Deep-sea mining and its far-reaching effects on marine life are becoming an increasing cause for concern as more profit-driven companies extract from the ocean’s seafloor for natural minerals.
The multiple sources of noise coming from the different components of deep-sea mining can adversely affect marine life across the water column, ranging from the surface level to the seabed (Alberts, 2021).
Here are some possible ways that deep-sea mining activities affect marine life along the water column:
1. At the seafloor
Main emissions of underwater noise:
- Acoustic monitoring
- Generally conducted near to the sea to obtain higher quality data
- Uses deep-towed multibeam echosounders, acoustic exploration activities produce mid-frequency (300kHz) and high amplitude sounds (above 200dB).
- Extraction machinery
- Produces additional noise and vibrations via dredging
The majority of these noises are produced almost continuously, resulting in wide-spreading implications on deep-sea marine creatures living just above the seabed such as crustaceans, fishes and cephalopods.
Possible impacts on marine life:
- Altered behaviours such as loss of coordination or serious hearing damage
2. At midwater
Main emissions of underwater noise:
- Riser systems
- The suction of material through the pipes of riser systems result in the production of continuous broadband sounds which can go up to 165 dB
- Motors of submersibles like Autonomous Underwater Vehicles (AUVs) and Remotely Operated Vehicles (ROVs)
- Noise emissions from submersibles can go beyond 200dB (OceanCare, 2021), a deadly level which can cause permanent hearing damage and even immediate death (Ortiz, 2022)
Possible impacts on marine life
- Behavioural change of midwater marine communities such as fish, sharks, squids and gelatinous animals like jellyfishes
- Disruption of communication and feeding patterns
- The release of harmful sediments could also suffocate marine life via the clogging of respiratory organs
3. At the surface-level
A large proportion of underwater noise from deep-sea mining activities is generated at the ocean’s surface (OceanCare, 2021). This is concerning due to the rich marine biodiversity that exists at this layer of the sea (OceanCare, 2021).
Main emissions of underwater noise:
- Acoustic exploration tools such as sonar and seismic airguns and vessels (OceanCare, 2021).
Possible impacts on marine life:
- Behavioural shifts such as loss of focus and evasion, stress, injuries and even death (OceanCare, 2021).
- Cetaceans, such as whales and dolphins are greatly affected by these sonar types of machinery as they overlap with their hearing ranges, resulting in strandings and habitat abandonment (Cholewiak et al., 2017; Pirotta et al., 2013).
With the growing recognition of marine noise pollution, what are some international regulations that have been put in place to manage the noise footprint of deep-sea mining? Are they effective?
Find out more in the next entry.
Until then, stay safe and stay woke! 🤔
References:
Alberts, E.C. (2021). If marine noise pollution is bad, deep-sea mining could add to the cacophony. Retrieved 27 Feb 2022, from https://news.mongabay.com/2021/11/if-marine-noise-pollution-is-bad-deep-sea-mining-could-add-to-the-cacophony/
Cholewiak, D., DeAngelis, A.I., Palka, D., Corkeron, P.J., Van Parijs, S.M. (2017). Beaked whales demonstrate a marked acoustic response to the use of shipboard echosounders. R. Soc. open sci. 4: 170940.
DSM Observer. (2020). https://dsmobserver.com/2020/07/what-impact-will-deep-sea-mining-have-on-midwater-habitats/#:~:text=By%20changing%20the%20physical%20and,comb%20jellies)%2C%20and%20squid.
OceanCare.(2021). Deep-Sea Mining: A noisy affair. Retrieved 26 February 2022, from https://www.oceancare.org/wp-content/uploads/2021/11/DeepSeaMining_a-noisy-affair_report_OceanCare_2021.pdf
Ortiz, P. (2022). DECIBEL EQUIVALENT TABLES: WHAT DOES EACH VOLUME SOUND LIKE? Retrieved 27 Feb 2022, from https://housegrail.com/decibel-equivalent-table-whats-how-loud/
Pirotta E., Laesser B. E., Hardaker A., Riddoch N., Marcoux M., Lusseau D. (2013). Dredging displaces bottlenose dolphins from an urbanised foraging patch, Marine Pollution Bulletin 74: 396-402.