AQUO PROJECT - RESEARCH ON SOLUTIONS FOR THE MITIGATION OF SHIPPING NOISE AND ITS IMPACT ON MARINE FAUNA SYNTHESIS OF GUIDELINES

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1 AQUO PROJECT - RESEARCH ON SOLUTIONS FOR THE MITIGATION OF SHIPPING NOISE AND ITS IMPACT ON MARINE FAUNA SYNTHESIS OF GUIDELINES Christian Audoly and Céline Rousset DCNS Research, Technopole de la Mer, Ollioules, France, christian.audoly@dcnsgroup.com Eric Baudin Bureau Veritas, Boulevard du Château, Neuilly sur Seine, France Thomas Folegot Quiet-Oceans, 65 place Nicolas Copernic, Plouzané, France AQUO is a Collaborative European Research Project of the 7th Framework Program, in the scope of theme Sustainable Surface Transport, topic coordinated with the Oceans of Tomorrow. The project started in October 2012 for three years duration (see the website The final goal is to provide policy makers with practical guidelines and solutions, in order to mitigate shipping underwater noise that can have negative consequences on marine fauna. The AQUO project addressed it by adopting a multi-disciplinary approach bringing together experts of naval industry, underwater acoustics and bioacoustics. After a general presentation of the project, the goal here is to synthesize the guidelines produced by AQUO project. Different types of solutions (ship design, ship operational parameters settings, ship traffic control) are assessed using three criteria: underwater radiated noise reduction, fuel efficiency and impact on marine fauna. For this last topic, an underwater noise footprint predictive model has been developed by Quiet-Oceans. This methodology allows identifying the most promising strategies for the mitigation of the impact of shipping noise on the marine fauna, and also the subjacent technical solutions. The results show that imposing a limit of underwater radiated noise to the noisiest ships seems to be the most effective solution, which is consistent with the recent Bureau Veritas notation NR614. After a presentation of some examples of concrete results, some conclusions on the main guidelines will be given with a proposal of actions plan. 1. Introduction As maritime traffic has steadily increased in the past decades and is expected to increase further (Figure 1), there is an increasing concern among the scientific community regarding the environmental impact and the consequences on marine life. One of these is underwater noise, considering the fact that a large proportion of animal species living underwater, not only mammals but also fish and invertebrates, uses sound or related physical quantities to swim, communicate between individuals, detect threats, or find preys. An important milestone was the adoption in 2008 by the European Community of the Marine Strategy Framework Directive (MSFD) [1], which requires the European Member States to monitor the environmental status of European maritime areas and to take appropriate measures to achieve a good environmental status by the year

2 Figure 1: Illustration of the concern with the increase of maritime traffic and the impact on marine life. In that context, the European Commission launched in 2011 a call for projects in the scope of the 7th Research Framework, theme «Transport», coordinated topic «Oceans of Tomorrow». The aim was as follows: the study of underwater noise radiated from ships, in particular propeller noise, including cavitation and interaction effect with the hull, and the search of noise control measures allowing the reduction of the emissions into the environment, the development of a predictive tool for the underwater noise generated by ship traffic in a given maritime area, couple to the ship automatic identification system (AIS), allowing the evaluation of the impact on marine life, to provide policy makers with solutions for the mitigation of the impact on marine life of ship traffic regarding underwater noise. The AQUO Project was built in response to that European call. Coordinated by DCNS Research and formed with a multi-disciplinary team of 13 European partners from academic or research laboratories, ship industry, small specialized companies and a classification society, it started in October 2012 and ended in December It should be noted that the International Maritime Organization (IMO) issued recently nonmandatory guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life [2]. The main objective of the AQUO Project is to go one step further by addressing explicitly the impact on marine life using an innovative methodology, and by providing practical solutions and tools for the mitigation of the impact on marine life of ship traffic regarding underwater noise, based on rigorous technical results using adequate tools for the assessment of possible solutions. Based on the AQUO Project final report Practical Guidelines [3], the purpose of this paper is to summarize the main conclusions and recommendations arising from the Project. An overview of the project is given first in section 2, with its organization and tasks completed. A definition for the underwater noise footprint of anthropogenic activity at sea is proposed. Also the dedicated methodology for the assessment of underwater noise related to shipping and the corresponding tool are described. The method is applied in section 3, using different test cases. After having established a comprehensive list of possible mitigation measures, an analysis is conducted in order to select the most efficient ones, in relationship with different scenarios. Some results are presented in the form of statistical noise maps. By introducing bioacoustics criteria and related scenarios, it is also possible to quantify a bioacoustics risk in relation to some marine species, 2. The AQUO Project and its methodology In order to handle the topic in its complexity, the AQUO Project has followed an innovative methodology. Dedicated tools have been developed and different advanced studies were carried out on different aspects. Most of technical reports are openly available ( 2 ICSV23, Athens (Greece), July 2016

