Hydrology, light and the use of organic and inorganic materials as structuring factors of biological communities in Mediterranean streams

Hydrological disturbances, light availability and nutrients are the most relevant factors determining the structure of the biological communities in Mediterranean rivers. While some hydrological disturbances are able to induce catastrophic effects, which may cause a complete reset in physical and biological conditions, continued enrichment or changes in light availability are factors leading to the progressive shift in the communities of autotrophs and heterotrophs in the systems. Primary production in Mediterranean streams shows relevant seasonal changes which mainly follows the variations in light availability. In most forested streams, the algal community is shade-adapted. Nutrient enrichment (especially phosphorus) leads to marked increases in primary production, but this increase is not lineal and there is a saturation of algal biomass even in the most enriched systems. The heterotrophs (bacteria, fungi) are related to the pattern of DOC availability (which most depends on the seasonal discharge and leaf fall dynamics) and to the available substrata in the stream. It has been repeatedly observed that shorttime increases of extracellular enzyme activities are related to the accumulation of autochthonous (algal) and/or allochthonous (leaves) organic matter on the streambed during spring and summer, this being more remarkable in dry than in wetter years. Flow reduction favours detritus concentration in pools, and the subsequent increase in the density and biomass of the macroinvertebrate community. In Mediterranean streams collectors are accounting for the highest density and biomass, this being more remarkable in the least permanent systems, in accordance with the effect of floods on the organic matter availability. Nutrients, through the effect on the primary producers, also affect the trophic food web in the streams by favouring the predominance of grazers

Introducció als Sistemes d'Informació Geogràfica

Amb aquest projecte es vol donar una visó global dels sistemes d'informació geogràfica (SIG), cada vegada més implantats a qualsevol àrea de la nostra societat (urbanisme, climatologia, medi ambient, hidrologia, vies de comunicació, cadastre, etc.). De fet, "qualsevol cosa" (riu, canal, camí, pont, contenidor, cotxe, tren, casa, fanal, senyal de trànsit, oficina, avió, vaixell, etc.) que hi ha a terra (a sota o a sobre) és candidata a ser georeferenciada.

El sistema cárstico de Sant Martí de Llémena

Descripció del sistema càrstic de Sant Martí de Llémena

Nota sobre la surgencia de Cinc-Claus, l'Escala

Sobre la surgència d'aigua entre materials calcaris a la població de Cinc Claus (L' Escala)

Estudio comparado de la génesis de espeleotemas silíceos en granitoides de climas semiáridos y templados húmedos

Silica speleothems take differenr forms such as cylindrical stems growing from either the floor or the ceiling in granitic caves. Mineralogically they are opal-A and accumulate in successive layers with a whiskery druse tip formed by gypsum crystals. Initially they are porous but progressively become infilled by opal precipitation. This results in formation of solid speleothems. their size is only a few millimetres long. Bacterial activity accelerate quartz dissolution

Aplicación de un modelo de mezcla total en acuífero cárstico

Por el fondo de un valle de la provincia de Girona mana un conjunto de surgencias cuyo caudal total anual se acercaa medio centenar de hectómetros cúbicos. Controlando no solo la cantidad de agua de salida sino también su calidad desde el punto de vista de su contenido en tritio y a partir de un modelo conceptual de mezcla uniforme de las aguas de recarga, ya com probado en otros sistemas, se acota la cadencia de participación en las surgencias de las distintas recargas anuales, as como el tiempo de renovación del volumen de agua del sistema hidrogeológico

Travertines and volcanic landforms in the eastern pyrenees margin

Travertines and volcanic landforms in the eastern pyrenees margin

Towards a database on societal impact of Mediterranean floods in the framework of the HYMEX project

The NW Mediterranean region experiences every year heavy rainfall and flash floods that occasionally produce catastrophic damages. Less frequent are floods that affect large regions. Although a large number of databases devoted exclusively to floods or considering all kind of natural hazards do exist, usually they only record catastrophic flood events. This paper deals with the new flood database that is being developed within the framework of HYMEX project. Results are focused on four regions representative of the NW sector of Mediterranean Europe: Catalonia, Spain; the Balearic Islands, Spain; Calabria, Italy; and Languedoc-Roussillon, Midi-Pyrenées and PACA, France. The common available 30-yr period starts in 1981 and ends in 2010. The paper shows the database structure and criteria, the comparison with other flood databases, some statistics on spatial and temporal distribution, and an identification of the most important events. The paper also provides a table that includes the date and affected region of all the catastrophic events identified in the regions of study, in order to make this information available for all audiences.

