underwater radiated noise

SILENV Ships oriented Innovative soLutions to rEduce Noise and Vibrations

FP7 - Collaborative Project n 234182

WP 1 : N&V related needs, quantification and justification

Document title: TASK 1.4 Underwater radiated noise

Deliverable

Reference Issue Dissemination status

D 1.3

Rev 10

PU

File name SILENV_D1-3_Rev10.pdf

Name Organisation

Author(s) Michel Andr

Enrico Rizzuto Tomaso Gaggero

UPC UNIGE UNIGE

Name Organisation Date

Checked by Enrico Rizzuto UNIGE April 30th 2010

Michel Andr UPC May 4th 2010

Approved by

TASK 1.4 Underwater radiated noise

D 1.3 Rev 10

Dissemination level : PUBLIC

SILENV Consortium, 2010, all rights reserved

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MANDATE

Description of work for SILENV Task 1.4: Underwater radiated noise Review current state of scientific knowledge on auditory sensitivity of marine mammals and fishes, Identify gaps in scientific knowledge. Review current national & international guidelines & regulations with regard to marine mammal & fish noise exposure, levels and criteria. Identify likely future regulatory scenarios. Define parameters of underwater noise measurements that need to be collected from ships in WP2 for mapping onto marine mammal & fish sensitivity.

REVISION HISTORY

ISSUE REASONS FOR CHANGES

Rev 2.0 Integration of UPC contribution

Rev 3.0 Integration between UPC and UNIGE contributions

Rev 4.0 Change position of definitions, change in text of chapt 5.3

Rev 5.0 Editorial changes (mainly references)

Rev 6.0 Addition of Chapter 9 Conclusions

Editorial changes (formal issues)

Rev 7.0 Revision of Chapter 9 Conclusions

Rev 8.0 Insertion of comments on DNV SILENT Class (Chapters 7,8,9)

Rev 9.0 Some minor typographical changes

Rev 10 Typographical correction of formulas in the Annex


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INDEX

1. THE PROBLEM OF NOISE POLLUTION: MARINE FAUNA AND ACOUSTIC HABITAT ............................................................................................................................. 5

2. REGULATORY FRAMEWORK ................................................................................. 102.1. INTERNATIONAL FRAMEWORK .......................................................................... 10

2.1.1. The United Nations (UN) .................................................................................. 102.1.2. Other international bodies ................................................................................ 13

2.2. REGIONAL FRAMEWORK .................................................................................... 152.2.1. The Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) .............................................................................................. 152.2.2. The Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and contiguous Atlantic area (ACCOBAMS) ................................... 172.2.3. The Helsinki Commission (HELCOM) .............................................................. 182.2.4. The Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention) ................................................................................ 182.2.5. The Joint Nature Conservation Committee (JNCC) ......................................... 19

2.3. NATIONAL FRAMEWORK .................................................................................... 192.3.1. The US Marine Mammal Protection Act (MMPA) ............................................ 192.3.2. The European Union (EU) ............................................................................... 192.3.3. The Italian situation .......................................................................................... 22

3. ANTHROPOGENIC NOISE SOURCES ..................................................................... 233.1. Sources of noise ................................................................................................... 23

3.1.1. Oil and gas exploration and exploitation .......................................................... 233.1.2. Dredging .......................................................................................................... 243.1.3. Marine wind farms ............................................................................................ 243.1.4. Explosions........................................................................................................ 243.1.5. Maritime Traffic ................................................................................................ 24

3.2. Ship noise .............................................................................................................. 263.2.1. Sources on board ships ................................................................................... 263.2.2. Propeller .......................................................................................................... 263.2.3. Machinery ........................................................................................................ 283.2.4. Flow Noise ....................................................................................................... 29

3.3. The ship as a whole source ................................................................................. 293.3.1. Directivity ......................................................................................................... 293.3.2. Other important parameters affecting the emission of the ship source ............ 31

4. EFFECTS OF ANTHROPOGENIC NOISE POLLUTION ON CETACEANS ............. 334.1. Classification of effects ........................................................................................ 364.2. Ranking of effects ................................................................................................. 374.3. Signal masking ...................................................................................................... 38


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4.4. Acoustic trauma (TTS/PTS) .................................................................................. 434.5. Behavioural effects ............................................................................................... 504.6. Non-auditory alterations or injuries .................................................................... 75

4.6.1. Bubble formation. Traumatic injuries caused by accidents .............................. 754.6.2. Stress ............................................................................................................... 784.6.3. Reproduction .................................................................................................... 79

5. EFFECTS OF ANTHROPOGENIC NOISE POLLUTION ON FISH AND INVERTEBRATES ............................................................................................................ 81

6. RISK ASSESSMENT ................................................................................................. 836.1. Definition ............................................................................................................... 836.2. Physical impact criteria ........................................................................................ 87

6.2.1. TTS and PTS ................................................................................................... 896.2.2. Criteria for behavioural change ........................................................................ 91

7. MEASUREMENT OF SHIP NOISE ............................................................................ 957.1. Characterization .................................................................................................... 957.2. Uncertainties and research needs ....................................................................... 957.3. Measurement protocol and analysis ................................................................... 95

7.3.1. ANSI-ASA 4.3 Data acquisition. ....................................................................... 967.3.2. ANSI-ASA 4.4 Distance measurement ............................................................ 977.3.3. ANSI-ASA 5.3 Sea surface conditions ............................................................. 977.3.4. ANSI-ASA 5.4 Hydrophone deployment .......................................................... 987.3.5. ANSI-ASA 5.5 Test course 5.6 Test sequence ................................................ 98

7.4. Data analysis ......................................................................................................... 997.5. DNV Silent Class Notation measurement procedures of underwater noise . 102

8. CRITERIA FOR SETTING LIMITS TO THE SHIPS NOISE .................................... 1038.1. ICES methodology .............................................................................................. 1038.2. DNV SILENT Class Notation ............................................................................... 1068.3. Alternative possibility ......................................................................................... 108

9. CONCLUSIONS ....................................................................................................... 109

10. REFERENCES...................................................................................................... 111

ACOUSTIC TERMINOLOGY (FROM TNO REPORT MEASURING UNDERWATER SOUND) ........................................................................................................................... 142


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1. THE PROBLEM OF NOISE POLLUTION: MARINE FAUNA AND ACOUSTIC HABITAT

Although this deliverable concerns underwater noise (and its effects) from shipping, there is a considerable lack of information, generally speaking, on the specific effects of shipping noise on the marine environment and it is not possible to separate these sources from others that are associated to different human activities. Therefore, all sources of noise will be addressed in the first part of this document, while the second part will specifically recommend a protocol for measuring the underwater radiated noise from shipping. The underwater environment has its own acoustic peculiarities1 and marine fauna (in particular mammals) is extraordinarily well adapted to them. In these animals acoustic communication and perception has acquired a privileged role compared with other senses and other zoological groups. They live in a medium which poorly transmits light but through which sound propagates very well, even over long distances, especially when frequencies are low or the sound is channeled by pressure and temperature gradients2. Marine mammals are acoustic specialists and depend heavily on sound for survival to communicate, to coordinate their movements, to navigate, to exploit and investigate the environment, to find food and mates and finally to avoid predators, and other threats.

These capabilities are the result of an evolution of the marine fauna to adapt to the sea habitat, whose acoustic aspects are of a paramount importance. As it will be better analysed in the following chapters, this acoustic habitat is nowadays altered by anthropogenic noise contributions that have direct and indirect effects on individuals and on populations of the various species. In particular as regards the communication aspect, what emerges by recent investigations, is that individuals and, accordingly, populations, rely on an acoustic habitat for establishing and maintaining normal interactions and when such habitat is degraded, acoustic communication is degraded, with dysfunctional consequences in the social system. The same concept applies to other vital aspects of living. In other words each species has his specific acoustic niche within a larger acoustic habitat; in analogy with human environments, each species needs his own level of acoustic comfort to behave according to his own evolution path. This then leads to the concept of an acoustic ecology and of the concern for its preservation.

