Acoustic Pollution

Acoustic pulses travel great distances in the ocean because they are trapped in an acoustic "wave guide". Author: Brian Dushaw.

Acoustic pollution in marine environments has emerged as a growing environmental concern due to its potential to affect cetaceans and other species by altering naturally occurring underwater soundscapes. Human-induced noises underwater, such as sonar testing, have been implicated as the likely cause of numerous whale strandings around the world.

Environmental organizations have even sued the U.S. military to block some kinds of testing in areas with large populations of marine mammals. Although military activity is prohibited in Antarctica, there is concern that research and other activities in the Southern Ocean could have negative impacts on marine organisms. Recent research has revealed that a significant number of stranded whales had hearing loss.

Compared to other areas, the Southern Ocean experiences limited amounts of research activities (such as seismic surveys) that generate large amounts of noise. However, there are some activities with the potential to have a high impact on cetaceans.

One example is the transmission of up to 205 decibels (louder than a jet engine and well above the level that can cause hearing damage in humans) of sound off Heard Island as part of the Acoustic Thermometry of Ocean Climate (ATOC) experiment. This is well above the levels that have been associated with whale strandings elsewhere.

Spectrogram of dolphin vocalizations. Source: Wikimedia Commons Spectrogram of humpback whale vocalizations. Source: Wikimedia Commons

A 2002 report from the Scientific Committee on Antarctic Research (SCAR) on the use of marine acoustic technology in the Antarctic found that there are few technologies in use in the Southern Ocean that are predicted to cause serious, long-term impacts to marine species. There are several other tools in use, however, including air guns (used in geological studies) and multi beam sonar, which have disruptive effects on behavior lasting a few days.

Because the Southern Ocean is a globally important feeding area for whales, ASOC believes that it is very important that noise-generating activities for any purpose are conducted with the protection of cetaceans, and other species that may be impacted by increased noise levels, in mind. In 2007, ASOC recommended the following to the Antarctic Treaty Parties:

• There should be a requirement to assess potentially significant marine acoustic impacts in any IEE and CEE relating to marine activities.

• Appropriate seismic guidelines to mitigate harm should be required for all vessels in the Antarctic that are conducting active seismic research.

• Reports on utilization of such measures and guidelines should be reported back to the CEP.

• The CEP and SCAR should establish a small working group of people with relevant expertise on acoustic impacts from various countries and disciplines, to share information, advance sound impact research, and develop appropriate tools for mitigating harm from intense sound emissions in the Antarctic.

For more information on the impact of noise on the environment, visit the Acoustic Ecology Institute’s website. AEI is a member of ASOC.