Abstract
The purpose of the present document is to give guidance on the setting of EU threshold values related to anthropogenic impulsive noise in the water1 . Such guidance is meant to be used by regulators and managers of the EU Member States (MS) aiming to achieve Good Environmental Status of their marine waters, as requested by the Marine Strategy Framework Directive (MSFD)2.
In this report, a clarification of the assessment framework is done based on concepts of habitat, effect ranges and habitat degradation. The guidance is based on the earlier work done by TG Noise in deliverable 1 (DL 1) providing a common methodology for the setting of EU threshold values for impulsive sound and on results from the Harmonize project. An introduction is further given on the Level of Onset of Biological adverse Effects (LOBE), the noise level above which an adverse biological effect on an indicator species is expected to occur. It should be underlined that this document as well as the recommended threshold values are only dealing with displacement as a result of anthropogenic impulsive noise. Other possible impacts of impulsive noise such as TTS, injury or death are not dealt with herein, since it is already covered by the Habitats Directive3 and the Environmental Impact Assessment Directive4.
A dual threshold approach is proposed recognising both temporal and spatial variability of potential disturbance effects related to exposure to underwater impulsive noise, where short-term is defined as 1 day, long-term is defined as 1 year and long-run is defined as the time it takes before a negative effect on the population occurs, which often is longer than one year.
The general principle is that a threshold value for the size of an area that can be exposed to impulsive noise for shorter time period is higher than that for a longer period.