A consideration of the acoustic ecology leads to the conclusion that there are costs associated with the modifications in acoustic habitat (e.g., in the reduction of feeding efficiency, mating success, predator avoidance), and these costs can affect primarily individuals and then populations.

Unlike other natural modifications in the habitat, these anthropogenic impacts are both quite recent and relatively rapid in an evolutionary time frame relevant to species adaptations.

1 Wenz, 1962 2 Urick, 1983; Richardson et al., 1995


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In the past hundred years the scale of anthropogenic noise introduced into the marine environment has grown to unprecedented levels. There is no doubt that in recent history, the larger oceangoing organisms, particularly cetaceans, have not yet developed the ability to adapt their auditory capacities to these powerful sound sources, whose impact on the functioning of their vital systems remains unknown.

The sources of marine noise pollution produced by human activity, includes, amongst others, maritime transport, oil and gas exploration and exploitation, industrial and military sonar, experimental acoustic sources, undersea explosions; military and civilian, engineering activities, supersonic aircraft noise and the construction and operation of sea-based wind farms.

Figure 1.1- Sound levels and frequencies from anthropogenic and natural sound sources in the marine environment3.

These sound sources invade the acoustic and physical space of marine organisms (Fig. 1.1) and there is no actual field of reference in which to foresee the negative consequences of these interactions on the oceans natural equilibrium, and their short, medium and long-term effects on marine biodiversity.

3 Boyd et al. 2008


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Sound sources as a result of human activity/action have shown physical, physiological and behavioral effects on marine fauna mammals, reptiles, fish and invertebrates -, impacts whose distinct seriousness will depend on the proximity of an animal to the sound source. These impacts, as we have already mentioned in the introduction, include a reduction in the abundance of fish species of up to 50% in prospected zones4, changes in behavior and in the migratory routes of cetaceans5 and damages of distinct orders, including physical, in marine invertebrates and vertebrates6.

Even though land based environmental noise has been regulated since some time, only recently has marine acoustic pollution been introduced in legal international frameworks7, becoming national regulations in countries such as the United Kingdom.

The Council of the European Cetacean Society, a society of some 500 European scientists dedicated to cetacean biology research, considers that8:

There is an urgent need for research into the effects of man-made acoustic pollution in the sea, research that must be conducted under the highest standards of scientific credibility, avoiding all conflicts of interest.

Non-intrusive mitigation measures must be developed and implemented as soon a possible.

There will have to be a limitation put on the use of powerful underwater sound sources until the short, medium and log term effects on marine mammals are known and the use of such sources is avoided in areas where concentrations of these animals are found.

Legislative instruments must be developed with regard to marine acoustic pollution that will permit compliance of European and national policies on the protection of marine biodiversity9.

Still even more recently, the Convention on Migratory Species (CMS), recognizing that

anthropogenic ocean noise constitutes a form of pollution which may degrade the marine environment and also have adverse effects on ocean fauna, even resulting in individual fatalities and reaffirming that the difficulty in determining the negative acoustic impact on cetaceans requires the drawing up of precautionary principles in cases where impact is possible,

4 Engs et al. 1993, Skalski et al. 1992 5 Richardson et al. 1995b, Gordon and Moscrop 1996 6 Bohne et al. 1985, Gordon et al. 1998, McCauley et al. 2000, Guerra et al 2004 7 These regulations include articles 192, 194 (2.3), 206 and 235 of UNCLOS 1982 and UNCED 1992. 8 Conclusions from the 17th International Conference held in Las Palmas, Canary Islands in March 2003, under the main theme of Marine Mammals and Sound. 9 Andr and Nachtigall 2007


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has just published among other resolutions10, one that urges bodies whom exercise jurisdiction over any species of marine organisms listed in the appendices of the CMS, to

develop methods of control on the impact of acoustic emissions arising from human activities in susceptible habitats that serve as gathering points or places of passage of endangered species, and to carry out environmental impact studies on the introduction of systems that may produce noise and their derived risks to marine mammal species.

Last January 2010, a report concerning the Descriptor of Good Environmental Status under the EUs Marine Strategy Framework Directive (MSFD) for inputs of energy and noise was released. The main output of the report concentrated in the definition of three indicators that are presented in the following table:

Table 1.1 Output of th EUs Marine Strategy Framework Directive (MSFD)

TG11 Energy

ATTRIBUTE Criteria to assess the descriptor

Indicators to be measured

Underwater noise - Low and mid-frequency impulsive sound

High amplitude impulsive anthropogenic sound within a frequency band between 10Hz and 10 kHz, assessed using either sound energy over time (Sound Exposure Level SEL) or peak sound level of the sound source. Sound thresholds set following review of received levels likely to cause effects on dolphins; these levels unlikely to be appropriate for all marine biota. The indicator addresses time and spatial extent of these sounds.

The proportion of days within a calendar year, over areas of 15N x 15E/W in which anthropogenic sound sources exceed either of two levels, 183 dB re 1Pa2.s (i.e. measured as Sound Exposure Level, SEL) or 224 dB re 1Papeak (i.e. measured as peak sound pressure level) when extrapolated to one metre, measured over the frequency band 10 Hz to 10 kHz

10 Ninth meeting of the parties, Rome 2008


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Underwater noise High frequency impulsive sounds

Sounds from sonar sources below 200 KHz that potentially have adverse effects, mostly on marine mammals, appears to be increasing. This indicator would enable trends to be followed.

The total number of vessels that are equipped with sonar systems generating sonar pulses below 200 kHz should decrease by at least x% per year starting in [2012].

Underwater noise low frequency continuous sound

Background noise without distinguishable sources can lead to masking of biological relevant signals, alter communication signals of marine mammals, and through chronic exposure, may permanently impair important biological functions. Anthropogenic input to this background noise has been increasing. This indicator requires a set of sound observatories and would enable trends in anthropogenic background noise to be followed.

The ambient noise level measured by a statistical representative sets of observation stations in Regional Seas where noise within the 1/3 octave bands 63 and 125 Hz (centre frequency) should not exceed the baseline values of year [2012] or 100 dB (re 1Pa rms; average noise level in these octave bands over a year).


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2. REGULATORY FRAMEWORK The problem of anthropogenic noise emissions in the sea has been assessed only in recent years. This problem has been analyzed mainly at a regional level, in particular for restricted areas where there is a higher concentration of species of marine mammals or fishes.

2.1. INTERNATIONAL FRAMEWORK At international level there are several associations which deal with the protection of marine mammals. In some of their regulations or treaties they cover underwater sound. In the following a short review of such regulations is presented.

2.1.1. The United Nations (UN)

The issue of underwater noise is currently under consideration by the United Nations. The topic has been included in the UN Secretary-Generals Report on Oceans and the Law of the Sea for the last four years. It has also been discussed during the United Nations Open-ended Informal Consultative Process on Oceans and the Law of the Sea (UNICPOLOS). In its 2006 Report to the UN General Assembly, UNICPOLOS suggested that the implementation of the ecosystem approach should be achieved also by understanding, through increased research, the impacts of underwater noise on marine ecosystems and taking into account those impacts. Furthermore, during the meeting of the Working Group established by the UN General Assembly in 2004 to consider the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction, it was recognized that other growing human pressures, including from ocean noise and dumping, required urgent action through international cooperation and coordination. In this regard, the precautionary and ecosystem-based approaches were considered fundamental principles, which had received wide acceptance within the international community. The UN General Assembly addressed the issue of underwater noise for the first time in its 2005 Resolution on Oceans and the Law of the Sea, which encourages further studies and consideration of the impacts of ocean noise on marine living resources. This formula was repeated in the 2006 and 2007 Resolutions, where the UN Division for Ocean Affairs and the Law of the Sea (DOALOS) is further requested to compile the peer-reviewed scientific studies it receives from Member States and make them available on its website.

