Spatio-temporal dynamics of fast-ice cracking and seal vocalizations near Syowa Station, East Antarctica, and their environmental correlates

The Antarctic sea ice dynamics and environmental conditions affect both biotic and abiotic processes. Comprehensive analysis of underwater soundscape enables spatio-temporal assessment of ecosystem responses to environmental variation. While underwater soundscape research has focused on West Antarctica, East Antarctica has received limited scientific attention. This study addresses that gap by using passive acoustic monitoring near Syowa Station, East Antarctica, during the austral summer to investigate the spatio-temporal dynamics of fast-ice cracking and seal vocalizations. In January, 2023, three underwater recorders (SoundTraps) were deployed in an equilateral triangle array (200-m baseline distance) off Syowa Station. The area is covered by fast ice for most of the year. A total of 289 813 sounds, i.e. seal vocalizations and ice cracking sounds, were detected from 203 h of recordings. Spatial overlap between the two sound types exceeded 90%, suggesting that seals aggregate near tide cracks formed by ice break-up. Generalized linear models revealed that tidal difference, air temperature, wind speed, and proximity to an icebreaker ship influenced the temporal variation of both sound types. These findings demonstrate that underwater soundscape monitoring allows effective visualization of sea ice cracking events and provides valuable insights into the potential environmental drivers of seal distribution in East Antarctica.