Context:
The reduced noise pollution during the novel coronavirus disease (COVID-19) pandemic made the birds and the bees and other terrestrial creatures flourished; and in the underwater world, too, anthrophony (human-made sounds) reduced substantially for long months in 2020. Scientists are now trying to understand the impact of these quiet months on the marine ecosystem.
Relevance:
GS-III: Environment and Ecology (Environmental Pollution & Degradation, Conservation of Ecology and Environment)
Dimensions of the Article:
- Understanding Ocean Noise / Acoustics
- The International Quiet Ocean Experiment (IQOE)
- What is Hydrophone?
Understanding Ocean Noise / Acoustics
The International Quiet Ocean Experiment (IQOE) has identified a network of over 200 non-military hydrophones (underwater microphones) in oceans across the world.
The three broad components of oceanic acoustics that are being studied are are:
- Geophony: Sounds created by non-biological natural events like earthquakes, waves and bubbling.
- Biophony: Sounds created by the ocean’s living creatures.
- Anthrophony: Sounds created by human beings (a large portion of which is shipping noise).
- According to ‘the Soundscape of the Anthropocene Ocean report’ published in Science Journal in 2021, geophony and biophony dominated the soundscape of oceans before the industrial era.
- In the short-term anthrophony masks the auditory signal processing by marine animals, weakening their ability to forage for food, escape a predator or attract a mate. In the long run, it can thin out the population of some underwater species.
- The oceans of the current geological era (Anthropocene era – when human-made disruptions largely influence the environment) are noisier than the pre-industrial times.
- During the first few days of the pandemic, ocean sound monitors at several places recorded a decibel (dB) drop.
- The hydrophones at the Endeavour node of Canada’s Neptune Ocean Observatory showed an average decrease of 1.5 dB in year-over-year mean weekly noise power spectral density at 100 hertz.
The International Quiet Ocean Experiment (IQOE)
- The International Quiet Ocean Experiment (IQOE) is an international scientific program to promote research, observations, and modelling to improve understanding of ocean soundscapes and effects of sound on marine organisms.
- IQOE is developing methods to make ocean acoustic data more comparable. These data will be compiled into a global dataset to establish trends in ocean sound and look for effects of the Covid-19 pandemic on ocean sound.
- The IQOE has identified a network of over 200 non-military hydrophones (underwater microphones) in oceans across the world.
What is Hydrophone?
- Just as a microphone collects sound in the air, a hydrophone detects acoustic signals under the water.
- Most hydrophones are based on a special property of certain ceramics that produces a small electrical current when subjected to changes in underwater pressure.
- When submerged in the ocean, a ceramic hydrophone produces small-voltage signals over a wide range of frequencies as it is exposed to underwater sounds emanating from any direction.
- By amplifying and recording these electrical signals, hydrophones measure ocean sounds with great precision.
-Source: Down to Earth Magazine
