Fluvial-Premoval, faces P-pollution in fluvial systems, a long-term and worldwide extremely relevant and complex environmental problem, which is difficult to solve and that is expected to increase in the future. We will follow a transdisciplinary and integrative approach, with innovative ideas stemming from principles and methods of advanced research in different but complementary research areas (fluvial biogeochemistry, microbial ecotoxicomics and restoration ecology) in collaboration with other research groups, companies and social actors interested in this environmental and water quality problem.
The central objective of this project is to gain insights about the factors and mechanisms controlling P dynamics in fluvial ecosystems subjected to human pressures and examine how microbial communities in fluvial biofilms integrate in-stream P status. The ultimate goal is to provide knowledge and tools to stream managers to assess problems associated with high P availability and to help mitigating them in stream and river ecosystems. The project is organized in two work packages (WP). In WP1 we will characterize P forms in the Ter river, along a gradient of human impact, and describe structural and functional attributes of biofilms using amplicon DNA sequencing and shotgun RNA sequencing. In this WP we will also assess, under controlled experimental conditions (indoor channels) differences in bioavailability between dissolved and particulate P, and also between organic and inorganic P and how it is modulated by lithology (calcareous vs siliceous), and assess its fate and effects on biofilms. These experiments will contribute to understand the patterns observed in the field and confirm the expected linkages between P availability and biofilm responses. Tasks included in WP2 will be conducted in the Urban River Lab experimental platform, in a 360-m reconstructed stream by bioengineering with in three 80-m reaches. We will evaluate how the hydromorphlogical characteristics of a reach, as a factor modifying hydrologic retention and habitat configuration, and changes in the relative availability of dissolved inorganic nitrogen and dissolved organic carbon, as a factor influencing biotic activity, can influence P retention at reach-scale in a receiving stream.
We will also investigate the role of biofilms in P uptake in each reach and assess how the reciprocal interactions between P availability and biofilm structural and functional attributes associated with P cycling vary among different habitats. Variability in biofilm P markers observed at habitat scale within reaches will then be compared to that observed at larger spatial scale in WP1. This comparison will allow expanding knowledge on the use of biofilm P markers across observational scales.