One of the most serious threats to cetaceans worldwide, but also one of the most difficult ones to properly address, is underwater noise pollution. Due to boat and ship marine traffic, military activities, seismic exploration, construction, etc., in the Mediterranean Sea the increasing levels of noise interfere with their sophisticated hearing systems severely harming these species.
Noise pollution can cause marine mammals to abandon their habitat and alter their behavior by directly disturbing them, by impairing their ability to communicate and to locate their prey, or by masking their acoustic signals over large areas; loud sounds may directly affect their hearing abilities by producing either temporary or permanent hearing loss. All these effects may be critical for the survival of marine mammals even causing injury and death.
The impacts of underwater noise depend on operational and environmental variables of the acoustic source and the physiological, sensory, and psychological characteristics of exposed animals.
Whilst brief or single acute exposures to sound may injure individual animals, long-term continuous noise from multiple sources (e.g. marine traffic) is potentially more serious as it could cause changes to behavior and habitat use that could affect whole populations.