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The Mediterranean region is anticipated to be (or, already is) one of the hot spots for climate change, where freshwater ecosystems are under threat from the effects of multiple stressors. Climate change is impacting natural resources and on the functioning of Ecosystem Services. The challenges about modelling climate change impact on water cycle in general and specifically on socio-economic dynamics of the society leads to an exponential amount of results that restrain interpretation and added value of forecasting at local level. One of the main challenges when dealing with climate change projections is the quantification of uncertainties. Modellers might have limited information or understanding from local river catchment management practices and from other disciplines with relevant insights on socio-economic and environmental complex relationship between biosphere and human based activities. Current General Circulation Models cannot fulfil the requirements of high spatial detail required for water management policy. This article reports an innovative transdisciplinary methodology to down scale Climate Change scenarii to river basin level with a special focus on the development of climate change narrative under SSP5-RCP8.5 combination called Myopic scenario and SSP1-RCP4.5 combination called Sustainable scenario. Local Stakeholder participative workshop in the Evrotas river basin provide perception of expected changes on water demand under to two developed scenario narratives.

Flow cessation affects river ecosystems submitted to low precipitation and increased water demand, and creates unfavourable conditions to aquatic biological communities. Diatoms are amongst the most sensitive biological groups to hydric stress, making them good indicators of preceding hydrological conditions. We here analyse the response of diatom assemblages to the duration and frequency of non-flow periods in 23 Mediterranean temporary streams. All of them experienced a strong decrease in water flow during summer, leading to a period of flow cessation. In addition, other ten permanent streams (zero dry days during the study period) were included in the study for comparative purposes. Temporary and permanent streams showed similar diatom species richness, evenness, and alpha diversity. However, beta diversity was higher in temporary than permanent streams, regardless rare taxa (

It is well established that a global sanitation crisis threatens humans. By comparison, much less attention has been given to address the effects of this crisis on the health of ecosystems. We provide examples of how sewage can affect natural ecosystems and where hotspots in sewage contamination commonly overlap with these habitats. We highlight these issues for some of the major ecosystems spanning across terrestrial, aquatic, and coastal realms. Recent studies reveal that untreated and poorly treated sewage elevates concentrations of nutrients, pathogens, endocrine disruptors, heavy metals, and pharmaceuticals in natural ecosystems. We show many large areas (10,000's of km2) across the globe with high levels of sewage contamination and that these contamination hotspots overlap extensively in occurrence with coral reefs, salt marshes, and fish-rich river systems. Given the global extent of sewage pollution in and near natural habitats, conservation biologists and managers must address this threat. However, because of its size, conservationists cannot solve this problem alone. We therefore argue that conservation must combine forces with the human health sector to create cross-disciplinary synergisms in innovation and efficiency. New sewage management solutions are emerging, such as waste-free toilets and resource recovery to generate fuel and drinking water; but more innovation is needed - a demand that will most effectively be reached through cross-sector collaboration.

Urban pollution and hydrological stress are common stressors of stream ecosystems, but their combined effects on ecosystem functioning are still unclear. We measured a set of functional processes and accompanying environmental variables in locations upstream and downstream of urban sewage inputs in 13 streams covering a wide range of water pollution levels and hydrological variability. Sewage inputs seriously impaired stream chemical characteristics and led to complex effects on ecosystem functioning. Biofilm biomass accrual, whole-reach nutrient uptake and metabolism (ecosystem respiration) were generally subsidized, whereas organic matter decomposition and biofilm phosphorus uptake capacity decreased with increasing pollutant concentrations. Hydrological stress affected stream ecosystem functioning but its effect was minor compared to the effects of urban pollution, due to the large inter-site variability of the streams. Changes appeared mainly linked to the concentration of pharmaceutically active compounds, followed by other chemical characteristics and by hydrology. The results point to the need to further improve sewage treatment, especially as climate change will stress riverine organisms and reduce the dilution capacity of the receiving streams.

Current approaches have failed to deliver a truly integrated management of the different elements of the urban water system, such as freshwater ecosystems, drinking water treatment plants, distribution networks, sewer systems and wastewater treatment plants. Because the different parts of urban water have not been well integrated, poor decisions have been made for society in general, leading to the misuse of water resources, the degradation of freshwater ecosystems and increased overall treatment costs. Some attempts to solve environmental issues have adopted the ecosystem services concept in a more integrated approach, however this has rarely strayed far away from pure policy, and has made little impact in on-the-ground operational matters. Here, we present an improved decision-making framework to integrate the management of urban water systems. This framework uses the ecosystem service concept in a practical way to make a better use of both financial and water resources, while continuing to preserve the environment This research was supported by the European Communities 7thFramework Programme (SANITAS ITN Project agreement 289193); as well as by the individual fellowships Ramon y Cajal (RYC-2013-14595) and Marie Curie Career Integration Fellowship (PCIG9-GA-2011-293535) to Lluís Corominas, and a José Castillejo (CAS15-00163) to Vicenç Acuña. Authors also acknowledge the support from the Economy and Knowledge Department of the Catalan Government (Consolidated Research Group 2014 SGR 291 - ICRA).

Pharmaceuticals are designed to improve human and animal health, but may also be a threat to freshwater ecosystems, particularly after receiving urban or wastewater treatment plant (WWTP) effluents. Knowledge on the fate and attenuation of pharmaceuticals in engineered and natural ecosystems is rather fragmented, and comparable methods are needed to facilitate the comprehension of those processes amongst systems. In this study the dynamics of 8 pharmaceuticals (acetaminophen, sulfapyridine, sulfamethoxazole, carbamazepine, venlafaxine, ibuprofen, diclofenac, diazepam) and 11 of their transformation products were investigated in a WWTP and the associated receiving river ecosystem. During 3 days, concentrations of these compounds were quantified at the influents, effluents, and wastage of the WWTP, and at different distances downstream the effluent at the river. Attenuation (net balance between removal and release from and to the water column) was estimated in both engineered and natural systems using a comparable model-based approach by considering different uncertainty sources (e.g. chemical analysis, sampling, and flow measurements). Results showed that pharmaceuticals load reduction was higher in the WWTP, but attenuation efficiencies (as half-life times) were higher in the river. In particular, the load of only 5 out of the 19 pharmaceuticals was reduced by more than 90% at the WWTP, while the rest were only partially or non-attenuated (or released) and discharged into the receiving river. At the river, only the load of ibuprofen was reduced by more than 50% (out of the 6 parent compounds present in the river), while partial and non-attenuation (or release) was observed for some of their transformation products. Linkages in the routing of some pharmaceuticals (venlafaxine, carbamazepine, ibuprofen and diclofenac) and their corresponding transformation products were also identified at both WWTP and river. Finally, the followed procedure showed that dynamic attenuation in the coupled WWTP-river system could be successfully predicted with simple first order attenuation kinetics for most modeled compounds This research was supported by the European Communities 7th Framework Programme Marie Curie Career Integration Grant PCIG9-GA-2011-293535. Authors also acknowledge the support from the Economy and Knowledge Department of the Catalan Government (Consolidated Research Group 2014 SGR 291 - ICRA) and the Spanish Ministry of Economy and Competitiveness for funding (CTM2015- 66892-R, CTM2012-38314-C02-01 and RYC-2013-14595)

