A new study called "Measuring Underwater Noise Levels Radiated by Ships in Indian Waters" has found that the increasing levels of underwater noise emissions (UNE) from ships in Indian waters are endangering the marine ecosystem.
The study measured the ambient noise levels by using an autonomous hydrophone system approximately 30 nautical miles away from the Goa coastline.
Marine sound pollution refers to excessive or harmful sound released into the ocean environment due to various human activities, including shipping, military sonar, oil and gas exploration, and recreational activities like boating and jet skiing.?
This type of pollution can negatively impact marine life in several ways. It can interfere with the communication, navigation, and hunting behaviours of marine mammals, such as whales, dolphins, and porpoises.?
Additionally, it can cause physical harm, such as damage to hearing and other physiological functions, which can lead to injury or death. Therefore, reducing marine sound pollution is critical for the preservation of the marine ecosystem.
The study found that the sound pressure levels of UNE in Indian waters are reaching between 102-115 decibels, relative to one microPascal, which is significantly higher on the East Coast than the West. Scientists use 1?Pa as the reference pressure for underwater sound.
Continuous shipping movement has been identified as a significant contributor to the increase in global ocean noise levels. UNE is threatening the lives of marine mammals, such as bottlenose dolphins, manatees, pilot whales, seals, and sperm whales.?
These species rely on sound as the primary form of energy for multiple behavioural activities, including mating, communal interaction, feeding, cluster cohesion, and foraging.
The frequencies of ships¡¯ underwater self-noise and machinery vibration levels overlap with the marine species¡¯ communication frequencies in the low-frequency range of less than 500 Hz.?
This overlapping is called masking, which may lead to a change in the migration route of marine species to the shallow regions, making it difficult for them to return to deeper water.
Moreover, the sound that radiates from ships on a long-term basis affects marine species, resulting in internal injuries, loss of hearing ability, change in behavioural responses, masking, and stress.?
Therefore, the study highlights the urgent need to address this issue and mitigate the impact of UNE on the marine ecosystem.
There are several initiatives at the global and Indian levels to safeguard marine ecosystems. At the global level, the Global Programme of Action (GPA) for the Protection of the Marine Environment from Land-based Activities is the only intergovernmental mechanism that addresses the connectivity between terrestrial, freshwater, coastal, and marine ecosystems.
The MARPOL Convention and the London Convention are also global initiatives that address marine pollution caused by ships and the dumping of waste.
In India, the Wild Life Protection Act of 1972 provides legal protection to many marine animals, and there are 31 major Marine Protected Areas in India that have been notified under this act. The Coastal Regulation Zone notification prohibits developmental activities and waste disposal in fragile coastal ecosystems.?
The Centre for Marine Living Resources and Ecology (CMLRE), an attached office of the Ministry of Earth Sciences, is also involved in developing management strategies for marine living resources through ecosystem monitoring and modelling.