2023_programme: Uncovering the Soundscape of the Ionian Sea: Acoustic Monitoring Data reanalysis, acquired during the HELPE's 2D/3D Marine Seismic Surveys, 2016-2023

• Session: 21. Underwater Noise - Modelling and Measurements
  Organiser(s): Alexander Gavrilov
• Lecture: Uncovering the Soundscape of the Ionian Sea: Acoustic Monitoring Data reanalysis, acquired during the HELPE's 2D/3D Marine Seismic Surveys, 2016-2023
  Paper ID: 2056
  Author(s): Fakiris Elias, Papatheodorou George, Mikoniatis George, Vavassis Yannis, Dimas Xenophon, Christodoulou Dimitris, Georgiou Nikos, Giannakopoulos Vasileios
  Presenter: Fakiris Elias
  Abstract: Hellenic Petroleum S.A. has undertaken five Marine Seismic Surveys in the Greek territorial waters of the Ionian Sea between 2016 and 2023. Those were coupled with intensive sound noise monitoring programs, applied to 13 monitoring stations with a longitudinal span of about 300km, from the Messinia regional unit to Corfu Island. Stations were mostly placed around Marine Protected Areas in coastal waters, collecting more than 350 hours of sound data. Two pre-calibrated EA-SDA14 (RTsys) compact embedded recorders were used equipped with two hydrophones each, a high sensitivity (215 dB) and a low sensitivity one (170 dB). The research vessel changed locations between the stations on a daily schedule. For each station, the research team deployed the underwater recording unit at 20m water depth to acquire sound data for 3 to 6 hours. The vessel was left drifting, hardly stabilized by using a floating anchor, to minimize self and flow noises. Noise sound pressure levels (SPLs) have been estimated regarding the zero to peak, peak to peak, and root mean square, as well as the sound exposure level (SEL), all integrated for 1s durations. The above SPL metrics have also been examined as a function of sound frequency components via third-octave bands (from 16 to 20,000 Hz center bands) while the 30s integrated power spectrum densities (PSD) have been estimated. The estimated SPLs gave insights into the footprints of the anthropogenic and biogenic factors on the soundscape of the Ionian Sea, including continuous ship traffic noises, impulsive noises, and fauna sounds, including marine mammals. Traffic noise SPL has been further assessed as a function of distance to the source versus frequency components. As far as we know, this is the first-ever regional-scale assessment of ambient noises in the Greek seas.
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• Corresponding author: Dr Elias Fakiris
  Affiliation: University of Patras
  Country: Greece
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