Controlled studies in a quarry on the Oak Ridge Reservation look at the potential environmental effects of tidal turbine noise on fish behavior.
The Acoustics Exposure Experiment for Sensitive Fish Species project was completed in FY2016. The primary objective of the study was to test the behavioral response of fish to sound emanating from MHK turbines using fish species (or related surrogate species) that have the characteristics that make them a concern for turbine noise effects (i.e., species of special concern, species of commercial or recreational value, and species with sensitive hearing ability). This project investigated the distance from a turbine at which the behavior of fish near the turbine is affected by the turbine noise (if affected at all).
MHK project developers may have difficulty getting licenses to deploy if they are unable to convince regulators that the noise created by a single turbine or an array of turbines will not significantly affect fish populations. For that reason, MHK developers and environmental regulators have great interest in better understanding how fish respond to sounds that emanate from hydrokinetic turbines. Unfortunately, there have been few studies conducted that have evaluated the effects of turbine sound on fish health or behavior. Although effects on health are possible if the sound exposure is of high enough power, a more likely affect is a disruption of normal behavior, which was the focus of this study. ORNL researchers conducted experiments in small water bodies where external conditions (such as extraneous noise) could be controlled.
In 2012, ORNL constructed an outdoor experimental system in a ¼ acre experimental pond and conducted studies on the effects of sound created by a hydrokinetic turbine on free swimming fish. Researchers tested three species (largemouth bass, pallid sturgeon, and paddlefish) exposed to a range of sound levels from a single turbine recording. The results of those tests revealed no responses over the range of volumes tested perhaps due to the confined nature of the test arena which might have produced an unnatural acoustic environment. For that reason, in 2014 the net pen and experimental system were moved to a quarry on the Oak Ridge Reservation. The quarry (100X larger than the pond used in the previous study) allowed for more natural attenuation of sound and better telemetry reception and locating of tagged fish.
Scientists surgically implanted transmitters in fish to track their movements during exposure to underwater broadcasts of recorded turbine noise.
Scientists surgically implanted transmitters in fish to track their movements during exposure to underwater broadcasts of recorded turbine noise. In addition, a second objective of the task was to complete a journal article based on results of earlier DOE-funded work related to MHK turbine noise. Researchers characterized the ambient and anthropogenic noise in a large river environment where deployment of hydrokinetic devices was being considered. Results of these studies were disseminated via journal publication. Publishing in peer-reviewed journals lends significant validation to the results and conclusions which is invaluable to both developers and regulators. Results can be used to reduce uncertainty as to possible environmental effects, direct additional information gathering, and in many cases, alleviate concerns related to specific environmental stressors, which can in turn speed the permitting process and reduce costs. The successful completion of these studies provided a viable experimental setup for marine organisms tested under other circumstances.