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

No abstract

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.

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

An experiment in >1000 river and riparian sites found spatial patterns and controls of carbon processing at the global scale.