Intermittently flowing streams and rivers should be recognized, afforded protection, and better managed.

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Biofilms can be regarded as early warning systems for detection of the effects of toxicants on aquatic systems, because they have been successfully used for detection of other environmental stressors (e.g. pH, salinity, organic pollution). A variety of methods is used for detection of the effects of toxicants by use of biofilms. The methods range from structurally-based to functionally-based, and from in vitro-based to systemic approaches. Physiological approaches may be appropriate for detection of acute effects. Among these methods, photosynthesis is more related to the effect of toxicants affecting algal communities, directly or indirectly, and extracellular enzyme activity is less specific. Selecting one or the other may depend on the suspected direct effect of the toxicant. Integrated studies have revealed the relevance of toxicants to top-down or bottom-up regulation of the biofilm community. Persistent or chronic effects should affect other biofilm indicators, for example growth or biomass-related factors (e.g. chlorophyll), or community composition. Among these, community composition might better reflect the effects of the toxicant(s), because this may cause a shift from a sensitive to a progressively tolerant community. Community composition-based approaches do not usually adequately reflect cause-effect relationships and require complementary analysis of properties affected in the short-term, for example physiological properties. The current array of methods available must be wisely combined to disentangle the effects of chemicals on biofilms, and whether these effects are transient or persistent, to successfully translate the chemical action of toxicants into the effect they might have on the river ecosystem.

1. Single-station diel oxygen curves were used to monitor the oxygen metabolism of an intermittent, forested third-order stream (Fuirosos) in the Mediterranean area, over a period of 22 months. Ecosystem respiration (ER) and gross primary production (GPP) were estimated and related to organic matter inputs and photosynthetically active radiation (PAR) in order to understand the effect of the riparian forest on stream metabolism. 2. Annual ER was 1690 g O 2 m )2 year )1 and annual GPP was 275 g O 2 m )2 year )1 . Fuirosos was therefore a heterotrophic stream, with P : R ratios averaging 0.16. 3. GPP rates were relatively low, ranging from 0.05 to 1.9 g O 2 m )2 day )1 . The maximum values of GPP occurred during a few weeks in spring, and ended when the riparian canopy was fully closed. The phenology of the riparian vegetation was an important determinant of light availability, and consequently, of GPP. 4. On a daily scale, light and temperature were the most important factors governing the shape of photosynthesis-irradiance (P-I) curves. Several patterns could be generalised in the P-I relationships. Hysteresis-type curves were characteristic of late autumn and winter. Light saturation responses (that occurred at irradiances higher than 90 lE m )2 s )1 ) were characteristic of early spring. Linear responses occurred during late spring, summer and early autumn when there was no evidence of light saturation. 5. Rates of ER were high when compared with analogous streams, ranging from 0.4 to 32 g O 2 m )2 day )1 . ER was highest in autumn 2001, when organic matter accumulations on the streambed were extremely high. By contrast, the higher discharge in autumn 2002 prevented these accumulations and caused lower ER. The Mediterranean climate, and in its effect the hydrological regime, were mainly responsible for the temporal variation in benthic organic matter, and consequently of ER.

International audienceWe evaluated nitrogen (N) removal efficiency by ri-parian buffers at 14 sites scattered throughout seven European countries subject to a wide range of climatic conditions. The sites also had a wide range of nitrate inputs, soil characteristics, and vegetation types. Dissolved forms of N in groundwater and associated hydrological parameters were measured at all sites; these data were used to calculate nitrate removal by the riparian buffers. Nitrate removal rates (expressed as the difference between the input and output nitrate concentration in relation to the width of the riparian zone) were mainly positive, ranging from 5% m 1 to 30% m 1 , except for a few sites where the values were close to zero. Average N removal rates were similar for herbaceous (4.43% m 1) and forested (4.21% m 1) sites. Nitrogen removal efficiency was not affected by climatic variation between sites, and no significant seasonal pattern was detected. When nitrate inputs were low, a very large range of nitrate removal efficiencies was found both in the forested and in the nonforested sites. However, sites receiving nitrate inputs above 5 mg N L 1 showed an exponential negative decay of nitrate removal efficiency (nitrate removal efficiency 33.6 e 0.11 NO 3 input , r 2 0.33, P 0.001). Hydraulic gradient was also negatively related to nitrate removal (r 0.27, P 0.05) at these sites. On the basis of this intersite comparison, we conclude that the removal of nitrate by biological mechanisms (for example, denitrification, plant uptake) in the riparian areas is related more closely to nitrate load and hydraulic gradient than to climatic parameters

21There is a growing pressure of human activities on natural habitats, which leads to 22 biodiversity losses. To mitigate the impact of human activities, environmental policies are 23 developed and implemented, but their effects are commonly not well understood because 24 of the lack of tools to predict the effects of conservation policies on habitat quality and/or 25 diversity. We present a straightforward model for the simultaneous assessment of terrestrial 26and aquatic habitat quality in river basins as a function of land use and anthropogenic 27 threats to habitat that could be applied under different management scenarios to help 28 understand the trade-offs of conservation actions. We modify the InVEST model for the 29 assessment of terrestrial habitat quality and extend it to freshwater habitats. We assess the 30 model reliability in a severely impaired basin by comparing modeled results to observed 31 terrestrial and aquatic biodiversity data. We believe that the developed model can be useful to assess potential levels of 37 biodiversity, and to support conservation planning given its capacity to forecast the effects 38 of management actions in river basins. 39 40 Keywords: anthropogenic threats; biodiversity; environmental management; habitat quality; 41 scenario analysis; river basin. 42 43 3

Non-perennial rivers and streams (NPRS) cover N 50% of the global river network. They are particularly predominant in Mediterranean Europe as a result of dry climate conditions, climate change and land use development. Historically, both scientists and policy makers underestimated the importance of NRPS for nature and humans alike, mainly because they have been considered as systems of low ecological and economic value. During the past decades, diminishing water resources have increased the spatial and temporal extent of artificial NPRS as well as their exposure to multiple stressors, which threatening their ecological integrity, biodiversity and ecosystem services. In this paper, we provide a comprehensive overview of the structural and functional characteristics of NPRS in the European Mediterranean, and discuss gaps and problems in their management, concerning their typology, ecological assessment, legislative and policy protection, and incorporation in River Basin Management Contents lists available at ScienceDirect Science of the Total Environment j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n vPlans. Because NPRS comprise highly unstable ecosystems, with strong and often unpredictable temporal and spatial variability -at least as far as it is possible to assess -we outline the future research needs required to better understand, manage and conserve them as highly valuable and sensitive ecosystems. Efficient collaborative activities among multidisciplinary research groups aiming to create innovative knowledge, water managers and policy makers are urgently needed in order to establish an appropriate methodological and legislative background. The incorporation of NPRS in EU-Med River Basin Management Plans in combination with the application of ecological flows is a first step towards enhancing NPRS management and conservation in order to effectively safeguard these highly valuable albeit threatened ecosystems.