FIELD NOTES: UNDERWATER NOISE RESEARCH IS UNDERWAY
Triton researchers preparing an acoustic monitoring instrument for deployment. (Photo by Shanon Dell | Pacific Northwest National Laboratory).
Many marine wildlife species, including mammals, fish, and invertebrates, use sound or acoustic signals in the ocean for a variety of life functions, such as communication, foraging, navigation, and reproduction. Underwater noise is a stressor that is of concern for regulators who permit the deployment of marine energy devices. Sound emissions from these devices may increase background noise levels which mask or alter sounds important for aquatic life and may cause stress or change behaviors of aquatic animals, impacting their overall community structure or even species survival rates. To better understand these potential sound disturbances, the Triton team studies many aspects of underwater noise in the marine environment, including the particle motion component of sound and how to reduce unwanted acoustic flow noise.
Understanding Acoustic Particle Motion
An acoustic particle motion sensor and hydrophone package deployed in Sequim Bay. (Photo by Shannon Dell | Pacific Northwest National Laboratory)
All sources of sound underwater generate both pressure and particle motion components. The majority of the research to date has focused on investigating the impacts of acoustic pressure on marine species, particularly marine mammals. However, all fishes and many aquatic invertebrates are sensitive to acoustic particle motion, making it an increasingly important topic for regulators to understand the possible environmental effects of marine energy devices.
Triton’s Acoustic Particle Motion research team, led by Joseph Haxel, is addressing this data gap to help address the possible environmental concerns related to offshore energy development. The team recently conducted the first of several field deployments in Sequim Bay to test a new, portable, battery-powered particle motion sensor and hydrophone instrument package. Using this equipment, the team aims to increase our understanding of the possible effects of acoustic particle motion to better characterize underwater noise from marine energy devices on sensitive fish and invertebrate species.
Shielding Against Flow Noise
Hydrophones donning different shields to test how well they reduce flow noise. The various flow noise mitigation materials tested include (from left to right): an oil filled shield, ballistic nylon, stocking nylon, and a control. (Photo by Michael Richlen | Pacific Northwest National Laboratory)
Flow noise is pseudo-sound, or non-acoustic pressure fluctuations from turbulence, caused by the flow of water past an acoustic sensor—similar to the sound you hear when riding a bicycle. As part of Triton’s underwater noise research, Emma Cotter leads the team developing and testing various flow shields intended to reduce the effects of flow noise generated by the turbulence from the energetic movement of water around stationary hydrophones. This research takes advantage of the currents in the Sequim Bay tidal channel, just outside of the PNNL research campus in Sequim, in an area that has been sited for future tidal turbine testing, research, and development. The team aims to inform practical underwater noise mitigation strategies that can be used by both researchers as well as wave and tidal energy developers to improve underwater noise characterization at marine energy sites.
TRITON LOVES MARINE RESEARCH
Triton research associate Alexandra Barker showing a calibrated sound projector before testing in Sequim Bay. (Photo by Shanon Dell | Pacific Northwest National Laboratory)
February is a month filled with love, so we’re revisiting a story that showcases the many research tools we use—and love—to study environmental effects related to marine energy deployment. Read more.
TRITON NEWS
YouTube Shorts features Triton’s Marine Wildlife Detection and Tracking Project
PNNL featured highlights from Triton’s six-day field campaign in La Porte, Texas, where the Triton team conducted research for the Marine Wildlife Detection and Tracking Project, in partnership with Sandia National Laboratories and the University of Houston. This effort employed a tethered balloon system and sensor package used to detect and track marine mammal surrogates in a coastal environment. This innovative application and use of different imaging technologies has the potential to be deployed at marine energy test sites and other remote locations to study and observe how marine species may interact with marine energy devices, like wave energy converters. Check out the highlight reel!
IN OTHER ENERGY NEWS
Watch the Ocean Energy Systems-Environmental Webinar on Planning Tools to Assist Marine Energy Stakeholders
On January 19, Ocean Energy Systems (OES)-Environmental held a webinar which discussed tools for designing and siting marine energy projects with environmental effects in mind. This webinar highlighted OES-Environmental's Management Measures Tool, AZTI's Wave Energy Converter — Environmental Risk Assessment (WEC-ERA) Tool, and the Marine Energy Environmental Toolkit for Permitting and Licensing developed by Kearns & West. View the recorded webinar and presentation slides.
Triton is designed to support the development and testing of more precise and cost-effective environmental monitoring technologies for marine energy. Pacific Northwest National Laboratory leads Triton on behalf of the U.S. Department of Energy’s Water Power Technologies Office.
Connect With Us
Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354
