Exploration of sound disturbance from unmanned aircraft systems in a coastal marine environment

Unmanned Aircraft Systems (UAS) provide a safer, cheaper and more efficient means of collecting and, with accompanying software, processing scientific data compared to conventional survey techniques. Marine Scientists are quickly discovering new applications for UAS that can not only allow them to replace survey tools such as manned aircraft and boats, but also to continue to open new avenues of research, providing the capabilities to answer previously challenging questions. Though assumed to be less intrusive than manned aircraft, there is extremely limited information on the potential for UAS acoustic and visual disruption caused by aircraft hovering or simply passing over animals and habitat. Anthropogenic sound in the marine environment can be highly disruptive and can alter animal behavior and vital life functions. In shallow coastal zones, boat noise has been shown to influence both vocalization rates and sound intensity of fish calls. No literature exists that has investigated UAS sound in any marine environment. The aim of this study was to provide preliminary data on UAS sound penetration characteristics into the water, as well as data on the effects of UAS engine sound on marine biophony. Using five separate UAS of various sizes and remote sensing capabilities, I flew at various heights over an autonomous acoustic recording system deployed in a coastal marine environment to learn how UAS sound penetrated the water and if it influenced vocalization rates of all nearby animals or call intensities of oyster toadfish. As hypothesized, lower altitudes and larger UAS had higher sound intensities, and the presence of UAS had no measurable impact on vocal production rate or intensity. I measured no acoustically-mediated disturbance from UAS missions in this developed coastal area. The observations of this study provide robust initial data and preliminary information on UAS acoustics in water and insight into their potential impacts on marine life.