The PIs propose to establish an integrated system along the south coast of Oahu, Hawaii. This site includes: an existing observing system with power and high bandwidth communications; a dynamic, highly permeable and biogeochemically active seafloor; is in close proximity to the deep ocean, which provides regular exposure to offshore geochemistry and variable physical forcing driven by internal tides and mesoscale eddies; a wide and predictable range of surface wave conditions; and the ability to forecast the arrival of significant surface wave events, thus greatly aiding the planning of experiments, deployment of instruments and implementation of event-driven sampling. The goal of the proposed research is to significantly advance the ability to measure transport of solutes into and out of permeable sediments, examine the seafloor's response to a wide range of physical oceanographic forcing, and determine the pelagic ecosystem response to these processes. The PIs propose to establish an array of physical sensors over depths of 10-40 m, collect high resolution temporal and spatial physical data over a range of oceanographic conditions; measure porewater concentrations of biogeochemically important constituents across the array; measure porewater exchange under a range of conditions, at both sandy and hard-bottom permeable seafloors; compare these porewater-seawater fluxes with those calculated using eddy correlation and water column profiling techniques; examine the optical (biological) response in the water column to physically driven sediment fluxes of nutrients; and determine the dynamics of the CO2 system in the surface water. Together, these tasks will enable them to resolve the physical and geochemical responses of benthic boundary layer systems in response to environmental changes.
