Climate change profoundly alters riverine flow regimes and community composition, affecting key ecosystem functions. We used an experimental mesocosm approach to examine how gradual flow velocity reduction (Experiment 1) and flushing events (Experiment 2) influence periphyton community composition and metabolism, with and without a macroinvertebrate assemblage. We prepared eight stream mesocosms with pre‐grown periphyton, half...

Streams naturally receive allochthonous particulate organic materials, but human activity may contribute additional plastic litter inputs, which can affect ecosystem functioning. Our objective was to assess the effect of plastic and bioplastic inputs on microbial biomass and function in a pristine mountain stream. To do that, fragments of plastics (polyethylene—PE, polypropylene—PP), bioplastics (polyhydroxyalkanoate—PHA, poly...

Stream dissolved oxygen (DO) dynamics are an outcome of metabolic activity and subsequently regulate ecosystem functions such as in‐stream solute and sediment reactions. The synchronization of DO signals in and across stream networks is both a cause and effect of the mode and timing of these functions, but there is limited empirical evidence for network patterns of DO synchrony. We used high frequency DO measurements at 42 sit...

Headwater streams are control points for carbon dioxide (CO 2 ) emissions to the atmosphere, with relative contributions to CO 2 emission fluxes from lateral groundwater inputs widely assumed to overwhelm those from in‐stream metabolic processes. We analyzed continuous measurements of stream dissolved CO 2 and oxygen (O 2 ) concentrations during spring and early summer in two Mediterranean headwater streams from which we evalu...

Wastewater treatment plant (WWTP) effluents alter water chemistry and in-stream nutrient uptake rates of receiving freshwaters, thus changing the magnitude and fate of the nutrients exported. In Mediterranean regions, the dilution capacity of receiving streams can vary strongly over time due to the seasonal occurrence of floods and droughts, causing temporal variability of nutrient uptake. We assessed the temporal patterns and...

Headwater streams can be important sources of carbon dioxide (CO 2 ) and methane (CH 4 ) to the atmosphere. However, the influence of groundwater–stream connectivity on the patterns and sources of carbon (C) gas evasion is still poorly understood. We explored these connections in the boreal landscape through a detailed study of a 1.4 km lake outlet stream that is hydrologically fed by multiple topographically driven groundwate...

Monitoring nutrient concentrations at fine‐scale temporal resolution contributes to a better understanding of nutrient cycling in stream ecosystems. However, the mechanisms underlying fine‐scale nutrient dynamics and its implications for budget catchment fluxes are still poorly understood. To gain understanding of patterns and controls of fine‐scale stream nitrogen (N) dynamics and to assess how they affect hydrological N flux...