In November 2022, the European Union (EU) agreed on, and published, new guidance for assessing and limiting impacts of anthropogenic (man-made) underwater noise. The new guidance was put together as part of Marine Strategy Framework Directive (MSFD) 2008/56/EC, which seeks to improve marine environmental policy through community action, including leading scientific research. Two technical documents have since been released, one giving guidance on assessing impacts of activities producing continuous noise (e.g. shipping), and the second for activities producing impulsive noises (e.g. pile driving, seismic surveys, explosive ordnance detonation). Although not yet legally binding, it is expected that these recommendations will be formally incorporated into future revisions of the MSFD.
“The spatial distribution, temporal extent and levels of anthropogenic … sound do not exceed levels that adversely affect populations of marine animals”
– MSFD Descriptor 11
In May 2017, MSFD Descriptor 11 outlined primary objectives that underwater anthropogenic noise not adversely affect populations of marine animals. The value, ambition, and scope of these objectives notwithstanding, until now there has been no consensus on how to effectively achieve this target. The new guidance seeks to address this by shifting management of anthropogenic sound from an emphasis on noise as a pressure in favour of management from an impact perspective (see DIPSR Framework for more explanation). Thus, rather than setting blanket limits on levels of sound being introduced into the environment, future noise-producing activities will be assessed using a more holistic approach considering the specific effects upon marine environments and species therein.
The scope of the new guidelines represents a step-change in environmental management policy. Current management strategies, such as those enforced in German legislation, are based on sound levels capable of causing acute physical harm to individual marine mammals. The new guidance expands upon this approach in several ways:
- The scope can be expanded to consider more and/or different indicator species, tailored to the specific habitat and/or environment in which an activity is being planned.
- Impacts are to be assessed using the Level of Onset of Biologically Adverse Effect (LOBE), defined as anything capable of reducing fitness, as supported with scientific evidence. This definition includes behavioural effects which typically occur at much lower noise levels (and thus greater distances from a sound source). Moreover, it requires potential impacts of noise to be assessed according to the most sensitive species/criteria.
- Although adverse effects of sound are based upon individual responses, the focus of impact assessment shifts to that of populations. Thus, impacts are to be assessed in terms of the proportional area of a habitat exposed to detrimental sound levels for a significant proportion of a designated time period, with specific restrictions placed upon the allowable area of significant detriment dependent on the activity and timeframe.
These changes are likely to profoundly affect how marine activities are risk-assessed. In the future it will likely no longer be sufficient to regulate activities merely according to source noise levels and their acoustic propagation. Rather, the cumulative noise exposure of an activity will have to be modelled for the whole environment in which an activity is taking place, according to realistic operational expectations. Moreover, these noise models will then have to be contrasted against an ever-growing body of scientific research into impacts of noise in marine species.
Although big changes may be on the horizon, Ocean Science Consulting Limited (OSC) is here to help clients navigate these new waters. OSC’s expertise in underwater acoustics and spatial distribution modelling, our proud history of researching effects of underwater noise, and above all our dedication to the betterment and protection of the marine environment mean we are well-placed to meet these new demands and challenges.
The impending changes might be formidable, but OSC welcome anything that protects and preserves our wonderful oceans.