Noise Pollution and Dolphin Communication

Transporting goods by water has long been the cheapest way of conducting trade. The global movement of goods by sea is crucial to the world economy (95% of manufactured goods are transported on container ships). But the shipping industry itself is relatively opaque, rarely heard about in the news and thus avoiding criticism for its various unsavoury elements, particularly its environmental and labour practices. One of these overlooked issues is the simple fact that ships are noisy, and this noise pollutes the oceans in which they travel, disturbing the wildlife living there. In particular, new research from the University of Maryland has examined the impact this noise has on how dolphins communicate with each other.

Dolphins are social animals, and communicate with each other using systems of whistles. These whistles are quite sonically complex, with varying pitches and frequencies in rising and falling patterns. Their system of communication is also highly sophisticated, with individuals having their own calls to identify who they are to the group. Dolphins use this system to maintain group cohesion and transmit information to other groups of dolphins, among other things.

However, researchers found that in noisy environments, such as the coast of Maryland, which is a busy shipping lane and home to many recreational boats, dolphins increased the pitch of their whistles, so as to be better heard over the low hum of boat engines, and reduced the complexity of their calls. Both results are quite interesting, and somewhat depressing (our noisy boats are destroying the beautiful symphony of dolphin communication); but while the first is a simple adaptation, the second is potentially quite complex. Much like trying to tell a friend something at a club, it seems as though the dolphins are trying to communicate in the most efficient way possible, by reducing the number and length of vocalizations required to do so,  so as to reduce to risk of key information being lost to the din of ships passing through overhead.

Image Courtesy of NOAA’s National Ocean Service via Wikimedia Images © 2011, some rights reserved

It isn’t clear if the dolphins have simplified their communication, or are communicating less. If they are doing the latter they are set to suffer, as communication is cornerstone of life for all social animals, and in situations where it is impaired survival becomes difficult. However, if they are doing the former the situation is not quite so dire, as no information has been lost despite the communication being shortened and simplified. While it is sad that we are forcing dolphins to speak in prose instead of poetry, as it were, the unfortunate situation may demonstrate their intelligence, as rather than each whistle only being able to express one idea, as is characteristic of simpler systems of communication, the same idea can be communicated at various levels of complexity with increasingly complex whistles. This would imply that the whistles are somewhat similar to human language, and that dolphins are smarter than previously thought. This, however, while interesting, is quite a tangent, as the research merely demonstrates that the dolphins increased the pitch and reduced the complexity of their whistles, and determining whether reduced complexity results in lost information or not is quite difficult to test.

Either way, beauty has been lost as the result of human activity, part of our long love-hate relationship with the oceans. We have consistently depended on the oceans for sustenance, and we have now structured global trade around marine transport, while at the same time abusing the seas with commercial whaling, nuclear testing, and pollution of various types. The simplification of dolphin calls is far from the greatest crime of the Anthropocene, but it is nonetheless part of the ultimate crime of this age, the destruction of the natural world to serve the desires of the powerful.



Banner Image: Image Courtesy of NASA via Wikimedia Images © 2004, some rights reserved