Spanish River Research Articles

Experimental floods: A new era for Spanish and Mediterranean rivers?

The provision of human-designed floods in regulated rivers is still an incipient worldwide practice. However, these floods have already been shown to have relevant effects on the ecogeomorphic integrity of rivers altered by flow regulation. In Spain, experimental floods were legally established in 2008 and were stipulated in two subsequent Basin Management Plans as compulsory practice for improving the functioning of strategic river reaches. Since that time, a number of flooding events have been carried out in rivers of Mediterranean condition. This paper reviews the main consequences of experimental flood releases in three Spanish river sites downstream of major hydraulic infrastructures. In each case, the ecologic and geomorphic effects of the releases are analysed in parallel with their causes and consequences, thereby providing a detailed understanding of the dynamics of each scenario. The Spanish examples and the lessons learned from them are contrasted with examples of experimental floods from other countries (U.S.A., Switzerland, Australia). Lastly, recommendations are proposed to improve the implementation of future experimental floods in Spain and other Mediterranean countries.

Temporal and spatial variability of ground level atmospheric methane concentrations in the Ebro River Delta

Deltas provide many worthy ecosystem services. Yet, delta basins are quite vulnerable, especially in the face of climate change, which can affect the outcome of both agriculture and biodiversity. Moreover, rice paddy cultivation is well known to contribute with strong emissions of greenhouse gases (GHGs), such as methane (CH4). Thus, knowing the atmospheric variability of CH4 in relation to the different stages of the rice culture cycle could help to improve GHGs' mitigation strategies in deltas.The Ebro River Delta, in the northwestern Mediterranean basin, forms part of the largest Spanish river basin and is mainly covered by rice fields. In this study, for the first time, ground level (40 cm a.g.l.) atmospheric CH4 concentrations have been monitored in this area, through twenty-seven car mobile transects, over the course of one year. Seasonal, diurnal and spatial variability of CH4 concentrations were studied to identify its relationship with rice cultivation, meteorological conditions and land-use distribution.With regard to seasonal variability, autumn transects showed the highest mean values for atmospheric CH4 (2.466 ppm) when dead rice straw is mixed with the sediment, and weed growth is prevented. Spring and summer measurements gave the highest mean CH4 values at dawn (1.897–3.544 ppm), whereas autumn and winter produced the mean values after sunset (2.148–2.930 ppm). Spatial differences were accounted for by proximity to urban areas, presence of shallow water storage structures, and distance to seawater.

Response of fish communities in rivers subjected to a high sediment load

Erosion and sediment yield are a significant problem in the Guadalquivir River basin. Such phenomena are largely driven by a land use devoted to intensive cultivation of olive trees, with a large socioeconomic influence in Andalusia. This sediment overload in rivers causes serious impacts on all fluvial ecosystem components. In this study we assess the chronic effect of sediment yield on fish communities at 104 river sites located in two different sub-catchments – the Bembézar and Guadajoz rivers – both with different lithological composition and erosion rates. Sediment yield was estimated using a semi-quantitative Factorial Score Model (FSM), developed specifically for Spanish rivers. The fish populations of both basins were evaluated in composition and abundances by the study of Fernández-Delgado et al., 2014. The influence of sediment yield on the fish community was analyzed using General Additive Models. The sediment yield was higher in the Guadajoz basin (921 T/Km2 per year) than in Bembézar (701 T/Km2 per year). In the former, fish communities were poorer in both fish density and diversity, with Luciobarbus sclateri as the only substantially present species and a significant relationship between sediment yield and load, and fish density. In contrast, in the Bembézar basin, sediment yield was correlated with total fish density, including Luciobarbus sclateri, Pseudochondrostoma willkommii, Cobitis paludica, Iberochondrostoma lemmingii, Anaecypris hispanica, and Cyprinus carpio. Intermediate values of sediment yield led to maximum densities, while those higher decreased the density of these species.

Measuring the Sustainability of Water Plans in Inter-Regional Spanish River Basins

This paper analyses and compares the sustainability of the water plans in the Spanish River basins according to the objectives of the Water Framework Directive. Even though the concept of sustainability has been traditionally associated with the triple bottom line framework, composed of economic, environmental, and social dimensions, in this paper sustainability has been enlarged by including governance aspects. Two multicriteria decision analysis approaches are proposed to aggregate the sustainability dimensions. Results show that the environmental dimension plays the most important role in the whole sustainability (40%) of water basins, followed by both economic and social criteria (25%). By contrast, the dimension of governance is the least important for sustainability (11%). A classification of the Spanish basins according to their sustainability indicates that the water agency with the highest sustainability is Western Cantabrian, followed by Eastern Cantabrian and Tagus. By contrast, Minho-Sil, Jucar, and Douro are the least sustainable.