2.1.1.1. The United Nations Convention on the Law of the Sea (UNCLOS)

The United Nations Convention on the Law of the Sea is the international agreement that resulted from the third United Nations Conference on the Law of the Sea (UNCLOS III), which took place from 1973 through 1982. The Law of the Sea Convention defines the rights and responsibilities of nations in their use of the world's oceans, establishing guidelines for businesses, the environment, and the management of marine natural resources. In particular the UNCLOS establishes duties on its contracting parties in respect of pollution of the marine environment from any source; Art 1(1)(4) LOSC states that: pollution of the marine environment means the introduction by man, directly or indirectly,


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of substances or energy into the marine environment, including estuaries, which results or is likely to result in such deleterious effects as harm to living resources and marine life, hazards to human health, hindrance to marine activities, including fishing and other legitimate uses of the sea, impairment of quality for use of sea water and reduction of amenities

The word noise is not explicitly mentioned, but the term energy could include noise.

2.1.1.2. The International Maritime Organization (IMO) The Convention establishing the International Maritime Organization (IMO) was adopted in Geneva in 1948 and IMO first met in 1959. IMO's main task has been to develop and maintain a comprehensive regulatory framework for shipping and its remit today includes safety, environmental concerns, legal matters, technical co-operation, maritime security and the efficiency of shipping.

The IMO covers the problem of underwater noise in: z Resolution A.927(22) 2001 GUIDELINES FOR THE DESIGNATION OF SPECIAL

AREAS UNDER MARPOL 73/78 AND GUIDELINES FOR THE IDENTIFICATION AND DESIGNATION OF PARTICULARLY SENSITIVE SEA AREAS. The purpose of these Guidelines is to provide guidance to Contracting Parties to the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78) in the formulation and submission of applications for the designation of Special Areas under Annexes I, II, and V to the Convention. These Guidelines also ensure that all interests - those of the coastal State, flag State, and the environmental and shipping communities - are thoroughly considered on the basis of relevant scientific, technical, economic, and environmental information and provide for the assessment of such applications by IMO. Contracting Parties should also review and comply with the applicable provisions of Annexes I, II, and V to the Convention in addition to these Guidelines. Below an abstract of the resolution is reported:

2.2 In the course of routine operations and accidents, ships may release a wide variety of substances either directly into the marine environment or indirectly through the atmosphere. Such pollutants include oil and oily mixture, noxious liquid substances, sewage, garbage, noxious solid substances, anti-fouling paints, foreign organisms and even noise. Many of these substances can adversely affect the marine environment and the living resources of the sea. Pollutants may also damage the environment as a consequence of shipping accidents. In addition, ships may cause harm to marine organisms and their habitats through physical impact. Habitats may be smothered through grounding and ships have been known to strike large marine mammals such as whales.

z Information document MEPC 57/INF.4 (17 December 2007). This document

advises the Committee of the issue of noise generated by international shipping and


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its potential adverse impact on marine life. It requests Member Governments to note this information; inform all interested entities, in particular those from the shipping industry, shipyards, and ship builders of this issue, and invite them to participate in the ongoing dialogue regarding identification of potential adverse impacts associated with vessel noise and the potential mitigation of those impacts; and submit any pertinent information on this issue to the U.S. Department of Commerce, National Oceanic & Atmospheric Administration, National Marine Fisheries Service, Ocean Acoustics Program.

z MSC 84/INF.4 (31 January 2008) This information paper advises the Committee of the issue of noise generated by international shipping and its potential adverse impact on marine life. It requests Member Governments to note this information; informs all interested entities, in particular those from the shipping industry, shipyards, and ship builders of this issue and invite them to participate in the ongoing dialogue regarding identification of potential adverse impacts associated with vessel noise and the potential mitigation of those impacts; and submit any pertinent information on this issue to the U.S. Department of Commerce, National Oceanic & Atmospheric Administration, National Marine Fisheries Service, Ocean Acoustics Program.

z MEPC 59/19/1 (6 May 2009). This document assesses the incidental introduction of

noise from shipping activities in the oceans. Main underwater noise sources from ships are analyzed. The Committee is invited to: c take note of this information; c urge IMO Governments and the industry, as a matter of urgency, to address

additional research needs identified in this report with a view of reporting back to the Corresponding Group; and

c urge IMO Governments to encourage a review of their merchant fleets in order to identify vessels that would benefit most from efficiency improving technologies that are also likely to reduce underwater noise output.

z MEPC 60/18 (18 December 2009) This document is the report of the

Correspondence Group on the issue of Noise from commercial shipping and its adverse impact on marine life. The Correspondence Group was established to identify and address ways to minimize the incidental introduction of noise from commercial shipping operations into the marine environment to reduce potential adverse impacts on marine life.


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2.1.1.3. Convention on the Conservation of Migratory Species of Wild Animals (CMS)

The Convention on the Conservation of Migratory Species of Wild Animals (also known as CMS or Bonn Convention) aims to conserve terrestrial, marine and avian migratory species throughout their range. It is an intergovernmental treaty concluded under the aegis of the United Nations Environment Programme, concerned with the conservation of wildlife and habitats on a global scale. Since the Convention's entry into force, its membership has grown steadily to include 113 (as of 1 January 2010) Parties from Africa, Central and South America, Asia, Europe and Oceania.

The CMS in Resolution 7.5 Wind turbines and migratory species underlines the importance in mitigating impact of noise and vibrations radiated from wind turbines and calls upon the parties to deal with, in general, pollution deriving from wind turbines.

In Resolution 8.22 Adverse Human Induced Impacts on Cetaceans (2005) we find:

Review, in collaboration with the scientific advisory bodies of CMS cetacean-related Agreements, the extent to which CMS and CMS cetacean-related Agreements, are addressing the following human induced impacts through their threat abatement activities:

i. entanglement and by-catch;

ii. climate change;

iii. ship strikes;

iv. pollution;

v. habitat and feeding ground degradation;

vi. marine noise;

2.1.2. Other international bodies

2.1.2.1. The International Union for the Conservation of Nature (IUCN) IUCN is the worlds oldest and largest global environmental network, a democratic membership union with more than 1000 government and NGO member organizations, and almost 11000 volunteer scientists in more than 160 countries. IUCN helps the world find pragmatic solutions to our most pressing environment and development challenges. It supports scientific research, manages field projects all over the world and brings governments, non-government organizations, United Nations agencies, companies and local communities together to develop and implement policy, laws and best practice. IUCN in his resolution RESWCC3.068 was the first to deal with underwater noise pollution problem at the global level. Below an abstract of the resolution is reported


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REQUESTS the Director General, with the assistance of IUCNs members, Commissions, and Council, to identify and implement measures to promote among world governments the reduction of anthropogenic ocean noise, such as by drawing this resolution to the attention of the secretariats of, and meetings of Contracting Parties to, UNEP Regional

Seas Programmes, UNEP Governing Council, and other relevant intergovernmental organizations, particularly those with whom IUCN enjoys observer status, and by keeping

Union members informed of progress on this issue;

2.1.2.2. The International Whaling Commission (IWC) The International Whaling Commission (IWC) was set up under the International Convention for the Regulation of Whaling which was signed in Washington DC on 2nd December 1946 . The purpose of the Convention is to provide for the proper conservation of whale stocks and thus make possible the orderly development of the whaling industry. The main duty of the IWC is to keep under review and revise as necessary the measures laid down in the Schedule to the Convention which govern the conduct of whaling throughout the world . Membership of the IWC is open to any country in the world that formally adheres to the 1946 Convention. Each member country is represented by a Commissioner, who is assisted by experts and advisers. The Chair and Vice-Chair are elected from among the Commissioners and usually serve for three years.

