Rivers In Spain Research Articles

Association of Acidotolerant Cyanobacteria to Microbial Mats below pH 1 in Acidic Mineral Precipitates in Río Tinto River in Spain.

This report describes acidic microbial mats containing cyanobacteria that are strongly associated to precipitated minerals in the source area of Río Tinto. Río Tinto (Huelva, Southwestern Spain) is an extreme acidic environment where iron and sulfur cycles play a fundamental role in sustaining the extremely low pH and the high concentration of heavy metals, while maintaining a high level of microbial diversity. These multi-layered mineral deposits are stable all year round and are characterized by a succession of thick greenish-blue and brownish layers mainly composed of natrojarosite. The temperature and absorbance above and below the mineral precipitates were followed and stable conditions were detected inside the mineral precipitates. Different methodologies, scanning and transmission electron microscopy, immunological detection, fluorescence in situ hybridization, and metagenomic analysis were used to describe the biodiversity existing in these microbial mats, demonstrating, for the first time, the existence of acid-tolerant cyanobacteria in a hyperacidic environment of below pH 1. Up to 0.46% of the classified sequences belong to cyanobacterial microorganisms, and 1.47% of the aligned DNA reads belong to the Cyanobacteria clade.

Digital reactivation of territories through geospatial cultural itineraries: the VIDA-HTL web application

The significant imbalances between human settlements and their surrounding environments, stemming from sector-specific policies and urban regional planning tools, constitute a primary factor in the resilience and responsiveness of territories in crisis scenarios. Within this context, the promotion of territorial heritage values emerges as a crucial means for the reactivation of vulnerable areas. Furthermore, the utilisation of technological resources, such as Geographic Information Systems (GIS), has proven to be highly effective in managing cultural landscape areas. This contribution aims to enhance the valorisation of territorial heritage through the geolocation of a system of architectural and archaeological assets of public interest, and by enabling the flexible design of cultural itineraries within the framework of slow tourism. For this purpose, a replicable methodology for the construction of a WebGIS application has been proposed. This methodology has been put into practice in the territorial area of the lower Guadalquivir River in Spain, which encompasses 73 municipalities and one UNESCO World Heritage Site, all interconnected by rural areas. A four-stage plan has been followed for the construction of the VIDA-HTL web application: (1) conceptualisation; (2) development; (3) technical verification; and (4) social viability. The fundamental approach of the web application is based on the comprehensive integration of subsystems related to cultural heritage on one hand, and to tourist and environmental services on the other. Two main functions for the exploration of cultural assets and designing cultural routes have been designed, which complement other capabilities implemented in the web application. As a result of a detailed standardisation process, 981 cultural assets and 43 supplementary data layers have been georeferenced and included in the web application, with customised itineraries available for planning within the study area. Additionally, 49 thematic cultural itineraries are proposed. Finally, the web application is complemented with the development of a collaborative hub, which encourages its use and enhances its capabilities. It is concluded that digital tools, such as that proposed, foster knowledge and valorisation of territorial cultural heritage, while contributing to greater local development. In this way, they function as a counterbalance to the development of metropolises and the global economy, thereby improving levels of regional resilience.

Pyriproxyfen Contamination in Daphnia magna: Identifying Early Warning Biomarkers.

Pyriproxyfen is an insecticide currently employed in numerous countries for the management of agricultural and indoor pests. Several studies indicate that this insecticide has been detected in multiple rivers, with concentrations reaching as high as 99.59 ng/L in the Júcar River in Spain. Therefore, the determination of some biochemical and genetic effects of this insecticide on aquatic organisms could serve as an early warning mechanism to identify potential disruptions in various biomarkers. Based on this, Daphnia magna organisms were exposed to pyriproxyfen sublethal concentrations for 21 days. Some biochemical parameters, including cholesterol, triglycerides, glucose, lactate, and LDH activity, were determined. Additionally, some genetic biomarkers associated with oxidative stress, heat shock proteins, lipid metabolism, hemoglobin, metallothioneins, and vitellogenin synthesis were evaluated in daphnids exposed to the insecticide for 21 days. LDH activity increased significantly in those daphnids exposed to the highest insecticide concentration (14.02 µg/L), while cholesterol levels decreased significantly. In contrast, glucose, total proteins, and triglycerides remained unaffected in D. magna exposed to pyriproxyfen. On the other hand, exposure to the insecticide led to notable alterations in gene expression among individuals. Specifically, genes associated with lipid metabolism and reproduction exhibited a significant reduction in gene expression. Fabd expression was decreased by approximately 20% in exposed daphnids, while vtg expression was suppressed as much as 80% when compared to control values. Furthermore, it was observed that the hgb1 and hgb2 genes, associated with hemoglobin synthesis, exhibited significant overexpression. Notably, the dysfunction observed in both hemoglobin genes was linked to an increase in pigmentation in Daphnia magna during the course of the experiment. These alterations in gene expression could serve as effective indicators of early contamination even at low pesticide concentrations.