Decisions on river rehabilitation actions are often based on cost-benefit analyses taking into account the costs and benefits of the considered management actions, but ecosystem services are often not included as benefits, despite recent evidences on the effects of river rehabilitations on ecosystem services. A cost-benefit analysis integrating market and non-market costs and benefits was undertaken in this study to assess the economic feasibility of a river rehabilitation project in a water scarce region, the Yarqon River Rehabilitation project (Israel). In this case, the costs included both the capital costs of implementing rehabilitation measures (including maintenance costs) and the opportunity costs of water allocation (foregone benefits to farmers from water provisioning for agriculture). The benefits of rehabilitation included the net marginal benefits of the cultural ecosystem services at local scale (estimated with a hedonic pricing method), and at regional scale (estimated with a value function transfer), in addition to the habitat service gene-pool protection (estimated with a replacement cost method). Bearing in mind the uncertainties surrounding water resource management decisions, especially in water scarce areas, a sensitivity and risk analysis was conducted using an analysis that included both Monte Carlo simulations and the standardized regression coefficients method. The rehabilitation of the Yarqon River provided positive net present values (approximately $139 million in 30-year period). This was thanks to the provision of cultural ecosystem services and despite the high rehabilitation costs, and that the massive water reallocation involved high foregone benefits to farmers. Therefore, these results highlight that river rehabilitation in water scarce regions can be economically viable due to the social amenity demand for urban rivers This research was supported by EU-ITN SANITAS (ITN-289193), a Marie Curie European Reintegration Grant (PERG07-GA-2010-259219) and a Career Integration Grant (PCIG09-2011-293365) within the 7th European Community Framework Programme, and the RYC-2013-14595 from the Spanish Ministry of Economy and Competitiveness. Authors acknowledge the support from the Economy and Knowledge Department of the Catalan Government through Consolidated Research Group (2014 SGR 291) Catalan Institute for Water Research

Most fluvial networks worldwide include watercourses that recurrently cease to flow and run dry. The spatial and temporal extent of the dry phase of these temporary watercourses is increasing as a result of global change. Yet, current estimates of carbon emissions from fluvial networks do not consider temporary watercourses when they are dry. We characterized the magnitude and variability of carbon emissions from dry watercourses by measuring the carbon dioxide (CO2) flux from 10 dry streambeds of a fluvial network during the dry period and comparing it to the CO2 flux from the same streambeds during the flowing period and to the CO2 flux from their adjacent upland soils. We also looked for potential drivers regulating the CO2 emissions by examining the main physical and chemical properties of dry streambed sediments and adjacent upland soils. The CO2 efflux from dry streambeds (mean ± SD = 781.4 ± 390.2 mmol m−2 day−1) doubled the CO2 efflux from flowing streambeds (305.6 ± 206.1 mmol m−2 day−1) and was comparable to the CO2 efflux from upland soils (896.1 ± 263.2 mmol m−2 day−1). However, dry streambed sediments and upland soils were physicochemically distinct and differed in the variables regulating their CO2 efflux. Overall, our results indicate that dry streambeds constitute a unique and biogeochemically active habitat that can emit significant amounts of CO2 to the atmosphere. Thus, omitting CO2 emissions from temporary streams when they are dry may overlook the role of a key component of the carbon balance of fluvial networks This research was funded by the Spanish Ministry of Economy and Competitiveness through the Projects CGL2011-30474-C02-01 and CGL2014-58760-C3-1-R.

In-stream attenuation of dissolved and particulate forms of carbon, nitrogen and phosphorus are a crucial ecosystem service, especially in watercourses downstream of chemical pollution point-sources (i.e. wastewater treatment plants). Most chemical-fate models assume that attenuation is directly proportional to the concentration of available dissolved organic carbon, and inorganic nitrogen and phosphorus compounds in watercourses, but there are multiple evidences of saturation and even inhibition of attenuation at higher concentrations. Our current comprehension of nutrient attenuation kinetics in streams remains a limiting factor for the development and calibration of predictive models of the chemical fate of these compounds in rivers, thus hindering the development and implementation of more effective regulatory strategies. Here, we assessed the in-stream attenuation of dissolved organic carbon, inorganic nitrogen (NH4+, NO2-, NO3-) and phosphorus (PO43-) compounds at increasing concentrations of these compounds, and analyzed the interaction between attenuation kinetics and biofilm structure and function. Specifically, the net balances of these compounds were assessed in artificial streams exposed to eight treatments following the gradient of WWTP contribution to the river flow (0, 14, 29, 43, 58, 72, 86, and 100% of WWTP effluent water). Results indicate that biological in-stream attenuation by a given biofilm of an effluent dominated watercourse might be saturated if exposed for short periods to high nutrient concentrations such as during combined sewer overflow events, but that communities can adapt if exposed long enough to high concentrations, therefore avoiding or at least minimizing saturation. More attention should be therefore given to the management of effluent-dominated watercourses, as reductions in the temporal variability of the discharged wastewater by WWTP might enhance attenuation and thus reduce water quality issues downstream.

The loss and degradation of natural habitats is a primary cause of biodiversity decline. The increasing impacts of climate and land use change affect water availability, ultimately decreasing agricultural production. Areas devoted to irrigation have been increased to compensate this reduction, causing habitat and biodiversity losses, especially in regions undergoing severe water stress. These effects might intensify under global change, probably contributing to a decrease in habitat quality. We selected four European river basins across a gradient of water scarcity and irrigation agriculture. The habitat quality in the basins was assessed as a function of habitat suitability and threats under current and future global change scenarios of irrigation. Results revealed that the most threatened regions under future scenarios of global change were among those suffering of water scarcity and with bigger areas devoted to irrigation. Loss of habitat quality reached 10% in terrestrial and 25% in aquatic ecosystems under climate change scenarios involving drier conditions. The aquatic habitats were the most degraded in all scenarios, since they were affected by threats from both the terrestrial and the aquatic parts of the basin. By identifying in advance the regions most vulnerable to habitat and biodiversity loss, our approach can assist decision makers in deciding the conservation actions to be prioritized for mitigation and adaptation to the effects of climate change, particularly front the development of irrigation plans

Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerage, and policy advocacy. GLOBAQUA studies six river basins (Ebro, Adige, Sava, Evrotas, Anglian and Souss Massa) affected by water scarcity, and aims to answer the following questions: how does water scarcity interact with other existing stressors in the study river basins? How will these interactions change according to the different scenarios of future global change? Which will be the foreseeable consequences for river ecosystems? How will these in turn affect the services the ecosystems provide? How should management and policies be adapted to minimise the ecological, economic and societal consequences? These questions will be approached by combining data-mining, field- and laboratory-based research, and modelling. Here, we outline the general structure of the project and the activities to be conducted within the fourteen work-packages of GLOBAQUA., This work has been supported by the European Communities 7th Framework Programme Funding under Grant agreement no. 603629- ENV-2013-6.2.1-Globaqua and by the Generalitat de Catalunya (Consolidated Research Groups “2014 SGR 418 - Water and Soil Quality Unit” and 2014 SGR 291 - ICRA). Damià Barceló acknowledges support from the Visiting Professor Program of King Saud University. Special thanks are due to all partners of the GLOBAQUA consortium and the peer review panel for ensuring quality results and fruitful collaboration within the project.

