The impact of human activities on marine wildlife has undoubtedly taken an unwanted course in the past years, with everything from the raising greenhouse emissions, to oil exploitation, and the use of military sonar leaving their mark on the future of whales and dolphins living in world’s oceans.

The attendees at the United Nations Environment Programme’s Convention on Migratory Species held in Rome warned about the increasing threat of rising noise levels on marine mammals who use sounds to communicate, forage for food and find mates.

The International Fund for Animal Welfare (IFAW) noted in a report released on the subject: “today, humankind is unleashing an acoustic onslaught on the seas.” The consequences on noise pollution already reflect in the behavior of some marine mammals, and in the increasing number of deaths among them.

To exemplify some of these changes it is important mentioning that some cetaceans (which also include whales and dolphins) were forced to change their calls in order to make themselves heard.

The reactions of these marine mammals to noise pollution should come as no surprise. Us humans reject even the lowest levels of noises, which can lead to psychological and physical stress, further affecting blood pressure, heart rate and cardiac output.

Imagine the effect ship engines, seismic surveys for gas and oil exploration, or military sonar training have on what used to be a world of silence. Mark Simmonds, Science Director of the Whale and Dolphin Conservation Society, explained that underwater, man-made noise, is triggering an acoustic fog and a cacophony of sound in many parts of the world seas and oceans.

This is particularly harmful for deep diving animals, such as the beaked whale. These noises often lead to marine mammals stranding. Researchers are reportedly still investigating two major stranding events in Madagascar and the United Kingdom, Simmonds said.

Marine mammals use sound to navigate, to find food, to attract mates, to establish their territory or for social interaction. Considering the sunlight only lights the ocean for about 200 meters in depth, the rest is complete darkness, and sound becomes the essential instrument in marine mammals’ life.

According to researchers, in addition to the damage and potentially lethal effects of direct noise on marine mammals, this is just one aspect of how human activities affect the underwater world.

The increase in greenhouse emissions not only affects what we see on land, but also life in the water. Fossil fuel burning means more CO2 in the atmosphere; more CO2 means changes in the ocean water pH.

This results in an ocean water chemistry change, with acidity rising at worrying levels. This also means that the water becomes less absorbent of low frequency sounds, which contributes to the ocean becoming even noisier.

Researchers and wildlife groups demanded better regulations, and called for action to embrace a quieter technology to help reduce the noise in the oceans.