Occurrence of drugs of abuse in surface water from four Spanish river basins: Spatial and temporal variations and environmental risk assessment

The present work investigates the occurrence of 22 drugs of abuse (DAs) and metabolites in surface water from four Spanish River basins: Llobregat, Ebro, Jucar and Guadalquivir. To this end, samples were collected from 77 selected sites in two sampling campaigns conducted in 2010 and 2011. Analyses were performed by means of on-line solid phase extraction-liquid chromatography-electrospray-tandem mass spectrometry (on-line SPE-LC-ESI-MS/MS). Cocaine, its metabolite benzoylecgonine, ephedrine, MDMA (ecstasy), and methadone and its metabolite EDDP were the most ubiquitous compounds, being present in more than 50% of the samples. Overall, DAs were present at low ng/L levels, showing comparatively higher concentrations in small tributary rivers impacted by wastewater treatment plant effluents. The results obtained did not show a clear relationship between the concentrations of DAs and the hydrological conditions of the river basins. Differences in the occurrence of DAs between river basins were observed, but only for MDMA this finding could be confirmed in both sampling campaigns. These results overall suggest similar drugs consumption in the studied areas. Estimation of potential ecotoxicological effects using Hazard Quotient (HQ) ratios and a concentration addition model showed that in four samples the presence of DAs could represent certain risk to aquatic organisms.

Recovery of the algae and macroinvertebrate benthic community after Didymosphenia geminata mass growths in Spanish rivers

This study aims to assess the ecological profile of the invasive alga Didymosphenia geminata in NW Spain, analysing the biotic and abiotic factors related to the presence of massive colonies and their effect on river benthos. Physical and chemical parameters were measured in three infested rivers during 2009 and 2010, and biological samples of benthic community were taken according to standard protocols. Collected data was compared with that of control stations located in the same rivers but presenting no evident infestations. The autoecology shown by D. geminata in this study supports former observations reporting the expansion of its ecological niche, with current velocity and nutrients concentrations the environmental variables that best explain the establishment and development of mats in the studied rivers. Regarding its impact, it was observed that the mass growths of this diatom produced a dramatic change in the composition of the algae and macroinvertebrate benthic community which persisted after their disappearance. These results led to the development of a geostatistical predictive model to identify potential risk of dispersion of this diatom in Spanish rivers. The expected distribution of this algae according to this model agreed in general with the actual observed infestations, thus validating it as a tool to prevent and manage future infestations.

Exploring the Capacity of Water Framework Directive Indices to Assess Ecosystem Services in Fluvial and Riparian Systems: Towards a Second Implementation Phase.

We explored the capacity of the biological and hydromorphological indices used in the Water Framework Directive (WFD) to assess ecosystem services by evaluating the ecological status of Spanish River Basins. This analysis relies on an exhaustive bibliography review which showed scientific evidence of the interlinkages between some ecosystem services and different hydromorphological and biological elements which have been used as indices in the WFD. Our findings indicate that, of a total of 38 ecosystem services analyzed, biological and hydromorphological indices can fully evaluate four ecosystem services. In addition, 18 ecosystem services can be partly evaluated by some of the analyzed indices, while 11 are not related with the indices. While Riparian Forest Quality was the index that was able to assess the largest number of ecosystem services (N=12), the two indices of macrophytes offered very poor guarantees. Finally, biological indices related to diatoms and aquatic invertebrates and the Fluvial Habitat Index can be related with 7, 6, and 6 ecosystem services, respectively. Because the WFD indices currently used in Spain are not able to assess most of the ecosystem services analyzed, we suggest that there is potential to develop the second phase of the WFD implementation taking this approach into consideration. The incorporation of the ecosystem services approach into the WFD could provide the framework for assess the impacts of human activities on the quality of fluvial ecosystems and could give insights for water and watershed management in order to guarantee the delivery of multiple ecosystem services.

