The present and future contribution of ships to the underwater soundscape

The present and future contribution of ships to the underwater soundscape

Possenti, Luca (NIOZ Royal Netherlands Institute for Sea Research)
de Nooijer, Lennart (NIOZ Royal Netherlands Institute for Sea Research)
de Jong, Christ (TNO)
Lam, Frans Peter (TNO)
Beelen, Simon (University of Twente)
Bosschers, Johan (Maritime Research Institute Netherlands (MARIN))
van Terwisga, T.J.C. (TU Delft Ship Hydromechanics and Structures; Maritime Research Institute Netherlands (MARIN))
Stigter, Marinus (TU Delft Fluid Mechanics)
Reichart, Gert Jan (NIOZ Royal Netherlands Institute for Sea Research; Universiteit Utrecht)

2024

Since the industrial revolution the ocean has become noisier. The global increase in shipping is one of the main contributors to this. In some regions, shipping contributed to an increase in ambient noise of several decibels, especially at low frequencies (10 to 100 Hz). Such an increase can have a substantial negative impact on fish, invertebrates, marine mammals and birds interfering with key life functions (e.g. foraging, mating, resting, etc.). Consequently, engineers are investigating ways to reduce the noise emitted by vessels when designing new ships. At the same time, since the industrial revolution (starting around 1760) greenhouse gas emissions have increased the atmospheric carbon dioxide fraction x(CO₂) by more than 100 μmol mol^-1. The ocean uptake of approximately one third of the emitted CO₂ decreased the average global surface ocean pH from 8.21 to 8.10. This decrease is modifying sound propagation, especially sound absorption at the frequencies affected by shipping noise lower than 10 kHz, making the future ocean potentially noisier. There are also other climate change effects that may influence sound propagation. Sea surface warming might alter the depth of the deep sound speed channel, ice melting could locally decrease salinity and more frequent storms and higher wind speed alter the depth of the thermocline. In particular, modification of the sound speed profile can lead to the appearance of new ducts making specific depths noisier. In addition, ice melting and the increase in seawater temperature will open new shipping routes at the poles increasing anthropogenic noise in these regions. This review aims to discuss parameters that might change in the coming decades, focusing on the contribution of shipping, climate change and economic and technical developments to the future underwater soundscape in the ocean. Examples are given, contrasting the open ocean and the shallow seas. Apart from the changes in sound propagation, this review will also discuss the effects of water quality on ship-radiated noise with a focus on propeller cavitation noise.

climate change
ocean noise
shipping
soundscape
underwater acoustics

http://resolver.tudelft.nl/uuid:9064fc3d-b39d-49f6-bd9c-64764980661e

https://doi.org/10.3389/fmars.2024.1252901

2296-7745

Frontiers in Marine Science, 11

Institutional Repository

review

© 2024 Luca Possenti, Lennart de Nooijer, Christ de Jong, Frans Peter Lam, Simon Beelen, Johan Bosschers, T.J.C. van Terwisga, Marinus Stigter, Gert Jan Reichart