The IWC, in Resolution 19986, included the impact of noise in its eight priority topics for research. The issue of noise has been also largely discussed in recent meetings (mainly since the 2004 meeting) and now the interest towards shipping noise is raising. This issue is the core topic to be discussed in the section of the Environmental concerns in the next meeting11 .

The following topics should be addressed:

- the general issue of potential chronic effects of anthropogenic noise on marine mammals and their acoustic habitats;

- the acoustic masking from low-frequency (


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2.1.2.3. The International Council for the Exploration of the Sea (ICES)

The International Council for the Exploration of the Sea (ICES) coordinates and promotes marine research on oceanography, the marine environment, the marine ecosystem, and on living marine resources in the North Atlantic. Members of the ICES community now include all coastal states bordering the North Atlantic and the Baltic Sea, with affiliate members in the Mediterranean Sea and southern hemisphere.

2.1.2.4. The International Fund for Animal Welfare

The International Fund for Animal Welfare works to improve animal welfare, prevent animal cruelty and abuse, protect wildlife and provide animal rescue around the world. From stopping the elephant ivory trade, to ending the Canadian seal hunt and saving the whales from extinction, IFAW works to create solutions that benefit both animals and people.

2.1.2.5. The Whale and Dolphin Conservation Society (WDCS)

WDCS, the Whale and Dolphin Conservation Society, is the world's most active charity (Registered No. 1014705) dedicated to the conservation and welfare of all whales, dolphins and porpoises (also known as cetaceans).

Established in 1987, WDCS is staffed by over 70 people, along with many volunteers, located in its office in Argentina, Australia, Austria, Germany, the UK and the US. This team of people is dedicated and determined to do their best for the animals and proud of the fact that WDCS's operating costs are kept to a minimum. The money raised is spent on urgent conservation, research and education projects that really do make a difference to the daily lives and long-term security of thousands of whales, dolphins and porpoises around the world.

2.1.2.6. The International Ocean Noise Coalition The International Ocean Noise Coalition (IONC) is a partnership of over 150 non-governmental organizations (NGOs) from around the world. With representatives on every continent, IONC was created to address the need for a global approach to combat human-generated (or "anthropogenic") ocean noise

2.2. REGIONAL FRAMEWORK

2.2.1. The Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS)

ASCOBANS was concluded in 1991 as the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS) under the auspices of the Convention on Migratory Species (CMS or Bonn Convention) and entered into force in 1994. In February 2008, an extension of the agreement area came into force which changed the name to "Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas"


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In Resolution N. 5 Effects of Noise and of Vessels (4 th MEETING OF THE PARTIES TO ASCOBANS 2003) we find:

Requests Parties and Range States to

introduce guidelines on measures and procedures for seismic surveys to

(1) alter the timing of surveys or to minimise their duration;

(2) reduce noise levels as far as practicable;

(3) avoid starting surveys when cetaceans are known to be in the immediate vicinity;

(4) introduce further measures in areas of particular importance to cetaceans;

(5) develop a monitoring system that will enable adaptive management of seismic survey activities;

Invites Parties and Range States to

(1) develop, with military authorities, effective mitigation measures including environmental impact assessments and relevant standing orders to reduce disturbance of, and potential physical damage to, small cetaceans;

(2) report before the Advisory Committee meeting in 2005, where possible, on approaches to reduce or eliminate adverse effects on small cetaceans by military activities;

(3) conduct further research into the effects on small cetaceans of:

(a) vessels, particularly high speed ferries;

(b) acoustic harassment devices, such as those used in fish farms and elsewhere;

(c) offshore extractive and other industrial activities;

(d) other acoustic disturbances.

This should include research on physical and behavioural effects, and be at the individual and population levels.

(4) conduct research and develop appropriate management measures and guidelines to minimize any adverse effects on small cetaceans of the above factors;

(5) develop and implement procedures to assess the effectiveness of any guidelines or management measures introduced;

(6) report on high energy seismic surveys per one degree by one degree rectangle using shot point density.


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2.2.2. The Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and contiguous Atlantic area (ACCOBAMS)

ACCOBAMS is the first Agreement binding the countries in these two subregions, and enabling them to work together on a matter of general interest. The purpose of ACCOBAMS is to reduce threats to cetaceans in Mediterranean and Black Sea waters and improve our knowledge of these animals. In Resolution 2.16 Assessment and Impact Assessment of Man-Made Noise adopted by the 2nd Meeting, we find:

1. Urges Parties and non Parties to take a special care and, if appropriate, to avoid any use of man made noise in habitat of vulnerable species and in areas where marine mammals or endangered species may be concentrated, and undertake only with special caution and transparency any use of man made noise in or nearby areas believed to contain habitat of Cuviers beaked whales (Ziphius cavirostris), within the ACCOBAMS area; 2. Urges Parties to facilitate national and international researches on the following subjects: - A collaborative and co-ordinated temporal and geographic mapping of local ambient noise (both of anthropogenic and biological origin); - The compilation of a reference signature database, to be made publicly available, to assist in identifying the source of potentially damaging sounds; - An assessment of the potential acoustic risk for individual target species in consideration of their acoustic capabilities and characteristics; 3. Urges Parties to provide the ACCOBAMS Scientific Committee with public, national or international, protocols/guidelines developed by military authorities with respect to use of sonar in the context of threats to cetaceans, and the information upon which they are based (including data and distribution models);

4. Urges Parties to consult with any profession conducting activities known to produce underwater sound with the potential to cause adverse effects on cetaceans, such as the oil and gas industry, oceanographic and geophysical researchers, military authorities, shoreline developers, and the aquaculture industry, recommending that extreme caution be exercised in the ACCOBAMS area. The ideal being that the most harmful of these activities would not be conducted in the ACCOBAMS area until satisfactory guidelines are developed;

5. Encourages the development of alternative technologies and require the use of best available control technologies and other mitigation measures in order to reduce the impacts of man-made noise sources in the Agreement area;

6. Charges the Scientific Committee to review the technical bases of this Resolution and to develop by the next Meeting of Parties a common set of guidelines on conducting activities known to produce underwater sound with the potential to cause adverse effects on cetaceans; 7. Invites Parties to report to the next Meeting of Parties about the progress made on this Resolution.


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2.2.3. The Helsinki Commission (HELCOM) The Helsinki Commission, or HELCOM, works to protect the marine environment of the Baltic Sea from all sources of pollution through intergovernmental co-operation between Denmark, Estonia, the European Community, Finland, Germany, Latvia, Lithuania, Poland, Russia and Sweden. HELCOM is the governing body of the "Convention on the Protection of the Marine Environment of the Baltic Sea Area" - more usually known as the Helsinki Convention. In Article 9 of the Convention the problem of noise is assessed, but only for pleasure craft:

Article 9

Pleasure craft

The Contracting Parties shall, in addition to implementing those provisions of this Convention which can appropriately be applied to pleasure craft, take special measures in order to abate harmful effects on the marine environment of the Baltic Sea Area caused by pleasure craft activities. The measures shall, inter alia, deal with air pollution, noise and hydrodynamic effects as well as with adequate reception facilities for wastes from pleasure craft.

2.2.4. The Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention)

The OSPAR Convention is the current legal instrument guiding international cooperation on the protection of the marine environment of the North-East Atlantic. Work under the Convention is managed by the OSPAR Commission, made up of representatives of the Governments of 15 Contracting Parties and the European Commission, representing the European Community.

OSPAR takes into consideration all threats on the marine environment. OSPAR published a report12 on the impact of noise considering many different noise sources. Specific publications refer to the shipping noise13 and to the impact of small touristic vessels14 .

