Encontrados 32 documentos, a visualizar página 1 de 4
Ecology of southern European pearl mussels (Margaritifera margaritifera): first...
Varandas, Simone; Lopes-Lima, Manuel; Teixeira, Amílcar; Hinzmann, Mariana; Reis, Joaquim; Cortes, R.; Machado, Jorge; Sousa, Ronaldo1. Southern European populations of Margaritifera margaritifera (L., 1758) are under-studied. From 1986 to 2001 this species was considered extinct in Portugal but between 2001 and 2002 six northern populations were found, five of which were previously unknown. 2. This study comprises a comparative study of the ecology and habitat requirements of two new populations in the rivers Beça and Terva (tributaries of ...
Modelling stream-fish functional traits in reference conditions: regional and l...
Oliveira, João; Segurado, Pedro; Santos, José M.; Teixeira, Amílcar; Ferreira, Maria Teresa; Cortes, R.Identifying the environmental gradients that control the functional structure of biological assemblages in reference conditions is fundamental to help river management and predict the consequences of anthropogenic stressors. Fish metrics (density of ecological guilds, and species richness) from 117 least disturbed stream reaches in several western Iberia river basins were modelled with generalized linear models...
Massive die-offs of freshwater bivalves as resource pulses
Sousa, Ronaldo; Varandas, S.; Cortes, R.; Teixeira, Amílcar; Lopes-Lima, Manuel; Machado, Jorge; Guilhermino, LúciaThe winter of 2009/2010 was particularly severe in Northern Portugal resulting in higher river flow levels. A study was undertaken to assess the impact of this situation on several populations of freshwater bivalves (e.g., Anodonta anatina, Corbicula fluminea, Margaritifera margaritifera, Potomida littoralis and Unio delphinus) in the catchments of the Rivers Minho, Douro, Taˆ mega, Tua and Sabor. Massive die-o...
Effects of landscape metrics and land use variables on macroinvertebrate commun...
Cortes, R.; Varandas, S.; Teixeira, Amílcar; Hughes, Samantha; Magalhães, Marco; Barquín, José; Álvarez-Cabria, Mario; Fernández, DiegoThe growing number of studies establishing links between stream biota, environmental factors and river classification has contributed to a better understanding of fluvial ecosystem function. Environmental factors influencing river systems are distributed over hierarchically organised spatial scales. We used a nested hierarchical sampling design across four catchments to assess how benthic macroinvertebrate comm...
Combining radio and PIT-telemetry to study the large and fine-scale movements o...
Teixeira, Amílcar; Cortes, R.Stream-resident salmonid movements have been the subject of numerous studies and their behaviour is relatively well-known (Harcup et al., 1984; Heggenes, 1988). For example, brown trout (Salmo trutta) is described as a sedentary species based on the behaviour displayed, often associated to the strong site attachment to a territory or home range (Bridcut & Giller, 1993; Armstrong & Herbert, 1997). Other salmonid...
Environmental drivers of benthic communities: the importance of landscape metrics
Cortes, R.; Varandas, S.; Hughes, Samantha; Magalhães, Marco; Teixeira, AmílcarThe distribution of aquatic communities is dependent on processes that act at multiplescales. This study comprised 270 samples distributed over 2 years and used a nested sampling design to estimate the variance associated with three spatial scales: basin, site and microhabitat. Habitat assessment was made using River Habitat Survey. The derived Habitat Quality Indices and the benthic composition were crossed wi...
Environmental drivers of benthic communities: the importance of landscape metrics
Cortes, R.; Varandas, S.; Hughes, Samantha; Magalhães, Marco; Teixeira, AmílcarThe distribution of aquatic communities is dependent on processes that act at multiplescales. This study comprised 270 samples distributed over 2 years and used a nested sampling design to estimate the variance associated with three spatial scales: basin, site and microhabitat. Habitat assessment was made using River Habitat Survey. The derived Habitat Quality Indices and the benthic composition were crossed wi...
Distribuição espacial dos bivalves de água doce nas bacias hidrográficas dos ri...
Varandas, S.; Teixeira, Amílcar; Lopes-Lima, Manuel; Sobral, Carina; Cortes, R.; Machado, JorgeEste trabalho teve por objectivo fazer um levantamento dos bivalves de água doce das bacias dos rios Tâmega, Tua e Sabor e encorajar a conservação das espécies autóctones e dos ecossistemas onde ocorrem. De referir que estas populações nativas são muito sensíveis a modificações súbitas e bruscas do habitat como secas, construção de barragens com consequentes descargas tóxicas, sobre-exploração dos recursos hídr...
Caracterização ecológica das populações de mexilhão-de-rio (Margaritifera marga...
Nogueira, Mónica Sofia Reis; Teixeira, Amílcar; Varandas, S.; Lopes-Lima, Manuel; Hinzmann, M.; Machado, Jorge; Cortes, R.Este estudo pretende caracterizar as condições ecológicas das populações de mexilhão-de-rio (Margaritifera margaritifera L.) e truta-de-rio (Salmo trutta L.) na bacia hidrográfica do rio Tua, nomeadamente nos rios Rabaçal e Tuela. A degradação ambiental (e.g. regularização, poluição) é um factor de regressão associado ao decréscimo da espécie M. margaritifera em Portugal que justifica a monitorização e avaliaçã...
Estudos preliminares de populações de náiades nos sectores terminais dos rios T...
Varandas, S.; Teixeira, Amílcar; Lopes-Lima, Manuel; Hinzmann, M.; Cortes, R.; Machado, JorgeO exíguo conhecimento das condições ecológicas presentes nos rios Tua e Sabor, que permitem a existência de populações viáveis das náiades Unio delphinus (anteriormente designado por Unio cf. pictorum), Anodonta anatina e Potomida littoralis, é condição básica para a monitorização destes ecossistemas. Neste sentido, no Verão de 2009 foram feitos estudos preliminares de caracterização do habitat e microhabitat u...
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