Mapping underwater sound noise and assessing its sources by using a self-organizing maps method

Area of Science:

• Marine acoustics
• Environmental noise mapping
• Underwater soundscape ecology

Background:

• Underwater noise pollution is a growing concern for marine ecosystems.
• Understanding noise sources is crucial for effective marine conservation.
• Adriatic coastal habitats face pressures from human activities and natural phenomena.

Purpose of the Study:

• To objectively map underwater noise and identify its primary sources in an Adriatic coastal marine habitat.
• To analyze the relationship between vessel activity, environmental factors, and underwater soundscapes.
• To evaluate the effectiveness of the self-organizing maps (SOM) method for underwater noise assessment.

Main Methods:

• Systematic sampling of sea ambient noise (SAN) at ten acoustic stations (2007-2009).
• Analysis of noise levels using 1/3 octave band centered frequencies and equivalent continuous sound pressure levels.
• Application of the self-organizing maps (SOM) method with vessel presence, type, and distance data.

Main Results:

• Two dominant underwater soundscapes were identified, linked to seasonal tourism, fishing, and wind/wave action.
• Recreational vessels emerged as the principal anthropogenic noise source, especially during tourist seasons.
• The SOM method proved effective in predicting SAN levels based on vessel distribution.

Conclusions:

• Self-organizing maps provide an efficient tool for mapping underwater noise and identifying sources.
• Anthropogenic noise, particularly from recreational vessels, significantly shapes Adriatic soundscapes.
• Findings support the broader application of this method for marine conservation and management efforts.