An introduction to Mediterranean deep-sea biology

This chapter presents the state of the art concerning the deep-sea Mediterranean environment: geology, hydrology, biology and fisheries. These are the fields of study dealt with in the scientific papers of this volume. The authors are specialists who have addressed their research to the Mediterranean deep-sea environment during the last years. This introduction is an overview but not an exhaustive review.

Using spatially distributed parameters and multi-response objective functions to solve parameterization of complex applications of semi-distributed hydrological models

Application of semi-distributed hydrological models to large, heterogeneous watersheds deals with several problems. On one hand, the spatial and temporal variability in catchment features should be adequately represented in the model parameterization, while maintaining the model complexity in an acceptable level to take advantage of state-of-the-art calibration techniques. On the other hand, model complexity enhances uncertainty in adjusted model parameter values, therefore increasing uncertainty in the water routing across the watershed. This is critical for water quality applications, where not only streamflow, but also a reliable estimation of the surface versus subsurface contributions to the runoff is needed. In this study, we show how a regularized inversion procedure combined with a multiobjective function calibration strategy successfully solves the parameterization of a complex application of a water quality-oriented hydrological model. The final value of several optimized parameters showed significant and consistentdifferences across geological and landscape features. Although the number of optimized parameters was significantly increased by the spatial and temporal discretization of adjustable parameters, the uncertainty in water routing results remained at reasonable values. In addition, a stepwise numerical analysis showed that the effects on calibration performance due to inclusion of different data types in the objective function could be inextricably linked. Thus caution should be taken when adding or removing data from an aggregated objective function.

Prospección geoquímica de flúor en las aguas superficiales del macizo Montseny (Barcelona y Girona)

En el Macizo Montseny-Guilleries se conocen antiguas explotaciones de fluorita y fluorita-baritina (Osor, Tagamanent, Espinelves, Sant Marcal, etc). Es por el1o que se ha utilizado el método de prospección geoquímica de flúor en aguas superficiales para detectar posibles zonas de interés hasta ahora desconocidas.

Community structure in mediterranean shallow lentic ecosystems: size-based vs. taxon-based approaches

The main environmental variables determining the community structure and the functioning of Mediterranean shallow lentic ecosystems are described. These ecosystems are characterized by the unpredictability of their water inputs and the high variability in their water level and physical and chemical composition. Variations in flooding, salinity, and water turnover are determinant in species composition and nutrient dynamics. Taxon-based and size-based approaches to the study of the community structure of aquatic organisms that colonise these ecosystems are also compared. The conventional taxonomic approach, based on the determination of species composition, has been used for the identification of patterns in species richness, distribution and temporal dynamics, and for ecological requirements of species and their potential use as ecological indicators. This taxonbased approach has been compared with a size-based approach, where individuals are classified by their size. Size-based approach gives complementary information about community structure and dynamics, especially when communities are dominated by a single species. The use of size diversity combined with species diversity is suggested for a more complete understanding of community structuring in this type of ecosystem. Detailed examples of two Mediterranean shallow lentic ecosystems, the salt marshes of the Empordà wetlands and the Espolla temporary karstic pond, which differ in hydrology and water origin, are used to discuss the suitability of these different approaches

Contaminación de suelos y aguas subterráneas por vertidos industriales

En los países industrializados, la contaminación de suelos y aguas subterráneas por el vertido incontrolado de residuos industriales es uno de los problemas más preocupantes que se plantean, ya que su eliminación no es fácil ni barata de realizar, y sus efectos persisten durante muchos años. En España este problema es especialmente notorio a causa de una gestión inadecuada derivada de la descoordinación existente entre los diferentes sectores involucrados: administración, empresas, técnicos y científicos. La ausencia de instalaciones suficientes para su tratamiento, ha llevado a la práctica de vertidos en los cauces de ríos y en el subsuelo o a su almacenamiento en vertederos incontrolados...