EARTH SCIENCE | OCEANS | OCEAN ACOUSTICS | ACOUSTIC SCATTERING
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Interaction uncertainties between tidal energy devices and marine animals have the potential to disrupt the tidal energy industry as it advances. Best-practices for environmental impact assessments (EIAs) must be explored that are able to provide conclusive recommendations for mitigating environmental impact concerns of tidal energy developments. As the tidal energy industry is moving closer to commercial-scale array installations, the development of standardised EIAs would allow for potential impact concerns for the marine environment to be identified and minimised early in the site-development process. In an effort to help formulate a standardised EIA framework that addresses knowledge gaps in fish-current interactions at tidal energy candidate sites, this study investigated changes in fish aggregations in response to tidal currents at a tidal energy candidate site in Australia prior to turbine installation. Here, we present the dataset collected for this study that includes tidal current information from Acoustic Doppler Current Profiler (ADCP) measurements, volume backscattering strength from a four-frequency biological echosounder (Acoustic Zooplankton and Fish Profiler – AZFP) as an indicator for fish biomass, and fish aggregation metrics calculated from volume backscatter in post-processing. ADCP and AZFP were installed on a bottom-mounted mooring and engaged in a concurrent sampling plan for ~2.5 months from December 2018 to February 2019. The mooring was deployed in the Banks Strait, a tidal energy candidate site located in the northeast of Tasmania, Australia, at a location favourable for tidal turbine installations considering current speed, depth, substrate, sediment type and proximity to shore. The ADCP dataset includes current velocity and direction measurements at a 1 m vertical and 1-sec time intervals. The raw AZFP dataset includes volume backscattering strength collected at 4-sec time intervals with a vertical resolution of 0.072 m in raw, and 0.1 m in pre-processed form. Fish aggregation metrics were derived in post-processing and are presented by the minute along with corresponding environmental conditions for current speed, shear, temperature, diel stage, and tidal stage compiled from both AZFP and ADCP datasets.
Ecosystem data was collected as part of an integrated study of the continental shelf over a 2 and a half year period between November 2015 and January 2018. Data were collected bi-monthly through the spring to autumn (November, January, March, May). Stations were situated perpendicular to shelf bathymetry, ranging in depth from ~50 m to 100 m near the edge of the shelf and were located between 5 km and 15 km from land; encompassing from south Storm Bay, past the southern tip of Bruny Island and into the Southern Ocean (south-east Tasmania, Australia). Data collected focused on each trophic level, characterizing the zooplankton community, fish schools and marine predators. The overarching aim of the study was to investigate the effects of long term warming, and a marine heatwave event on zooplankton dynamics in terms of community response variables and the flow-on effects of changing lower-trophic level dynamics for top predators.