12 OSPAR 2009, PN 436 13 OSPAR 2009b, PN 440, in press 14 OSPAR 2008. PN 369


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2.2.5. The Joint Nature Conservation Committee (JNCC)

JNCC is the statutory adviser to Government on UK and international nature conservation. Its work contributes to maintaining and enriching biological diversity, conserving geological features and sustaining natural systems. JNCC delivers the UK and international responsibilities of the four country conservation bodies - Council for Nature Conservation and the Countryside, the Countryside Council for Wales, Natural England and Scottish Natural Heritage.

2.3. NATIONAL FRAMEWORK

2.3.1. The US Marine Mammal Protection Act (MMPA) The Marine Mammal Protection Act (MMPA) of 1972 prohibits the taking of marine mammals, and enacts a moratorium on the import, export, and sale of any marine mammal, along with any marine mammal part or product within the United States

In particular:

the centrepiece of the Act is its moratorium on taking in section 101(a). The moratorium established a general ban on the taking of marine mammals throughout areas subject to U.S. jurisdiction and by any person, vessel or conveyance subject to the jurisdiction o the United States on the high seas.

Take is defined under section 3(13) of the act to mean

to harass, hunt, capture or kill any marine mammal.

This early recognition of the importance of harassment for marine mammals was further developed under the 1994 amendments (part of the reauthorisation of the US Act made in that year), when the US Congress provided the following statutory definition of the term harassment: any act of pursuit, torment or annoyance which: 1. Level A Harassment has the potential to injure a marine mammal or marine mammal stock in the wild; or 2. Level B Harassment has the potential to disturb a marine mammal or a marine mammal stock in the wild by causing disruption of behaviour patterns, including but not limited to migration, breathing, nursing, breeding, feeding or sheltering

2.3.2. The European Union (EU)

In 2004 the European Parliament adopted a Resolution on the environmental effects of high-intensity active naval sonar. This Resolution calls upon the European Union (EU) and its Member States to adopt a moratorium on the deployment of high intensity active naval sonar, until a global assessment of their cumulative environmental impact on marine mammals, fish and other marine life has been completed.


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The recent EU Marine Strategy Framework Directive (2008/56/EC) specifically mentions the problem of noise pollution and provides a legal framework for addressing this issue. The Directive represents the first international legal instrument to explicitly include man-made underwater noise within the definition of pollution (Article 3 (8)), which needs to be phased out in order to achieve the good environmental status (GES) of European marine waters by 2020 (Article 1). The Directive identifies 11 environmental descriptors, the 11th is the anthropogenic noise (the introduction of energy, including underwater noise, at levels that do not adversely affect the marine environment) to achieve the GES (Annex I (11)) and sets out clear obligations for member states to address this form of pollution.

A working group has been established to develop the protocols and metrics for these descriptors (see section 1 of this document). With this Directive the underwater noise is now an issue of great relevance and all member states have to face with it as they are obliged to provide an evaluation of the good status of their seas based on those descriptors.

The European Union Habitat Directive states that it is not permissible to deliberately disturb in the wild, any creature which is enlisted in Annex IV (a), where all Cetaceans (and several other marine mammals) are listed. In addition to species protection, the Habitats Directive also makes provision for the site-based protection of a range of marine mammal species (listed in Annex II), including bottlenose dolphins and harbour porpoises and all species of seal. To achieve this, Special Areas of Conservation (SAC), as well as Marine Protected Areas (MPA) should be proposed and designated as key tools for marine mammals protection.

However, the Directive does not cite noise explicitly15 . With few exceptions related with high power acoustic sources (explosions, sonars, seismic surveys) that may have a direct immediate impact on marine mammals, underwater noise is largely unregulated16 .

The following list includes all the EU regulations on the protection of the marine habitat. Since there is not yet any specific regulation on noise, this is the most exhaustive list that is available at the moment of writing this deliverable, where the effects of noise can be framed.

Council Decision of 1 March 1984 on the conclusion of the Protocol concerning Mediterranean specially protected areas (84/132/EEC)

Council Directive 85/337/EEC of 27 June 1985 on the assessment of the effects of

certain public and private projects on the environment

15 Pavan, 2007 16 McCarthy, 2004


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Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora

Council Decision 98/249 of 7 October 1997 on the conclusion of the Convention for

the protection of the marine environment of the north-east Atlantic

Council Regulation No 1626/94 of 27 June 1994 laying down certain technical measures for the conservation of fishery resources in the

Council Directive 97/62/EC of 27 October 1997 adapting to technical and scientific

progress Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora

Council Decision 98/392 of 23 March 1998 concerning the conclusion by the

European Community of the United Nations Convention of 10 December 1982 on the Law of the Sea and the Agreement of 28 July 1994 relating to the implementation of Part XI thereof

Council Decision 1999/800 of 22 October 1999 on concluding the Protocol

concerning specially protected areas and biological diversity in the Mediterranean, and on accepting the annexes to that Protocol (Barcelona Convention)

Council Decision 1999/337of 26 April 1999 on the signature by the European

Community of the Agreement on the International Dolphin Conservation Programme

Directive 2000/60/EC of the European Parliament and of the Council of 23 October

2000 establishing a framework for Community action in the field of water policy

Directive 2001/42/EC of the European Parliament and of the Council of 27 June 2001 on the assessment of the effects of certain plans and programmes on the environment

Commission Decision 2006/613/of 19 July 2006 adopting, pursuant to Council Directive 92/43/EEC, the list of sites of Community importance for the Mediterranean biogeographical region (notified under document number C(2006) 3261)

Commission Decision 2008/95/of 25 January 2008 adopting, pursuant to Council Directive 92/43/EEC, a first updated list of sites of Community importance for the Macaronesian biogeographical region (notified under document number C(2008) 286)


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Commission Decision 2008/335/EC of 28 March 2008 adopting, pursuant to Council Directive 92/43/EEC, a first updated list of sites of Community importance for the Mediterranean biogeographical region (notified under document number C(2008) 1148)

Directive 2008/56/EC of the European Parliament and of the Council of 17 June 2008 establishing a framework for community action in the field of marine environmental policy (Marine Strategy Framework Directive)

Commission Decision 2009/95/EC of 12 December 2008 adopting, pursuant to Council Directive 92/43/EEC, a second updated list of sites of Community importance for the Mediterranean biogeographical region (notified under document number C(2008) 8049)

Commission Decision of 22 December 2009 on adopting, pursuant to Council Directive 92/43/EEC, a second updated list of sites of Community importance for the Macaronesian biogeographical region (notified under document C(2009) 10414)

2.3.3. The Italian situation

As specific national rules are lacking, in Italy the legal reference framework is the Habitats Directive. The Office of Protected Marine Resources (Ministry of the Environment) is in charge for authorizing high impact activities, e.g. seismic surveys, and for providing basic mitigation guidelines to minimize impact on marine fauna. But no office in charge of controls exists, and the effectiveness of the whole regulatory system is unclear.

In support of a stronger implementation of mitigation procedures, a recent law (L. 8 febbraio 2006, n. 61) allows extending Italian jurisdiction beyond the national waters, creating special Ecological Protection Zones.


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3. ANTHROPOGENIC NOISE SOURCES

3.1. Sources of noise Marine life is threatened by habitat degradation caused by intense human activities such as fisheries, ship traffic, pollution, and coastal development. In addition to being affected by chemical pollution, cetaceans and other vertebrates are affected by noise pollution17. At present, noise represents a ubiquitous form of marine pollution, especially in areas of heavy maritime traffic and developed coasts. Intense underwater noise is generated by airguns, widely used for geophysical explorations for oil and gas industry as well as for academic and administrative purposes, by high power sonar, either military or civil, by ship traffic, by shoreline and offshore construction works, and by a series of other commercial, scientific, military and industrial sources. With the most powerful sources (airguns, sonars, and explosions) this may lead to direct injure of animals in the nearby of the source. General ship traffic, heavy industries on the coast and a variety of different human activities, on the other side, generally dont generate such intense noise; but this different acoustic pollution is constant over time and may affect large areas. It may result very dangerous not to individual animals, but to entire populations. The increased background noise, in fact, affects underwater life as airborne noise does on terrestrial animals, included human beings. However, considering that sound in water travels 5 times faster than in air, and that the density of the water transmit acoustic energy very efficiently over distances much greater than in air, the underwater noise effects may extend over very large water volumes. The knowledge that man-made noise can affect marine life, marine mammals in particular, and the need for a regulatory system to mitigate such effects, has increased over the past few years, mainly in the context of military sonars and seismic surveys. Increasing concern is now given to all types of noise pollution, including shipping noise, and extends to consider other zoological groups such as fishes and invertebrates.