The effluents of wastewater treatment plants (WWTPs) include a complex mixture of nutrients and pollutants. Nutrients can subsidise autotrophic and heterotrophic organisms, while toxic pollutants can act as stressors, depending, for instance, on their concentration and interactions in the environment. Hence, it is difficult to predict the overall effect of WWTP effluents on river ecosystem functioning. We assessed the effects of WWTP effluents on river biofilms and ecosystem metabolism in one river segment upstream from a WWTP and three segments downstream from the WWTP and following a pollution gradient. The photosynthetic capacity and enzymatic activity of biofilms showed no change, with the exception of leucine aminopeptidase, which followed the pollution gradient most likely driven by changes in organic matter availability. The effluent produced mixed effects on ecosystem-scale metabolism. It promoted respiration (subsidy effect), probably as a consequence of enhanced availability of organic matter. On the other hand, and despite enhanced nutrient concentrations, photosynthesis-irradiance relationships showed that the effluent partly decoupled primary production from light availability, thus suggesting a stress effect. Overall, WWTP effluents can alter the balance between autotrophic and heterotrophic processes and produce spatial discontinuities in ecosystem functioning along rivers as a consequence of the mixed contribution of stressors and subsidisers This research was supported by the Spanish Ministry of Economy and Competitiveness and FEDER foundings through the SCARCE Consolider-Ingenio CSD2009-00065 and ABSTRACT CGL2012-35848 projects, and the European Communities 7th Framework Programme Funding under Grant agreement no. 603629-ENV-2013-6.2.1-Globaqua. We especially thank the people who assisted in the field and in the laboratory. A thorough review of the manuscript by Prof. Roger I. Jones and two unknown reviewers is deeply appreciated too. We also want to acknowledge financial support in terms of predoctoral grants from the University of the Basque Country (I. Aristi), the Basque Government (M. Arroita), as well as a postdoctoral grant ‘Juan de la Cierva’ (jci-2010-06397) (D. von Schiller) and a Marie Curie European Reintegration Grant (PERG07-GA-2010-259219) (V. Acuña). This work was partly supported by the Basque Government (Consolidated Research Group: Stream Ecology 7-CA-18/10)

Protecting the ecological health of rivers relies on maintaining intact flows from source areas to downstream navigable waters (1). Yet the U.S. Environmental Protection Agency (EPA) intends to rescind legal protection of tributary rivers, streams, and wetlands that do not have year-round flows (temporary waterways) and whose surface waters contribute flow to permanent navigable waters (2). This decision would severely damage the condition and uses of many U.S. waters, both temporary and navigable.

Organic micro-contaminants (OMCs) enter in freshwaters and interact with other contaminants such as carbon nanoparticles, becoming a problem of unknown consequences for river ecosystems. Carbon nanoparticles (as fullerenes C60) are good adsorbents of organic contaminants and their interaction can potentially affect their toxicity to river biofilms. We tested the C60 interactions with selected OMCs and their effects on river biofilms in different short-term experiments. In these, river biofilms were exposed to C60 and three OMCs (triclosan, diuron, or venlafaxine) and their respective mixtures with fullerenes (C60 + each OMC). The effects were evaluated on structural, molecular, and functional descriptors of river biofilms. Our results showed that C60 did not cause toxic effects in river biofilms, whereas diuron and triclosan significantly affected the heterotrophic and phototrophic components of biofilms and venlafaxine affected only the phototrophic component. The joint exposure of C60 with venlafaxine was not producing differences with respect to the former response of the toxicant, but the overall response was antagonistic (i.e., decreased toxicity) with diuron, and synergistic (i.e., increased toxicity) with triclosan. We suggest that differences in the toxic responses could be related to the respective molecular structure of each OMC, to the concentration proportion between OMC and C60, and to the possible competition between C60 pollutants on blocking the receptors of the biological cell membranes. We conclude that the presence of C60 at low concentrations modified the toxicity of OMC to river biofilms. These interactions should therefore be considered when predicting toxicity of OMC in river ecosystems. © 2018 Freixa, Acuña, Gutierrez, Sanchís, Santos, Rodriguez-Mozaz, Farré, Barceló and Sabater., We would like to thank Ferran Romero for his help in the molecular analysis, Lorenzo Proia for his help in using MicroResp technique, and Maria Casellas for laboratory assistance.

Inland waters substantially contribute to global carbon fluxes, and within them, low-order forested streams are important processors of allochthonous organic matter (OM) inputs. Leaf litter quantity and quality are expected to change in response to global change (e.g., climate change, land use change) but few long-term studies exist to better understand these shifts. The goal of this study was to assess the quantity and quality of OM sources to determine which global and local environmental factors control the dynamics of OM at the reach scale. The study was performed on a Mediterranean stream edged by a deciduous riparian forest over a 10-yr-time period. Riparian inputs, benthic and transported OM, and its carbon and nitrogen content were determined. The quantity of riparian inputs (912 ± 56 g dry mass m−2 yr−1) was comparable to temperate regions with deciduous riparian forests, but the Mediterranean climate determined the different dynamics of these inputs. El Nino Southern Oscillation was strongly related to the interannual variability in riparian inputs through changes in precipitation. The annual amount of inputs depended on previous cumulated nonflow periods, with successive nonflow periods causing a progressive decrease in riparian inputs. The distribution of inputs throughout the year followed either a unimodal or bimodal pattern according to the absence or presence of a nonflow period in summer. In addition, drought caused lower quality (higher carbon : nitrogen molar ratio) riparian inputs. Changes in the quantity and quality of OM were explained by both present and past local and global factors.

During summer drought, Mediterranean fluvial networks are transformed into highly heterogeneous landscapes characterized by different environments (i.e., running and impounded waters, isolated river pools and dry beds). This hydrological setting defines novel biogeochemically active areas that could potentially increase the rates of carbon emissions from the fluvial network to the atmosphere. Using chamber methods, we aimed to identify hot spots for carbon dioxide (CO2) and methane (CH4) emissions from two typical Mediterranean fluvial networks during summer drought. The CO2 efflux from dry beds (mean ± SE = 209 ± 10 mmolCO2m-2 d-1) was comparable to that from running waters (120 ± 33 mmol m-2 d-1) and significantly higher than from impounded waters (36.6 ± 8.5 mmol m-2 d-1) and isolated pools (17.2 ± 0.9 mmol m-2 d-1). In contrast, the CH4 efflux did not significantly differ among environments, although the CH4 efflux was notable in some impounded waters (13.9 ± 10.1 mmol CH4 m-2 d-1) and almost negligible in the remaining environments (mean\0.3 mmol m-2 d-1). Diffusion was the only mechanism driving CO2 efflux in all environments and was most likely responsible for CH4 efflux in running waters, isolated pools and dry beds. In contrast, the CH4 efflux in impounded waters was primarily ebullition-based. Using a simple heuristic approach to simulate potential changes in carbon emissions from Mediterranean fluvial networks under future hydrological scenarios, we show that an extreme drying out (i.e., a four-fold increase of the surface area of dry beds) would double the CO2 efflux from the fluvial network. Correspondingly, an extreme transformation of running waters into impounded waters (i.e., a twofold increase of the surface area of impounded waters) would triple the CH4 efflux. Thus, carbon emissions from dry beds and impounded waters should be explicitly considered in carbon assessments of fluvial networks, particularly under predicted global change scenarios, which are expected to increase the spatial and temporal extent of these environments This research was funded by the Spanish Ministry of Economy and Competitiveness through the projects CGL2011-30474-C02-01 and CGL2014-58760-C3-1-R

