DOI: 10.5061/dryad.9s4mw6mtf
title: Underwater soundscape indicates low anthropogenic influence around two sub-Antarctic islands

description: Contributions and effects of anthropogenic activities on the underwater
 soundscape of the sub-Antarctic regions remain poorly studied. Over 21
 months (April 2021 to December 2022), we recorded underwater noise levels
 amid two sub-Antarctic Prince Edward Islands (PEIs) within an offshore
 marine protected area (MPA) to quantitatively investigate the sources of
 underwater noise and the impact of such noise on the detectability of
 marine mammal vocalizations. We measured underwater noise levels within
 the low (20–120 and 121–800 Hz), medium (801–25000 Hz), and high
 (25001–48000 Hz) frequency bands. Wind speed was the primary predictor of
 low and medium-frequency underwater noise levels, whereas iceberg volume
 was the primary predictor at the high-frequency band. Probabilities of
 detecting vocalizations of Antarctic blue, fin, humpback, Antarctic minke,
 and killer whales decreased with increasing noise levels. On the contrary,
 probabilities of detecting sei and Madagascan pygmy blue whales increased
 with noise levels. Overall, these novel results indicate that geophonic
 noise dominates the underwater soundscape of the PEIs in the absence of
 intense anthropogenic activities such as marine traffic, and that
 conservation efforts through this MPA might be protecting this remote
 region from anthropogenic activities.
description: # Underwater soundscape indicates low anthropogenic influence around two
 sub-Antarctic islands Dataset DOI:
 [10.5061/dryad.9s4mw6mtf](10.5061/dryad.9s4mw6mtf) ## Description of the
 data and file structure Acoustic data were collected between two
 sub-Antarctic islands, Marion Island and Prince Edward Island, Southern
 Ocean using a SoundTrap deployed 5 m off the seafloor. Marine mammal
 acoustic occurrence and underwater noise levels were determined from these
 collected data. #### Files and variables These files contain the formatted
 data on underwater noise levels, baleen and killer whale acoustic
 occurrence around the Prince Edward Islands, to reproduce the analyses
 presented in the paper. **killers_processed_data_1hr.csv**: Contains data
 on the hourly acoustic presence of killer whale vocalizations and noise
 levels at different frequency bands for the period April 2021 to May 2022
 used in the random forest model analysis. * **Year**: The year when the
 data was collected. * **Month**: The month when the data was collected. *
 **Day**: The day when the data was collected. * **Hour**: The hour (UTC)
 when the data was collected. * **SOCPA**: Hourly presence and absence of
 killer whale social calls indicating acoustic occurrence and communication
 of dolphins. The value is given as 0 or 1, where 1 means acoustic presence
 and 0 means acoustic absence. * **FORPA**: Hourly presence and absence of
 killer whale foraging sounds (i.e. echolocation) indicating acoustic
 occurrence and foraging of dolphins. The value is given as 0 or 1, where 1
 means acoustic presence and 0 means acoustic absence. * **hz20_120**:
 20–120 Hz frequency band noise level measured as equivalent continuous
 sound pressure level in dB re 1 μPa. * **hz121_800**: 121–800 Hz frequency
 band noise level measured as equivalent continuous sound pressure level in
 dB re 1 μPa. * **hz801_25000**: 801–25000 Hz frequency band noise level
 measured as equivalent continuous sound pressure level in dB re 1 μPa. *
 **hz25001_48000**: 25001–48000 Hz frequency band noise level measured as
 equivalent continuous sound pressure level in dB re 1 μPa.
