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Thursday: 03/20/2014

Thursday: 03/20/2014. Go to: Kahoot.it Pin is : 1581 Enter Your Name. Thursday: 03/20/2014. Each individual must answer the following questions in complete sentences: Sketch and label, or describe the flow of air & sound when a small cetacean uses echolocation to find prey.

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Thursday: 03/20/2014

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  1. Thursday: 03/20/2014 Go to: Kahoot.it Pin is: 1581 Enter Your Name

  2. Thursday: 03/20/2014 Each individual must answer the following questions in complete sentences: • Sketch and label, or describe the flow of air & sound when a small cetacean uses echolocation to find prey. • Describe four major physiological adaptations that deep-diving cetaceans have to dealing with high pressure. • What are the four modern whaling countries and what justification is used by each for this illegal practice (not all answers will be found in the notes)? • What are two major differences between mysticeti and odontoceti? Give an example of each animal. • Explain the conservation laws that were passed in 1911, 1972, and 1985.

  3. Acoustics and Biology Acoustics • loudness (amplitude or pressure level) • pitch (frequency) Use of sound by marine animals • Predation/defense • Communication and social interaction

  4.  Same frequency, Different amplitude Same amplitude, Different frequency Amplitude determines sound level pressure or loudness Frequency determines “pitch”

  5. Loudness (Amplitude, sound level) Chart shows loudness in dB of some things we are familiar with Sound levels in air and water have different reference levels, so 0 dB (air) ≈ 26 dB (water)

  6. Marine animal sounds can be made up of multiple frequencies The sound spectrum gives the pressure level at each frequency Intensity  pressure2 dB = 10 Log10(intensity)

  7. Spectrogram shows how sound spectrum changes over time

  8. An invertebrate example: snapping shrimp claw crab Snapping shrimp make noise to stun their prey. They create a cavitation bubble that “snaps” as it collapses. http://www.dosits.org/resources/all/featuresounds/snappingshrimp/ http://stilton.tnw.utwente.nl/shrimp/

  9. A fish example: Atlantic Croaker Some fish use sound for courting and as a fright response

  10. Toothed whales Smaller (1.5 to 17 m long) Social Most are not migratory Chase and capture individual fish, squid, crabs Use sound to echolocate, communicate Baleen whales Larger (15 to 30 m long) Often solitary Long annual migrations Feed on aggregations of krill, copepods, small fish Use sound only to communicate

  11. Baleen (mysticete) whales Toothed (odonticete) whales

  12. http://www.dosits.org/audio/interactive/#/46

  13. Larger whales produce lower-frequency sound • Larger whales can dive deeper • Toothed whales forage deeper than baleen whales

  14. Outgoing sound is generated by the vocal cords and projected through the melon. Incoming sound is received through the jaw, which transmits sound waves through a fat channel to the “ear” (auditory bulla).

  15. Social calls Frequency (Hz) Dolphins live in social groups that stay together 5-10 years. They have “signature whistles” that can be used to recognize individuals at distances of >500 m. Time (s)

  16. Communication frequencies Toothed Baleen Thick bars: most common vocalizations Thin lines: extremes of frequency

  17. Echolocation using echoes from sound pulses or clicks Whale can determine distance, angle, size, shape, etc. from sound echoes

  18. Echolocation frequencies Mellinger 2007

  19. Toothed whale prey Squid and large fish are: • More likely to be solitary • Good acoustic targets (squid pens and fish swim bladders have density different from water) Plankton are: • More likely to aggregate • Poorer acoustic targets (density similar to water) Baleen whale prey

  20. A good invention for listening to whales: acoustic whale tag (D-Tag) • Acoustic sensors (hydrophones) and 3D accelerometers in a waterproof, pressure-resistant case, mounted on suction cups • Carefully sneak up on whale, attach D-Tag • Record audio, pitch, roll, heading and depth • Tag pops off, floats to surface 18 hours later Mark Johnson with D-Tag

  21. Long-Term Geotags:

  22. Toothed whale foraging:Beaked whales dive deep to find prey Natacha Aguilar de Soto (Yellow indicates echolocation) Peter Tyack et al.

  23. Baleen whale foraging: Right whales dive to bottom of the mixed layer where plankton are most concentrated Fig. 4. Eubalaena glacialis and Calanus finmarchicus. (a-d) Examples of diving and tracking observations during feeding behavior. Contoured C. finmarchicus C5 abundance estimated from the OPC casts is shown. Color scale shown in (d) applies to all plots. () Times of visual contacts. () Times and locations at which a resurfacing occurred and a conductivity-temperature depth/optical plankton counter (CTD/OPC) cast was conducted. Solid and dashed lines indicate the sea floor and the top of the bottom mixed layer, respectively, measured at the location of each CTD/OPC cast. Baumgartner and Mate 2003

  24. Marine mammal sound levels are generally between 100 and 200 dB Baleen whales Toothed whales Seals, sea lions, and walruses Manatees and dugongs Echolocation (toothed whales)

  25. Worcester & Spindel 2005

  26. Blue whales migrate and communicate over long distances

  27. Man-made noise in the ocean These add constant background noise Outboard engine 6,300 Hz Commercial Ship 10 to 20,000 Hz Airgun 10 to 500 Hz Up to 232 dB Low-Frequency Active Sonar 100 to 500 Hz 230 to 240 dB These are loud enough to damage tissues and cause hearing loss

  28. Humans add noise to the ocean Potential effects of man-made sounds on marine mammals: • Temporary or permanent hearing loss or impairment • Disruption of feeding, breeding, nursing, acoustic communication and sensing • Death from lung hemorrhage or other tissue trauma • Psychological and physiological stress

  29. Since the invention of propeller-driven motors (~150 years ago), • Background noise level in the ocean has increased by ~45 dB • Lowest background noise f has dropped from ~100 Hz to ~7 Hz After motors ~7 Hz Before motors ~100 Hz After motors ~75 dB Before motors ~30 dB

  30. Can use transmission-loss curves to calculate the effective communication range Blue whale song 20 Hz, ~155 dB Pre-motor noise level 30 dB Whale song stays above ambient noise level for ~2,000 km e.g. San Diego to Seattle (area 10,000,000 km2 ) Current noise level 75 dB Whale song stays above ambient noise level for ~60 km e.g. New Brunswick to NYC (area 10,000 km2) Blue whale

  31. Range of effective communication for blue whale singing at 20 Hz and 155 dB Range before mid-1800s Current range

  32. Noise-induced mass strandings Mass strandings associated with Navy sonar activity The Bahamas (2000): 14 beaked whales, 1 spotted dolphin, 2 minke whales Cranial Bleeding Naval Training Exercise: SONAR The Canary Islands (2002): 14 beaked whales Gas bubbles and bleeding in multiple organs, likely from surfacing too quickly

  33. Noise-induced mass strandings Mass strandings associated with air guns Tasmania and New Zealand (2004): 208 whales and dolphins Mass Stranding: ExxonMobile Seismic Testing Senegal and Madagascar (2008): 200 pilot whales and melon-head whales Mass Stranging: Dolphins & Seismic Testing Northern Peru (February 2012) 900+ dolphins stranded or washed ashore dead • Middle Ear Bleeding • Cracked bones in ear • Hemorrhage in mandibular fat • Air bubbles in liver, kidneys, bladder, and blood vessels • Pulmonary emphysema * The last two are associated with acute decompression syndrome

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