Abstract:
Deep-sea mineral exploitation is likely to become a reality in the near future, despite limited understanding
of deep-ocean ecosystems and the potential impacts of such activities. In response, the EU Horizon TRIDENT project
aims to develop monitoring methodologies and tools to assess environmental impacts, forecast outcomes, and support
informed decision-making. The apparatus associated with deep-sea industrial activities is expected to generate two
main impacts: sediment plumes and acoustic noise. This work presents the TRIDENT tool for monitoring and mapping
anthropogenic noise from deep-sea exploitation, along with results from preliminary experiments and validation.
To cover the large spatial coverage of noise in the open ocean, the tool integrates wind, shipping, and sound
propagation models. Baseline soundscapes (without exploitation activity) are simulated using the Hildebrand model
for wind noise, while shipping noise is derived from AIS data converted to source levels via the JOMOPANS-ECHO
model and propagated using the Bellhop ray-tracing code with GEBCO bathymetry and Copernicus environmental data.
Noise from exploitation activities is incorporated using source levels obtained from sensors installed on the
machinery. Data from a 12-day sea trial in May 2025 at the Tropic Seamount were used to generate baseline maps
and evaluate model performance. Validation against multi-platform observations across depths shows that model
captures the main characteristics of median sound pressure levels in the 10 Hz-4 kHz band, with best agreement
near 100 Hz and discrepancies up to 10 dB at lower and higher frequencies. A simulated exploitation scenario
using three sources at the 6 m, 500 m, and 1000 m indicates that instantaneous sound pressure levels remain
below thresholds for temporary auditory effects (>180 dB). However, cumulative sound exposure levels may exceed
thresholds within ~10 km of the source. At distances of 100 km, exploitation activities increase median sound
pressure levels by 25-65% across the frequency band, potentially reducing habitat suitability for marine species.
These results demonstrate the capability of the TRIDENT framework to reliably predict and map noise impacts in
deep-sea environments and highlight the importance of predictive acoustic tools to support environmentally
responsible deep-sea resource management.