Capturing Variability Marine Soundscapes: Elephant Island, Antarctica – A Case Study

• Main Authors: Burkhardt, Elke, Boebel, Olaf, Meister, Marlene, Spiesecke, Stefanie, Thomisch, Karolin, Opzeeland, Ilse C.
• Format: Conference Object
• Language: unknown
• Published: 2019
• Subjects: Antarc*; Antarctic; Antarctica; Blue whale; Elephant Island; Leopard Seal
• Online Access: https://epic.awi.de/id/eprint/50751/; https://hdl.handle.net/10013/epic.70f7206d-5769-4508-804e-3036ea34dab2

Here we present a comprehensive description of the acoustic environment approximately 31 km west-northwest of Minstrel Point, Elephant Island, Antarctica at 210 m water depth based on three years (Jan 2013 – Feb 2016) of subsampled (5 min per hour) passive acoustic recordings. Long-term spectrograms reveal a notable recurrence of acoustic environments between years. Fin and Antarctic blue whale calls dominate the low (< 100 Hz) part of the biophonic spectrum energetically from end of January to late July/early August. November through early January are dominated by leopard seal vocalizations at around 300 Hz. Concurrently, the geophonic spectrum exhibits strong fluctuations between days, both due to storm and tidal influences, causing flow and shackle noise from the instrumentation itself. Manual analysis of every second day of the subsampled data by visual and aural screening (employing short term spectrograms) was used to examine the data in greater detail for additional acoustic contributions and to assign the various acoustic signatures to their sources. Six cetacean and two pinniped species were identified based on their acoustic signatures and analysed for seasonal and diel patterns in occurrence. Anthrophonic signatures were attributed to air guns on 3 % of the analysed days. Vessel noise was noted between 10 and 12 % of days on annual averages, occurring mainly in austral summer and fall with sporadic events throughout the remainder of the year. This work illustrates the value of soundscape studies and provides a first step towards understanding the actual contribution of sound sources in their respective acoustic context and overall local noise budget.