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Item Underwater acoustic propagation modeling and utilization for marine hydrokinetic devices(Montana State University - Bozeman, College of Engineering, 2024) Hafla, Erin Christine; Chairperson, Graduate Committee: Erick JohnsonOver the last two decades, there has been growing concern surrounding the increase in underwater anthropogenic sounds as expanding human populations interact with marine life and look for alternative energy production methods. That concern has led to a significant push worldwide to understand how propagated sound interacts with the surrounding marine environment. Marine hydrokinetic (MHK) devices are an alternative source of renewable energy available, which generate electricity from the motion of tidal and ocean currents, as well as ocean waves. Sounds produced by MHKs tend to overlap the frequency range common to both marine fauna communication and behavior. Preliminary measurements indicate that sound level values fall near the total sound decibel limitations presented by regulatory bodies. To date, the power optimization of MHK arrays has been prioritized over how its sound is produced, directed, and may impact the marine soundscape. There is a gap in knowledge regarding how marine fauna may respond to these sounds and what their physical and behavioral impact may be, and an absence in measured levels from insitu MHK deployments. A model for predicting the propagation of sound from an array of MHK sources in a real environment is essential for understanding potential impacts on a surrounding system. This work presents a fully three-dimensional solution to a set of coupled, linearized velocity-pressure equations in the time-domain as applied to underwater systems, and is an alternative sound propagation model to the Helmholtz and wave equation methods. The model is validated for a single source located within a series of increasingly complex two-dimensional and three-dimensional shallow water environments and compared against analytical solutions, examples from literature, and recorded sound pressure levels collected from Sequim Bay, WA. An uncertainty analysis for an array of MHK devices is presented to further understand how multiple turbine signals interact with one another in increasingly complex systems. This research presents a novel use of the velocity-pressure equations to analyze the variability associated with sound sources as sound propagates through a selected environment to inform the design and deployment of a MHK device or array of devices to minimize potential future impacts.Item Combination of acoustic telemetry and side-scan sonar provides insight for lake trout Salvelinus namaycush suppression in a submontane lake(Montana State University - Bozeman, College of Letters & Science, 2021) Siemiantkowski, Michael James; Chairperson, Graduate Committee: Christopher S. GuyExpansion of an invasive Lake Trout Salvelinus namaycush population in Swan Lake, Montana threatens a core area population of Bull Trout Salvelinus confluentus in Montana. Given the increased efficacy of suppression using novel embryo suppression methods, there is renewed interest in Lake Trout suppression in Swan Lake. The specific questions of this study were: 1) where are Lake Trout spawning, 2) where are the most used spawning sites, 3) what is the amount of spawning habitat, 4) does the estimated spawning area differ between estimates from telemetry locations and side-scan sonar imagery of suitable spawning substrate, and 5) how much phosphorous and nitrogen would be added to Swan Lake if carcass-analog pellet treatments were implemented? Acoustic tags were implanted in 85 Lake Trout in July and August of 2018 and 2019. Nightly tracking efforts during September, October, and November of 2018 and 2019 resulted in 1,744 relocations for 49 individual Lake Trout. Kernel-density analysis was used to evaluate Lake Trout aggregation locations identifying 10 distinct spawning sites -- corroborating previous studies. Visual observation of Lake Trout embryos confirmed spawning at three sites with the remaining seven sites considered to be unconfirmed spawning sites. All confirmed spawning sites were located in the littoral zone along areas of steep bathymetric relief and were the most used across both spawning seasons. In 2019, side-scan sonar imaging was used to classify and quantify the total area of suitable spawning substrate, which comprised 12.8% of the total surface area estimated for confirmed sites and 11.4% for unconfirmed spawning sites. Simultaneous treatment of all confirmed and unconfirmed spawning sites would require 205,709 + or - 86 kg of carcass-analog pellet material, resulting in 370.4 + or - 0.2 kg of phosphorous and 7,487.9 + or - 3.1 kg of nitrogen inputs to Swan Lake. Thus, pellet treatment would increase the Carlson's trophic state index (TSI) values from 20.8 to 27.7 for total phosphorous, and from 22.1 to 26.2 for total