Recording, in-situ processing and near real-time satellite transmission of acoustic data from a low-cost marine drifter buoy

Marine acoustic pollution has become a pervasive, yet largely invisible, threat to marine ecosystems, with existing monitoring technologies presenting significant economic and logistical barriers that limit widespread implementation. Rising levels of anthropogenic noise from shipping, construction, and resource extraction mask communication between marine species, disrupt behaviour, and can cause physiological harm across a wide range of taxa. This thesis addresses the critical need for more accessible marine acoustic monitoring by developing and validating a low-cost, satellite-linked acoustic drifter buoy system capable of real-time underwater noise assessment. The thesis begins with a general introduction to marine soundscapes and underwater radiated noise (URN), covering how anthropogenic sound overlaps with biological sound and the respective impacts on the environment. Chapter 1 concludes by highlighting current technological limitations that constrain marine acoustic research to accessible coastal environments. The engineering development of an autonomous acoustic monitoring buoy is considered in Chapter 2, presenting the design compromises necessary for balancing performance against cost, durability, and power consumption. The system integrates onboard third-octave band acoustic data processing, Iridium satellite communication, and autonomous operation within a waterproof housing constructed for £1,765, representing a 96% cost reduction (on components) compared to existing commercial alternatives while maintaining internationally recognised scientific measurement standards. Acoustic data from two seasonal deployments off Dawlish, UK (autumn 2024 and spring 2025), are shared in Chapter 3, demonstrating successful autonomous operation across 106 hours of field testing. Acoustic analysis revealed pronounced diel patterns in anthropogenic noise frequencies, with spring deployments showing day-night differences of up to 11.5 dB re 1µPa²Hz⁻¹ at 100 Hz, providing quantitative evidence of human activity in coastal marine soundscapes. Seasonal comparisons indicated consistently elevated acoustic power during autumn, with spring nighttime levels 4.0-6.5 dB re 1µPa²Hz⁻¹ lower across all measured frequencies. The thesis concludes with a discussion, Chapter 4, on how the presented technological approach in the thesis provides a pathway for democratizing marine acoustic monitoring, enabling distributed monitoring networks previously constrained by economic barriers. The research establishes proof-of-concept for systematic marine acoustic pollution assessment required for evidence-based conservation, while identifying development priorities for scaling to operational monitoring capabilities that could transform marine environmental management from localized studies to comprehensive ecosystem-scale coverage.<p></p>

Author dc:creator

• Tom Knowles (21039482)

• Marine
• Technology
• Acoustics
• Conservation
• Ocean
• Drifter
• Buoy
• Satellite
• Low-cost
• Sound
• Soundscape
• Monitoring

Statement dc:rights

• All rights reserved

Identifier

10779/exe.32324289.v1

OAI identifier oai:identifier

oai:figshare.com:article/32324289