Current trends indicate that the duration of the period with no surface flow experienced by temporary waterways is increasing. Even though several studies have already characterised the effects of non-flow periods on stream ecosystems, the consequences of their increasing duration remain poorly understood. Replicate artificial streams were used to characterise the effects of the duration of the non-flow period on stream biofilm processes. We hypothesised that increased duration of the non-flow period would differentially influence autotrophic and heterotrophic processes and promote heterotrophy (lower P: R ratios). We aimed to identify possible non-linearities and thresholds in the disturbance-response relationships between the duration of the non-flow period (six treatments) and stream biofilm processes (six ecological variables representing autotrophic or heterotrophic processes). The duration of the non-flow period proved to be important for the balance between autotrophic and heterotrophic processes in stream biofilms, with the autotrophic processes being less resistant but more resilient. Autotrophic and heterotrophic processes also differed in terms of disturbance-response relationships, which were linear for most autotrophic ecological variables and sigmoid logistic for heterotrophic variable. Hence, non-flow periods had an immediate effect on autotrophic processes, but the effect on heterotrophic processes was delayed and completed only after crossing the ecological threshold of complete desiccation. These differences involved a shift towards lower P: R ratios at longer durations of the non-flow period. However, the high resilience of autotrophic processes, mainly related to the ability of diatoms to recover, limited the shift towards lower P: R ratios to the non-flow period and to the first weeks after flow return. This study demonstrates the complex effects of flow intermittency on stream biofilm processes, and emphasises the relevance of the duration of the non-flow period as a predictor of the effects on temporary waterways This research was supported by a Marie Curie European Reintegration Grant (PERG07-GA-2010-259219) within the 7th European Community Framework Programme, by the Spanish Ministry of Economy and Competitiveness through its financial support through the project CARBONET (CGL2011-30474-C02-01) and by the European Union through the European Regional Development Fund (FEDER)

Aquatic organisms from freshwater ecosystems impacted by waste water treatment plant (WWTP) effluents are constantly exposed to constant concentrations of pharmaceuticals, endocrine disruptors and related compounds, among other anthropogenic contaminants. Macroinvertebrates inhabiting freshwater ecosystems might be useful bioindicators of exposure to contaminants, since their lives are long enough to bioaccumulate, but at the same time may integrate short-term changes in the environment. However, studies about potential bioaccumulation of emerging contaminants in these organisms are very scarce. The objectives of this study were to develop an analytical methodology for the analysis of 41 pharmaceuticals and 21 endocrine disruptors in freshwater invertebrates. In addition, bioaccumulation of these contaminants in three macroinvertebrate taxa inhabiting a waste water treatment plant -impacted river was evaluated. The method for the simultaneous extraction of both families of compounds is based on sonication, purification via removal of phospholipids, and analysis by ultra performance liquid chromatography coupled to a mass spectrometer (UPLC-MS/MS) in tandem. Recoveries for pharmaceuticals were 34-125%, and for endocrine disruptors were 48-117%. Method detection limits (MDLs) for EDCs were in the range of 0.080-2.4 ng g-1, and for pharmaceuticals, 0.060-4.3 ng g-1. These pollutants were detected in water samples taken downstream the waste water treatment plant effluent at concentrations up to 572 ng L-1. Two non-esteroidal anti-inflammatory drugs, diclofenac and ibuprofen, and four endocrine disruptors - estrone, bisphenol A, TBEP, and nonylphenol - were detected in at least one macroinvertebrate taxa in concentrations up to 183 ng g-1 (dry weight). An isobaric interference was identified during the analysis of diclofenac in Hydropsyche samples, which was successfully discriminated via accurate mass determination by TFC-LTQ Orbitrap This study has been financed by Spanish Ministry o fEconomy and Competitiveness through the project SCARCE (Consolider-Ingenio 2010CSD200900065). This work was partly supported by the Generalitat de Catalunya (Consolidated Research Group: Catalan Institute for water Research 2014 SGR 291)

Freshwater ecosystems are confronted with multiple chemical, biological and physical stressors. Co-occurring stressors commonly result in additive responses, but non-additive interactions may also occur, hindering our predicting capacity. Despite growing interest in multiple stressor research, the response of freshwater communities to co-occurring chemical and climate change-related physical stressors remains largely unexplored. Here, we used a microcosm approach to evaluate the effect of the combined action of chemical and physical stressors on river biofilms. Results showed that additive responses dominated, whereas 14.5% of all responses were non-additive (75% antagonisms and 25% synergisms). Among these non-additive interactions, physical stressors dominated over chemicals and drove the overall responses. Overall, the occurrence of these non-additive interactions, together with the dominance of the climate-change related physical stressors, might lead to unexpected responses as a result of climate change.

River ecosystems are subject to multiple stressors that affect their structure and functioning. Ecosystem structure refers to characteristics such as channel form, water quality or the composition of biological communities, whereas ecosystem functioning refers to processes such as metabolism, organic matter decomposition or secondary production. Structure and functioning respond in contrasting and complementary ways to environmental stressors. Moreover, assessing the response of ecosystem functioning to stressors is critical to understand the effects on the ecosystem services that produce direct benefits to humans. Yet, there is more information on structural than on functional parameters, and despite the many approaches available to measure river ecosystem processes, structural approaches are more widely used, especially in management. One reason for this discrepancy is the lack of synthetic studies analyzing river ecosystem functioning in a way that is useful for both scientists and managers. Here, we present a synthesis of key river ecosystem processes, which provides a description of the main characteristics of each process, including criteria guiding their measurement as well as their respective sensitivity to stressors. We also discuss the current limitations, potential improvements and future steps that the use of functional measures in rivers needs to face. © 2017 The Author(s), This work has been supported by the EU 7th Framework Programme Funding under Grant agreement no. 603629-ENV-2013-6.2.1-Globaqua. Additional financial support has been provided by the Basque Government under Grant agreement no. IT951-16. We also acknowledge financial support in terms of pre-doctoral and post-doctoral grants from the University of the Basque Country (O. Pereda, L. Solagaistua, I. Aristi, M. Arroita, A. Martínez) and from the Spanish Ministry of Economy and Competitiveness (S. Monroy).