Water temperature forecasting for Spanish rivers by means of nonlinear mixed models

Abstract Study region 43 rivers in Spain with measurement stations for air and water temperatures. Study focus River water temperatures influence aquatic ecosystem dynamics. This work aims to develop transferable river temperature forecasting models, which are not confined to sites with historical measurements of air and water temperatures. For that purpose, we estimate nonlinear mixed models (NLMM), which are based on site-specific time-series models and account for seasonality and S-shaped air-to-water temperature associations. A detailed evaluation of the short-term forecasting performance of both NLMM and site-specific models is undertaken. Measurements from 31 measurement sites were used to estimate model parameters whereas data from 12 additional sites were used solely for the evaluation of NLMM. New hydrological insights for the region Mixed models achieve levels of accuracy analogous to linear site-specific time-series regressions. Nonlinear site-specific models attain 1-day ahead forecasting accuracy close to 1 °C in terms of mean absolute error (MAE) and root mean square error (RMSE). Our results may facilitate adaptive management of freshwater resources in Spain in accordance with European water policy directives.

Study of Water Quality in a Spanish River Based on Statistical Process Control and Functional Data Analysis

The control of chemical and physicochemical properties of water bodies is essential to guarantee a proper environment, not only for the species of a certain habitat, but also for human health. In this sense, the study of pollution and its variability can be assimilated to the detection of outliers (anomalous values that indicate the deviation of the measured variable compared to the defined objectives). In this paper, two methods have been used and compared for detecting outliers: statistical process control and functional data analysis (FDA). These techniques have been tested on three key water quality variables: turbidity, electrical conductivity and dissolved oxygen. Data were continuously recorded in 2008 using an automatic monitoring station located in the Ebro River (NE Spain). The results of the research show FDA as a powerful tool for this kind of study, since it takes into account the time correlation structure of the data. This research is focused on an essential natural resource, water. The study intends to provide analysts with a methodology for detecting anomalous values (possible pollution episodes) within a large dataset of measurements. The collection of information of natural resources is a basic task for their management and control, but the analysis of gathered data is frequently difficult due to the vast number of measurements taken in the field. This work is focused on water, but the methodologies presented here can be applied to other natural data. Thus, geoscientists and geoengineers might find this research useful for interpreting many kinds of data and detecting anomalous episodes among them with an objective approach.

Transcriptomic, biochemical and individual markers in transplanted Daphnia magna to characterize impacts in the field

Daphnia magna individuals were transplanted across 12 sites from three Spanish river basins (Llobregat, Ebro, Jucar) showing different sources of pollution. Gene transcription, feeding and biochemical responses in the field were assessed and compared with those obtained in re-constituted water treatments spiked with organic eluates obtained from water samples collected at the same locations and sampling periods. Up to 166 trace contaminants were detected in water and classified by their mode of action into 45 groups that included metals, pharmaceuticals, pesticides, illicit drugs, and other industrial compounds. Physicochemical water parameters differentiated the three river basins with Llobregat having the highest levels of conductivity, metals and pharmaceuticals, followed by Ebro, whereas the Jucar river had the greatest levels of illicit drugs. D. magna grazing rates and cholinesterase activity responded similarly than the diversity of riparian benthic communities. Transcription patterns of 13 different genes encoding for general stress, metabolism and energy processes, molting and xenobiotic transporters corroborate phenotypic responses differentiated sites within and across river basins. Principal Component Analysis and Partial Least Square Projections to Latent Structures regression analyses indicated that measured in situ responses of most genes and biomarkers and that of benthic macroinvertebrate diversity indexes were affected by distinct environmental factors. Conductivity, suspended solids and fungicides were negatively related with the diversity of macroinvertebrates cholinesterase, and feeding responses. Gene transcripts of heat shock protein and metallothionein were positively related with 11 classes of organic contaminants and 6 metals. Gene transcripts related with signaling paths of molting and reproduction, sugar, protein and xenobiotic metabolism responded similarly in field and lab exposures and were related with high residue concentrations of analgesics, diuretics, psychiatric drugs, β blockers, illicit drugs, trizoles, bisphenol A, caffeine and pesticides. These results indicate that application of omic technologies in the field is a promising subject in water management.