Microplastics in water, sediments and macroinvertebrates in a small river of NW Spain

Microplastics (MPs; plastic particles < 5 mm in size) are very common nowadays and ubiquitous in the environment and can cause harm to aquatic organisms. Around 300 million metric tonnes of plastic are manufactured each year and they are regularly mismanaged. Therefore, MPs are frequently found in the environment. Anthropogenic activity in urban areas is considered one of the major sources of MPs. In view of this, we hypothesized, that MPs are present in all areas of rivers, even in riverheads. We analyzed macroinvertebrates in an urban river for MPs and discuss their potential environmental impact. We collected water samples from the centre of the river and filtered the water. Additionally, we collected sediment samples from the the bottom (S1 and S2, both samples collected specifically for sediments analysis) and from the benthic sediment (S3, sample collected for macroinvertebrates identification) from which macroinvertebrates were sampled for MP analysis and for taxonomic identification in order to estimate the water quality of the river, following the protocol for calculating the IBMWP (MAGRAMA, 2011). Sampling took place in the Gafos River (NW Spain) during summer 2020 at three different sampling sites at the head of the river called upstream (G1), in the middle part of the river and upstream of a town (G2) and in the downstream area before the river mouth in the Atlantic Ocean (G3). Different microplastic fibres and particles were found in all water samples (G1, G2 and G3) and in some of the sediment samples. Analysis of the different types of microplastics was carried out by Fourier-transform infrared spectroscopy in attenuated total reflectance mode (ATR- FTIR). The majority of microplastics in water, sediment and biota consisted of polyvinyl chloride (PVC) and polyethylene terephthalate (PET) and the abundances of MPs were very similar. We found more MP particles in biota and water (35 pieces in each compartment) than in sediments (28). Microplastics were found in the cases of Trichoptera families like Lepidostomatidae and Limnephilidae, and inside the body of some Odonata families such as Gomphidae. This confirms the presence of MPs in aquatic organisms and in habitats of an urban river in Spain. Since MPs have been found in freshwater habitats globally, future studies should analyse which macroinvertebrates could be used as MP bioindicators.

A Low-Cost and Do-It-Yourself Device for Pumping Monitoring in Deep Aquifers

Water crises due to climate change, high population growth and increasing demands from industry and agriculture claim for increasing efficiency and universalizing water resources management strategies and techniques. Water monitoring helps providing necessary evidences for making sound decisions about managing water resources both now and in the future. In this work, a low cost and “do it yourself” communication device is proposed to record water production and energy consumption of electric pumpings from deep boreholes/wells, and to predict the impact of the ongoing and previous pumpings in the evolution of the water level in the aquifer. The proposal incorporates an edge-computing approach for the simulation of the aquifer response in real-time. Computation of results of interest is performed at the sensor, minimizing communication requirements and ensuring almost immediate results. An approximated solution to physically based modeling of aquifer response is computed thanks to the a priori expression of the water level time evolution in a reduced basis. The accuracy is enough to detect deviations from expected behaviour. The energy consumption of the device is very much reduced with respect to that of a full modelling, which can be computed off-line for calibrating reduced model parameters and perform detailed analyses. The device is tested in a real scenario, in a mountain subbasin of the Ebro river in Spain, obtaining a good trade-off between performance, price, and energy consumption.