Wastewater effluents increase the nutrient load of receiving streams while introducing a myriad of anthropogenic chemical pollutants that challenge the resident aquatic (micro)biota. Disentangling the effects of both kind of stressors and their potential interaction on the dissemination of antibiotic resistance genes in bacterial communities requires highly controlled manipulative experiments. In this work, we investigated the effects of a combined regime of nutrients (at low, medium and high concentrations) and a mixture of emerging contaminants (ciprofloxacin, erythromycin, sulfamethoxazole, diclofenac, and methylparaben) on the bacterial composition, abundance and antibiotic resistance profile of biofilms grown in artificial streams. In particular, we investigated the effect of this combined stress on genes encoding resistance to ciprofloxacin (qnrS), erythromycin (ermB), sulfamethoxazole (sul1 and sul2) as well as the class 1 integron-integrase gene (intI1). Only genes conferring resistance to sulfonamides (sul1 and sul2) and intI1 gene were detected in all treatments during the study period. Besides, bacterial communities exposed to emerging contaminants showed higher copy numbers of sul1 and intI1 genes than those not exposed, whereas nutrient amendments did not affect their abundance. However, bacterial communities exposed to both emerging contaminants and a high nutrient concentration (1, 25 and 1 mg L−1 of phosphate, nitrate and ammonium, respectively) showed the highest increase on the abundance of sul1 and intI1 genes thus suggesting a factors synergistic effect of both stressors. Since none of the treatments caused a significant change on the composition of bacterial communities, the enrichment of sul1 and intI1 genes within the community was caused by their dissemination under the combined pressure exerted by nutrients and emerging contaminants. To the best of our knowledge, this is the first study demonstrating the contribution of nutrients on the maintenance and spread of antibiotic resistance genes in streambed biofilms under controlled conditions. Our results also highlight that nutrients could enhance the effect of emerging contaminants on the dissemination of antibiotic resistance.

A mesocosm case study was conducted to gain understanding and practical knowledge on biofilm emerging contaminants biodegradation capacity under stressor and multiple stressor conditions. Two real life scenarios: I) biodegradation in a pristine intermittent stream experiencing acute pollution and II) biodegradation in a chronically polluted intermittent stream, were examined via a multifactorial experiment using an artificial stream facility. Stream biofilms were exposed to different water flow conditions i.e. permanent and intermittent water flow. Venlafaxine, a readily biodegradable pharmaceutical was used as a measure of biodegradation capacity while pollution was simulated by a mixture of four emerging contaminants (erythromycin, sulfisoxazole, diclofenac and imidacloprid in addition to venlafaxine) in environmentally relevant concentrations. Biodegradation kinetics monitored via LC-MS/MS was established, statistically evaluated, and used to link biodegradation with stress events. The results suggest that the effects of intermittent flow do not hinder and may even stimulate pristine biofilm biodegradation capacity. Chronic pollution completely reduced biodegradation in permanent water flow experimental treatments while no change in intermittent streams was observed. A combined effect of water flow conditions and emerging contaminants exposure on biodegradation was found. The decrease in biodegradation due to exposure to emerging contaminants is significantly greater in streams with permanent water flow suggesting that the short and medium term biodegradation capacity in intermittent systems may be preserved or even greater than in perennial streams.

Este artículo contiene 15 páginas, 5 figuras, 1 tabla., Wastewater discharges introduce antibiotic residues and antibiotic-resistant bacteria (ARB) into surface waters. Both inputs directly affect the streambed resistome, either by exerting a selective pressure that favour the proliferation of resistant phenotypes or by enriching the resident communities with wastewater-associated ARB. Here, we investigated the impact of raw and treated urban wastewater discharges on epilithic (growing on rocks) and epipsammic (growing on sandy substrata) streambed biofilms. The effects were assessed by comparing control and impact sites (i) on the composition of bacterial communities; (ii) on the abundance of twelve antibiotic resistance genes (ARGs) encoding resistance to b-lactams, fluoroquinolones, sulphonamides, tetracyclines, macrolides and vancomycin, as well as the class 1 integron-integrase gene (intI1); (iii) on the occurrence of wastewater-associated bacteria, including putative pathogens, and their potential linkage to target ARGs. We measured more pronounced effects of raw sewage than treated wastewater at the three studied levels. This effect was especially noticeable in epilithic biofilms, which showed a higher contribution of wastewater-associated bacteria and ARB than in epipsammic biofilms. Comparison of correlation coefficients obtained between the relative abundance of both target ARGs and operational taxonomic units classified as either potential pathogens or nonpathogens yielded significant higher correlations between the former category and genes intI1, sul1, sul2 and ermB. Altogether, these results indicate that wastewater-associated micro-organisms, including potential pathogens, contribute to maintain the streambed resistome and that epilithic biofilms appear as sensitive biosensors of the effect of wastewater pollution in surface waters., This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) through projects TRACE (Water JPI Pilot Call, Ref. 281347) to CMB and BRIDGES (Ref. CGL2015-69043-P) to XTM, and by the Generalitat de Catalunya (Consolidated Research Groups 2014, SGR 291-ICRA).

Biofilm communities are exposed to long periods of desiccation in temporary streams. We investigated how water flow intermittency affected the bacterial community structure colonizing three different streambed compartments in a Mediterranean stream. Massive parallel sequencing revealed different bacterial communities in biofilms from sand sediments and cobbles. Bacterial communities were similar (62% of shared operational taxonomic units) in the epipsammic and hyporheic biofilms, and more diverse than those in the epilithic biofilms. The non-flow phase caused a decrease of bacterial diversity in the biofilms, when communities included only bacterial taxa assumed to be adapted to water stress. The most sensitive bacterial communities to flow intermittency were in the epilithic, where the exposure to physical stress was the highest. In sand sediments a wide group of bacterial taxa was tolerant to desiccation. During non-flow the proliferation of opportunistic taxa in the superficial compartments evidenced the biological link with the terrestrial environment. Bacterial communities better tolerate rewetting than desiccation, since a major number of taxa tolerant to rewetting occurred in all biofilms. Overall, bacterial communities in sandy compartments showed higher resistance to flow intermittency than those in epilithic biofilms. Droughts are severely increasing in temperate regions worldwide and are usually associated with temporal and spatial increases of non-flow periods in streams and rivers. As a result, many systems become temporary, with unknown biogeochemical and ecological consequences for biodiversity

Temporary watercourses that naturally cease to flow and run dry comprise a notable fraction of the world’s river networks, yet estimates of global carbon dioxide (CO 2 ) emissions from watercourses do not consider emissions from these systems when they are dry. Using data from a sampling campaign in a Mediterranean river during the summer drought period, we demonstrate that the CO 2 efflux from dry watercourses can be substantial, comparable to that from adjacent terrestrial soils and higher than from running or stagnant waters. With an up-scaling approach, we show that including emissions from dry watercourses could increase the estimate of CO 2 emissions from watercourses in our study region by 0.6–15%. Moreover, our results tentatively illustrate that emissions from dry watercourses could be especially important in arid regions, increasing the estimate of global CO 2 emissions from watercourses by 0.4–9%. Albeit relatively small, the contribution of dry watercourses could help to constrain the highly uncertain magnitude of the land carbon sink. We foresee that in many areas of the world, the expected increase in the extent of temporary watercourses associated with future global change will increase the relevance of CO 2 emissions from dry watercourses.

Dams regulate downstream hydrology and modify water quality, which in turn can impinge on the biota, especially in rivers naturally subject to large hydrological variability, such as those under Mediterranean climate. The effect of dams on biofilms was analysed in three tributaries (Cinca, Siurana and Montsant) of the Ebro River (NE Spain). We hypothesized that flow regulation would lead to lower spatial variability of biofilms on the streambed and to a decrease in their metabolic rate per unit biomass, especially during low flow periods. Biofilm characteristics were studied in five transects evenly spaced along river reaches upstream (control) and downstream (impact) of dams in each river, along with riverbed granulometry, hydraulics and water chemistry. Chlorophyll-a, respiratory activity, photosynthetic capacity and efficiency, and extracellular enzymatic activities (β-d-glucosidase, alkaline phosphatase and leucine-amino-peptidase) of epilithic biofilms were measured in different seasons. Spatial variability of chemical and biological variables was reduced downstream of the dams. Chlorophyll-a concentration, photosynthetic efficiency and respiration capacity were higher in impact than in control reaches, but generally, low inorganic phosphorus concentrations resulted in comparable phosphatase activities downstream and upstream of dams. On the other hand, β-d-glucosidase and leucine-amino-peptidase activities were higher at impact reaches. Biofilms were thicker and metabolically more active at the impact reaches, with higher ability to transform dissolved organic matter. Overall, results from this study provide evidence that dams can largely affect the structure and activity of river biofilms, with foreseeable important consequences for river ecosystem functioning. Copyright © 2014 John Wiley & Sons, Ltd.

