Study Tags Man-made Noise As 'Major Pollutant'

A new study Wednesday says the noise human beings create should be considered as a "major global pollutant."

Scientists at Queen's University Belfast said in the Royal Society's Biology Letters discovered that noise affects many species of amphibians, arthropods, birds, fish, mammals, mollusks, and reptilians.

Aircraft, ships, factories, road traffic, and oil drilling are all human activities that produce noise, most of which is usually below 4kHz. The propellers of those items are thought to overlap with frequencies at which many animals communicate, and may lose their sense of direction once disoriented.

The researchers reviewed more than 100 investigations on the impact of noise on a wide variety of animals, from mollusks to mammals. The experts recorded different aspects of animals' behaviors and other factors such as hormonal changes before and after being exposed to noise.

The scope of any shift from pre-noise behavior was calculated on a scale. The latest research used these calculations and put them together for six groups of animals, including fish and birds. 

Studies have found noise pollution to be associated in poorer human health. However, experts underscored that noise could also affect wildlife, from disrupting their communication to affecting where they live and the efficiency with which they forage for food.

Hansjoerg Kunc, the co-author of the research from Queen's University Belfast, pointed out that the issue should be seen as "[many species respond] to noise rather than a few species being particularly sensitive to noise."

"The interesting finding is that the species included [a range] from little insects to large marine mammals such as whales," he Kunc told AFP. He said he and his team did not expect to find a response to noise across all animal species.

Their paper explained that an animal's response to the clatter of human activity is not necessarily direct, and cannot be easily termed as positive or negative.

Human-made noise, for example, has been shown to interfere with the sonar detection systems that bats use to find their insect prey, making it more difficult for the flying mammals to catch insects.

"[Bats] try to locate their prey via acoustic cues," Kunc told The Guardian. The co-author explained that the bats [could not] hear the humanmade noise, which causes the mammals to fly longer and have more time and energy to search for food.

He added the predator might suffer in the case of bats because they cannot locate their prey. "The prey - in cases where species where potential catch relies on sound to detect predators - might suffer because they might not be able to hear them early enough to escape," Kunc said.

The situation may be good news for the bugs, the paper said, as potential prey may directly benefit from anthropogenic noise. However, Kunc cautioned that the more exceptional picture is still one of severe disruption across the natural environment. 

The authors noted that human noise pollution and the animal response to it needs to be discussed in the context of an ecosystem, especially when considering conservation efforts.

"Noise must be [regarded] as a [pressing issue] of environmental change and pollution as it [concerns] both aquatic and terrestrial species," the researchers said.

"Our analyses provide the quantitative evidence necessary for legislative bodies to regulate this environmental stressor more effectively," they added.