Passive Acoustic Monitoring Noise in the Ocean

Transcription

1 Passive Acoustic Monitoring Noise in the Ocean

2 Passive Acoustic Monitoring Monitor anthropogenic sound in the ocean and limit exposure of marine mammals to that sound Lots of sources of sound in the oceans Anthropogenic noise Biological noise Other forms of ocean noise The role of Passive Acoustic Monitoring in protecting marine life

3 Noise in the Ocean

4 Physics of the Ocean Absorption

5 Noise in the Ocean 5

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7 Passive Acoustic Monitoring - Sorting the animals from the noise Generally If we are protecting animals from noise we are in a very noisy environment We need to understand the noise We need to understand the animals We need to find the animals amongst the noise and then track and position them relative to the noise source If they are within a danger zone then the source is stopped.

8 Noise in the Ocean Noise in the ocean can be considered in three areas Anthropogenic noise Man made, shipping, pile driving Noise from ocean Fauna Whales, fish, Natural non biological noise Wind, rain, waves, seismic

9 Anthropogenic Sounds

10 Noise in the Ocean Anthropogenic Noise - Examples

11 Noise in the Ocean Anthropogenic Noise - Seismic Survey

12 Noise in the Ocean Anthropogenic Noise - Seismic Survey

13 The Seismic Exploration Process

14 Seismic Exploration Sound Source

15 Seismic Survey Vessel PGS Titan Anthropogenic Noise - Seismic Survey Streamer Deck Work Boat

16 Seismic 200cu inch Air Gun

17 Seismic Air Gun (High Gain) Notice how the biological signal can clearly be seen on the spectrogram. In practice filters are often used to lower the gain of mitigation systems at low frequencies to avoid clipping

18 Noise in the Ocean Anthropogenic Noise - Seismic Survey The source level of an air gun array Often quoted as 250 db re 1mPa at 1m But the actual source pressure never reaches this level The numbers represent a virtual source Actual levels at 1m are significantly lower Error is caused by back projection to 1m The source is distributed source and not a point

19 Noise in the Ocean Anthropogenic Noise Piling Inshore

20 Noise in the Ocean Anthropogenic Noise Piling - Oil & Gas Piling is used to create anchors in the seabed that are used to secure floating oil and gas facilities Typically in water depths 500m to 3000m Small number of large piles Very large vessels and piling tools

21 Piling - Offshore Wind Installation of offshore wind turbine foundations in shallow water Require piling to the seabed 1,000kg hammer at 10/m/s Wave travels downwards (pushes pile into ground) Radiates sound Through water horizontally into the sea bed

22 Offshore Wind Monopile or tower design Multiple, smaller piles for tower/frame designs Space Frame (Tripod) Space Frame (Jacket) Space Frame (Tri-pile)

23 Monopiles Most common for turbines Hammered into the sea bed

24 Offshore Wind - Vessels Transport and install turbine structures

25 Offshore Wind Floating Statoil Hywind is a floating turbine it can be floated into position but will still need anchors that will need piling

26 Sound Source Measurement Case Study - B6 Jetty Milford Haven

27 Drilling Drilling offshore does not produce high sound levels but can produce low-frequency sound that can affect certain species May be on or near location for months

28 Propeller Cavitation Spectrogram

29 Propeller Cavitation Can account for 80-85% of ship radiated noise

30 Anchor Handling Spectrogram

31 Ordnance Many areas have unexploded ordnance on the seabed. Average one detonation a week This must be cleared for pipeline and cable routes, and for offshore wind installations Normally means detonation in-situ This must be mitigated

32 Naval SONAR SONAR (Sound Navigation And Ranging) is a means of determining the distance to an acoustically reflective object or surface. An acoustic pulse is emitted, and the two way travel time of that pulse is measured. From the knowledge of the speed of sound through water, the distance can be calculated. Some Naval SONAR used for submarine detection are high power and in the 1-10kHz band. Navies under pressure to research impact and mitigate (NOAA) as required

33 Cylindrical Sonar Arrays

34 Hull Mounted Sonar Arrays (HMS)

35 LFA Military Sonar

36 Aircraft - Sikorski Sea King

37 Anthropogenic Noise Summary Anthropogenic noise in the sea is mostly intentional and useful but with repercussions on wildlife It comes from a wide range of activities Frequency range from fractions of Hz to Hundreds of khz Mitigation measures are generally regulatory requirement Trend is to more regulation world wide and for more detailed local regulation Individual species, Particular areas

38 Biological Noise

39 Noise in the Ocean Noise from Fauna The full range of marine animals that produce (and by inference) hear or are affected by noise in the ocean is unknown The known frequency range is from a few Hz to hundreds of khz. The prime areas of concern are Marine Mammals and fish however Crustacea also produce sounds