3.1.1. Oil and gas exploration and exploitation

Oil and gas production activities produce low frequency sub-aquatic noise18 in different phases of operation: drilling (perforations), installation and removal of open sea structures and associated transport. Among these, it is the drilling process phase19 that produces the highest sound pressure levels.

The noise from drill ships is produced by perforating equipment, propellers and propulsion stabilizers deployed to maintain the ships position. The most commonly used drilling equipment is called a jack-up rig (self-raising towers or platforms). In addition, drilling generates auxiliary noise through supply ships and helicopter support activities.

17 Richardson et al., 1995 18


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The activities associated with hydrocarbon industries have historically made up the greatest source of acoustic activity in shallow waters (


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Vessel traffic is not evenly distributed in the oceans, but rather over established routes and coastal areas; these are designed in order to minimize distances.

Seaports are also a source of noise; even though only a few dozen ports control the majority of the worlds shipping, hundreds of additional smaller ports and harbors also make a significant impact, depending on their characteristics and location. In the same way small boats dont contribute a great deal in global marine noise, they do act as sources of local and coastal noise pollution.

Ship noise is fundamentally generated from three elements: the engine, propeller and associated machinery and the flow of water over the hull. Ships can also provoke cavitation24, i.e. the creation of cavities (hollow areas of water) or pressure zones inferior to the ambient underwater pressure, caused by the rapid movement of an object (vessel, propellers) through its medium. The subsequent filling up of these empty spaces produces sound. Cavitation accounts for up to 80-85% of all noise made by maritime shipping traffic25.

24 Ross 1987, 1993. 25 Vessel noise oscillates between minimum levels from 115 dB re 1 Pa at 1 m (meter) for small boats (Au and Green 2000) to 180-190 dB re 1Pa at 1 m for Supertankers (Hildebrand 2005). There is considerable information available in maritime traffic literature and source levels (Gray and Greely 1980; Institute of Shipping Economics and Logistics 1989; Jennete 1993; Lloyds Register of Ships 1989; Molinelli et al. 1990; Revello and Klingbeil 1990; Ross 197; Scrimger et al. 1990; Scrimger and Heitmeyer 1991, Richardson et al. 1995b; Erbe and Farmer 2000).


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3.2. Ship noise

The target of the SILENV project is related to noise emissions from ships. With reference to Chapter 2 of the present report, the impact the noise produced by ships can have on the marine wildlife leads to two possible scenarios: one in close proximity of noisy ships where temporary or permanent loss of hearing capabilities can be generated and a second one over large distances where the noise irradiated by a number of ships merges into a relatively constant and diffused background noise, creating problems of masking of useful signal. This seems to be the major concern. As there is a relationship between commercial shipping and the amount of underwater background noise and given that shipping activities are increasing and expected to expand into new areas, (e.g.: the Arctic), the related background noise levels are bound to continue to rise.

3.2.1. Sources on board ships

The ship is a complex source of noise, resulting from the superposition of several contributions, see Figure 3.1.

The various sources will be analysed within the project, here below a short summary will be presented

Figure 3.1 Sources of underwater noise on board ships (from MEPC 59/19, IMO 2009)

3.2.2. Propeller

The propeller is an important source of underwater noise. There are four principle mechanism which generate noise in propellers. They can be subdivided in two families: non-cavitating and cavitating contributions


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Non Cavitating

These phenomena are common for all propellers in the sense that either for cavitating propellers these mechanisms generate noise. They are the following: z The displacement of the water by the propeller blade profile

z The pressure difference between the suction and pressure surfaces of the propeller blade when they are rotating

For propellers in non-cavitating state, in the radiated noise spectra, it is possible to identify distinct tones associated to the blade frequencies together with a broad band noise at higher frequencies.

The blade rate noise is due to that fact that propeller is normally operating behind a vessel and so works in a circumferentially varying wake field. This causes a fluctuating angle of incidence on the blade sections which reflects on pressure harmonics which generate noise.

The broad-band noise is associated to the turbulence both in the incident flow and at the trailing edge of the section of the blade.

Cavitating

These phenomena are peculiar of propellers in cavitating operational conditions. They are the following: z The periodic fluctuation of the cavity volumes caused by operation of the blades in

the variable wake filed behind the vessel

z The sudden collapse process associated with the life of a cavitation bubble

The blade rate is a signal generated at the blade passing frequencies and its harmonics. This is usually the dominant source of low frequency tonals at high speeds, when the propeller is heavily cavitating. The phenomena is due to non uniform wake inflow velocity. The pressure on a blade surface varies due to this wake and also due to the change in hydrostatic pressure as a function of its depth below the water surface. Both of these effects make the pressure lowest in the upper region of the propeller blades motion. If the rotation speed is sufficiently high, a cavity will be formed; it rapidly collapses when pressure increases as the blade turns downward (or anyway the conditions for its formation are no more valid). Since this collapse occurs every time a blade passes through the same region (in the same hydrostatic and hydrodynamic conditions), noise will be generated at the blade rate and its harmonics

The collapse of cavitation bubbles creates shock waves and hence noise. This is essentially white noise covering a frequency band up to 1 MHz26.

26 J. Carlton


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Other types of radiated noise from propellers are:

z Induced vibrations: the propeller can induce vibrations on the structure of the hull

and generate underwater noise. Above the cavitation inception speed, the shape and peak frequency of the wideband cavitation spectrum do not change appreciably with ship speed.

z Propeller singing: This is a typical phenomena affecting marine propellers. It is related to the periodic detachment of vortices, which induce a vibration of the blade (tonal component). It can be overcome by modifying the trailing edge of the blade itself.

3.2.3. Machinery

The main engines used in shipping are listed below: z Diesel Electric: The noise signatures of the diesel-electric ships typically contained

energy from the diesel generators and from the electric propulsion motors in combination with the frequency converters. The levels of electric propulsion motor noise energy, and the frequencies at which they occurred, varied by ship and with propulsion shaft rpm.

z Diesel: typical propulsion noise contributors included the diesel engines and the reduction gears. Because diesel engine rpm varied according to propulsion demand, these signature components occurred at frequencies that depended upon ships speed.

z Turbines: Propulsion turbines, turbine generators, and reduction gears were the dominant sources of propulsion system noise on the steam turbine equipped ship.

z Auxiliary machinery: Noise components from rotating auxiliary machinery and other shipboard equipment also contribute noise to a ships overall signature, but usually at lower levels than the propulsion systems. Examples of noise-generating auxiliary equipment include: air conditioning plants; water, hydraulic, and oil pumps; motor generators; and ventilation fans.

Most of the seagoing ships are equipped with two or four stroke diesel engines for the main propulsion and about all the ships are equipped with four stroke diesel engines for what concerns auxiliary. Both of them are important sources of noise because of their potential to induce structure-borne vibrations that radiate via the hull. At lower vessel speed, induced vibrations generated by the operating machinery, are the predominant noise sources at frequencies below 100 Hz27. The noise radiated in water by the engines has tonal components due topiston slap, that is the impact of the piston against the wall of the cylinder caused by reversals in the direction of the piston side force.

27 NOAA, 2007


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In Figure 3.2 an example of a noise spectrum of a propulsion system: tonal components are associated to single sources as shown in the legend.