Climate change projections in the Mediterranean region are associated with more frequent extreme climate conditions, which could alter water availability and impact the delivery of ecosystem services. We assess the change in the delivery of three hydrological ecosystem services, one provisioning (water), and two regulating (water purification and erosion control), in the heavily humanized Llobregat River basin (Catalonia, NE Spain) in recently observed extreme wet and dry years. Results indicate that impacts on the delivery of services were especially important in dry years. The main sources of water supply were located in the northern part of the basin and they were the most affected by annual rainfall reduction. Drinking water and hydropower production were highly threatened in dry years, when benefits were almost 100% reduced with respect to the benefits obtained in normal years. The regulating service water purification provided higher benefits in dry years, when water quality was more likely to be compromised due to a decreased dilution capacity. Water purification benefits in normal years increased 127% in dry years. According to our results, no benefit was provided by water purification in wet years. Collectively, our findings emphasize that hydrological ecosystem services in semi-arid basins which are subject to chronic human pressure are very sensitive to the climate conditions of extreme years. We also find a spatial decoupling among areas of service supply and areas where the service is demanded. Management efforts in Mediterranean basins should consider both of these aspects.

Intermittent water flow regimes characterize streams in many world regions, especially those with arid and semiarid climates. During cease to flow conditions, biofilms on streambed sediments may be exposed to desiccation. Environmental conditions and resource availability change with desiccation and may influence biofilm functioning and whole stream ecosystem processes. Rainfall events during the nonflow phase can rehydrate streambed sediments, but the effect of these pulses on biofilm functioning is unclear. This study aimed to analyze the effects of a rehydration event on biofilm functional diversity during the nonflow period in a subtropical Australian stream. Biofilms from three different stream pools on the same reach; one permanently water-covered and the other two differing in their desiccation time were studied. Biofilms initially differed owing to the time they were exposed to dry conditions but rehydration events significantly increased biofilm functional diversity, producing a “reset” effect on the desiccation exposure, as after that bacterial functioning decreased again because of the new dry conditions. The observed rapid biofilm responses to rehydration during flow intermittency might be essential in sustaining biofilm functional diversity in intermittent streams.

Ecosystem services would be incorporated into decision making more often if researchers were to focus more on the demand for these services rather than the supply. This implies examining the economic, decision making and technological context of the end-user before trying to attribute economic values to well known biological processes. This paper provides an example of how this research approach for ecosystems services could unfold. In the Llobregat River in northeastern Spain, higher stream temperatures require water treatment managers to switch on costly water treatment equipment especially during warm months. This creates an opportunity to align the economic interests of downstream water users with the environmental goals of river managers. A restored riparian forest or an increase in stream flow could reduce the need for this expensive equipment by reducing stream temperatures below critical thresholds. We used the Stream Network Temperature Model (SNTEMP) to test the impact of increasing shading and discharge on stream temperature at the intake of the drinking water treatment plant. The value of the stream temperature ecosystem services provided by existing forests is €79,000 per year for the water treatment facility, while additional riparian forest restoration along the Llobregat River could generate economic savings for water treatment managers in the range of €57,000–€156,000 per year. Stream restoration at higher elevations would yield greater benefits than restoration in the lower reaches. Moderate increases in stream discharge (25%) could generate savings of €40,000 per year.

The services of natural ecosystems are clearly very important to our societies. In the last years, efforts to conserve and value ecosystem services have been fomented. By way of illustration, the Natural Capital Project integrates ecosystem services into everyday decision making around the world. This project has developed InVEST (a system for Integrated Valuation of Ecosystem Services and Tradeoffs). The InVEST model is a spatially integrated modelling tool that allows us to predict changes in ecosystem services, biodiversity conservation and commodity production levels. Here, InVEST model is applied to a stakeholder-defined scenario of land-use/land-cover change in a Mediterranean region basin (the Llobregat basin, Catalonia, Spain). Of all InVEST modules and sub-modules, only the behaviour of the water provisioning one is investigated in this article. The main novel aspect of this work is the sensitivity analysis (SA) carried out to the InVEST model in order to determine the variability of the model response when the values of three of its main coefficients: Z (seasonal precipitation distribution), prec (annual precipitation) and eto (annual evapotranspiration), change. The SA technique used here is a One-At-a-Time (OAT) screening method known as Morris method, applied over each one of the one hundred and fifty four sub-watersheds in which the Llobregat River basin is divided. As a result, this method provides three sensitivity indices for each one of the sub-watersheds under consideration, which are mapped to study how they are spatially distributed. From their analysis, the study shows that, in the case under consideration and between the limits considered for each factor, the effect of the Z coefficient on the model response is negligible, while the other two need to be accurately determined in order to obtain precise output variables. The results of this study will be applicable to the others watersheds assessed in the Consolider Scarce Project.

[EN] Dams fragment river systems worldwide, and Mediterranean-climate rivers, characterised by highly seasonal hydrographs and adapted biotas, are particularly impacted by flow regulation. Whereas the effects of flow regulation on hydrology, sediment transport and biodiversity have long been examined, responses at the food-web level remain understudied. Environmental variation is a key control of food-web structure. Thus, we predicted that flow regulation would impact food-chain length (FCL) via changes in the flow variation regime, and we tested this prediction in a set of flow unregulated to completely regulated reaches in a Mediterranean river basin. In each reach, we characterised flow variation, together with two other putative controls of FCL (productivity and habitat size). We combined community data with carbon and nitrogen stable isotopes to estimate food-chain length, and Bayesian mixing models allowed estimates of dietary proportions of consumers. Flow variation was paramount in controlling FCL in the studied river network, and this same control largely explained the degree of omnivory among top predators. Thus, omnivory mechanisms were the main proximate structural mechanism allowing shifts in food-web structure and linking disturbance regimes to FCL. Our results suggest that flow regulation in Mediterranean rivers may impact food-web structure even when no significant changes in community composition are observed. If highly variable Mediterranean streams become increasingly affected by flow regulation, the resulting more stable conditions could enhance intraguild predation and thus lengthen riverine food chains., We thank Roberto Merciai, Jose Andres Lopez and Joan Font for their help in the field, Lina Ramirez-Solano and Emili Garcia-Berthou for their help with analyses and Marc Montenegro for the illustrations in Fig. 1. The Sabo Lab at Arizona State University and anonymous reviewers provided suggestions that improved the quality of the article. This study was funded by the Spanish Ministry of Economy and Competitiveness through the SCARCE project (CSD2009-00065). Authors acknowledge the support from the Catalan Government through the Consolidated Research Groups 'Fluvial Dynamics Research Group (2014 SGR 645)' and the 'Catalan Institute for Water Research (2014 SGR 291)'.

