An ultrasonic ant fouling system brings the tube-bundle of a box-cooler, the wall of a sea-chest or the hull of a ship in ultrasonic vibration. This vibration generates an environment in which the larvae of marine organisms do not want to settle. The vibration is so weak, that a large part of the organisms already present, survive.
Attenuation is very high in the ultrasonic range, at 30 meters or so distance from the source of the sound, the sound has dissipated, is no longer audible.
Therefore, the impact on the environment of ultrasonic anti fouling systems is absolutely zero. This includes marine mammals such as whales, dolphins and porpoises.