Assessing anthropogenic noise impacts and relevant soundscape cues for marine invertebrates: leveraging squid and coral reefs as model systems

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biological Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2021.Sound is utilized by marine animal taxa for many ecologically important functions, and these taxa are vulnerable to adverse effects of anthropogenic noise on hearing and behavior. However, little is known about marine invertebrates’ responses to anthropogenic noise, and the ambient environmental sounds (“soundscapes”) they detect and respond to. Most acoustic studies report sound pressure (detected by mammals and some fish), but few report particle motion, the back-and-forth vibratory component of sound detected by marine invertebrates. I investigated invertebrate use of and response to sounds in two facets: 1) behavioral responses of longfin squid, Doryteuthis pealeii to anthropogenic noise, and 2) particle motion of coral reef soundscapes in the U.S. Virgin Islands. In laboratory-based experiments I exposed D. pealeii to construction noise originally recorded from an offshore wind farm. I found significant increases in squids’ alarm responses and in failed prey capture attempts during noise. Conversely, noise exposure had no significant effects on reproductive behaviors of groups of D. pealeii, indicating high motivation of these squid to reproduce during this stressor. Collectively, these experiments revealed the importance of considering behavioral context in studies and regulatory decisions regarding invertebrates’ susceptibility to anthropogenic noise impacts. In studying coral reef soundscapes, I reported particle motion trends over several months for coral reefs varying in habitat quality, including coral cover and fish abundance. I found acoustic properties over which particle motion closely scaled with pressure, and others over which it did not. I compared soundscape data with particle motion hearing thresholds, and found that invertebrates may only detect high amplitude and low frequency transient sound cues on reefs, such as those produced by fishes. My research bring new insights on natural and anthropogenic sound cues detectable by marine invertebrates, and how and when invertebrates will be vulnerable to anthropogenic noise pollution.My graduate work was funded in part by the US Department of Interior, Bureau of Ocean Energy Management Environmental Studies Program through Interagency Agreement Number M17PG00029 with the U.S. Department of Commerce, National Oceanic and Atmospheric Administration (funding to Aran Mooney and Jenni Stanley). My work was also supported by the NSF Biological Oceanography award OCE-1536782 (funding to Aran Mooney). I received tuition and stipend support from the National Science Foundation Graduate Research Fellowship Program [Grant No. 2388357]. The Academic Program Office at the Woods Hole Oceanographic Institution provided tuition and stipend support as well as travel support. The MIT Student Assistance Fund, the Aquatic Noise 2019 Organizing Committee, and the Acoustical Society of America also provided travel support