NOISE POLLUTION
1. Context
A new study has found that noise generated by human activity makes it harder for dolphins to communicate and coordinate with each other. As the levels of underwater noise increase, these mammals have to shout to each other.
2. What is Ocean Noise?
- Ocean noise refers to sounds made by human activities that can interfere with or obscure the ability of marine animals to hear natural sounds in the ocean.
- Various marine animals rely on their ability to decipher sounds. It is considered as an effecient means of communication underwater and helps the marine animals stay alive by avoiding predators too.
- Over the last century, human activities such as exploration, shipping, energy exploration etc create heavy loads of noise pollution that travels far away affecting the natural radars of the marine ecosystem.
- Dolphins are social mammals that communicate through squeaks, whistles and clicks. They also use echolocation in order to locate food and other objects. Therefore, anthropogenic noise coming from large commercial ships, military sonars or offshore drilling can severely impact their well-being.
3. How was the study takes place?
- To make their observations, researchers places two dolphins, named Delta and Reese, at an experimental lagoon and trained them to press their underwater buttons located at either end of the enclosure within one second of each other.
- Both dolphins were also made to wear recording tags that documented their sound and motion.
- Delta and Reese were released from a starting point during each trail, and in some trails, one was held back for five to 10 seconds while the other was released immediately.
- In case of delayed-release trails, the dolphins had to depend on just vocal comminication to coordinate the button press.
- Researchers conducted around 200 such trails and used underwater speakers to create different sound environments with in experimental lagoon.
4. Findings of this study
- It was found that as it got noisier underwater, both dolphins changed their behaviour to communicate and work together.
- Apart from raising the volume and increasing the length of their calls, they also changed their body language -they turned their bodies towards each other and swam across the lagoon to be closer to each other.
- Researchers noted despite these attempts to compensate for the noisy background, the dolphins had less success with the task.
- According to the study, “cooperative task success decreased in the presence of noise, dropping from 85 per cent during ambient noise control trials to 62.5 per cent during the highest noise exposure.”
- Previous studies have demonstrated that dolphins change their behaviour when they come across boats but, before the latest research, no one observed how anthropogenic noise can impact the coordination among these aquatic creatures.
5. Impacts of Oceanic Noise Pollution
- Marine animals are known to use sound to navigate, find food and protect themselves. As sound travels faster in water than air, it makes for an important mode of communication because it can convey a lot of information quickly and over long distances.
- Anthropogenic Noise drowns the natural soundscapes and puts the marine ecosystem in stress.
- Baby clown fishes wander into the sea directionless due to heavy noise and are unable to find their way home.
- In case the noise settles in more permanently, the animals leave the place for good.
- Such forced evacuations reduce the population sizes and the animals give up their territories which brings competition for biological resources at other places.
- Animals also face hearing loss due to noise pollution.
- Scientists believe that fish species rely on sounds during reproductive activities, including mate attraction, courtship and mate choice.
- Several studies and incidents have shown that sounds made by drilling, commercial ships and military operations lead to disruption of marine life.
6. How can we reduce human-made underwater noise pollution?
- Regulations could be introduced to reduce underwater noise pollution from shipping and other sources.
- Measures to reduce vessel Collisions with marine mammals have already been implemented in some places, including most recently along the US east coast. These include instructions to avoid areas with known concentrations of whales, and to reduce speed in vulnerable areas.
- As sound can carry for thousands of miles underwater, the effects of noise pollution cannot be avoided solely via route and speed alterations.
- The European Commission’s ongoing LIFE-PIAQUO project aims to develop and test tools to reduce underwater noise pollution and its impacts on Mediterranean aquatic biodiversity.
- Among other measures, it is exploring the optimisation of propellers to limit cavitation - the formation of vapour bubbles - the main origin of ship underwater radiated noise.
- Like land vehicles, ships could also be required to install mufflers to reduce the noise emitted by their engines.
- Investment in electric shipping which is quieter conventional shipping, could help combat noise pollution too.
For Prelims & Mains
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For Prelims: Ocean Noise, LIFE-PIAQUO project, Noise Pollution, Marine ecosystem, Shipping, and Energy exploration.
For Mains: 1. What is Ocean Noise? Explain the consequences of Noisy Oceans and How can we reduce human-made underwater noise pollution?
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Source: The Indian Express
