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In marine strategies (D11), the impact of underwater noise is identified as one of the great environmental challenges. Generally unknown by society, and difficult to address from a technical and scientific point of view, it is a matter of great complexity and in continuous updating.

The impact of underwater noise can crucially interfere with the basic biological functions of numerous species, including cetaceans, as well as fish, molluscs or bivalves. That is why the integration of this environmental aspect in the management of marine protected areas is a challenge to guarantee the conservation of these species and fishing resources.

For this reason, the project has sought to bring this problem closer to society and establish methodological guidelines that help to undertake its study in a way that is consistent with European guidelines, both from the technical point of view and in the management of marine spaces, to contribute to achieving the good environmental status of seas and oceans.

The main objective of this project has focused on supporting the implementation of measures for the prevention and/or mitigation of impacts by underwater noise in marine protected areas, for which the following has been pursued:

• To promote research on underwater noise by predicting sound pressure caused by human activities in a marine Natura 2000 Network case study.
• Facilitate the management and monitoring of underwater noise in marine protected areas.
• To provide tools for the standardisation and facilitation of underwater noise measurements in accordance with European standards.
• To bring information closer to society and to promote public awareness of the problem of underwater noise.

• Application of an underwater noise propagation model in the Cabo de Palos-Islas Hormigas marine reserve.
• Recommendations for monitoring underwater noise in marine protected areas.
• Preparation of a methodological guide for the measurement of underwater noise.
• Campaign to raise awareness and environmental information on underwater noise.
• Dissemination and communication of the project.

• One of the main results of this project is the creation of an interactive map showing the changes in underwater sound levels generated by navigation in this space during 2019. The viewer, available online and freely accessible, is capable of displaying daily noise maps associated with maritime traffic from AIS data from vessels that have sailed in the study area and numerical models of underwater acoustic propagation.

Therefore, for the first time, the potential capacity is available to analyse which areas of this studied environment (and at what times) are subject to greater acoustic pressure, allowing the detection of priority areas for action in which to propose studies such as; the impact on marine fauna, or of a socio-economic nature, such as determining how these noise levels would change with the application of mitigation measures (for example, limiting the maximum speed of ships), among others.

• One of the conclusions of this study, which can be observed through the tool, is the clearly seasonal distribution of underwater noise in the marine reserve, with significant differences between the coldest and warmest months, the latter showing a greater influx of boats circulating in the area.

• It is also clear that this study has an influence on the maritime routes of the large cargo ships, which pass about 20 kilometres from the marine reserve, and which support a practically constant flow of ships that, on average, are larger and faster than the rest of the vessels identified.

• This work reflects the need to monitor underwater noise levels in marine areas with high biological value and the usefulness of software tools to analyse complex information.

• Future development of this viewer could include the ability to make real-time noise maps, make predictions, distinguish between natural and artificial sound, or integrate whale presence probability models to conduct impact studies.

• Within the framework of this project, a technical guide has also been developed with basic guidelines to address the measurement of underwater sound in accordance with international standards and recommendations.

• In addition to a list of recommendations for the management of underwater noise in marine protected areas.

The actions developed in the project are aimed at contributing to the implementation of the Marine Strategies Framework Directive (Directive 2008/56/EC).