Mostrando ítems 31-50 de 80
Rodríguez Lozano, Pablo (Fecha de defensa: 2016-01-29)
Wildfires are expected to increase in frequency and intensity because of climate change and changes in land use and management. In last decades, the research on fire effects on aquatic systems has grown, but it has been ...
Miró Pastó, Alexandre (Fecha de defensa: 2016-01-08)
Pyrenean high mountain lakes are naturally fishless due to natural barriers that have prevented the natural colonisation of fish species from lower streams. However, there have been numerous trout introductions to such ...
Safont Crespo, Elisabet (Fecha de defensa: 2016-02-09)
This thesis is aimed at the study of the flora and vegetation of the Guayana Highlands (GH), a set of -50 table mountains (called tepuis) located in the Guayana Shield of northern South America. Special emphasis is put on ...
Gaudes Saez, Ainhoa (Fecha de defensa: 2011-07-07)
This thesis focuses on the study of the meiofaunal community in streams and rivers of the Mediterranean region. It approaches to a community level from a functional point of view, studying their response as a whole to ...
Ejarque Gonzalez, Elisabet (Fecha de defensa: 2014-11-17)
Rivers play a key role in the global biogeochemical functioning, as they link the biogeochemical cycles of the terrestrial and oceanic systems. In the framework of the carbon cycle, streams and rivers receive dissolved ...
Nikolakopoulou, Myrto-Georgia (Fecha de defensa: 2021-01-29)
Freshwater degradation has been largely attributed to excess nutrient concentrations of anthropogenic origin. Freshwater degradation in combination with water scarcity are the reason of severe stress on water resources ...
Sanpera Calbet, Isis (Fecha de defensa: 2014-04-11)
Streams are complex and highly diverse ecosystems. Within the stream network, headwater streams (1st to 3rd order) are highly important. Headwaters represent most of the total length, influence the structure and functioning ...
Romaní i Cornet, Anna M. (Fecha de defensa: 1997-10-21)
Helerotrophic (cetoenzymatic and respiratory activities) and autotrophic (photosynthetic activity) metabolism on epilithic strearn biofilms have been measured, analyzed and studied in this thesis.<br/><br/>The main objective ...
Solà Ortega, Carolina (Fecha de defensa: 2004-07-21)
L'abril de 1998, durant l'accident miner d'Aznalcóllar, més de 6 milions de m3 de llots i aigües àcides altament contaminades amb metalls pesants van ser vessats al riu Guadiamar (Sevilla), destruint els ecosistemes fluvials ...
Vázquez Garcia, Eusebi (Fecha de defensa: 2013-10-11)
The studies presented in this thesis focus on the biogeochemistry of dissolved organic matter (DOM) in an intermittent stream in a Mediterranean climate zone, with great emphasis on extreme hydrologic events: floods and ...
Martínez Ricart, Aurora (Fecha de defensa: 2016-04-08)
Habitats commonly occur as more or less interconnected patches constituting spatial heterogeneous mosaics. Connectivity and interactions among habitats can determine their functioning. Therefore, ecological patterns and ...
Castro Català, Núria de (Fecha de defensa: 2016-02-05)
Aquatic systems are under pressure from multiple stressors that affect the structure, the functioning, and the health of species, communities and ecosystems. One of the main human pressures affecting the Earth’s ecosystems ...
Pueyo Puntí, Salvador (Fecha de defensa: 2003-03-25)
This work is the result of a search for general (or nearly general) regularities at ecosystem level, and an exploration of their practical relevance in our relations with the environment.<br/>I began by adding some new ...
Muñoz Camarillo, Gloria (Fecha de defensa: 2013-04-05)
El mejillón cebra, Dreissena polymorpha (Pallas, 1771), es conocido por ser una de las especies invasoras de agua dulce más dañinas, tanto desde el punto de vista ecológico como económico, a nivel mundial. Este exitoso ...
Mendoza Barberá, Guillermo de (Fecha de defensa: 2013-06-20)
“Lake macroinvertebrates and the altitudinal gradient in the Pyrenees [Los macroinvertebrados lacustres y el gradiente altitudinal en los Pirineos]” is a thesis about freshwater macroinvertebrate communities inhabitting ...
Gera, Alessandro (Fecha de defensa: 2013-06-21)
Overall, this thesis is an attempt at approaching seagrass ecosystems from a landscape perspective, with the aim of increasing knowledge about the processes generating patterns at large spatial scales, and understanding ...
Bartumeus i Ferré, Frederic (Fecha de defensa: 2005-06-17)
ENGLISH ABSTRACT:<br/><br/>The general aim of this thesis was to develop a theoretical framework in order to study large-scale animal movements and/or dispersal processes as random search strategies. The framework was ...
Muñoz Gràcia, Isabel (Fecha de defensa: 1990-02-23)
La major part de la concentració de carboni i nitrogen que arriba al Mediterrani des de l'Ebre és en forma dissolta, mentre que en el cas del fòsfor la concentració en la forma particulada pot ser més important, especialment ...
Ordóñez Salinas, Jaime (Fecha de defensa: 2010-09-21)
La disponibilidad y calidad del agua que se encuentra en los embalses depende de factores relacionados directamente con las características de la cuenca a la que pertenece el río embalsado, como las cargas de nutrientes ...
Prado Villegas, Patricia (Fecha de defensa: 2007-02-23)
La revaluació a gran escala espacial (> de 300 Km) i mitjançant mètodes de quantificació directa, del impacte de l'herbivorisme en els ecosistemes de <i>Posidonia oceanica</i> va revelar pèrdues de biomassa foliar molt ...