Visuals of plastic waste, oil spills, and choking black smoke come to mind when we think of marine pollution. While these poisons severely affect marine ecosystems, there is another genre of pollution that is invisibly impacting life underwater -- noise pollution. Research has found that noise pollution can adversely impact marine flora and fauna.
Loud or prolonged noise above a certain decibel level causes noise pollution. It leads to adverse health effects in not just humans but other organisms as well.
According to the World Health Organization (WHO), sounds of volume lower than 70dB are not dangerous for living organisms no matter what the length of exposure. Noise higher than 85dB can cause health issues if exposure is longer than eight hours a day. Higher levels need shorter durations to have adverse effects.
What causes noise pollution in the oceans?
Seismic drills from oil rigs, sonars, survey devices, noise from shipping vessels, watercraft, and wind farms are among the common causes of pollution in water. Some of these sounds can be louder than expected.
Each species is impacted in a different way by excessive levels of noise pollution. Noise pollution can disturb and negatively impact behaviour, physiology, and reproduction to such an extent that it can lead to higher levels of mortality in many species.
“Imagine having to raise your kids in a place that’s noisy all the time. It’s no wonder many marine animals are showing elevated and detectable levels of stress due to noise,” said marine ecologist Joe Roman, University of Vermont.
A recent review of 10,000 studies published in the journal Science found that such changes in the level of noise can affect creatures from shrimps to whales.
“For many marine species, their attempts to communicate are being masked by sounds that humans have introduced,” said Carlos Duarte, a marine ecologist at the Red Sea Research Center in Saudi Arabia and co-author of the paper.
A new study published in Communications Biology also found that noise was harming marine plants at a cellular level, leading to the plants uprooting themselves completely. Seagrasses capture and store nearly 27.4Tg of carbon each year, and make up crucial elements of the aquatic ecosystem.
What can be done?
Unlike in the case of oil and plastic pollution, it is easier to reduce noise pollution in the ocean. But in order to have a measurable impact, better monitoring tools along with greater awareness are needed.
“When people think of threats facing the ocean, we often think of climate change, plastics and overfishing. But noise pollution is another essential thing we need to be monitoring,” said Neil Hammerschlag, a University of Miami marine ecologist.
The research review in the Science journal also highlighted the steps that can be taken to reduce the effects of noise pollution in the world’s oceans.
Governmental policies setting higher standards to reduce noise from ship propellers, creation of sound bubbles around wind farms, judicious use of sonar equipment, pile driving and seismic underwater devices can also contribute to lessening the noise in the oceans.
(Edited by : Shoma Bhattacharjee)