40 Noise in the Ocean Fauna - Marine Mammals

41 Noise in the Ocean Fauna - Two Suborders of order Cetacea Suborder Odontoceti (toothed whales) Echolocate (bio sonar) Includes blackfish, sperm whale, dolphins, porpoises and beaked whales Suborder Mysticeti (baleen whales) Have rows of baleen plates instead of teeth Includes blue whale, fin whale, humpback whale, gray whale, right whales and many others

42 Noise in the Ocean 42

43 Odontocetes Conical shaped teeth for prey capture Huge variation in body type and size Single blow hole Use Echolocation Communication Killer Whale Jawbone

44 Variation in Body Size 1-20 metres

45 Echolocation Sensing environment Produce clicks that travel out, hit objects and reflect back Produced by a structure in the airway Sound received through the lower jaw Low frequency clicks travel further but can only be used for big objects High frequency clicks can discriminate small objects but don t travel as far

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47 Common Dolphin Whistles

48 Deepest Diver: Sperm Whale Dive depth: 3km~1.5 miles

49 Sperm Whale Clicks

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51 Sperm whale clicks powerful broadband, used for echolocation of prey and topography, also communication as codas Detectable using PAM at up to 6 km (varies depending on vessel noise)

52 Sperm whale skull Note concave skull where the frontal sac sits Reflects clicks through the spermaceti and junk (melon)

53 Click energy travels back through the spermaceti organ and is reflected off the frontal sac into the junk where it is focused The reflections form a multi pulse click which allows whale size to be determined by clicks alone Returning clicks are picked up by the lower jaw and transmitted to the inner ear via a fat filled canal

54 Mysticetes: The Baleen Whales Typically very large 2 blowholes Low frequency vocalizations Baleen instead of teeth

55 Noise in the Ocean 55

56 Baleen Plates Hang as parallel rows from the upper jaw Are made of keratin Are used as a strainer to capture food Allows Baleen whales to eat krill and small fish by the ton

57 Baleen Whales

58 Blue Whale The Largest animal ever: up to 33 metres long Hz vocalisations - moans

59 Fin Whale Up to 27 metres long Hz vocalisations - moans

60 Bryde s Whale Up to 15 metres long Hz vocalisations moans and pulses

61 Humpback Whale Up to 18 metres long Hz elaborate song (with much higher harmonics)

62 Humpback Whale

63 Grey Whale Up to 15 metres long 200Hz 1 KHz vocalisations grunts and pulses

64 Bowhead Whale Up to 20 metres long Hz vocalisations - moans

65 Southern Right Whale Up to 17 metres long Hz vocalisations moans and grunts

66 Right Whale tones

67 ??? Spectrogram

68 Other Marine Mammals Walrus Bell tone Walrus bell tone

69 Walrus Spectrogram

70 Other Marine Mammals Pinnipeds ringed seal

71 Dugong

72 Fish Atlantic Croaker Family Sciandae: Drums, Croakers and Weakfishes Atlantic Croaker Micropogonus undulatus

73 Atlantic Croaker

74 Fish Whitesided Grunt Family Haemulidae Grunts Whitesided Grunt

75 Whitesided Grunt

76 Fish Various Courting Haddock Flying Gurnard

77 Crustacea Snapping Shrimp Crustacea: Alphus Synalpheus spp., etc.:

78 Snapping Shrimp Spectrogram

79 Snapping Shrimp Spectrogram

80 Snapping Shrimp Single Click

81 Snapping Shrimp Noise Generation Video

82 Crustacea Stridulating Crab

83 Natural Noise in the Ocean

84 Natural Noise in the Ocean Wave motion and action Seismic Activity Volcanism Ice Movement These all contribute to background noise in the ocean

85 Arctic Ice & Micro Seismic Events Micro Seismic

86 Summary Marine mammals are an extremely diverse and specialised group They have evolved from land mammals and are closely related to Hippopotamus Sub order of cetaceans; Odontocetes echolocation Mysticetes baleen plates Characteristic vocalisations Hearing Responses uncertain

87 Summary Marine mammals, fish and crustacians produce a wide range of noises over a wide frequency range Anthropogenic noise covers the same frequencies and can be of much greater intensity The science on the likely impact is not established Mitigation of anthropogenic noise is a major concern in such a complex environment Passive Acoustic Monitoring is at the leading edge of mitigation for the impact of sound on marine mammals

88 Passive Acoustic Monitoring

89 Mitigation of Anthropogenic Noise Most Countries have regulation on noise in the ocean Large noises in the Oceans are subject to permits Often limit how close a marine mammal can get to the sound source Typically 500m to 2km Species dependent Use Passive Acoustic Monitoring to detect animals in the exclusion zone as well as visual observers Generally difficult due to vessel noise around the source

90 Sperm Whale Detection during a Seismic Survey

91 Dolphin Detections

92 Humpback Whale Detection

93 Passive Acoustic Monitoring Extracting Signal from Noise Operator skill is very important to the success of operation Looking for advances in detection capability Improvement in Signal to noise Need more knowledge of animal vocalisations and noise in the ocean Still so much to learn about the ocean and its animals

94 Thank You