Automatic Detection of Aquatic Weeds: A Case Study in the Guadiana River, Spain

The spread of aquatic invasive plants is a major concern in several zones of the world's geography. These plants, which are not part of the natural ecosystem, cause a negative impact to the environment, as well as to economy and society. In Spain, large areas of Guadiana (the second longest river in Spain) have been invaded by such plants. Among the strategies to address this problem, monitoring and detection play an important role to control the spatio-temporal distribution of the invasive plants. The main objective of this work is to develop a methodology able to automatically detect the geo-location of aquatic invasive plants using remote sensing and machine learning techniques. To this end, several classification algorithms have been applied to freely available multispectral satellite imagery, collected by ESA's Sentinel-2 satellite. A quantitative and comparative assessment is conducted using different machine and deep learning algorithms, from classical methods such as unsupervised K-means to supervised random forests (RFs) and convolutional neural networks (CNNs). This study also proposes a methodology for validating the obtained classification results, generating synthetic ground truth images based on available high spatial resolution imagery. The obtained results demonstrate the suitability of some of the considered algorithms for automatic detection of aquatic weeds in satellite images with medium spatial resolution.

Efficient Reservoir Modelling for Flood Regulation in the Ebro River (Spain)

The vast majority of reservoirs, although built for irrigation and water supply purposes, are also used as regulation tools during floods in river basins. Thus, the selection of the most suitable model when facing the simulation of a flood wave in a combination of river reach and reservoir is not direct and frequently some analysis of the proper system of equations and the number of solved flow velocity components is needed. In this work, a stretch of the Ebro River (Spain), which is the biggest river in Spain, is simulated solving the Shallow Water Equations (SWE). The simulation model covers the area of river between the city of Zaragoza and the Mequinenza dam. The domain encompasses 721.92 km2 with 221 km of river bed, of which the last 75 km belong to the Mequinenza reservoir. The results obtained from a one-dimensional (1D) model are validated comparing with those provided by a two-dimensional (2D) model based on the same numerical scheme and with measurements. The 1D modelling loses the detail of the floodplain, but nevertheless the computational consumption is much lower compared to the 2D model with a permissible loss of accuracy. Additionally, the particular nature of this reservoir might turn the 1D model into a more suitable option. An alternative technique is applied in order to model the reservoir globally by means of a volume balance (0D) model, coupled to the 1D model of the river (1D-0D model). The results obtained are similar to those provided by the full 1D model with an improvement on computational time. Finally, an automatic regulation is implemented by means of a Proportional-Integral-Derivative (PID) algorithm and tested in both the full 1D model and the 1D-0D model. The results show that the coupled model behaves correctly even when controlled by the automatic algorithm.

Environmental flows and the mitigation of hydrological alteration downstream from dams: The Spanish case

Dams cause significant alteration in natural flow patterns of rivers throughout the world. As a response, many countries have established environmental flows (e-flows) to reduce hydrological alteration and mitigate ecosystem degradation. This paper assesses hydrological changes downstream from dams in 22 rivers in Spain, 12 of them located in northern wetter regions (Duero and Ebro basins) and the remaining 10 in southern drier regions (Guadalquivir and Júcar basins). First we compared pre-dam and post-dam instream flow patterns, and then we considered a third period starting with the implementation of e-flows. We quantified changes in mean annual flows, monthly flows, and magnitude and timing of extreme flows (1-day maximum, 95th percentile, 1-day minimum and 5th percentile). The analysis aimed at: i) characterizing hydrological alteration in regulated rivers in four river basins in Spain, with a special focus on differences across regions; and (ii) assessing the capacity of the implemented e-flows to mitigate flow regime alteration downstream from dams. All the studied rivers displayed significant changes in magnitude and timing of flows after the dam construction. A quite homogenous trend was observed in the drier basins, where mean annual flows and annual extreme flows decreased significantly. The wetter basins showed no uniform patterns in mean annual flows, while 1-day maximum and 95th percentile flow values decreased. In contrast to drier basins, 1-day minimum and 5th percentile flow values increased markedly. In most cases, the natural Mediterranean annual hydrograph was inverted, with the high-flow period occurring during the low precipitation months (summer) and the low-flow period during the wet season. After e-flows implementation, these patterns of hydrological alteration remained almost unchanged, pointing to a limited capacity of current e-flows to mitigate the hydrological impacts downstream from dams.