Other causes of machinery vibration can be:

Unbalanced rotating shafts

Repetitive discontinuities, e.g. gear teeth, armature slots or turbine blades

Reciprocating parts, e.g. combustion in engine cylinders

Cavitation and turbulence in fluids flowing through pipes, pumps, valves, condensers

Mechanical friction

Figure 3.2 Noise from propulsion system (from Vendittis and Arveson, 2000).

3.2.4. Flow Noise

Noise due to the flow on the hull, and in particular on the appendages, is usually overlapped by other types of underwater radiated noise. It could became an important component for high speed vessels. In general flow noise is confined to a region near the hull and does not transmit to far distances.

3.3. The ship as a whole source

3.3.1. Directivity

In Figure 3.3, two directivity plots are presented for the same ship: on the left at 9.3 Hz (blade rate tone) and for a higher frequency band.


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9.3 Hz tone 340-360 Hz noise band

Figure 3.3 Directivity plots for a ship (parameters of the curves: levels in dB re: 1 Pa @ 1 m)- azimuthal graphs: the grid corresponds to angular positions in the

vertical and horizontal planes (from Vendittis and Arveson, 2000)

As it can be seen, the first plot shows a comparatively regular emission in horizontal planes, while for the upper frequency a marked directional behavior is shown.

In the latter case the bow aspect radiation is partially blocked due to the presence of the hull, and the stern aspect radiation is partially absorbed in the bubble wake of the ship. The levels are highest in directions somewhat aft of the beam aspects. This directivity could be the consequence of reflections of cavitation noise from the sides of the ship, or due to geometry of the propeller.

The directivity of ship sources is confirmed by the outcomes of experiments reported in Figure 3.4. The surveys relate to three separate runs of a ship and data collected from four BURBs acquisition systems. Open symbols are individual measurements and solid symbols are average values in 5 classes.


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Figure 3.428 One-third octave averaged SLS vs. aspect angle (0 bow, 90 beam, 180 stern) at four frequencies from straight-line transits at 10 knots

In Figure 3.4, the maximum levels are found near the beam aspect.

According to Averson and Vendittis in Radiated noise characteristics of a modern cargo ship, at long ranges low-frequency sound originates mainly from a fairly narrow sector of depression angles between about 4-10 degrees (the depression angles are measured in the vertical plane).

This could be important considering the problem of masking for cetaceans, but on the other hand, this observation is more related to propagation at large distances than to a specific characteristics of the source.

3.3.2. Other important parameters affecting the emission of the ship source

There are some macro parameters that play a fundamental role in the shape and intensity of the radiated spectra of underwater noise radiated by whole ships.

Dimensions. In general increasing dimensions generate an increase in the sound levels at 1 yard29. In general the maximum of the spectra shifts towards higher frequencies with the decrease of the dimensions30.

28 Trevorrow et al. 2008 29 Mitson, 1995 30 Kipple,2007


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Figure 3.5 Effect of vessel size (noise spectra in third octave bands) from Kipple, 2007

Speed: The noise in general increases with increasing speed (as the main sources on board operate at a higher energy level) but it is important to underline that usually the optimal sound level condition is at the design point. Off design conditions (for example travel at reduced speed near the coast) cause higher emissions from the propulsive plant. This is important because it underlines that reducing the speed may not always be the right strategy to reduce radiated noise.

Loading conditions: Usually ships in ballast conditions generate higher levels due to easier propeller cavitation when hydrostatic pressure on the propeller is lower.

Type of propeller: (fixed or controllable pitch propellers, pods) CPP seem to give more problems as regards underwater noise. There is ample evidence that noise level can increase very dramatically especially when pitch is altered instead of alter the rotational rate to change speed of the vessel. This because the angle of attack is modified by the same quantity for all blade profiles through a rigid rotation but the angle of attack varies with a certain law along the blade because of the different tangential speed. This could generate even a negative angle of attack or anyway it makes the blade to work very far from the deign conditions.

Ship maintenance: Underwater radiated noise seems to be not dependent on ship maintenance. Damaged and therefore cavitating propellers (e.g. due to or increased by barnacles) are usually repaired during dry-docking when also pitch may be checked31.

31 MEPC,2009


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4. EFFECTS OF ANTHROPOGENIC NOISE POLLUTION ON CETACEANS

Noise can severely interfere with the life of marine mammals. Noise pollution can cause marine mammals to abandon their habitat32 and/or alter their behaviour by direct disturbance or by masking their acoustic signals over large areas33; higher sound levels could directly affect their hearing capabilities by producing either temporary or permanent hearing losses34 . All these effects may be critical for the survival of marine mammals. Some high energy sound sources can have immediate impacts and even trigger mortality events, as recently evidenced by several dramatic and well documented atypical mass strandings (mass strandings are defined as 2 or more animals stranded in the same area) of beaked whales (e.g. Greece 1996, Bahamas 2000, Canary Islands 2002)35. In some cases anthropogenic high power sound sources (up to 250 dB re 1 Pa at 1m distance) radiate low- to high-frequency sound and individual animals are exposed to high levels of sound (> 160 dB re 1 Pa) over relatively short periods of time (acute exposure), e.g. in some military sonar operations. In other cases potential exposure to high noise levels can occur for longer periods, weeks and months, as in the case of seismic surveys or some construction works (i.e. pile driving for construction of ports, bridges)36. Seismic surveys and low-frequency naval sonar, other than high levels close to the source, may radiate low-frequency sound over very large areas thereby exposing populations to lower sound levels (< 160 dB re 1 Pa) over relatively long periods of time (chronic exposure). Continuous exposure to low frequency sound is also the effect of distant shipping noise, multiple distant seismic surveys or construction works37 . Regarding received levels, it is generally accepted that levels greater than 120 dB re 1Pa may produce behavioural changes38 and levels greater than 150 dB can lead to effects ranging from severe behavioural disruption to TTS (Temporary Threshold Shift), that means temporary lowering of the hearing sensitivity; levels greater than 170-180 dB are considered able to produce PTS (Permanent Threshold Shift), that means permanent hearing loss, deafness and physical damage, including death in some circumstances. These numbers are debatable, they may vary according to environmental context, behavioural context and to specie, as demonstrated by Cuviers beaked strandings that occurred after (multiple) exposures at levels believed safe.

32 Borsani et al., 2007 33 Payne & Webb, 1971; Hildebrand, 2005 34 Simmonds and Lopez-Jurado, 1991; Richardson et al., 1995; NRC, 2000; NRC, 2003; Gordon et al., 2004 35 DAmico, 1998; Frantzis, 1998; Evans and England, 2001; NOAA, 2001; Dep't of the Environment, 2002; Evans and Miller, 2004; Fernndez, 2005 36 Borsani et al., 2007 37 Tyack, 2003; Nieukirk et al., 2004; Borsani et al., 2007; Pavan, personal observation 38 Richardson et al., 1995; Moore et al, 2002


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Although atypical mass strandings represent the most dramatic class of incidents related to acute sound exposure, at least for certain marine mammal species (beaked whales)39, it should be remembered that the effects of repeated non lethal exposures and of increased noise levels are generally unknown but may potentially have significant both short and long term effects. Furthermore, the biology of disturbance and the effect of noise on the fecundity of marine mammals and their prey species are not well understood.

Noise may not always have an immediate impact on cetacean populations but may indirectly effect them through its effects on prey abundance, behaviour and distribution. Cetaceans can be divided into two major groups by their dietary requirements, (1) Piscevores, and (2) Planktivores. Odontocetes fall into the former group and mysticeti into the latter, although it should be noted that their diet may overlap.

