Underwater Noise Emissions

Context: According to a new Study, the rising Underwater Noise Emissions (UNE) from ships in the Indian waters are posing a threat to the Marine Ecosystem.

What are the Key Highlights of the Study?

• The measurement of the ambient noise levels was carried out by deploying a hydrophone autonomous system around 30 nautical miles from the Goa coastline.
  • Hydrophones are underwater microphones that can pick up sound waves in water and convert them into electrical signals.
• Increased UNE Levels: The sound pressure levels of UNE in the Indian waters are 102-115 decibels, relative to one microPascal (dB re 1µ Pa).
  • The East Coast level is slightly higher than that of the West. There is an increase by a significant value of about 20 dB re 1µPa.
• Causes: Continuous shipping movement is identified to be a major contributor to the increase in the global ocean noise level.
• Impacts:
  • Threat to marine life: Increased levels of UNE are endangering the lives of marine mammals whose essential behavioural activities rely on sound as the main form of energy.
  • Masking of important sounds: Ships’ noise and vibrations in the low-frequency range (<500 Hz) can mask marine species’ communication frequencies, potentially altering migration routes and impeding their return to deeper waters.
  • Long-term effects: The sound that radiates from ships on a long-term basis affects them and results in internal injuries, loss of hearing ability, change in behavioural responses, masking, and stress.

About Ocean Noise Pollution

• 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.
• Sources of ocean noise pollution:
  • The main sources are human activities such as shipping, oil and gas exploration and production, construction, and naval sonar.
  • Other sources include commercial and recreational fishing, and underwater blasting.
  • Climate change also contributes to ocean noise pollution through the melting of sea ice and the increased frequency of storms.
• The critical role played by sound in the lives of marine animals:

Stats IQ: Global Scenario of Ocean Noise Pollution

• According to a 2019 report from the United Nations, shipping is responsible for the majority of ocean noise pollution, with the number of ships increasing by 2.5% per year.
• The report states that shipping traffic in some areas is now up to 10 times higher than in the 1960s, and this increase in noise is having a detrimental impact on marine life.
• Another report, published in the journal “Nature” in 2018, found that ocean noise has increased by roughly 3 decibels per decade since the 1960s, with some areas experiencing increases of up to 10 decibels per decade.

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