Microbial biofilms, flow heterogeneity and organic carbon cycling: bridging basic and applied research

Stream ecosystems have arguably experienced the most dramatic habitat loss during the last decades and a new era of restoration ecology is now emanating. Understanding the relationships between habitat heterogeneity, biodiversity and ecosystem functioniong across scales is imperative for successful restoration practices. Biofilms, which are now recognized as the dominant form of microbial life in many aquatic ecosystems, are particularly important in streambeds where they govern major ecosystems processes and ecosystem health. However, in contrast to detrimental biofilms from medical and industrial systems, the structure and function of environmental biofilms and their ecosystem implications remain obsure. Here, I propose a first comprehensive study that relates flow as the major physical determinant in streams to biofilm structure and function at both the cellular and community level. I consider microbial biofilms as ecologically functional communities and postulate the interplay of their architecture, community composition and function as a response to an oligotrophic flow environment. Next, these microscale relationships will be upscaled to streams as inherently heterogeneous flow landscapes to explain more global processes such as carbon cycling and selfpurification. I postulate niche differentiation and complementarity as the mechanisms underlying these large- scale biogeochemical processes. In fact, spatial flow heterogeneity creates biofilm structural and functional differentiation which results in the complementary use of resources. The empirical knowledge of this proposal will be then used to test current engineering approaches relevant to selfpurification. This proposal thus integrates timely concepts in stream and microbial ecology with cutting-edge techniques and bridges basic and applied research.

Stream ecosystems have arguably experienced the most dramatic habitat loss during the last decades and a new era of restoration ecology is now emanating. Understanding the relationships between habitat heterogeneity, biodiversity and ecosystem functioniong across scales is imperative for successful restoration practices. Biofilms, which are now recognized as the dominant form of microbial life in many aquatic ecosystems, are particularly important in streambeds where they govern major ecosystems processes and ecosystem health. However, in contrast to detrimental biofilms from medical and industrial systems, the structure and function of environmental biofilms and their ecosystem implications remain obsure. Here, I propose a first comprehensive study that relates flow as the major physical determinant in streams to biofilm structure and function at both the cellular and community level. I consider microbial biofilms as ecologically functional communities and postulate the interplay of their architecture, community composition and function as a response to an oligotrophic flow environment. Next, these microscale relationships will be upscaled to streams as inherently heterogeneous flow landscapes to explain more global processes such as carbon cycling and selfpurification. I postulate niche differentiation and complementarity as the mechanisms underlying these large-scale biogeochemical processes. In fact, spatial flow heterogeneity creates biofilm structural and functional differentiation which results in the complementary use of resources. The empirical knowledge of this proposal will be then used to test current engineering approaches relevant to selfpurification. This proposal thus integrates timely concepts in stream and microbial ecology with cutting-edge techniques and bridges basic and applied research.