Therefore, there is a growing consensus about the potential impact of man-made sound on marine fauna. The conscious awareness of this issue has been reinforced by a series of strandings coinciding with the exposure to man-made sound sources. Anthropogenic originated sound can affect cetaceans in different ways, and these effects can be on an individual or group level. The question of how and why man-made sound affects marine mammals is controversial and it is therefore essential to consider that the control and adjustment of marine noise is a question that could demand great financial cost, and yet it remains vital for research into this area to be continued in the future. By now, the following associations can be established:

Table 4.1 Types of anthropogenic sound that can affect marine mammals40

Source Effects of greatest concern

Ships Masking Habitat displacement

Airguns (compressed air) Masking Physical trauma Auditory loss Behavioral changes Habitat displacement Behavior conditioning effects

Intense low or mid frequency sonar activity Physical trauma Auditory loss Behavioral change Behavior conditioning effects

39 Frantzis, 1998; Evans and England, 2001; NOAA, 2001; Dep't of the Environment, 2002; Evans and Miller, 2004; Fernndez, 2005 40 Boyd et al. 2008


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Pile driving Physical effects Auditory loss Behavioral change Behavior conditioning effects

Other types of sonar (deepwater soundings, trawlers, fishing boats)

Masking Auditory loss Behavioral change Behavior conditioning effects

Dredgers Behavioral change Habitat displacement Behavioral conditioning effects

Drilling Auditory loss Behavioral change Behavior conditioning effects

Towed fishing materials Behavioral change Behavior conditioning effects Habitat displacement

Explosions Physical trauma Auditory loss Behavioral change Behavior conditioning effects

Recreational boats Masking Behavioral change Behavior conditioning effects

Acoustic hardware Behavior conditioning effects

Airplanes Behavior conditioning effects


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4.1. Classification of effects

Based on the information provided in the background document41, and as defined by Richardson et al. (1995), the effects of (anthropogenic) noise on the marine fauna can be grouped in simplified, progressively increasing scale as: Negligible Behavioural responses: change in the animals behaviour in general. For instance,

change of feeding or mating habits due to avoidance of a noisy area; Masking: decrease in the perception capabilities of sounds of interest (for example

communication or echolocation signals) due to interfering noise generally at similar frequencies;

Temporary threshold shift (TTS): a temporary elevation of the hearing threshold due to noise exposure: depends on exposure level, sound type and duration. It may impair temporarily the detection or predator avoidance capabilities of the individual, or his orientation capabilities (also with reference to deep diving procedures)

Permanent threshold shift (PTS ): a permanent elevation of the hearing threshold due to noise exposure (partial deafness, a kind of physical injury that has long term consequences for the animal): depends on exposure level, sound type and duration;

Injury: tissue damages at different levels, including embolies, due to high level sound exposure;

Death (or lethal injuries) It should be emphasised that this is a very preliminary scale based on effects derived from information on documented responses and modelling exercises. The scale is rather subjective:e.g. among non lethal effects and death there is a continuum spectrum of consequences of increasing seriousness where a number of reference points can be set.42 Taking into account that noise has potential effects on a wide range of distances, up to several kilometres, the above effects can also be subdivided into short-range ones, occurring only in the immediate vicinity of the source and / or within the area the activity is carried out (for example vicinity of a high power sound source) or long-range ones, occurring at larger distances. Yet, zones of noise influences are so diverse and depending on so many variables, that a further split in spatial scales of effects is difficult to quantify.

Another note on the above classification is that it is based on direct effects, affecting individuals and/or populations within a given species. Other effects may influence different aspects of the habitat that can interfere on the survival capabilities of that species. For example, noise can cause a decrease in the population which constitutes a primary element in the diet of a given species, which will be therefore affected in an indirect way.

Finally, it should be noted that the impact of noise is very much dependent on the specific noise source, in terms of intensity and spatial localisation.

41 OSPAR, 2009a 42 Parsons and Dolman, 2004


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4.2. Ranking of effects

The discussion and debate over how marine mammals may be affected by human noise in the ocean43, has mostly been directed at understanding the physiological impacts from short-term, small-scale (i.e., acute), high intensity exposures. However, there is recognition that long-term, large-scale (i.e., chronic), low intensity exposures might also be affecting individuals and populations, and acoustic masking is often mentioned or implied as a probable detrimental mechanism44.

IMO (2008) states that the primary concern regarding potential adverse effects of shipping noise is not related to acute exposures, but rather to the general increase in background ambient noise that may result from vessel operation. That is to say, the potential environmental impacts from ship noise are likely related to masking of communication systems. While there is insufficient data to conclude that ambient noise levels are increasing in large areas of the ocean as a function of vessel sounds, two recent studies off California analysing measurements over several decades do indicate changes that, for these particular areas, suggest an increasing trend in background noise of ~ 3 dB/decade in the low-frequency band45 . Because of the logarithmic nature of sound and what is known about hearing systems in mammals, seemingly changes in background noise levels can result in large reductions of communication range. It is likely that for a broad range of marine mammals, acoustic masking is having an increasingly prevalent impact on acoustic information transfer including both communication and other key activities such as navigation and prey/predator detection. The aspect of masking will be analysed in details in the following section.

43 National Research Council 2000, 2003, 2005, Cox et al. 2006, Southall et al. 2007 44 Payne & Webb, 1971, NRC 2000, 2003, Southall 2005, McDonald et al. 2006, Nowacek et al. 2007, Hatch et al. 2008 45 Andrew et al, 2000; McDonald et al, 2006


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4.3. Signal masking

The process known as auditory signal masking happens when noise reduces, partially or completely, the capacity to hear sound or signals. The scope of interference depends on the spectrum and the temporal-spatial relationship between the signals and the masking noise, among other factors46. In addition to the acoustic effects of overlapping from auditory masking, trauma associated to noise can result in an either lethal or sublethal impact. The lethal impacts are those that cause immediate death to a subject exposed directly to an intense sound emission. The sublethal impacts are those cases where the auditory loss is caused by an exposure to perceivable sound, and are called acoustic trauma. In these cases, a sound exceeds the tolerance limit of the ear. Basically, any sound that a mammal can hear can induce, at a certain level, a lesion to the ear, causing a reduction in sensitivity. The minimal level at which a sound (frequency) can be heard is called hearing threshold. If an individual requires a significantly higher intensity than the normal level for the species, this will be translated as a hearing loss marked by a shift in the threshold level. Any particular noise at a sufficiently high level will shift the hearing threshold, while other noise at the same level will not cause similar changes. The question is to know if a received emission produces a temporal or permanent loss. (see point 5.2). We can conclude that masking is the increase of the auditory threshold for a sound due to the presence of another sound47. It has been confirmed48 that signal masking is particularly pronounced if the spectral frequency of the masking noise superimposes the critical band surrounding the frequency of the signal.

The majority of underwater activities produce low frequency sound. This noise can potentially mask the communication signals of all baleen whale species that use frequencies below 1 kHz and some odontocetes, such as sperm whales. The direct consequences of this masking of communication and related signals can be diverse: group dispersal, reducing a fundamental part of their interaction with the natural environment (echolocation)49, impaired feeding ability and the separation of mothers from young with usually fatal consequences for the calf. It is believed that continuous noise is more detrimental than temporal signals50 and that low frequency sounds possess a greater masking effect than higher frequencies51. There is still no data on the effect of low frequency masking, nor direct measurements with baleen whales.

46 Southall et al. 2007 47 Erbe 1997 48 Fletcher 1940, in Johnson et al. 1989 49 Andr and Natchtigall, 2007 50 Richardson et al. 1995b 51 Erbe 1997


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The responses of different species to the presence of ambient noise have different results, some of which have been documented. For example, sperm and pilot whales have been observed to cease vocalizations during the exposition of intense noise sources52. The contrary has also be shown as in the case of Beluga whales53 and dolphins54 which increase the intensity and frequency of their vocalizations to compensate for the presence of ambient noise. Despite these strategies, it is likely that the level of efficient communication has been reduced and that this reduction has limited their ability to re

underwater radiated noise

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