Comparative Hydrodynamic Analysis by Using Two−Dimensional Models and Application to a New Bridge

This document develops a methodology that evaluates the impact on the environment of the rivers produced by the creation of civil infrastructures. The methodology is based on the two-dimensional hydrodynamic calculation by using shallow water equations both in the conditions prior to the creation of the infrastructure, and in the new conditions after the infrastructure is created. Subsequently, several characteristics, such as water depth and velocity, among others, are compared between the initial and final conditions, and a two-dimensional zoning of the changes observed is obtained. The methodology herein presented is useful to verify the impact that the implantation of different infrastructures around the river currents could produce. In addition, it is also relevant for carrying out a study taking into account different infrastructure options related to river currents, as well as for selecting the most suitable one. By using the methodology presented, changes on the regime of the currents caused by the infrastructures can be deduced, including a qualitative and quantitative zoning of the changes, with a special emphasis on some characteristics, such as depth and velocity. The methodology is applied in a case study for the creation of a road bridge over the Jalon River in Spain.

The Contribution of Rain Gauges in the Calibration of the IMERG Product: Results from the First Validation over Spain

AbstractAfter 5 years in orbit, the Global Precipitation Measurement (GPM) mission has produced enough quality-controlled data to allow the first validation of their precipitation estimates over Spain. High-quality gauge data from the meteorological network of the Spanish Meteorological Agency (AEMET) are used here to validate Integrated Multisatellite Retrievals for GPM (IMERG) level 3 estimates of surface precipitation. While aggregated values compare notably well, some differences are found in specific locations. The research investigates the sources of these discrepancies, which are found to be primarily related to the underestimation of orographic precipitation in the IMERG satellite products, as well as to the number of available gauges in the GPCC gauges used for calibrating IMERG. It is shown that IMERG provides suboptimal performance in poorly instrumented areas but that the estimate improves greatly when at least one rain gauge is available for the calibration process. A main, generally applicable conclusion from this research is that the IMERG satellite-derived estimates of precipitation are more useful (r2 > 0.80) for hydrology than interpolated fields of rain gauge measurements when at least one gauge is available for calibrating the satellite product. If no rain gauges were used, the results are still useful but with decreased mean performance (r2 ≈ 0.65). Such figures, however, are greatly improved if no coastal areas are included in the comparison. Removing them is a minor issue in terms of hydrologic impacts, as most rivers in Spain have their sources far from the coast.

Hydro-Meteorological Characterization of Major Floods in Spanish Mountain Rivers

Spain, one of the most mountainous countries in Europe, suffers from frequent river flooding due to specific climatic and topographic features. Many headwaters of the largest rivers in Spain are located in mountainous areas of mid-to-high elevation. These include the Pyrenees, the Central System, and the Cantabrian mountains, that have a sustained snowpack during the winter months. Most previous research on flood generation in Spain has focused on intense rainfall events, and the role of snowmelt has been ignored or considered marginal. In this paper we present a regional-scale study to quantify the relative importance of rainfall versus snowmelt in the largest floods recorded in mountain rivers in Spain during the last decades (1980–2014). We further analyzed whether catchments characteristics and weather types may favor the occurrence of rainfall or snowmelt induced floods. Results show that in 53% of the 250 analyzed floods the contribution of rainfall was larger than 90%, and in the rest of events snowmelt contribution was larger than 10%. Floods where snowmelt was the main contributor represented only 5% of the total events. The average contribution of snowmelt represents 18% of total runoff in floods that were analyzed. The role of snowmelt in floods, rather than triggering the event, was usually amplifying the duration of the event, especially after the peak flow was reached. In general, the importance of snowmelt in floods is greater in catchments with characteristics that favor snow accumulation. However, this does not apply to floods where contribution of snowmelt was larger than 90%, which tend to occur at catchments at mid-elevations that accumulate unusual amounts of snow that melt rapidly. Floods were more frequent under both cyclonic and anticyclonic synoptic situations over the Iberian Peninsula, as well as under advection of western and eastern flows. Our results contribute to the ongoing improvement of knowledge about the role of snow in the hydrology of Spanish rivers and on the importance of mountain processes on the hydrology of downstream areas.

