Mitigation of Underwater Radiated Noise Related to Shipping and Its Impact on Marine Life: A Practical Approach Developed in the Scope of AQUO Project

Abstract

There is increasing concern within the scientific community about the underwater noise due to anthropogenic activity and its impact on marine life, with negative consequences on biodiversity and sea resources. In that context, the European Marine Strategy Framework Directive stated in 2008 that the anthropogenic noise due to shipping was to be mitigated. To address this issue, the European Union (EU) project “Achieve QUieter Oceans by shipping noise footprint reduction” (AQUO) (www.aquo.eu) started in October 2012 with a duration of four years. The project brought together experts from shipbuilding, underwater acoustics, and bioacoustics, with a multidisciplinary approach. In this paper, after giving a brief overview of the project structure, the methodology proposed by the AQUO project to set guidelines for controlling the underwater noise from commercial shipping is presented in more detail. Such a methodology is aimed at identifying the most promising strategies for the mitigation of the impact of shipping noise on marine fauna. Different technical as well as operational solutions are evaluated by taking into account the impact on marine life, the feasibility in terms of ship design, and the cost effectiveness, also considering fuel efficiency. While technical solutions are usually more effective at the design stage both in terms of costs and performance, operational solutions can potentially be adopted without any modification to the existing fleet. Furthermore, operational prescriptions can be set by national/local authorities who cannot directly intervene on ship configurations. The different solutions have been evaluated by means of numerical modeling carried out by using a Noise Footprint Assessment Model derived from the Quonops too

A Meta-Analysis to Understand the Variability in Reported Source Levels of Noise Radiated by Ships From Opportunistic Studies

“…Even though a variability exists from one study to another, a large consensus seems established in the scientific community that speed reduction does indeed favors a decrease of the noise budget attributed to the merchant fleet (e.g., Audoly et al, 2017). However, this reduction of the instantaneous underwater noise radiated comes at the expense of an increase of the time spent by ships in a speed-restricted zone, hence potentially exposing nearby marine mammals to noise pollution for longer periods of time (McKenna et al, 2013;Chion et al, 2017).…”

“…Merchant ships' underwater noise have several origins, the principal being machinery, propellers, and cavitation (Audoly et al, 2017). It is well-known that variations in merchant ships' source levels exist inside a given vessel class and from one class to another (see e.g., Figure 2 of Veirs et al, 2016).…”

Review of Research Results Concerning the Modelling of Shipping Noise

“…Gaggero [29] also compared the predictions using these models and the measured results. Thirdly, although both the AQUO project's model and the Wittekind's model are based on the noise mechanism [23,30], the related parameters and modelling conditions are not easy to obtain. For the AQUO project's model, three main noise sources are assumed as functions of frequency and speed (at least two different speeds are required), which are difficult to obtain during the measurement of non-cooperative ships [24].…”

Towards an optimal design for ecosystem-level ocean observatories

“…In addition, it is important that observatories be designed to better understand their invasive impact to comply with international legislation (e.g. underwater noise as an ecological descriptor; Audoly et al 2016Audoly et al , 2017. Therefore, there is a need for observatories to have built-in capabilities to monitor their own effect on the surrounding habitat and biota.…”