3 2.1 Organization and tasks completed The project included five technical work packages, and two other work packages for management, dissemination and exploitation activities (Figure 2). Figure 2: Organization of AQUO Project. The completed tasks, illustrated on Figure 3, are summarized below. WP1 - Noise footprint assessment model: The main objective was to develop a tool for the estimation of the underwater noise footprint related to maritime traffic, able to run either in real-time, either on simulated scenarios. This was completed thanks to the Quonops software platform developed and operated by Quiet-Oceans. The tool was checked and calibrated by comparison to other computer tools and to experimental data [10]. WP2 - Noise sources: The first objective was to build generic models to represent underwater noise radiated from ships by equivalent noise sources in a parametric form depending on ship category, size, and speed [11]. The second objective was to validate or to develop numerical or scale model experimental techniques to predict radiated noise from ships mostly focusing on propeller noise with or without cavitation. WP3 - Measurements: The main objective was to gather experimental data at sea, in order to feed the other work packages with accurate and well-documented data. Scale one measurements were done at sea on six different vessels (two research vessels, a small fishing vessel, a coastal tanker, and a passenger ferry), including underwater radiated noise and vibratory and acoustic on-board measurements. For two vessels, a direct observation of propeller cavitation was available, allowing detailed studies on cavitation and related underwater noise. In another task, long-term recordings of underwater noise were obtained thanks to the deployment of autonomous buoys in a test maritime area. Another aspect was the development of new measurement methods, in particular an improved procedure for measurement of underwater radiated measurement from ships, applicable in both shallow and deep waters, including a detailed analysis of measurement uncertainties. WP4 - Sensitivity of marine life: Dedicated bioacoustic experiments were done on three marine species (harbour porpoises, cod fish, and cephalopods). For example, the experiments on harbour porpoises consisted in auditory evoked potential laboratory measurements with individuals submitted to sound reproducing ship radiated noise in order to study possible consequences on audition or behaviour. A synthesis study allowed the derivation of bioacoustic criteria. WP5 Guidelines: Using the results and tools developed previously, this work package consisted in assessments and in parametric studies in order to estimate, in a quantitative way as far as possible, the efficiency of the different noise control solutions or mitigation measured under consideration, taking into account three aspects: intrinsic reduction of ship radiated noise, ship fuel efficiency, and impact on marine life. ICSV23, Athens (Greece), July

4 Figure 3: Illustration of some technical tasks completed in AQUO Project. 2.2 Underwater noise footprint indicators and related methodology Although the notion of noise footprint has been defined and used routinely for a long time for environmental airborne noise issues, this is not the case in underwater acoustics. To overcome this lack of framework, the AQUO Project has developed an approach, illustrated on Figure 4, taking into account three aspects: the emitters, the environment, and the receptors. Figure 4: Methodology for underwater noise footprint assessment. The underwater noise footprint in relationship with anthropogenic activity at sea, here shipping, has been defined as The representation of the noise level arising from maritime activities that affects a portion of the sea. It includes the description of the noise sources and the propagation of the sound in the ocean environment that can be represented as a noise map, without frequency 4 ICSV23, Athens (Greece), July 2016