Vegetation encroachment ratios in regulated and non-regulated Mediterranean rivers (Spain): An exploratory overview

Vegetation encroachment is an expected response of rivers to a decrease in their flow variability and flood magnitude and frequency. It frequently occurs together with channel narrowing and a decrease in braiding, both of which are likely associated with different human alterations but most frequently with river damming. Vegetation encroachment ratios display a wide range of values according to local hydrologic and geomorphic contexts and dam operation management, and thus, they are very site specific. As vegetation interacts with fluvial processes, understanding the mechanisms that promote encroachment is important for predicting river trends and designing proper management and restoration measures. Our research aimed to explore the causal relationship between flow regulation and vegetation encroachment in Mediterranean rivers in Spain. We quantified vegetation encroachment and channel changes over the last 50 years in 13 river reaches, 5 of which corresponded to non-regulated rivers and 8 of which were located in rivers regulated by large dams. We analysed aerial orthophotographs from 1956, 1977 and 2011 or later up to 2014, according to image availability. We considered 1956 conditions as a reference and quantified ratios of changes in riparian vegetation cover, active channel width and braiding index over two periods, 1956–1977 and 1978–2011. We quantified the changes in the flow regime and clustered rivers according to their hydrological pattern, looking for potential hydrological drivers of the observed changes over time.Vegetation encroachment, channel narrowing and braiding decreases occurred in all the studied rivers. Significant differences in annual ratios between the studied periods were found for both vegetation encroachment and channel narrowing, but no statistically significant differences were found between the regulated and non-regulated rivers or between the hydrological river groups previously clustered by flow variables. After discussing existing literature, we suggest a multi-scale approach to understanding river changes over time, encompassing larger historical perspectives. We hypothesize a generalized hydrologic decline since the beginning of the 20th century affecting rivers at the broad-regional scale would be overlapping the effects of land cover changes (i.e., renaturalization) at the catchment scale in reducing flood intensity and sediment supply. River damming would reinforce these patterns at river segment scale, in turn overlapping the influence of local geomorphic and ecological features. This hypothesis, which should be tested by further research, may explain the constancy of encroachment and channel narrowing regionally reported but with a wide variety of change ratios, determining converging trajectories of Iberian rivers that have also been found in other regions.

Exploring longitudinal trends and recovery gradients in macroinvertebrate communities and biomonitoring tools along regulated rivers

Flow regime alteration by dams has been recognized as a major impact factor for aquatic communities. Spain is currently the member state of the EU with the largest number of large reservoirs. With the broad objective of diminishing the ongoing river degradation trend through the management of environmental flows and the use of biomonitoring tools, we investigated the effects of dams on stream macroinvertebrates in several regulated rivers in Spain with contrasting environmental settings. Specifically, we studied longitudinal trends in macroinvertebrate communities to test: i) if currently used biomonitoring tools and multivariate community analyses can detect hydrological impact responses and biological recovery; ii) if an applicable quantification of the recovery gradient, in terms of distance downstream from dams, can be obtained for Iberian fluvial systems; iii) if macroinvertebrate community structure respond different to flow regulation, depending on the contrasting environmental river typologies; and iv) if the type and intensity of hydrological alteration modulates the observed community responses/recovery.Biotic indices and metrics displayed a decrease in 5 out of 6 systems immediately downstream of infrastructure. Complete recovery could not be clearly detected, but some recovery patterns started at a distance >11km. Multivariate community patterns and biomonitoring metrics showed the most pronounced hydrological alteration impacts and weaker recovery of the downstream macroinvertebrate communities within dammed Mediterranean streams (comparing to other rivers with continental or oceanic climate influence). Finally, both the intensity and type of hydrological alteration (highlighting the alteration of the floods and droughts components) were related to changes in common biomonitoring metrics. Our results could help in recognizing heavily modified water bodies (sensu European Water Framework Directive) downstream of dams or the delineation of fluvial zones or reserves. Furthermore, applied research areas dealing with environmental flows or the bioassessment of hydrological impacts could benefit from our main findings.