Non-stationary flood frequency analysis in continental Spanish rivers, using climate and reservoir indices as external covariates

Abstract. Recent evidences of the impact of persistent modes of regional climate variability, coupled with the intensification of human activities, have led hydrologists to study flood regime without applying the hypothesis of stationarity. In this study, a framework for flood frequency analysis is developed on the basis of a tool that enables us to address the modelling of non-stationary time series, namely, the "generalized additive models for location, scale and shape" (GAMLSS). Two approaches to non-stationary modelling in GAMLSS were applied to the annual maximum flood records of 20 continental Spanish rivers. The results of the first approach, in which the parameters of the selected distributions were modelled as a function of time only, show the presence of clear non-stationarities in the flood regime. In a second approach, the parameters of the flood distributions are modelled as functions of climate indices (Arctic Oscillation, North Atlantic Oscillation, Mediterranean Oscillation and the Western Mediterranean Oscillation) and a reservoir index that is proposed in this paper. The results when incorporating external covariates in the study highlight the important role of interannual variability in low-frequency climate forcings when modelling the flood regime in continental Spanish rivers. Also, with this approach it is possible to properly introduce the impact on the flood regime of intensified reservoir regulation strategies. The inclusion of external covariates permits the use of these models as predictive tools. Finally, the application of non-stationary analysis shows that the differences between the non-stationary quantiles and their stationary equivalents may be important over long periods of time.

Which are, what is their status and what can we expect from ecosystem services provided by Spanish rivers and riparian areas?

By applying the framework proposed by Millennium Ecosystem Assessment, we analysed the current state and trends of 20 ecosystem services provided by Spanish rivers and riparian areas using 139 indicators. We compared the obtained results with the Europe and UK assessment. It is the first document that attempts to analyse the importance of services provided by Spanish rivers and riparian areas, and it forms part of the evaluation carried out for the Spanish Millennium Ecosystem Assessment. Among the provisioning services, freshwater, hydropower energy and genetic resources were classified as high importance, and water regulation and self-purification capacity, and natural hazard mitigation are among the regulating services, with landscape-aesthetic values and recreation and ecotourism featuring among the cultural services. About 61 % of the assessed ecosystem services are currently declining or degrading, but are higher than the percentage calculated for Europe (45 %) or for the UK (53 %). All regulating services are degrading, especially water regulation, natural hazard mitigation, soil formation and fertility and biological control, and the cultural services related to rural populations. Likewise, the biodiversity of Spanish aquatic ecosystems is decreasing rapidly. Land use changes and overexploitation of biological and mineral raw materials have been the main direct drivers of change in Spanish rivers and riparian zones, and relate directly to increase urbanised areas and irrigated agriculture. Finally, we draw some considerations on alternative models for aquatic ecosystems management which maintain aquatic ecosystem services and their biodiversity.

Development of a multiresidue method for analysis of pesticides in sediments based on isotope dilution and liquid chromatography-electrospray–tandem mass spectrometry

Because of the complexity of the sediment matrix, selective methods are necessary to identify and quantify different kinds of pesticides at a time. In this context, a multiresidue method based on isotope dilution and final analysis by liquid chromatography-electrospray–tandem mass spectrometry (LC-ESI–MS/MS) was developed for the determination of 26 pesticides and transformation products in sediment. The method developed comprises pressurized liquid extraction (PLE) and further purification of the extract by solid phase extraction (SPE) prior to analysis. In the process of method optimization various SPE cartridges as well as PLE and SPE elution solvents were evaluated. Due to the relatively high volatility of some compounds (e.g., propanil), special attention was paid to the evaporation step. Experiments comparing different pressures and times during solvent evaporation were performed with the aim to improve the recovery of these compounds. Matrix effects were also studied even though they were corrected through the use of 23 deuterated compounds as surrogate standards for quantification. The analytical method developed showed good validation parameters in terms of linearity, sensitivity (limits of detection in the pgg−1 or low ngg−1 range and limits of determination below 80ngg−1), accuracy (relative recoveries between 92 and 118%, except for malaoxon (66.5%)), and repeatability (relative standard deviations between 1.5 and 17%, for all compounds except the acidic herbicides). Its main advantage is the simultaneous analysis of pesticides with a large variety of physical–chemical properties, as well as its improved accuracy due to the use of the isotope dilution method. Application of the method to the analysis of 5 real samples from 4 different Spanish rivers revealed the presence of 5 of the 26 target compounds, being chlorpyrifos, diuron and diazinon the most ubiquitous, as expected, due to their high bioaccumulation and low mobility features.

