One environmental stressor of interest for the marine energy community is the potential effect of underwater noise on marine species. To date, underwater noise research has largely focused on investigating the impacts of sound pressure on marine animals, specifically mammals. However, all fishes and many marine invertebrates rely on acoustic particle motion and substrate vibration rather than acoustic pressure to detect underwater sounds.
In the animation, the waves—which come from a source on the left—represent sound pressure, and the movement of the red particles represents particle motion. (Animation courtesy of Dr. Dan Russell, Pennsylvania State University)
Underwater sound, or acoustic energy, can be characterized by two components. The first, sound pressure, travels as an acoustic wave compressing and decompressing water molecules as it travels through water. The second, particle motion, occurs when individual particles interact and oscillate with the pressure waves but do not travel with them. When this vibrational energy travels through the sediment, it is known as substrate vibration.
Why is particle motion important?
The vector sensor hydrophone as it is prepared for deployment in Sequim Bay, WA. (Photo by Shanon Dell | Pacific Northwest National Laboratory)
Studies have shown that particle motion is detected by invertebrates and fishes that use sound. But only sound pressure is typically used for measuring underwater noise and its effects on marine species. To date, there is very limited information from particle motion measurements in the field around marine energy converters, how these measurements relate to sound pressure, and how animals respond to particle motion and substrate vibration. Triton’s Acoustic Particle Motion Project, led by acoustic scientist and principal investigator Dr. Joe Haxel, aims to address some of these knowledge gaps.
To advance particle motion measurements to evaluate marine energy-related underwater noise, the Triton team worked with industry partners at JASCO Applied Sciences and Geospectrum Technologies Inc. to build and test a vector sensor hydrophone instrument package, which measures both particle motion and sound pressure. Through this testing and development work, the project aims to improve capabilities for holistically characterizing underwater noise around marine energy devices.
Triton will also conduct dose-response experiments in tanks to dig into complex, unaddressed questions about how particle motion and substrate vibration may affect fishes and invertebrates. The project team is exploring behavioral and physiological effects from controlled exposures using projected underwater sounds and vibrations. Using physiological indicators, such as stress hormone levels collected from fish and crustaceans, the team can assess responses while correlating behavioral observations with different acoustic stimuli. Stay tuned as this project develops!
Spotlight: Our Particle Motion Partners
Triton’s Acoustic Particle Motion Project is a multidisciplinary research effort made possible through collaboration with an experienced team of fish biologists, physicists, engineers, regulators, and acousticians.
The project began in 2022 with a workshop that convened a diverse group of marine energy stakeholders and researchers in the fields of underwater acoustics and fish physiology. At the workshop, Haxel and project partner Dr. Arthur N. Popper led meaningful discussions about the need for particle motion research to fully address regulatory concerns related to underwater noise impacts. These conversations led to a perspective paper on “Marine Energy Converters: Potential Acoustic Effects on Fishes and Aquatic Invertebrates,” and set the foundation for the project’s current research activities and upcoming controlled experiments at Pacific Northwest National Laboratory’s unique facilities at the Richland and Sequim campuses.
Popper is a professor emeritus of biology at the University of Maryland, College Parkand a leading expert in particle motion and fish hearing physiology whose understanding of these topics comes from decades of research and scientific inquiry.
Dr. Shane Guan from the BOEM Environmental Studies Program is another key partner in the project with expertise in marine acoustics and substrate vibration. Guan shares, “results from this study would provide valuable knowledge to BOEM for science-informed decision-making and environmental impact assessment when planning offshore renewable energy development."
Triton is grateful for its many partners making this research possible!
News
Triton at American Fisheries Society Meeting
Quantitative ecologist Dr. Kate Buenau will be presenting a talk about Triton’s Probability of Encounter Modelproject at the upcoming2024 American Fisheries Society Meeting (AFS) in Honolulu, Hawaii. The talk, titled “Modeling Salmon Smolt Turbine Encounter Risk in the Kvichak River, Igiugig, Alaska,” will be part of a symposium about Partnering for Innovation and Fish Protection in the Clean Energy Transition. This session will include a series of presentations about various efforts to understand renewable energy system impacts on aquatic ecosystems. Kate will share about the model’s capabilities and the project’s collaboration with local communities, developers, and academic partners.
The talk will take place on Tuesday, September 17, 2024. Interested in connecting with Triton at AFS? Please reach out!
Webinar on Social Perceptions of Offshore Wind's Environmental Effects
The U.S. Offshore Wind Synthesis of Environmental Effects Research (SEER) effort, led by PNNL and the National Renewable Energy Laboratory (NREL) with support from the Department of Energy's Wind Energy Technologies Office, hosts a free, public webinar series to share the latest research on the potential environmental effects of offshore wind energy development.
The next webinar, "Social Perceptions of the Environmental Effects of Offshore Wind Energy Development," will take place on Wednesday, August 21, 2024, from 1:00 to 2:00 p.m. EDT. The panelists will discuss how perceptions of offshore wind’s environmental effects shape public opinion and community engagement and how to best communicate environmental information to the public. Register here.
OES-Environmental's Workshop on Environmental Effects of Permitting for Off-Grid Applications
Most research and monitoring for marine energy devices have focused on large (grid-scale) machines. However, marine energy has great potential to power remote coastal and island communities, and to provide power at sea for offshore aquaculture, ocean observations and navigation markers, and other uses. Join OES-Environmental to explore what level of environmental effects might be expected from smaller scale (off-grid) wave, tidal, and other marine energy devices, and to determine what additional information is needed to streamline permitting. This in-person workshop will be held at the International Conference on Ocean Energy 2024 in Melbourne, Australia, September 17–19, 2024.
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 Department of Energy’s Water Power Technologies Office.
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Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99354
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