Application of a risk-based approach to continuous underwater noise at local and subregional scales for the Marine Strategy Framework Directive

The Marine Strategy Framework Directive's (MSFD) goal of achieving Good Environmental Status (GES) in European waters presents Member States (MS) with a significant challenge in measurement and monitoring of a suite of descriptors of GES, some of which are poorly understood. To address the burden for MSs of monitoring and measuring environmental status and trends over vast areas, provisions have been made for the use of risk-based approaches to assessment and monitoring. Here, a standardised risk-based approach is described, aligned with the articles of the directive and with the DAPSI(W)R(M) conceptual frame. This risk approach is then applied at two different spatial scales for the risks associated with continuous underwater noise (D11C2). The first case is a subregional scale application for the North East Atlantic assessing risk under data poor conditions while the second case focuses on the Bay of Biscay, using the same process but under data rich conditions. The parallel applications of the risk-based approach illustrate that it is a powerful tool that can provide useful outputs, even where significant data gaps and limitations in understanding exist. We demonstrate the adaptability and wider applicability of the risk-based approach and finally make recommendations as to how improvements in data availability and accessibility could increase the confidence in the outputs.