OTZ ON

We propose to design, build, and deploy technologically advanced bioacoustics and carbon flux sensor packages that will be used on state-of-the-art oceanographic moorings systems. These moorings will be co-located (operating in the same general water mass while remaining sufficiently separated to avoid acoustical and optical interference) to measure critical oceanographic parameters. This configuration will employ one shallow bioacoustics system (~300m) and one deep bioacoustics system (~700m) to achieve full-water-column coverage of the twilight zone. We will be adding the following instruments to the mooring package currently deployed that includes a SIMRAD EK80 and a sediment trap. Acoustic Doppler Current Profiler (ADCP). The addition of an ADCP will support measurements of ocean currents throughout the water column. An ADCP (Fig. 3) is a hydroacoustic current meter that measures the velocity of water currents over a range of depths. The ADCP will provide physical oceanographic data that can be used to interpret patterns of biomass and carbon flux measured at the mooring site. Install sediment traps and Underwater Vision Profiler (UVP) cameras on both deep and shallow moorings. A comprehensive understanding of the distribution, abundance, and dynamics of particulate matter and organisms in pelagic environments is crucial to predict the export and sequestration of biogenic carbon. These traps and cameras will take regular measurements of particles and organisms at sampling frequencies that are compatible with other standard oceanographic instruments. This approach holds great potential to reveal factors that regulate distribution and abundance patterns. The Underwater Vision Profiler (Fig. 4), a commercial, off-the-shelf device with integrated lighting systems, is designed to quantify large (>100 µm) aggregates and zooplankton at the same time in a known volume of water. Co-locating sediment traps with a UVP on both mooring systems will be a powerful technological advance for quantifying carbon fluxes through the twilight zone. Install high-definition camera systems adjacent to the bioacoustics systems on each mooring. Active acoustics represent a powerful tool for investigating biomass distributions and movements of organisms throughout the water column. Acoustic echograms contain little taxonomic information, however. Without knowledge of the types and aspects of fish and other organisms creating acoustical returns, it is not possible to gain comprehensive scientific understanding of life in the twilight zone. With simultaneous collection of optical data, it becomes possible to attribute the strength of the acoustic returns to specific organisms. This more comprehensive knowledge will contribute to the creation of an environmental model of migrating organisms, enabling refined biomass estimates and extrapolations that can impact fisheries management, carbon budgets, and other economically and socially significant concerns. We are currently in discussions with Juice Robotics, LLC to create a custom-designed camera system that will meet our needs. Juice Robotics produces a commercial off-the-shelf, economical camera system named DEEPi (Fig. 5) that may be a good candidate for customization and deployment as part of the OTZ Observation Network. This unit has a depth rating of 1000m, and includes onboard power, recording, and an output for a modular LED.