Sound is a dominant feature of the underwater marine environment because of natural (biological sources, underwater earthquakes, wind) and human-made (anthropogenic) sound sources. Underwater noise anthropogenic sources are commonly related to maritime transport, deep-sea mining, fishing, and construction. This study assessed the potential impact of offshore wind farming activity on the global sound pressure of the Gulf of Lions area. The results suggest an increase of global sound pressure due to offshore wind farming activities and maritime traffic, hence, potential adverse effects on the marine environment.
Questions this practice may help answer:
- To what extent do maritime traffic and offshore windfarm operations contribute to underwater noise and pollute existing oceanic soundscapes?
Sound is a dominant feature of the underwater marine environment because of natural and anthropogenic sound sources. Underwater noise generated by maritime activities adversely affects the marine environment producing different types of effects on the pelagic organisms, increasing mortality, hearing impairment, masking communication and disturbing their behaviour. Underwater noise coming from anthropogenic sources commonly related to shipping, deep-sea mining, fishing, construction, and offshore wind farming. One of the main challenges facing EU MS with MSP processes is having to carry out a coherent and effective distribution of human activities in the marine environment while assessing the possible impacts and pressures that may affect species and habitats to ensure the responsible use of marine resources.
A stark development in offshore wind farming is expected in the coming years. However, the newness of this sector means there is a lack of informative studies related to specific Mediterranean aspects. This sector's impacts on the marine environment need to be studied and analysed, including underwater noise.
Aspects / Objectives:
This study evaluates the continuous noise present underwater in the Gulf of Lion due to marine traffic and how offshore wind farming can play a relevant role with respect to the total soundscape and the influence of underwater noise on marine ecosystems and species.
The methodology followed to carry out the assessment of underwater sounds consisted of:
- Computing the Automated Identification Data (AIS) in the region of interest and evaluating the noise radiated to the medium by each navigating ship.
- Applying a suitable sound propagation method considering a specific bandwidth, the characteristics of the speed of sound in the water column and the properties of the sea bottom.
- Establishing a temporary framework for the assessment considering a time window regarding the marine traffic snapshots considered.
- Obtaining statistical metrics regarding the sound pressure level to be compared with the results offered by experimental data.
- Performing experimental measurements at given locations with the aim of validating global results of noise by means of local experimental measurements.
Main Outputs / Results:
This study confirms that the development of maritime traffic and offshore wind farming activity would increase the value of sound pressure in the Gulf of Lion. These findings need to be challenged against experimental data and observation to study, in particular, the influence of maritime traffic and windfarm operation on the total underwater noise in the area and the impacts on wildlife.
The described approach and methodology can be replicated in other basins and areas where maritime traffic and offshore wind farms are planned to be developed.
Spanish Institute of Oceanography (IEO, CSIC)
Costs / Funding Source:
Towards the operational implementation of MSP in our common Mediterranean Sea (Msp-MED)
Grant Agreement Nr: 887390
Manuel Bou-Cabo manuel.bouieo.csic.es Instituto Español Oceanografía