Biofilm responses to multiple stressors associated to global change in river ecosystems

The main goal of this thesis is to investigate the effects of consequences of global change on fluvial biofilms. To achieve this objective a multi-marker approach has been used at different experimental scales. Our results revealed that the consequences of eutrophication and riparian simplification caused changes in biofilm spatial organization, microbial structure and functioning. This thesis evidenced that pharmaceuticals and antibiotics detected in Llobregat River waters may cause responses at the base of river food web with still unknown consequences for freshwater ecosystems. Furthermore, we demonstrated that the bactericide Triclosan reduces the capacity of biofilm to remove phosphorus from water column. Our results also evidenced that drought episode may affect biofilms structure and function amplifying the toxicity of Triclosan for these communities. Finally, our study validates the use of biofilm phosphorus uptake capacity as a tool for the understanding of pollutions’ consequences for river self-depuration capacity