5 weighting. It can be used to assess the effect or impact of anthropogenic sound on marine life, using suitable indicators. That methodology was implemented into the Quonops tool, which was adapted for the needs of the project [7]. In practice, the process for a maritime area under study is as follows: Collecting information on ship traffic through the AIS system. This allows obtaining the list of ships sailing in the area, and their type, position and speed along time. Collecting data regarding the physical description of the area (bathymetry, speed of sound in the water column, sea floor properties). At each time step, a map of underwater noise as shown on the left of Figure 5 can be computed. The input are the source levels of each vessel, estimated from the parameters obtained through AIS and by using the parametric models derived in WP2 [11]. The propagation losses between the sources and each point in the area (the receiving points) are computed using underwater acoustic propagation models, selected in accordance with the environment and frequency (several models may be required to cover the frequency band of interest). Some studies were conducted in cooperation with the SONIC Project to verify the validity of the approach [8]. Figure 5: Process for the derivation of statistical indicators of underwater noise in an area noise map in a given frequency band at a given instant (left); variation of noise along time at a given observation point (top right); noise level expressed as a percentile at the observation point (bottom right). It is important to note that the noise level at a given observation point varies strongly with time, in relation with the passage of vessels in the vicinity, resulting in a series of peaks whose levels depend on the source level and on the propagation loss between the emitter and the receiver. In order to have a robust indicator of the environmental noise status, also relevant for the time periods of interest (generally several days, weeks or months), we introduce the notion of percentile, which is the probability for noise to be above a given value during a percentage of time. In the example of Figure 5, the 50 th percentile corresponds to about 78 db ref 1µPa², meaning that during 50% of the time, the noise levels exceed that value, to be compared to the natural ambient noise which is about 61 db ref 1µPa² (100 th percentile). The output is a statistical indicator of underwater noise expressed for a selected percentile. An example for the Ushant area is shown on the left of Figure 6 for the 125 Hz third octave frequency band. These maps allow obtaining a first assessment of the environmental status, by identifying the noisy areas (dark blue) and the quiet areas (green). On that example, we clearly distinguish the shipping lanes offshore Brittany, as well as a transition from shallow to deep waters, leading to a modification in propagation losses and consequently of underwater noise level. Furthermore, it is possible to post-process the data in order to obtain an assessment of the bioacoustic risk for a marine species of interest. For that purpose, it is necessary to define a representa- ICSV23, Athens (Greece), July

6 tive scenario. For example, for cod, a possible criterion is the risk of acoustic masking or behaviour change during communication between individuals during the mating period. On the right side of Figure 6, we can see that some proportion of the area is affected (yellow and orange colors). Figure 6: Underwater noise footprint indicators. 3. Assessment of the efficiency of mitigation measures In the scope of WP5, a comprehensive list of possible mitigation solutions was established. These can be split into three categories: Reduction of radiated noise from each vessel thanks to improved design. Although some of these can be considered in retrofit, most of them must be decided at early design stage. It includes the choice of propulsion system (for example the type of engine or the preference for diesel-electric plant), the systematic use of elastic mounting devices and the design of improved propellers with higher cavitation inception speed. The second category, which can apply to existing fleet aims at reducing the noise radiated from each vessel through optimized operational parameters and improved maintenance. For example a reduction in service speed generally leads to a reduction of radiated noise. However, this may be not the case for ships equipped with variable pitch propellers, and some AQUO studies showed that suitable blade pitch settings can reduce significantly and even suppress propeller cavitation. The third category, also applicable to existing fleet, refers to mitigation measures considered at ship traffic control level. For example, it consists in concentrating or diluting the traffic, grouping vessels in convoys or modifying the traffic scheme. These different solutions were analysed in the scope of AQUO Project on three aspects: Intrinsic reduction of ship radiated noise [9], Fuel efficiency, Environmental impact in a maritime area, in relationship with bioacoustics issues. Results regarding the third aspect are detailed below. Starting from an initial situation or reference traffic scheme such as represented on the left of Figure 6, it is possible to simulate different mitigation measures by replaying the same scenario but with modified parameters, for example by acting on the radiated noise level of each vessel in the area. Maps of the difference in the statistical indicators between the modified and initial situations are obtained. Again in the same case study, Figure 7 shows some of the results obtained. The areas in dark green correspond to a significant reduction (3 to 6 db, or even more), while the areas in yellow correspond to a small degradation. Besides, the areas in light blue correspond to locations where the mitigation measure allows achieving a status similar to natural ambient noise, which is of course adequate for marine life. We can see that the most efficient solution consists in limiting the radiated noise of the noisiest vessels, which is consistent with the rule note proposed by Bureau Veritas [5]. On the other hand, modifying the traffic scheme is a less convincing solution, as a noise increase appears in some sub-areas. 6 ICSV23, Athens (Greece), July 2016

