Quantifying Soundscapes in the Ross Sea, Antarctica Using Long-Term Autonomous Hydroacoustic Monitoring Systems

• Published in: Frontiers in Marine Science
• Main Authors: Yun, Sukyoung, Lee, Won Sang, Dziak, Robert P., Roche, Lauren, Matsumoto, Haruyoshi, Lau, Tai-Kwan, Sremba, Angela, Mellinger, David K., Haxel, Joseph H., Kang, Seung-Goo, Hong, Jong Kuk, Park, Yongcheol
• Other Authors: Korea Institute of Marine Science and Technology promotion, NOAA Pacific Marine Environmental Laboratory
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Frontiers Media SA 2021
• Subjects: Antarctic; Austral; Balleny Islands; Hydrurga; Ross Sea; Southern Ocean; Terra Nova Bay; Antarc*; Antarctica; Balaenoptera musculus; Hydrurga leptonyx; Ice Shelves; Korea Polar Research Institute; Leopard Seals; Sea ice
• Online Access: http://dx.doi.org/10.3389/fmars.2021.703411; https://www.frontiersin.org/articles/10.3389/fmars.2021.703411/full

Deployment of long-term, continuously recording passive-acoustic sensors in the ocean can provide insights into sound sources related to ocean dynamics, air–sea interactions, and biologic and human activities, all which contribute to shaping ocean soundscapes. In the polar regions, the changing ocean climate likely contributes to seasonal and long-term variation in cryogenic sounds, adding to the complexity of these soundscapes. The Korea Polar Research Institute and the U.S. National Oceanic and Atmospheric Administration have jointly operated two arrays of autonomous underwater hydrophones in the Southern Ocean, one in the Terra Nova Bay Polynya (TNBP) during December 2015–January 2019 and the other in the Balleny Islands (BI) region during January 2015–March 2016, to monitor changes in ocean soundscapes. In the BI region, we found distinct seasonal variations in the cryogenic signals that were attributed to collisions and thermal/mechanical fracturing of the surface sea ice. This is consistent with sea-ice patterns due to annual freeze–thaw cycles, which are not clearly observed in TNBP, where frequent blowing out of sea ice by katabatic winds and icequakes from nearby ice shelves generate strong noise even in austral winters. Another advantage of passive acoustic recordings is that they provide opportunities to measure biodiversity from classifying spectral characteristics of marine mammals: we identified 1. Leopard seals ( Hydrurga leptonyx 200–400 Hz), most abundant in the BI region and TNBP in December; 2. Antarctic blue whales ( Balaenoptera musculus distinctive vocalization at 18 and 27 Hz), strong signals in austral winter and fall in the BI region and TNBP; 3. Fin whales ( B. physalus fundamental frequency in the 15–28 Hz and overtones at 80 and 90 Hz), maximum presence in the BI region during the austral summer and spring months; 4. Antarctic minke whales ( B. bonaerensis 100–200 Hz), strongest signals from June to August in the BI region; 5. Humpback whales in TNBP; 6. Unidentified whales ...