Using eddy correlation to measure oxygen flux as an indicator of the health of aquatic systems

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Water transports dissolved gases (e.g., oxygen; O2), nutrients, and other chemicals to and from river and lake sediments and aquatic organisms, as well as imparting hydrodynamic forces on them. Understanding the fate and transfer of dissolved O2 through biological and biogeochemical processes is essential to understanding the functioning of aquatic ecosystems as well as their remediation/recovery. The eddy correlation technique, which measures O2 concentration in the smallest turbulent, provides an accurate measurement of O2 flux. Measuring oxygen flux using eddy correlation is essential to achieve these goals, but my existing eddy correlation system (RTI funded in 2007) is obsolete and beyond repair. This has limited the research opportunities available to members of my lab.      To restore this essential capacity to my lab, I am requesting support to purchase a replacement eddy correlation system. The requested system uses a fibre--optic oxygen sensor to measure O2 along with a fast response PAR light logger, multiparameter sonde, and an acoustic Doppler current profiler to measure environmental conditions during eddy correlation measurements. The requested system uses optical--based oxygen sensors, which are more robust and less stirring sensitive than the electrochemical sensors used in older, now-obsolete models. Consequently, the new system will significantly advance our ability to examine the fate and transfer of a key biogeochemical constituent in aquatic environments.      The proposed eddy correlation system is urgently needed by my research program. Without it, we are unable to determine the causes of low oxygen levels (hypoxia) in lakes, the health of endangered freshwater mussel species, and the productivity of aquatic vegetation. Moreover, we are not able to advance our ecohydrological models from the laboratory to the field. The proposed equipment is essential to my NSERC Discovery research program and will support important collaborations with research partners in provincial and federal agencies. These activities are of particular importance because of concerns about declining water quality (e.g., hypoxia or low oxygen), and demands to restore these aquatic ecosystems to provide economic and ecological benefits to Canadians.