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...

We investigated photoinhibition on natural communities of ammonia oxidizing (AO) archaea (AOA) and bacteria (AOB) embedded in complex stream biofilms, and its implications on nitrogen uptake at biofilm scale. Based on the strong photoinhibition previously exhibited by free living and cultured AOA and AOB, we expected AO activity to decrease in biofilms experimentally exposed to light, reducing the contribution of microbial nit...

Stream microbial communities and associated processes are influenced by environmental fluctuations that may ultimately dictate nutrient export. Discharge fluctuations caused by intermittent stream flow are increasing worldwide in response to global change. We examined the impact of flow cessation and drying on in‐stream nitrogen cycling. We determined archaeal ( AOA ) and bacterial ammonia oxidizer ( AOB ) abundance and ammoni...

Large‐scale factors associated with the environmental context of streams can explain a notable amount of variability in patterns of stream N cycling at the reach scale. However, when environmental factors fail to accurately predict stream responses at the reach level, focusing on emergent properties from small‐scale heterogeneity in N cycling rates may help understand observed patterns in stream N cycling. To address how small...

We monitored the effects of wastewater treatment plant (WWTP) inputs on the recovery of stream biofilms after a large flood event that eroded most of the former biofilm communities. We monitored biomass recovery, chlorophyll a , nitrogen content, and stable isotope natural abundance ( 15 N) over 8 weeks in light‐ and dark‐exposed biofilms upstream and downstream from WWTP inputs, respectively, as well as the abundance of ammon...