Graduation Year

2022

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Organismal Biology

Reader 1

Angela Sremba

Reader 2

Sarah Gilman

Abstract

For this study, a year of data from the Ross Sea in 2016 was analyzed to determine marine mammal temporal presence and distribution as well as other sounds contributing to the ocean soundscape. With an increase in anthropogenic noise, the ocean soundscape is constantly changing, affecting the marine ecosystem. Many marine mammal species rely on vocalizations to forage and communicate; therefore, an increase in both anthropogenic and environmental noise can contribute to changes in the species’ presence and distribution. Since visual surveys are limited by weather and ship access and often underestimate populations in ice covered areas, a more accurate method to study marine mammals in these remote polar areas is necessary. Passive acoustic monitoring (PAM) allows for the study of marine mammals in remote polar regions through the deployment of acoustic hydrophones to record their vocalizations over long periods of time in these harsh environments. Hydrophone data collected in the western Ross Sea in 2016 was analyzed to provide a census of habitat use for marine mammals as well as document environmental and anthropogenic sound in the region. This data was used to identify what species are present in this area and the seasonal patterns of their vocalizations. Sounds were visually identified and aurally confirmed using the Raven Pro interactive sound analysis software. Data was reviewed from mid-December 2015 through December 2016 for acoustic presence of biological, environmental, and anthropogenic sound. Sound detections for each category were as follows: biological sound included leopard seal and humpback whale calls, environmental sound included ice breaking and wind, and anthropogenic sound included shipping, hydrophone noise, and acoustic modem noise. Both environmental and anthropogenic signals were present year-round, with the majority of signals detected to be ice breaking and noise from the hydrophone system. The leopard seal vocalization peaks occurred in the austral spring and summer, while humpback whale vocalizations were only present during the austral winter and spring seasons. Humpback whale peak vocalization occurred in November. As more information is acquired about the dynamic ocean soundscape and through passive acoustic monitoring, the effects of rising anthropogenic noise amidst rising sea surface temperatures on marine mammal vocalizations can be studied.

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