Relevance of Intermittent Rivers and Streams in Agricultural Landscape and Their Impact on Provided Ecosystem Services-A Mediterranean Case Study.

Ecosystem services (ES), as an interconnection of the landscape mosaic pieces, along with temporal rivers (IRES) are an object of research for environmental planners and ecological economists, among other specialists. This study presents (i) a review on the importance of IRES and the services they can provide to agricultural landscapes; (ii) a classification tool to assess the impact of IRES to provide ES by agricultural landscapes; (iii) the application of the proposed classification to the Caia River in order to identify the importance of this intermittent river for its surrounding agricultural landscape. The classification of the ES follows the Common International Classification of Ecosystem (CICES) classification that was adapted for the purposes of this study. Firstly, the list of ES provided by agricultural landscape was elaborated. In the next step, we assessed the potential of IRES to provide ES. Next, IRES impacts to ES within the agricultural landscape were evaluated according to observations from the conducted field monitoring in the study area. This study focuses on the relevance of the intermittent Caia River—a transboundary river in Spain and Portugal—and its ephemeral tributaries in the agricultural landscape. Our study estimates that each hydrological phase of IRES increases the ES provided by the agricultural landscape. However, the dry phase can potentially have negative impacts on several services. The intensification of the agricultural sector is the main provision of the water resource within the Caia River basin, but we were able to identify several other ES that were positively impacted. The present study is in line with the conclusions of other authors who state that IRES constitute a valuable resource which should not be underestimated by society.

Geographic Analysis of Motor Neuron Disease Mortality and Heavy Metals Released to Rivers in Spain.

The etiology of motor neuron disease (MND) is still unknown. The aims of this study were to: (1) analyze MND mortality at a fine-grained level; and (2) explore associations of MND and heavy metals released into Spanish river basins. MND deaths were extracted from the Spanish nationwide mortality registry (2007–2016). Standardized mortality ratios (SMRs) for MND were estimated at a municipal level. Sites that emitted quantities of heavy metals above the regulatory thresholds were obtained from the European Pollutant Release and Transfer Register database (2007–2015). The relative risks for non-exposed and exposed municipalities (considering a downstream 20 km river section) by type of heavy metal were analyzed using a log-linear model. SMRs were significantly higher in central and northern municipalities. SMRs were 1.14 (1.10–1.17) higher in areas exposed to heavy metals than in non-exposed areas: 0.95 (0.92–0.96). Considering the different metals, we found the following increased MND death risks in exposed areas: 20.9% higher risk for lead, 20.0% for zinc, 16.7% for arsenic, 15.7% for chromium, 15.4% for cadmium, 12.7% for copper, and 12.4% for mercury. This study provides associations between MND death risk and heavy metals in exposed municipalities. Further studies investigating heavy metal exposure are needed to progress in MND understanding.

El puente sobre el Tajo de Eiffel en España

El texto describe y analiza el puente construido sobre el río Tajo por Gustave Eiffel en las cercanías de Cáceres, una de las obras más relevantes de la primera etapa del célebre ingeniero francés, y la mayor de las mismas construida en España. A partir de los planos hallados en diversos archivos, y de otras fuentes históricas, se analiza la obra y el proceso seguido para llevarla a cabo, y se repasa la importancia que tuvo tras su finalización. Al final del escrito, las conclusiones subrayan los puntos destacados del mismo y proponen distintas cuestiones relacionadas con las obras públicas históricas.

