PANAJI
The trends in the measured noise levels studied at specific marine sites in Goa have shown that the noise levels due to anthropogenic sources are increasing over the period of measurement and these may interfere with the frequencies used by the aquatic species for their livelihood.
The consistent excessive noise levels may be fatal to the aquatic ecosystem as it hampers communication between the marine animals and, in the long run, be a major threat to the existence of biodiverse marine sites in the State.
A team of BITS Pilani Goa carried out research at a site close to Grade Island Archipelago near the coast of Goa, about 16 km west of the Dabolim airport and developed a device to combat the soundscapes of the shallow marine underwater environment.
Commodore K Laxmi Narasimha Chary (retd) VSM, in pursuit of his PhD degree, under the supervision of Dr M K Deshmukh and Dr Nitin Sharma at the department of Electrical and Electronics Engineering has attempted to develop a comprehensive marine soundscape at the marine site and it is for the first time that such a device has been developed. A marine soundscape is essentially a comprehensive representation of existing sound (or noise) levels in an underwater environment.
It may be noted that the Grande Island Archipelago is globally recognized as a biodiverse site. Also, the existence of higher levels of noise in the range of 10 Hz to 10 kHz is recorded at the site, which confirms that the noise levels due to anthropogenic sources such as shipping and boat traffic and off-shore constructions etc, are regularly contributing to the soundscape at the site.
The measurements have been carried out at the site using three distinct innovative methods and recorded over a long period, spanning several years. It was found that the measured noise is mostly a low-frequency noise ranging from near zero to 10 kHz, which confirms the presence of diverse biophonic sources, including a variety of fish, snapping shrimps and dolphins near the site.
The soundscapes are a useful decision-making aid to a wide range of stakeholders such as the Navy, underwater instrument manufacturing companies, offshore oil and renewable energy industries, offshore construction companies, marine biologists, departments of fisheries, environmentalists, oceanographers and regulatory bodies for environmental impact assessment.
The study of soundscapes is an emerging field of research that attempts to provide important baseline information on environmental conditions and the biological composition of the underwater environment. The underwater soundscapes are also useful for forewarning in the event of pending natural calamities such as tsunamis and coastal floods.
The marine site is characterized in terms of measured values of the existing noise levels and corresponding frequencies and also their variation over time of day, month, season and year.
There is an urgent need to measure underwater noise levels and establish baseline soundscapes for the site. To this end, there is scope for developing appropriate measurement schemes using the available technologies and appropriate formats of soundscapes for standardization.