Stream metabolism at both ecosystem and functional-compartment scales was measured in a low-order Pampean stream (La Choza) over a 3-wk period to characterize metabolic rates and discern the contribution of each functional compartment (submerged macrophytes, benthos, floating macroalgae, water column, and hyporheic zone) to ecosystem metabolism. La Choza stream is an autotrophic ecosystem during low flows and has gross primary production rates of up to 22 g O2 m−2d−1, which are among the highest reported in the literature and set an upper bound on how productive streams can be in the absence of light and nutrient limitations. Floating macroalgae provided most of the primary production (30–90%), whereas the hyporheic zone provided most of the ecosystem respiration (40–80%). The differential effects of high flows on the different functional compartments depressed the production∶respiration ratio, suggesting a strong relationship between flow and metabolism. Thus, low flows enhanced primary productio...

13 páginas, 6 figuras., Temporary streams are a dominant surface water type in the Mediterranean region. As a consequence of their hydrologic regime, these ecosystems contract and fragment as they dry, and expand after rewetting. Global change leads to a rapid increase in the extent of temporary streams, and more and more permanent streams are turning temporary. Consequently, there is an urgent need to better understand the effects of flow intermittency on the biogeochemistry and ecology of stream ecosystems. Our aim was to investigate how stream nutrient availability varied in relation to ecosystem contraction, fragmentation and expansion due to hydrologic drying and rewetting. We quantified the temporal and spatial changes in dissolved nitrogen (N) and phosphorus (P) concentrations along a reach of a temporary Mediterranean forest stream during an entire contraction–fragmentation–expansion hydrologic cycle. We observed marked temporal changes in N and P concentrations, in the proportion of organic and inorganic forms as well as in stoichiometric ratios, reflecting shifts in the relative importance of in-stream nutrient processing and external nutrient sources. In addition, the spatial heterogeneity of N and P concentrations and their ratios increased substantially with ecosystem fragmentation, reflecting the high relevance of in-stream processes when advective transport was lost. Overall, changes were more pronounced for N than for P. This study emphasizes the significance of flow intermittency in regulating stream nutrient availability and its implications for temporary stream management. Moreover, our results point to potential biogeochemical responses of these ecosystems in more temperate regions under future water scarcity scenarios., This study was funded by the European Union through the Mediterranean Intermittent River ManAGEment (MIRAGE) project (ref: FP7 ENV 2007 1, http://www.mirage-project.eu). Additional funds were provided by the project CGL2007-65549/BOS and the Consolider-Ingenio projects CSD2009-00065 (SCARCE) and CSD2007-00067 (GRACCIE) of the Spanish Ministry of Science and Innovation. D. von Schiller was supported by a fellowship of the German Academic Exchange Service and ‘‘laCaixa’’ Foundation.

To evaluate the role of the benthic community within headwater stream ecosystems, it is crucial to understand the mechanisms of the processes dominating their turnover rates and temporal dynamics. To analyze the benthic community dynamics of an intermittent Mediterranean stream (Fuirosos, Spain), we developed a mechanistic model that describes the most important ecosystem components (five functional feeding groups of invertebrates, periphyton, and benthic organic matter) under consideration of important transformation processes. The model is an extension of that developed for application to the prealpine River Sihl (Switzerland). A combination of prior knowledge from the literature and information from field observations within a Bayesian framework is used to constrain plausible ranges of the estimated model parameters and to evaluate the uncertainty of the model outcome. The Bayesian inference resulted in a realistic description of most of the main features of the system, offered insights into the degree of information the data contains about model parameters, and also made it possible to quantify the dependence structure of the parameter estimates. Local and global sensitivity analyses revealed that rate parameters for growth and death of invertebrate functional feeding groups are most influential on the model results and additional information on these parameters would be most helpful to reduce output uncertainty. The study clearly points out the importance of organic matter dynamics, as allochthonous organic matter is the main energy source in this Mediterranean headwater stream. Hydrological disturbances of the system such as droughts and floods lead to complex colonization patterns which would require additional data to support a more detailed description by an extended model. Furthermore, the study shows that it is possible to deal with a complex ecological model with eight state variables and more than 60 parameters in a Bayesian framework.

River floodplains are composed of a shifting mosaic of aquatic and terrestrial habitats. Each habitat type exhibits distinct environmental and ecological properties. Temperature is a key property driving ecological processes and controlling the composition and distribution of biota. However, given the size and complexity of floodplains, ground surveys based on point measurements are spatially limited. In this study, we applied thermal infrared (IR) imagery to quantify surface temperature patterns at 12–15 min intervals over 24 h cycles in two near-natural Alpine river floodplains (Roseg, Tagliamento). Furthermore, vertical temperature distribution was measured at 3–5 min intervals in unsaturated gravel sediment deposits (at 1 cm distances; 0–29 cm depth). Each habitat type exhibited a distinct thermal signature creating a complex thermal mosaic. The diel temperature pulse and maximum daily temperature were the main thermal components that differentiated habitat types. In both floodplains, exposed gravel sediments exhibited the highest diel pulse (up to 23°C), whereas in aquatic habitats the pulse was as low as 11°C (main channel in the Roseg floodplain). In the unsaturated gravel sediment deposits, the maximum diel kinetic temperature pulse ranged from 40.4°C (sediment surface) to 2.7°C (29 cm sediment depth). Vertically, the spatiotemporal variation of temperature was about as high as horizontally across the entire floodplain surface. This study emphasized that remotely sensed thermal IR imagery provides a powerful non-invasive method to quantitatively assess thermal heterogeneity of complex aquatic and terrestrial ecosystems at a resolution required to understand ecosystem processes and the distribution of biota.

Aquatic river habitat types have been characterized and classified for over five decades based on hydrogeomorphic and ecological variables. However, few studies considered the generation of underwater sound as a unique property of aquatic habitats, and therefore as a potential information source for freshwater organisms. In this study, five common habitat types along 12 rivers in Switzerland (six replicates per habitat type) were acoustically compared. Acoustic signals were recorded by submerging two parallel hydrophones and were analysed by calculating the energetic mean as well as the temporal variance of ten octave bands (31·5 Hz–16 kHz). Concurrently, each habitat type was characterized by hydraulic and geomorphic variables, respectively. The average relative roughness, velocity-to-depth ratio, and Froude number explained most of the variance of the acoustic signals created in different habitat types. The average relative roughness predominantly affected middle frequencies (63 Hz–1 kHz), while streambed sediment transport increased high-frequency sound pressure levels (2–16 kHz) as well as the temporal variability of the recorded signal. Each aquatic habitat type exhibited a distinct acoustic signature or soundscape. These soundscapes may be a crucial information source for many freshwater organisms about their riverine environment. Copyright © 2010 John Wiley & Sons, Ltd.

