Een presentatie van Ron Kastelein van SEAMARCO over zijn akoestisch onderzoek naar het effect van geluid op zeezoogdieren en vissen in hun leefomgeving. Wat voor geluiden kunnen deze dieren horen en op welke frequentie? Wat is het effect van door de mens geproduceerde geluidsbronnen op de activiteiten in het leven van het dier, zoals het vergaren van voedsel, het detecteren van natuurlijke vijanden en het vinden van soortgenoten? Gegeven op dag 2 van Soundbites by Merford met als thema: Duurzaamheid. http://www.merford.nl/soundbites

1. Akoestisch onderzoek voor een
duurzaam gebruik van het mariene milieu
Ron Kastelein
SEAMARCO
Symposium
Merford
1 November 2012, Gorinchem 1

2. Noise reduction measures pump & filtration system
(To reduce TTS before a session)

3. Measures to reduce the pool’s reflectivity
Coconut mats lining the walls
Sand layer on the bottom

4. Bio-filteration for clean and clear water
4

5. Importance of sound for marine fauna
5
Even during the day, when diving to depth, vision is useless

6. Marine fauna often forages at night or 24/246

7. Sound is as important to marine mammals and fish
as light is to most terrestrial animals
7

8. Marine animals use sound for:
• Communication (find partner)
• Navigation (just listening or echolocation)
• Food finding (just listening or echolocation)
• Avoiding predators
Natural and anthropogenic background noise may
reduce the efficiency of these activities
8

9. Natural noise sources
Biological Non-
Non-biological
9

10. Anthropogenic activities producing underwater noise
Shipping Dredging Wind parks
Fisheries Detonations Seismic surveys
Oil & Gas Pile driving Sonars
10

11. Anthropogenic noise and marine fauna
• Can they hear it, & at what distance ?
• Does it damage their ears & at what distance ?
• Does it influence their behavior, & at what distance ?
11

12. Potential effects of sound
12
Level decreases with distance & thus effect decreases

13. Detection of sound
Level
Spectrum
Sound Duty cycle
Water temp
Water depth On/off slope
Salinity Signal
Propagation
Bottom contour duration
Sediment type
Marine animal species Hearing properties organism
Basic audiogram
Critical ratio
Ambient noise
(masking, Audibility Directivity hearing
reducing Signal duration-thresholds
detection)
Attentiveness
Detection
13

14. Basic audiogram (hearing thresholds)
Q: It’s 20 dB, can they hear it ? A: Which frequency ?
Pain threshold
Audible
Speech
2,000 4,000 16,000
14
Same SPL:0.5, 1, 2, 4, 8, 16 kHz Staircase: 2 kHz
Staircase:

15. Hearing study with harbor porpoise

16. Hearing study with harbor porpoise
Heard > not heard > heard
(Example of 1 frequency)

17. Hearing study with harbor seal

18. Hearing study with harbor seal
Heard > heard > not heard 18

19. Underwater audiograms (hearing threshold curves)
120
Harbor porpoise (Kastelein et al., 2010)
110
100
Sound Pressure Level (dB re 1 uPa)
Harbor seal (Kastelein et al., 2009)
90
80
70
60
50
40
30 Human hearing range
20
0.1 1 10 100 1000
Frequency (kHz)
Each species has a different
hearing range & sensitivity
19
depending on their ecology

20. Masking
Acoustic masking is like fog in the visual world
20

21. HF Masking is freq. dependent
LF
Filter bands in cochlea
128 64 16 2 0.25
kHz
2 kHz tone masked by 20-250 Hz band noise
2 kHz tone masked by 1-4 kHz band noise

22. Masking of communication
22

23. Masking of fish
communication
dB re 1 uPa/1m - 1/3-octave bands
Shipping noise
200 Fish & ships
190
Free-field SL
180
170
160
150
140
10
20
40
80
1 60
3 15
6 30
1.25
2.5k
5k
1 0k
2 0k
4 0k
23
Frequency [Hz]

24. Short duration signals more easily masked
Long vocalizations can be heard in “gaps” in noise
5000ms
120
4000ms
50% Detection threshold (dB re 1 µPa)
110 3000ms
100 2500ms
90 2000ms
1500 ms
80
900 ms
70
600 ms
60
100 ms
50 50 ms
40 10 ms
30 5 ms
1 ms
20
0.1 1 10 100 1000 0,5 ms
Frequency (kHz) 0,1 ms
Sound demonstration, 2 kHz: loud quiet

25. Temporary hearing Threshold Shift (TTS)
(“Rock concert effect”)
Baseline Noise exposure Post-noise
exposure
hearing
hearing
threshold threshold
25

26. Hearing threshold (dB)
Noise exposure
Baseline TTS growth Plat. Recov. Back to baseline
Recov.
Time
26

27. Ecological effect of TTS depends on:
• The duration of TTS (exposure duration)
• Recovery of hearing after noise is gone/reduced
• The affected hearing frequency
27

28. “Loud sounds”
Permanent hearing Threshold Shift (PTS)
28

29. Effect of sound on behavior
29

30. Three types of potential effects of u/w sounds
1) Effects on behavior
a) Use of space
b) Activity level
2) Masking (Listening and echolocation)
3) Effects on hearing sensitivity (TTS & PTS)
30

31. Example of a clear behavioral effect
The name “harbor porpoise” was given
because this toothed whale entered harbors
31
Vessels were driven by man and wind power

32. Modern harbor of Rotterdam: no more porpoises
32

33. • Under each ship there is half a sphere of noise
• A part of the sphere is the “Zone of discomfort”,
which is not entered by a porpoise
noise noise

34. Example of behavioral response to sound
Effect of sonar sweeps
Mitigation: up-sweep versus down-sweep34

35. Example of results of a Behavioral Response Study
35

36. Example of a behavioral response to sound
Harbor seal, Lofitech AHD
36
Mitigation of pile driving

37. Example of a behavioral response to sound
Sea Bass, 500 Hz (hearing up to ~1 kHz)
Mitigation: Fauna Guard 37

38. Fauna Guard
Reduced fish mortality by underwater explosions
38
Van Oord, Dredging and Marine Contractors

39. Effects detours due to aversive sounds:
• Less time for foraging
• Potential displacement to less favorable
foraging areas
• Increased activity level leads to increased food
requirement
• Mother calf separation
39

40. Need for underwater sound criteria (ARBO)
Criteria range
Cumulative effects due to multiple sound sources
40

41. Population Consequence of Acoustic Disturbance
(PCAD model)
Translation effects on individuals to effects on populations
National Research Council (2005)
41

42. Research to reduce
environmental impact of
human activities at sea
42
researchteam@zonnet.nl