AMBIENT NOISE AND MARINE MAMMALS: LESSONS FROM PILOT STUDIES OF SHIP NOISE MONITORING IN THE DANISH WATERS.

摘要

1 INTRODUCTION The last decade has seen a rapid increase in the interest in ambient underwater noise and the possible negative effects on marine life by the increased anthropogenic contribution to the noise~1. Most recently this has resulted in incorporation of an underwater noise indicator for good environmental status, as part of the EU marine strategy framework directive (MSFD)~2. The MSFD operates with pressure indicators, i.e. indicators which should reflect the amount of acoustic energy emitted into the environment. One set of indicators is intended to reflect the contribution from large ships and is identified as the one-third octave band levels at 63 Hz and 125 Hz, respectively. In contrast to these pressure indicators are impact indicators, which are intended to reflect the impact on target species rather than just measure the contribution. Whereas pressure indicators really only are required to correlate well with the source (i.e. large ships) are impact indicators required to include assumptions on how the noise is perceived by target species and how these react to the noise. Some of the difficulties with both types of indicators were investigated, based on recordings of ship noise in the Inner Danish Waters (Great Belt and Kadet Trench).