**1. Introduction**

Globally, there have been sustainability concerns due to the so-called development bogey which is slowly manifesting as a major cause of environmental degradation [1]. The oceans and other marine environments have been ignored so far because of perceived absence of direct impact on human well-being. However, in the recent times, we have been observing more and more attention being turned toward the oceans as it has been realized that marine ecosystems are a continuum of the universe and any disruptions there can impact human habitat on land as well [2].

The science and technology advances have made it more and more accessible to reach the deepest of the depths in the oceans, and we are realizing the challenges and opportunities that exist in the marine ecosystem. The vast undersea resources have significant potential for socioeconomic growth for mankind; however, the

exploration and exploitation should be done in a calibrated manner to address sustainability concerns. Blue economy has become a buzz word in strategic discussions and vision formulations; however, the environment impact assessment (EIA) at times lacks multiple dimensions of the marine eco-concern due to the human intervention with the undersea ecosystem. Acoustic habitat degradation always escapes attention of the scientific and political community due to high resource requirement and the relative inaccessibility of the undersea domain [3].

The stressed resource on land is encouraging us to look at the oceans for economic growth and prosperity. The blue economy has emerged as the new buzz word with significant potential to complement economic development using the oceans and its resources. The blue economy has multiple dimensions, and the emphasis is on sustainable growth; however, on ground, the unregulated and unscrupulous rush toward oceans for economic gains has made it a serious cause of concern. The traditional blue economic activities include shipping, ports, oil and gas exploration, fishing, deep sea mining, marine tourism and other marine industries. In the recent times, we are also seeing massive growth in emerging industries like aquaculture, carbon sequestration (or blue carbon) and renewable energy production such as wind, wave and tidal energy. **Figure 1** gives a broad pictorial representation of the multiple activities associated with the blue economy [4].

The availability of so-called modern science and technology tools has made the deepest of the oceans accessible, and thus, the humans are able to exploit and explore the vast resources of the undersea domain with ease. The uneven distribution of resources and know-how among the global powers coupled with the fragmented geopolitical approach toward regulating global commons are major obstacles for ensuring sustainability. There is vested interest among the global powers in ensuring complete lack of transparency and non-equitable extraction of the high-value resources available in the undersea domain. The environmental impact assessment (EIA) is skewed, and the real impact on the marine ecosystem never gets evaluated given the complex dimensions and dynamics of the marine ecosystem. Acoustic habitat degradation is one such issue that has escaped attention and attained monstrous proportion [5].

The ocean ambient noise or the background din in the seas has multiple sources both natural as well as anthropogenic. Theoretically, ambient noise cannot be directly linked to a specific identifiable source; however, it is attributable to general

**Figure 1.** *Multiple activities associated with blue economy.*

### *Acoustic Habitat Degradation Due to Shipping in the Indian Ocean Region DOI: http://dx.doi.org/10.5772/intechopen.90108*

types of sources. The natural sources include geophysical activities like windgenerated waves, earthquakes, precipitation, cracking of ice and many more as well as biological sources from marine species like whale songs, dolphin clicks and fish vocalizations. The anthropogenic noise originates from human-driven activities like shipping, geophysical surveys, oil and gas exploration, dredging and sonar transmissions. The classical ambient noise plot by Wenz GM, way back in the post Second World War period (valid even today), gives a clear segregation of the sources based on the frequency bands. The extreme low frequency (<1 KHz) is dominated by distant shipping followed by wind-generated noise up to 15 kHz [6]. **Figure 2** gives the Wenz curve with clear domination of the shipping noise in the low frequency region.

Among the multiple activities under the blue economic umbrella, the shipping has some unique characteristics that merit attention while we want to analyze the sustainability concerns in the blue economy or the acoustic habitat degradation in the undersea domain [8]. These include the following:


The geostrategic relevance of the Indian Ocean Region (IOR) in the twenty-first century needs to be understood in a holistic manner. The economic development of any nation is closely linked to its trade and energy supply. The geostrategic location of the IOR ensures that it is the center of gravity for the sea lanes of communications (SLOCs) not only for the nations in the IOR but also for nations in the entire Indo-Pacific and beyond. The energy supplies from the middle-east, and the raw material from Africa to the growing economies in the South East Asia (China, Japan, Korea and others) and the return passage of finished goods from South East Asia to Africa and Europe put IOR in a very strategic position [9].

It is not only the commercial ships but also the naval ships that get deployed to protect the SLOCs given the volatile security situation in the region puts the number count of ships at an alarming level contributing to the high ambient noise. The socioeconomic conditions and also the socio-political situation of the nations in the IOR ensure poor design and manufacturing (with high radiated noise levels) of the ships in region and also limited regulatory provisions to be able to address the concerns of acoustic habitat degradation [10].

**Figure 2.** *Wenz curve [7].*

The subsequent sections in the chapter attempt to address the larger issue of acoustic habitat degradation in the IOR due to shipping. In Section 2, we present the basics of underwater radiated noise (URN), the mechanism of generation of URN, acoustic stealth requirements for the naval platforms, ship design and management issues include, e.g., to contain URN, measurement and analysis aspects and more. Section 3 brings the challenges and opportunities in the IOR at all levels, geostrategically, geopolitically and geophysically. In Section 4, we discuss the use of sound by the marine species and articulate the relevance of sound for these species. Section 5 elaborates on the acoustic habitat degradation due to shipping noise. Section 6 enumerates the regulatory provisions that exist globally and the specific limitations in the IOR. In Section 7, we conclude by giving some way ahead and leads for addressing this serious concern of acoustic habitat degradation in the IOR due to shipping noise.