nitrogen. Based on a TSI threshold value of < 40 for an oligotrophic lake, the use of carcass-analog pellets could be a feasible addition to renewed Lake Trout suppression efforts in Swan Lake.Item Acoustic propagation modeling for marine hydrokinetic applications(Montana State University - Bozeman, College of Engineering, 2016) Johnson, Charles Nathan; Chairperson, Graduate Committee: Erick JohnsonThe combination of riverine, tidal, and wave energy have the potential to supply over one third of the United States' annual electricity demand [1]. However, in order to deploy and test prototypes and commercial installations, marine hydrokinetic (MHK) devices must meet strict regulatory guidelines. These regulations mandate the maximum amount of noise that can be generated and sets particular thresholds for determining disturbance and injury caused by noise. In the absence of measured levels from in-situ deployments, a model for predicting the propagation of a MHK source in a real hydroacoustic environment needs to be established. An accurate model for predicting the propagation of a MHK source(s) in a real-life hydro-acoustic environment has been established. This model will help promote the growth and viability of marine, water, and hydrokinetic energy by confidently assuring federal regulations are meet and harmful impacts to marine fish and wildlife are minimal. A 3D finite-difference solution to the governing velocity-pressure equations is presented and offers advantages over other acoustic propagation techniques for MHK applications as spatially varying sound speeds, bathymetry, and bed composition that form complex 3D interactions can be modeled. This solution method also allows for the inclusion of complex MHK sound spectra from turbines and/or arrays of turbines. A number of different cases for hydro-acoustic environments have been validated by both analytical and numerical results from canonical and benchmark problems. Several of these key validation cases are presented in order to show the applicability and viability of a finite difference numerical implementation code for predicting acoustic propagation in a hydro environment. With the model successfully validated for hydro-acoustic environments, more complex and realistic MHK sources from turbines and/or arrays can be modeled. A systematic investigation of MHK relevant scenarios is presented with increasing complexity including a single- and multi- source investigation, a random phase change study, and a hydro-acoustic model integrationItem Spatial and temporal entrainment of fish from Hauser Reservoir, Montana(Montana State University - Bozeman, College of Letters & Science, 2010) Spinelli, Justin Philip; Chairperson, Graduate Committee: Alexander V. ZaleManagement of fish populations in Hauser Reservoir, Montana, is hindered by undesirable and unpredictable downstream entrainment of fish through Hauser Dam. My objectives were to estimate spatial and temporal entrainment of fish larger than 100 mm total length through Hauser Dam and identify environmental and operational conditions influencing entrainment. I quantified entrainment using hydroacoustics at the turbine intakes from July 2007 to November 2008 and the spillway from May to July 2008. Species composition was characterized using multiple netting gears. I investigated the relationships between entrainment and conditions in the reservoir and at the dam using multiple linear regression. Total entrainment was 145,470 (95% CI = 138,144 - 152,796). About 60% of entrained fish were smaller than 220 mm. Annual entrainment from summer to autumn was higher in 2007 (N = 79,031; 95% CI = 73,861 - 84,201) than in 2008 (N = 52,513; 95% CI = 47,830 - 57,196). I applied species composition by size to the hydroacoustic data to identify entrained fish species, but many fish (N = 55,529; 95% CI = 50,337 - 60,721) could not be reliably assigned to species because concurrent net catches did not include individuals of similar size. Total entrainment was mostly made up of rainbow trout (33.3%) and walleye (30.2%). Spillway entrainment was 16% of total entrainment and was correlated with spillway discharge; turbine entrainment was not. Turbine entrainment increased from summer to autumn in both years, probably in response to autumn turnover and releases of hatchery rainbow trout. On average, 9.0% (SD = 1.2%) of hatchery fish were entrained soon after being stocked in the reservoir. Most regression models were equally ranked using Akaike Information Criterion corrected for small sample size indicating that a combination of conditions were influencing entrainment. Spatial and temporal patterns of entrainment at Hauser Dam were typical of other facilities in that entrainment varied in response to a changing combination of operational and environmental conditions. Identification of these patterns of entrainment allows managers to evaluate effects to the reservoir population and make more informed decisions.