Underwater Noise - The neglected threat to marine life

Anthropogenic underwater noise is a major conservation problem having serious impacts on marine species in all oceans. Noise comes from offshore construction, transport as well as resource exploration and extraction, and adds to the cumulative environmental impacts from other anthropogenic pressures. The EU Marine Strategy Framework Directive requires anthropogenic noise to be at levels that do not adversely affect the marine environment. However, the focus to date has been on monitoring with no widely agreed ways yet to assess whether Good Environmental Status is being achieved with respect to underwater noise. While such assessments are ongoing, there is considerable scope for reducing noise at source, which is usually the most effective way of reducing impacts to marine species and habitats. In this paper, we will first summarise main noise sources and their impacts on the marine environment, we will then identify shortcomings in current underwater noise regulation and mitigation, and finally recommend ways to more effectively implement current legislation in order to apply concrete measures to protect our oceans from excessive noise. Specifically, we recommend using risk maps and noise budgets to address cumulative noise impacts, setting noise thresholds immediately, preventing any widespread increase in noise, particularly by reducing and preventing noise at source, managing noise at the ecosystem level through spatio-temporal measures, and regional and interregional coordination and collaboration.