système fluvial au monde et le plus diversifié en espèces, reste encore relativement mal répertoriée malgré toute l'attention que le bassin suscite au niveau de la communauté scientifique internationale. La répartition spatiale des espèces dans le bassin, et notamment celle des poissons d'eau douce, reste encore assez peu documentée, très parcellaire et dispersée entre les pays et institutions, associée à une taxonomie parfois confuse. Il en va de même pour la distribution des habitats aquatiques et des formes fluviales associées à l'échelle de l'ensemble du bassin, la dimension de celui-ci limitant l'acquisition de données de terrain. Améliorer la connaissance sur la répartition de la biodiversité et des habitats aquatiques dans le bassin versant de l'Amazone est pourtant une étape cruciale afin de pouvoir appréhender les facteurs et processus à l'origine de la diversification des espèces, identifier les zones à protéger prioritairement (hotspots de biodiversité) et mieux évaluer la vulnérabilité des espèces face aux changements globaux. Ce travail de thèse découle de l'ensemble de ces constats et vise à réduire les lacunes importantes de connaissances soulevées.The aquatic biodiversity of the Amazon basin, the largest and most species rich river basin on Earth, is still relatively poorly documented despite all the attention received from the international scientific community. Knowledge about the spatial distribution of species, and in particular of freshwater fishes, is very fragmented and dispersed between countries and institutions. The distribution of river forms has been also poorly explored at the scale of the entire basin, its continental dimension limiting the acquisition of field data. Improving the knowledge on the distribution of biodiversity and aquatic habitats in the basin is however a crucial step to better understand the factors and processes behind species diversification, identify priority areas for conservation (biodiversity hotspots) and assess the species vulnerability to global changes. This thesis work aims to reduce these significant knowledge gaps
Time for decisive actions to protect freshwater ecosystems from global changes
No full textFreshwater ecosystems and their biodiversity provide fundamental services to humans such as nutritional resources production, water provisioning, water purification, recreation, and more globally climate regulation. Anthropogenic impacts on freshwater ecosystems and their biodiversity are already strong and will most probably increase in the near future. Anthropogenic drivers are widely known and include in particular, climate change, habitat shrinking and/or modification due to land-use (e.g. water abstraction for human and agricultural consumption, urbanization), habitat fragmentation and homogenization in stream flow dynamics due to the damming of rivers, introduction of non-native species, dumping of nutrient or organic loadings increasing eutrophication processes, and biodiversity over-exploitation. Here, I review the current and future effects of these anthropogenic drivers on freshwater ecosystems and their biodiversity and provide some few examples of existing solutions, either technological, nature-based or policy-based, that could be applied globally to halt and/or minimize their negative consequences. However, success will require systemic changes across public policy and a sufficient political will to do so
Freshwater ecosystems under threats with global change
No full textFreshwater ecosystems and their biodiversity provide fundamental services to humans such as nutritional resources production, water provisioning, water purification, recreation, and more globally climate regulation. Impacts due to anthropogenic drivers on freshwater ecosystems and their biodiversity, are already strong and several will face higher risk of impacts in the near future. These anthropogenic drivers are widely known and include in particular, climate change, habitat shrinking and/or modification due to land-use (e.g. water abstraction for human and agricultural consumption, urbanization), habitat fragmentation and homogenization in stream flow dynamics due to the damming of rivers, introduction of non-native species, dumping of nutrient or organic loadings increasing eutrophication processes, and biodiversity over-exploitation. Here, I review the current and future effects of these anthropogenic drivers on freshwater ecosystems and their biodiversity and provide some few examples of existing cost-effective solutions, either technological, nature-based or policy-based, that could be applied globally to halt and/or minimize their negative consequences. However, success will require systemic changes across public policy and a sufficient political will to do so
Macroinvertebrate food web structure in a floodplain lake of the Bolivian Amazon