Priority and emerging flame retardants in rivers: Occurrence in water and sediment, Daphnia magna toxicity and risk assessment

The occurrence, partitioning and risk of eight polybrominated diphenyl ethers (PBDEs), nine new brominated (NBFRs) and ten organophosphorus flame retardants (OPFRs) were evaluated in three Spanish rivers suffering different anthropogenic pressures (Nalón, Arga and Besòs). OPFRs were ubiquitous contaminants in water (ΣOPFRs ranging from 0.0076 to 7.2μgL−1) and sediments (ΣOPFRs ranging 3.8 to 824μgkg−1). Brominated flame retardants were not detected in waters, whereas ΣPBDEs ranged from 88 to 812μgkg−1 and decabromodiphenyl ethane (DBDPE) reached 435μgkg−1 in sediments from the River Besòs, the most impacted river. The occurrence of flame retardants in river water and sediment was clearly associated with human activities, since the highest levels occurred near urban and industrial zones and after wastewater treatment plants discharge. Daphnia magna toxicity was carried out for OPFRs, the most ubiquitous flame retardants, considering individual compounds and mixtures. Toxicity of nine tested OPFRs differed largely among compounds, with EC50 values ranging over three magnitude orders (0.31–381mgL−1). Results evidenced that these compounds act by non-polar narcosis, since their toxicity was proportional to their lipophilicity (Kow). Furthermore, their joint toxicity was additive, which means that single and joint toxicity can be predicted knowing their concentration levels in water using quantitative structure activity relationships (QSARs) and predictive mixture models. Based on these results, a risk assessment considering joint effect was performed calculating and summing risk quotients (RQs) for the water and sediment samples. No significant risk to D. magna (ΣRQs <1) was observed for any of the monitored rivers.

Morphological description and ecology of some rare macroalgae in south-central Spanish rivers (Castilla-La Mancha Region)

Moreno Alcaraz, J.L., Canales Monteagudo, L. & Aboal Sanjurjo, M. 2013. Morphological description and ecology of some rare macroalgae in southcentral Spanish rivers (Castilla-La Mancha Region). Anales Jard. Bot. Madrid 70(1): 81-90. The Castilla-La Mancha Region (south-central Spain) is scarcely studied in terms of freshwater algae. However, both the implementation of the Water Framework Directive (2000/60/CE) and the evaluation of the ecological state of European aquatic ecosystems have increased the intensity and frequency of water body monitoring, including the rivers, lakes and wetlands of this region. Thus, our knowledge on algal biodiversity and the geogra phical distribution of many species is rapidly increasing. In this study we describe the occurrence, ecological conditions and morphological characteristics of five algal species which are rare at the European level: Nostochopsis lobata Wood ex Bornet & Flahault, Batrachospermum atrum (Hudson) Harvey, Chroothece richteriana Hansg., Oocardium stratum Nageli and Tetrasporidium javanicum Mobius. In addition, we include Hydrurus foetidus (Vill.) Trev., a more common alga in Spain, since this is the first record for the region. Finally, we compare morphological and ecologi cal characteristics of the studied populations with other European records.

Integrated Risk Index of Chemical Aquatic Pollution (IRICAP): Case studies in Iberian rivers

The hazard of chemical compounds can be prioritized according to their PBT (persistence, bioaccumulation, toxicity) properties by using Self-Organizing Maps (SOM). The objective of the present study was to develop an Integrated Risk Index of Chemical Aquatic Pollution (IRICAP), useful to evaluate the risk associated to the exposure of chemical mixtures contained in river waters. Four Spanish river basins were considered as case-studies: Llobregat, Ebro, Jucar and Guadalquivir. A SOM-based hazard index (HI) was estimated for 205 organic compounds. IRICAP was calculated as the product of the HI by the concentration of each pollutant, and the results of all substances were aggregated. Finally, Pareto distribution was applied to the ranked lists of compounds in each site to prioritize those chemicals with the most significant incidence on the IRICAP. According to the HI outcomes, perfluoroalkyl substances, as well as specific illicit drugs and UV filters, were among the most hazardous compounds. Xylazine was identified as one of the chemicals with the highest contribution to the total IRICAP value in the different river basins, together with other pharmaceutical products such as loratadine and azaperol. These organic compounds should be proposed as target chemicals in the implementation of monitoring programs by regulatory organizations.