Plastid‐encoded rbcL phylogeny suggests widespread distribution of Galdieria phlegrea (Cyanidiophyceae, Rhodophyta)

The rare microscopic red alga Galdieria phlegrea (Cyanidiohyceae, Rhodophyta) has been discovered in the extremely acid Tinto River in Spain and this occurrence is here related to previous knowledge about the distribution and ecology of this enigmatic alga. The taxonomic affiliation of the new isolate of G. phlegrea was revealed by reconstructing the phylogeny of plastid‐encoded rbcL. According to this phylogeny, the Tinto River alga is closely related to other G. phlegrea strains originating from extreme habitats in Czechia, Italy and Turkey, suggesting a wider distribution and higher ecological versatility than previously thought. The results suggest that G. phlegrea, and then possibly also other cyanidiophycean algae, are not as restricted to strongly acidic and hot microhabitats as previously believed, which, in turn, may indicate that they may commonly have been overlooked and possibly are much more widespread than is currently believed.

Numerical simulation of 2D real large scale floods on GPU: the Ebro River

Modern flood risk management and mitigation plans incorporate the presence of numerical models that are able to assess the response of the system and to help in the decision-making processes. The shallow water system of equations (SWE) is widely used to model free surface flow evolution in river flooding. Although 1D models are usually adopted when simulating long rivers due to their computational efficiency, 2D models approximate better the behaviour in floodplains of meandering rivers using a fine mesh which implies unaffordable computations in real-world applications. However, the advances on parallelization methods accelerate computation making 2D models competitive. In particular, GPU technology offers important speed-ups which allow fast simulations of large scale scenarios. In this work, an example of the scope of this technology is presented. Several past flood events have been modelled using GPU. The physical domain (middle part of the Ebro River in Spain) has a extent of 477 km2, which gives rise to a large computational grid. The steps followed to carry out the numerical simulation are detailed, as well as the comparison between numerical results and observed flooded areas reaching coincidences up to 87.25 % and speed enhancements of 1-h of simulation time for 1-day flood event. These results lead to the feasible application of this numerical model in real-time simulation tools with accurate and fast predictions useful for flood management.

Challenging exploration of troubled waters: a decade of surveys of the giant freshwater pearl mussel Margaritifera auricularia in Europe

The critically endangered Giant Freshwater Pearl Mussel Margaritifera auricularia was presumed extinct before its rediscovery in Spain in 1985 and France in 2000. Since then, numerous surveys have been set up to search for living populations in France and Spain. This article presents an up-to-date account of species distribution based on available data, i.e. the literature, museum collections and recent field surveys, and provides unpublished molecular data for France. There are still three populations of the Giant Freshwater Pearl Mussel in the Ebro River in Spain, and eight populations in France (two in the Loire watershed, one in the Charente watershed, two in the Garonne watershed and three in the Adour watershed). The biggest population lives in the Charente River with an estimated 100,000 individuals. Recruitment is very scarce in all populations but living specimens estimated to be less than 10 years old have been found in the Ebro in Spain and in the Vienne, Charente, Dronne and Adour rivers in France. The recent rediscovery of populations in France was mainly a result of intensive dedicated surveys including scuba diving. Subsequent advances in knowledge show how large rivers and downstream ecosystems remain a terra incognita for the hydrobiologist.

Environmental stressors as a driver of the trait composition of benthic macroinvertebrate assemblages in polluted Iberian rivers

We used the trait composition of macroinvertebrate communities to identify the effects of pesticides and multiple stressors associated with urban land use at different sites of four rivers in Spain. Several physical and chemical stressors (high metal pollution, nutrients, elevated temperature and flow alterations) affected the urban sites. The occurrence of multiple stressors influenced aquatic assemblages at 50% of the sites. We hypothesized that the trait composition of macroinvertebrate assemblages would reflect the strategies that the assemblages used to cope with the respective environmental stressors. We used RLQ and fourth corner analysis to address the relationship between stressors and the trait composition of benthic macroinvertebrates. We found a statistically significant relationship between the trait composition and the exposure of assemblages to environmental stressors. The first RLQ dimension, which explained most of the variability, clearly separated sites according to the stressors. Urban-related stressors selected taxa that were mainly plurivoltine and fed on deposits. In contrast, pesticide impacted sites selected taxa with high levels of egg protection (better egg survival), indicating a potentially higher risk for egg mortality. Moreover, the trait diversity of assemblages at urban sites was low compared to that observed in pesticide impacted sites, suggesting the homogenization of assemblages in urban areas.