NNMREC Passive Acoustic Monitoring for Tidal Energy Projects Brian Polagye, Chris Bassett, and Jim Thomson University of Washington Northwest National Marine Renewable Energy Center Ecological and Environmental Monitoring April 7, 2011

NNMREC Evaluating Acoustic Effects Marine Mammal Behavioral Response to Sound Sound Received by Marine Mammal Individual Life History Context for Received Sound  Sound generated by turbine  Site-specific sound propagation  Marine mammal hearing sensitivity  Ambient noise from other sources  Marine mammal activity state  Exposure to similar sounds

NNMREC Quantifying Sound from Turbines Common spectral peaks (100 Hz – 3 kHz) AHD at fish farm Bedload transport Nearby shipping Data collected by Scottish Association of Marine Sciences  OpenHydro turbine (6 m diameter)  Drifting EARs data collection  Compare drift series to identify turbine-specific features

NNMREC Marine Mammal Hearing Sensitivity Southall et al. (2007) Marine mammal exposure criteria Turbine Noise

NNMREC Implication for Received Levels Broadband Levels Mid-frequency Cetaceans 4x reduction in area ensonified to 120 dB

NNMREC Stationary Hydrophone Measurements Loggerhead DSG  Autonomous hydrophone (32 GB capacity)  80 kHz sampling  2% duty cycle for 3 months

NNMREC Temporal and Spatial Variability Cumulative Probability Density Hydrophone Deployments Temporal variability dominates over spatial variability

NNMREC Vessel Traffic Monitoring with AIS  Automatic Identification System (AIS) transponders required on all vessels greater than 300 tonnes gross weight and passenger vessels  Continuous data collection and archiving

NNMREC Data Assimilation SPL (dB re 1 μPa) Distance to closest vessel (km) Vessel ProximityNoise Correlation Vessel noise drives broadband noise levels Source: Chris Bassett, forthcoming PhD dissertation

NNMREC Implication for Evaluating Noise Effects

NNMREC Sound during High Currents Hydrophone Response Current Velocity

NNMREC Flow Shield Experiment Hydrophone with Flow Shield Unshielded Hydrophone Doppler Velocimeter Sample volume aligned with hydrophone element High Velocity Region Quiescent Region High Porosity Foam Hydrophone Element Hydrophone Pressure Case Source: Chris Bassett, forthcoming PhD dissertation

NNMREC Pseudo-Sound Identification Unshielded Hydrophone Hydrophone with Flow Shield Source: Chris Bassett, forthcoming PhD dissertation

NNMREC Propagating Sound during High Currents  Bedload transport ―Elevated noise at 5-50 kHz ―Consistent with size of gravel and shell hash observed during ROV surveys; O(1 cm)  Turbulent flow over rough surfaces ―Potential contribution from advected turbulence ―Cannot measure velocity fluctuations directly at frequencies of interest (e.g., > 300 Hz) (Hz) (Thorne, 1986) Source: Chris Bassett, forthcoming PhD dissertation

NNMREC Measuring Noise from Tidal Turbines ParameterStationary Hydrophone Drifting Hydrophone Pseudo-Noise FilteringPhysical shieldInherent filtering Measurement DurationMonthsHours Deployment DepthSeabed or Turbine frame Variable (easiest near surface) Spatial ResolutionLowHigh Temporal ResolutionHighLow Long-term, low- intensity monitoring Short-term, spatial characterization

NNMREC Thank You This material is based upon work supported by the Department of Energy and Snohomish County PUD under Award Number DE  Joe Talbert for keeping all equipment in working order.  Sam Gooch, Joe Graber, and Alex DeKlerk for helping turn around instrumentation.  Captains Andy Reay-Ellers for piloting skills during instrumentation deployment.