 **baleen_processed_data_1hr.csv**: Contains data on the hourly acoustic
 presence of six baleen whale vocalizations and noise levels at different
 frequency bands for the period April 2021 to December 2022 used in the
 random forest model analysis. * **Year**: The year when the data was
 collected. * **Month**: The month when the data was collected. * **Day**:
 The day when the data was collected. * **Hour**: The hour (UTC) when the
 data was collected. * **dpa**: Hourly presence and absence of blue whale
 D-calls indicating acoustic occurrence of foraging activities of blue
 whales. The value is given as 0 or 1, where 1 means acoustic presence and
 0 means acoustic absence. * **pa40Hz**: Hourly presence and absence of fin
 whale 40 Hz pulses indicating acoustic occurrence of foraging activities
 of whales. The value is given as 0 or 1, where 1 means acoustic presence
 and 0 means acoustic absence. * **pa20Hz**: Hourly presence and absence of
 fin whales 20 Hz pulses indicating acoustic occurrence of communication
 activities of whales. The value is given as 0 or 1, where 1 means acoustic
 presence and 0 means acoustic absence. * **madpa**: Hourly presence and
 absence of Madagascan pygmy blue whale calls indicating acoustic
 occurrence of communication activities of whales. The value is given as 0
 or 1, where 1 means acoustic presence and 0 means acoustic absence. *
 **antpa**: Hourly presence and absence of Antarctic blue whale Z-calls
 indicating acoustic occurrence of communication activities of whales. The
 value is given as 0 or 1, where 1 means acoustic presence and 0 means
 acoustic absence. * **humpa**: Hourly presence and absence of humpback
 whale songs indicating acoustic occurrence of communication activities of
 whales. The value is given as 0 or 1, where 1 means acoustic presence and
 0 means acoustic absence. * **minpa**: Hourly presence and absence of
 Antarctic minke whale bioduck calls indicating acoustic occurrence of
 communication activities of whales. The value is given as 0 or 1, where 1
 means acoustic presence and 0 means acoustic absence. * **seipa**: Hourly
 presence and absence of sei whale upsweep calls indicating acoustic
 occurrence of communication activities of whales. The value is given as 0
 or 1, where 1 means acoustic presence and 0 means acoustic absence. *
 **hz20_120**: 20–120 Hz frequency band noise level measured as equivalent
 continuous sound pressure level in dB re 1 μPa. * **hz121_800**: 121–800
 Hz frequency band noise level measured as equivalent continuous sound
 pressure level in dB re 1 μPa. * **hz801_25000**: 801–25000 Hz frequency
 band noise level measured as equivalent continuous sound pressure level in
 dB re 1 μPa. * **hz25001_48000**: 25001–48000 Hz frequency band noise
 level measured as equivalent continuous sound pressure level in dB re 1
 μPa. **noise_processed_data_1hr_FINAL.csv**: Contains data on the hourly
 acoustic noise levels at different frequency bands for the period April
 2021 to December 2022 used in the random forest model analysis. *
 **Year**: The year when the data was collected. * **Month**: The month
 when the data was collected. * **Day**: The day when the data was
 collected. * **Hour**: The hour (UTC) when the data was collected. *
 **hz20_120**: 20–120 Hz frequency band noise level measured as equivalent
 continuous sound pressure level in dB re 1 μPa. * **hz121_800**: 121–800
 Hz frequency band noise level measured as equivalent continuous sound
 pressure level in dB re 1 μPa. * **hz801_25000**: 801–25000 Hz frequency
 band noise level measured as equivalent continuous sound pressure level in
 dB re 1 μPa. * **hz25001_48000**: 25001–48000 Hz frequency band noise
 level measured as equivalent continuous sound pressure level in dB re 1
 μPa. * **windsp**: Absolute wind speed in m s^-1^. * **wdn**: Absolute
 wind direction in degrees North. * **adt**: Absolute dynamic topography
 which represents the height of the sea surface relative to the
 Earth's geoid in m (Please note that this variable is not used in the
 current study.). * **wave_height**: Wave height indicates the at-sea
 observed total wave field in m. * **wave_period**: Wave period in seconds
 (s) representing the time when majority of the wave energy is
 concentrated. * **wave_dir**: Wave direction - variable is not used in
 this study. * **tp**: Total precipitation (m) consisting of accumulated
 liquid and frozen water from rain and snow that falls to the ocean's
 surface. * **current**: Ocean current (cm s ^-1^) used as frontal
 activities proxy around the mooring location. * **total_giga_tons**:
 Iceberg (less than 3 km in length) volume measured in total gigatons. *
 **vnumber**: Weighted number of vessels up to 53 km. ## Code/software All
 data can be viewed in MS Excel or R statistical software.