Genetic and phenoptypic differentiation of zebra mussel populations colonizing Spanish river basins

Zebra mussel populations in Ebro and Mijares Rivers (northern Spain) were analyzed to study the mechanisms by which this aquatic species deals with pollution. Variability analyses of mitochondrial cytochrome oxidase I gene and of one nuclear microsatellite were performed for ten populations from the Ebro River and one from the Mijares River. Comparison of these results with those from five additional European populations indicated that the Spanish populations constitute a homogeneous gene pool. Transcriptome analyses of gill samples from a subset of the Spanish populations showed changes on expression levels that correlated with variations in general fitness and loads of heavy metals. The less polluted upstream Ebro populations showed overexpression of mitochondrial and cell proliferation-related genes compared to the more polluted, downstream Ebro populations. Our data indicate that heavy metals were the main factors explaining these transcriptomic patterns, and that zebra mussel is resilient to pollutants (like mercury and organochlorine compounds) proved to be extremely toxic to vertebrates. We propose that zebra mussel populations sharing a common gene pool may acclimate to different levels and forms of pollution through modulations in their transcriptomic profile, although direct selection on genes showing differential expression patterns cannot be ruled out.

Phenotypic and genotypic characteristics of Phormidium-like cyanobacteria inhabiting microbial mats are correlated with the trophic status of running waters

Polyphasic analysis was carried out of natural samples and strains isolated from Phormidium mats, collected from different Spanish rivers with distinct water quality. 16S rRNA gene analysis separated five main clusters in a phylogenetic tree corresponding to five main, previously observed morphotypes. Two isolated strains and three natural samples had a relatively homogeneous morphology, which could correspond to Phormidium autumnale, and their sequences grouped in a well-supported cluster (morphotype–genotype I). However, ultrastructural differences were found among representatives from this cluster, and three clades could be separated in a further phylogenetic analysis. The samples belonging to the first clade were characteristic of hypertrophic waters, while representatives of the second grew in mesotrophic conditions, and those of the third in eutrophic waters. These results suggested that our representatives of morphotype–genotype I belong to three different species. According to our results and other published data, complementary information was obtained on the basis of morphological, phylogenetic and ecological criteria. Morphotype–genotype II, corresponding to Phormidium terebriforme, is a potential indicator of polluted waters. Oscillatoria tenuis, corresponding to morphotype–genotype III, is characteristic of eutrophic conditions. Phormidium mats identified as Phormidium corium (morphotype–genotype IV) were found to be characteristic of waters with low nutrient levels. Finally, morphotype–genotype V, identified as Phormidium aerugineo-caeruleum was dominant in oligo- to mesotrophic conditions.

Haematophagous feeding of newly metamorphosed European sea lampreys Petromyzon marinus on strictly freshwater species

Approximately 6% of the freshwater living northern straight-mouth nase Pseudochondrostoma duriense in two Spanish rivers had attached post-metamorphic sea lamprey Petromyzon marinus. Minimum prey size was 16·1 cm fork length and 56·3 g mass. The condition factor of attacked P. duriense was 16% lower than that of unattacked conspecifics.

River Restoration in Spain: Theoretical and Practical Approach in the Context of the European Water Framework Directive

River restoration is becoming a priority in many countries because of increasing the awareness of environmental degradation. In Europe, the EU Water Framework Directive (WFD) has significantly reinforced river restoration, encouraging the improvement of ecological status for water bodies. To fulfill the WFD requirements, the Spanish Ministry of the Environment developed in 2006 a National Strategy for River Restoration whose design and implementation are described in this paper. At the same time many restoration projects have been conducted, and sixty of them have been evaluated in terms of stated objectives and pressures and implemented restoration measures. Riparian vegetation enhancement, weir removal and fish passes were the most frequently implemented restoration measures, although the greatest pressures came from hydrologic alteration caused by flow regulation for irrigation purposes. Water deficits in quantity and quality associated with uncontrolled water demands seriously affect Mediterranean rivers and represent the main constraint to achieving good ecological status of Spanish rivers, most of them intensively regulated. Proper environmental allocation of in-stream flows would need deep restrictions in agricultural water use which seem to be of very difficult social acceptance. This situation highlights the need to integrate land-use and rural development policies with water resources and river management, and identifies additional difficulties in achieving the WFD objectives and good ecological status of rivers in Mediterranean countries.