Underwater Noise is A Threat To Marine Life
Using naval sonar has also been associated with the mass stranding of whale species in the Caribbean, Europe, and East Asia. Mass stranding events involve entire pods of animals simultaneously beaching themselves.
Examination of the dead whales revealed they had suffered trauma similar to decompression sickness. This was believed to have been caused by sudden changes in their deep diving behavior following exposure to sonar.
Arrested Development.
Over the past two decades, research has also revealed the widespread impact of chronic noise exposure on animal behavior and physiology. These impacts can extend well beyond the noise source and affect vast areas of the ocean.
Laboratory studies on the sea hare – a marine slug – revealed that exposure to boat noise led to a 21% reduction in successful embryo development. Hatched individuals also suffered a 22% higher death rate than sea hares not exposed to boat noise.
These findings demonstrate the negative effects of a common source of underwater noise on animal development and survival. If these laboratory results can be applied to natural environments, then such impacts could threaten entire populations of marine species in particular areas.
Disrupted Behaviors.
Observing animals’ movements, feeding, communication, resting, and social interactions provide scientists with a method for exploring the effects of noise.
The behavioral impacts of noise on marine mammals are particularly well studied due to conservation concerns and their reliance on sound for communication, foraging, and navigation. Many of these species move large distances, and long-range communication is crucial for coordinating social interactions and reproduction.
But the sounds produced by large marine mammals are of a similar low-frequency range to much of the noise produced by humans. The noise produced by ships tends to be below 2 kHz, which overlaps with the vocal frequencies produced by many large mammals. Blue whales, for example, produce frequency vocalizations of less than 100 Hz, meaning their calls can be lost in the background din.