7 Figure 7: Ushant area Influence of two solutions for the mitigation of shipping noise footprint for the 25 th percentile in the 125 Hz third-octave band. (a) by imposing a limit value on ship radiated noise; (b) by traffic regulation, imposing a 10 km minimum distance between vessels. Different scenarios have been simulated in three test areas (Ushant offshore Brittany, Obsea area near Barcelona, and Antares area near Toulon). The detailed results are available in report [3]. Also, some additional analyses have done using maps of bioacoustic risk, regarding fish and marine mammals. 4. Conclusions and recommendations The AQUO Project has demonstrated the feasibility to monitor in real time the underwater noise footprint related to shipping in a maritime area, using a predictive tool connected to AIS information and environmental information for the area. Robust indicators can be obtained in the form of statistical noise maps. In addition, an assessment of the bioacoustics risk for marine life can be done by using specific criteria and post-processing of the data. However, the predicted tool must be checked or calibrated with in-situ long-term recordings of underwater noise in sample points, for example by deploying acoustic buoys in the area (7], [10]. The tool has also been used on simulated data in order to evaluate the efficiency of different mitigation measures, allowing the justification of the recommendations arising from the AQUO Project. In consistency with the MSFD, the managers of maritime areas could have at their disposal the tools or information allowing the assessment of the environmental status regarding underwater noise and its impact on marine fauna. If the environmental status is found to be not satisfactory, mitigation measures could lead to regulations where shipping restrictions could be applied to the noisiest vessels in some sensitive areas and periods of the year. This would be incentive for ship owners and ship industry to improve the fleet of future vessels regarding underwater noise emissions, and in that case, the design choices must be done at early design stage. Recommended related technical solutions for commercial ships are the adoption of more silent propulsion configurations (such as diesel-electric where applicable), the systematic use of elastic devices, and the design of propellers by considering acoustical requirements in particular the increase of cavitation inception speed. Besides that, the noise emissions from existing vessels can be improved by reducing the sailing speed (however with precautions in the case of ships equipped with variable pitch propellers), optimum propulsion plant operational settings, and proper maintenance. The topic is discussed further in the AQUO final report [3] and the common guidelines document with the SONIC Project [6]. In the short term, the main recommendation is to launch pilot projects for the actual implementation of the methodology and tools developed in the AQUO Project for some areas of interest in European Waters which are sensitive regarding marine fauna. ICSV23, Athens (Greece), July

8 Other recommendations, targeting more specifically the scientific community are: the need for larger number of reliable data for underwater radiated noise levels of commercial ships and so, the proposal of creating a database [12] (the standardization work in progress in the ISO committee for underwater acoustics are pushing in that direction). Another topic addresses underwater bioacoustics of marine fauna. As a matter of facts, despite the research done recently, important gaps remain in the knowledge of the effect of sound. ACKNOWLEDGEMENTS This work was developed in the frame of the collaborative project AQUO (Achieve QUieter Oceans by shipping noise footprint reduction), funded by the European Commission within the Call FP7 SST : Assessment and mitigation of noise impacts of the maritime transport on the marine environment, Grant agreement no , coordinated topic "The Ocean of Tomorrow". The content of this paper does not reflect the official opinion of the European Union. Responsibility for the information and views expressed in the paper lies entirely with the authors. REFERENCES 1 European Commission, Maritime Strategy Framework Directive 2008/56/EC, pp. L164/19-40, IMO, Guidelines for the reduction of underwater noise from commercial shipping to address adverse impacts on marine life, MEPC.1/Circ.833, 7 April Synthesis of recommendations. Underwater Noise Footprint of Shipping: The Practical Guide. AQUO Project, report D5.8 (2015). 4 Silent Class Notation Rule Note, DNV-GL, Underwater Radiated Noise (URN), Rule Note NR 614 DT R00 E, Bureau Veritas, Guidelines for Regulation on UW noise from commercial shipping, prepared by AQUO and SONIC Projects, 30 November Folegot, T., van der Schaar, M., Clorennec, D., Brunet, P., Six, L., Chavanne, R., and André, M., Monitoring Long Term Ocean Noise in European Waters, Proceedings of the IEEE-MTS Oceans 15 Conference, Genoa, Italy, May, (2015). 8 Colin, M., Ainslie, M., de Jong, C., Binnerts, B., Beeks, T., Ostberg, M., Karasalo, I., Folegot, T., Clorennec, D., Sertlek, O., Jansen, E., Definition and results of test cases for shipping sound maps. Proceedings of the IEEE-MTS Oceans 15 Conference, Genoa, Italy, May, (2015). 9 Audoly, C., Rousset, C., Salinas, R., Rizzuto, E., Hallander, J., Baudin, E., Mitigation measures for controlling the ship underwater radiated noise, in the scope of AQUO Project,. Proceedings of the IEEE- MTS Oceans 15 Conference, Genoa, Italy, May, (2015). 10 Gaggero, T., Karasalo, I., Östberg,, M., Folegot, T., Six, L., van der Schaar, M., André, M., Rizzuto, E., Validation of a simulation tool for ship traffic noise, Proceedings of the IEEE-MTS Oceans 15 Conference, Genoa, Italy, May, (2015). 11 Audoly, C., Rousset, C., Leissing, T., AQUO Project Modelling of ships as noise sources for use in an underwater noise footprint assessment tool, Proceedings of Internoise Conference, Melbourne, Australia, November, (2014) 12 Development of UW Noise Database, final report. SONIC Project, report D2.2 (2015). 8 ICSV23, Athens (Greece), July 2016