There is evidence of an ongoing alteration of the flow regime owing to climate change forcing, which has resulted in substantial increases in the frequency and magnitude of extreme events such as floods and droughts. Such changes in the flow regime may have major implications in freshwater ecosystems and, in particular, in the organic carbon dynamics in semiarid stream ecosystems. Much is known about the role of extreme flow events on structuring stream ecosystems, but few studies explored the effects of extreme flow events magnitude, timing, and sequence on stream ecosystems. To assess the effect of extreme events on stream organic C dynamics, a simple and flexible modeling approach was applied to simulate the organic carbon dynamics in a simplified river reach. The river reach model was initially calibrated and tested using long-term data for stream water velocity and amount of organic carbon in sediment. After that, multiple scenarios differing in the extreme flow events (floods and droughts) sequence and magnitude were used to simulate the effects of possible flow regime changes on the stream organic carbon dynamics. Initial expectations were that: (i) an increase in the magnitude or frequency of extreme flow events would reduce the amount of organic carbon respired within the simulated river reach, and (ii) relationship between the timings of the extreme flow events and of the litterfall input would influence considerably the effects of the extreme flow events. Results pointed out that: (i) the amount of processed carbon respect the amount entering the ecosystem was affected by extreme events such floods and droughts, but the relevance of those events differed along the year, with a maximal effect during the litterfall period; (ii) extreme event timing rather than the magnitude was more relevant to the stream organic carbon dynamics; and (iii) the amount of respired carbon in the ecosystem could be amplified or reduced depending on event sequence. Increasing awareness of the role of inland waters in the global carbon cycle and the shaping role of hydrology on the stream organic carbon dynamics stress the need to better quantify carbon fluxes and the hydrological controls on these fluxes.

Summary 1. Water temperature is a key characteristic of stream ecosystems that is gaining scientific and managerial relevance as maximum temperatures in aquatic ecosystems increase worldwide. 2. To assess the effect of surface–subsurface water exchange on stream water temperature patterns, four alluvial reaches in the Tagliamento River basin (NE Italy), constrained by geomorphic knickpoints at the upper and lower end, and two to four hyporheic flowpaths within each reach, were continuously studied during summer 2007 and winter 2007–08. Water temperature was continuously monitored at the upstream and downstream knickpoints of the floodplains, as well as at discrete upwelling areas within each reach. Discharge and vertical hydraulic gradient were measured along the alluvial reaches, and the residence time and chemistry of upwelling water were assessed four times during the study. 3. Discharge variation along the study reaches revealed that massive hyporheic exchange occurred in all sites, ranging from 21% in reach 2–52% in reach 1. End member mixing analysis showed little influence of ground water, as almost all upwelling water was freshly infiltrated hyporheic water. Importantly, hyporheic exchange flows shaped surface temperature at the upwelling locations in all study reaches, providing potential thermal refugia for aquatic biota. At sites with highest hyporheic flow rates, net temperature change was also reflected at the floodplain scale. 4. The magnitude of the thermal change along a hyporheic flowpath was not related to the flowpath length but to the estimated 222Rn water age. Reduction in the diel thermal amplitude by hyporheic flows rather than net temperature change, reduced temperature extremes. Therefore, restoration activities to create thermal refugia should consider the role of hyporheic flows and enhance the exchange between surface and hyporheic waters.

Summary 1. Global warming has increased the mean surface temperature of the Earth by 0.6 °C in the past century, and temperature is probably to increase by an additional 3 °C by 2100. Water temperature has also increased, which in turn can affect metabolic rate in rivers. Such an increase in metabolic rate could alter the role of river networks in the global C cycle, because the fraction of allochthonous organic C that is respired may increase. 2. Laboratory-based incubations at increasing water temperature were used to estimate the temperature dependence of benthic respiration in streams. These experiments were performed on stones taken from seven reaches with different thermal conditions (mean temperature ranging 8–19 °C) within the pre-alpine Thur River network in Switzerland, June–October 2007. 3. The activation energy of respiration in different reaches along the river network (0.53 ± 0.12 eV, n = 94) was similar, indicating that respiration was constrained by the activation energy of the respiratory complex (E = 0.62 eV). Water temperature and the thickness of the benthic biofilm influence the temperature dependence of respiration and our results suggest that an increase of 2.5 °C will increase river respiration by an average of 20 ± 1.6%.

Organic matter inputs, transport, and storage, ecosystem metabolism, and organic C turnover length were measured in a forested Mediterranean 3rd-order stream (Fuirosos) over a period of 3 y. Meteorological patterns influenced the organic matter dynamics of Fuirosos through 2 pathways: summer weather and flood pulses. Summer rains affected the timing of litter fall and the extent of flow intermittency, which gave rise to accumulations of organic matter in the streambed in dry years. With the onset of flow, these organic matter accumulations were the energy sources for considerable ecosystem respiration (30 g O2 m−2 d−1). Interflood periods punctuated by flood pulses determined cycles of steady accumulation and abrupt removal of stored organic matter. During the interflood periods, the efficiency of organic matter processing increased continuously. The seasonal changes in the riparian forest influenced the ecological consequences of the flood pulses. Resilience of the ecosystem, measured in terms of...

Ecosystem services provide multiple benefits to human wellbeing and are increasingly considered by policy-makers in environmental management. However, the uncertainty related with the monetary valuation of these benefits is not yet adequately defined or integrated by policy-makers. Given this background, our aim was to quantify different sources of uncertainty when performing monetary valuation of ecosystem services, in order to provide a series of guidelines to reduce them. With an example of 4 ecosystem services (i.e., water provisioning, waste treatment, erosion protection, and habitat for species) provided at the river basin scale, we quantified the uncertainty associated with the following sources: (1) the number of services considered, (2) the number of benefits considered for each service, (3) the valuation metrics (i.e. valuation methods) used to value benefits, and (4) the uncertainty of the parameters included in the valuation metrics. Results indicate that the highest uncertainty was caused by the number of services considered, as well as by the number of benefits considered for each service, whereas the parametric uncertainty was similar to the one related to the selection of valuation metric, thus suggesting that the parametric uncertainty, which is the only uncertainty type commonly considered, was less critical than the structural uncertainty, which is in turn mainly dependent on the decision-making context. Given the uncertainty associated to the valuation structure, special attention should be given to the selection of services, benefits and metrics according to a given context This research was supported by the Spanish Ministry of Economy and Competitiveness through the project SCARCE (Consolider-Ingenio 2010 CSD2009-00065), the postdoctoral grant “Juan de la Cierva” (JC2011-09116, to MT), and the Ramón y Cajal grant (RYC-2013-14595, to LC), as well as by a Marie Curie European Reintegration Grant (PERG07-GA-2010-259219, to VA), and a Marie Curie Career Integration Grant (PCIG9-GA-2011-293535, to LC).

Pharmaceuticals are designed to improve human and animal health, but even the most beneficial pharmaceuticals might raise some questions concerning the consequences of exposure to non-target organisms. To illustrate this situation and using diclofenac as a case-study, we analyze global consumption and occurrence data to identify hot spots of consumption without occurrence data, review the scientific literature on the harmful environmental effects to determine whether the observed concentrations in freshwater are of environmental concern, summarize the current pharmaceutical and environmental policies to highlight policy gaps, and suggest a series of research and policy recommendations, which can be summarized as follows: we need to improve the current knowledge on occurrence in freshwaters to properly implement environmental policies (i), diclofenac might pose a risk to non-target organisms in freshwater (ii); the harmful effects that some pharmaceuticals may have on the environment are not always addressed by environmental policies (iii). Keywords: Diclofenac, Pharmaceuticals, Environmental risks, Ecotoxicity, Freshwater ecosystems, Environmental policies