Anthropogenic noise is a growing threat to marine life due to the incrementation of human activity in the marine environment. In Europe, the Directive 2008/56/EC of the European Parliament and of the Council was published with the aim of establishing a framework for community action in the field of marine environmental policy. The directive introduces underwater acoustic energy, as detailed in Descriptor 11, and stipulates that the member states should set the threshold levels at which a good environmental status can be achieved by means of long-term monitoring campaigns.
This research presents the results of a long-term underwater noise monitoring campaign with a duration of three years in the port of Cartagena located on the south-eastern coast of Spain, focusing on the monthly and annual variation patterns of low-frequency continuous noise. The acquired data are classified according to the source of the acoustic noise into shipping, other anthropogenic, and natural noise measurements. These three groups of measurements are processed in order to obtain one-third octave band levels centered at 63 and 125 Hz, as well as the overall bandwidth of unweighted Sound Pressure Level (SPL).
The analysis of the measurements shows an increase in the annual average overall band of 4 and 3 dB of the natural and shipping noise, respectively, from 2013 to 2015. This monitoring campaign provides accurate acoustic values to establish threshold levels to achieve good environmental status and recommendations to conduct monitoring programs and regulations to control underwater noise pollution.
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