Microbial ecology at cabled seafloor observatories

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The VENUS and NEPTUNE cabled observatories operated by the University of Victoria offer unprecedented opportunities for the time series study of how marine organisms respond to changes in their environment. My research program will pioneer the use of these observatories to study the ecology of marine microorganisms. A series of research projects will develop an observatory toolbox of approaches and methodological protocols for the direct and indirect study of microbial processes that are important to ecosystem function. We will study how environmental factors influence the way in which microbes control the bioavailability of nitrogen, produce food for hydrothermal vent organisms and decompose organic debris in sediments. Direct studies will quantify microbial standing stock variations, community structure and metabolic processes, in relation to environmental variables. Indirect studies will focus on the dynamics of bioturbation, a key physical variable that influences microbial growth and metabolism. Two projects will be undertaken at the NEPTUNE observatory site in the Main Endeavour hydrothermal vent field on the Juan de Fuca Ridge. A remotely-activated water sampler will collect vent fluid samples for a study of microbial denitrification in the subsurface environment below the seafloor, in relation to fluid chemistry. The second hydrothermal project will use remote-controlled cameras to study the dynamics of macroscopic microbial mat growth in relation to fluid discharge and faunal grazing activity. At the NEPTUNE site in Barkley Canyon, on the continental margin, cameras and micro-profiling sensors will be used to investigate the relationship of bioturbation of surface sediments by the macrofauna, to seasonal habitat variables. In coastal Saanich Inlet, at the site of the VENUS observatory's future water column profiler instrument package, we will study microbial nitrification in the photic zone, emphasizing a previously observed imbalance in the two successive steps in nitrification (ammonium oxidation and nitrite oxidation) and its relationship to tidal mixing. This work will also serve to prepare experiments for an automated microbial gene analyzer to be installed on the VENUS profiler in 2012.