No full textTwo stable isotopes δ13C and δ15N were used to identify the energy sources and trophic relationships of the main freshwater macroinvertebrates in a floodplain lake of the Beni River (Bolivian Amazonia). Four energy sources (seston, bottom sediment, periphyton, and aquatic macrophytes) and macroinvertebrate communities were collected during three periods of the river hydrological cycle. Macroinvertebrates showed greater temporal variation in isotope values than their food sources. Six trophic chains were identified: four were based on seston, periphyton, C3 macrophytes, and bottom sediments, and the last two chains on a combination of two carbon sources. One mixed seston and periphyton sources during the wet season while the other mixed periphyton and macrophytes sources during the wet and dry seasons. Periphyton was the most important energy source supporting the highest number of trophic levels and consumers. The macrophytic contribution was only significant during the dry season. Bottom sediments constituted a marginal energy source. As each season is associated with different physical and chemical conditions, processes organizing macroinvertebrate food web structure in the Beni floodplain seem strongly linked to hydrological seasonality.Fil: Molina, Carlos Israel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina. Universidad Mayor de San Andrés; Bolivia. Instituto de Investigación para el Desarrollo; BoliviaFil: Gibon, François Marie. Instituto de Investigación para el Desarrollo; Bolivia. Universite Pierre et Marie Curie; Francia. Muséum National d'Histoire Naturelle; FranciaFil: Oberdorff, Thierry. Universite Pierre et Marie Curie; Francia. Muséum National d'Histoire Naturelle; Francia. Centre National de la Recherche Scientifique; FranciaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; ArgentinaFil: Pinto, Julio. Universidad Mayor de San Andrés; BoliviaFil: Marín, Rubén. Universidad Mayor de San Andrés; BoliviaFil: Roulet, Marc. Instituto de Investigación para el Desarrollo; Bolivi
Indice multimetrico de integridad biotica bentica para la cuenca del rio Chipiriri, Cochabamba-Bolivia
No full textCon el propósito de desarrollar un índice multimétrico para evaluar la calidad biológica de los ríos de la Cuenca Chipiriri (Bolivia), tomamos muestras de macroinvertebrados bentónicos y medidas ambientales en dos grupos de sitios distribuidos uniformemente en toda la cuenca, 38 sitios con mínima perturbación antropogénica y 29 sitios perturbados. Usando los datos del primer grupo de sitios, desarrollamos modelos estadísticos sencillos de modo que expliquen adecuadamente los patrones observados de 12 diferentes variables biológicas tomadas en cuenta; posteriormente, seleccionamos las varialbes biológicas más efectivas qe respondieron de forma significativa a efectos de perturbación. Finalmente, sumando los valores de las variables biológicas seleccionadas obtuvimos el índice final que distinguió claramente la variación de la calidad biológica de las condiciones naturales y perturbadas. Los métodos y consideraciones descritas en este trabajo podrían emplearse para desarrollar un índice de integridad ecológica en otras regiones, incluyendo nuevos parámetros a esta escala
Comparison of aquatic macroinvertebrate communities from Intermittent and perennial bolivian headwater andean Streams: implications for future climate change
No full textEl impacto de la estacionalidad de los ríos sobre las comunidades de macroinvertebrados fue estudiado en ríos de la zona Altoandina de Bolivia, durante la época de transición y época seca del año 2008. En nueve arroyos intermitentes y nueve permanentes se colectaron muestras de macroinvertebrados y parámetros ambientales. A traves de análisis multivariados, se determinaron relaciones entre variables biológicas (según riqueza, abundancia, composición trófica y rasgos biológicos) con las variables ambientales. La estacionalidad no tuvo efecto significativo sobre la riqueza ni densidad de macroinvertebrados, tampoco se encontraron efectos notorios sobre la composición trófica ni los rasgos biológicos (tipo de respiración), pero sí encontramos diferencias significativas en la composición taxonómica, especialmente en la proporción de Ephemeroptera, Plecoptera y Trichoptera (EPT); asimismo, encontramos que existen otras variables ambientales como la profundidad, solidos disueltos y pH que tienen mayor efecto que la intermitencia en la riqueza y densidad total. De acuerdo a datos climáticos de la región Andina de Bolivia se sabe que en el futuro habrá una disminución del agua, incluso la desecación temporal en varios ríos de la zona, esto debido a la disminución de los glaciares. De esta manera, el futuro cambio climático reflejado a través de la estacionalidad de los ríos, tendrá mayor efecto en los cambios de la estructura taxonómica que en la estructura funcional, lo que indica que probablemente tendrá implicaciones más fuertes en la conservación de taxa que en la composición de los rasgos de la comunidad de macroinvertebrados.The impact of hydrologic non-permanence (intermittent streams) on benthic macroinvertebrate communities was investigated in Bolivian head Andean streams. Samples of benthic macroinvertebrates and environmental variables were taken in nine intermittent and nine permanent streams during dry and transition to dry seasons during 2008. Using different multivariate analyses, we determined relationships between biological variables (richness, density, trophic composition and biological traits) and environmental variables. Hydrologic non-permanence had no significant effect on total species richness, total density, trophic composition or physiological traits (i.e. respiration). However, significant effects were found on taxonomic composition, specifically on taxonomic richness of Ephemeroptera, Plecoptera and Trichoptera. Likewise, we found that environmental variables such as profundity, total dissolved solids and pH have more important effects on total richness and density than hydrologic non-permanence itself. Thus, climate change would likely have stronger implications for taxa conservation than for the functional characteristics of stream macroinvertebrate communities.Fil: Moya, Nabor. Universidad Mayor de San Simón; BoliviaFil: Gibon, François Marie. Muséum National d'Histoire Naturelle; FranciaFil: Oberdorff, Thierry. Muséum National d'Histoire Naturelle; FranciaFil: Rosales, Claudio. Universidad Mayor de San Andrés; BoliviaFil: Dominguez, Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentin
- …
