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Thursday: 03/20/2014Each individual must answer the following questions in complete sentences:

1.Sketch and label, or describe the flow of air & sound when a small cetacean uses echolocation to find prey.

2.Describe four major physiological adaptations that deep-diving cetaceans have to dealing with high pressure.

3.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)?

4.What are two major differences between mysticeti and odontoceti? Give an example of each animal.

5.Explain the conservation laws that were passed in 1911, 1972, and 1985.

Acoustics and Biology

Acoustics• loudness (amplitude or pressure level) • pitch (frequency)

Use of sound by marine animals• Predation/defense• Communication and social interaction

Same frequency,Different amplitude

Same amplitude,Different frequency

Amplitude determines sound level pressure or loudnessFrequency determines “pitch”

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)

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)

Spectrogram shows how sound spectrum changes over time

Snapping shrimp make noise to stun their prey.They create a cavitation bubble that “snaps” as it collapses.

http://stilton.tnw.utwente.nl/shrimp/

claw crab An invertebrate example: snapping shrimp

http://www.dosits.org/resources/all/featuresounds/snappingshrimp/

Some fish use sound for courting and as a fright response

A fish example: Atlantic Croaker

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

Toothed (odonticete)

whales

Baleen(mysticete)

whales

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

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

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).

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)

Fre

quen

cy (

Hz)

Social calls

Communication frequencies T

ooth

ed

Bal

een

Thick bars: most common vocalizationsThin lines: extremes of frequency

Whale can determine distance, angle, size, shape, etc. from sound echoes

Echolocation using echoes from sound pulses or clicks

Mellinger 2007

Echolocation frequencies

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

Toothed whale prey

-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 laterMark Johnson with D-Tag

A good invention for listening to whales: acoustic whale tag (D-Tag)

Long-Term Geotags:

Toothed whale foraging:Beaked whales dive deep to find prey

Natacha Aguilar de Soto

Peter Tyack et al.(Yellow indicates echolocation)

Baumgartner and Mate 2003

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.

Baleen whale foraging: Right whales dive to bottom of the mixed layer where plankton are most concentrated

Baleen whales

Toothed whales

Seals, sea lions, and walruses

Manatees and dugongs

Echolocation (toothed whales)

Marine mammal sound levels are generally between 100 and 200 dB

Worcester & Spindel 2005

Blue whales migrate and communicate over long distances

Airgun10 to 500 HzUp to 232 dB

Outboard engine6,300 Hz

Commercial Ship10 to 20,000 Hz

Low-Frequency Active Sonar100 to 500 Hz230 to 240 dB

These are loud enough to damage tissues and cause hearing loss

These add constant background noise

Man-made noise in the ocean

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

Before motors~30 dB

After motors~75 dB

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

Before motors~100 Hz

After motors~7 Hz

Blue whale song20 Hz, ~155 dB

Pre-motor noise level30 dBWhale song stays above ambient noise level for ~2,000 kme.g. San Diego to Seattle(area 10,000,000 km2 )

Current noise level75 dBWhale song stays above ambient noise level for ~60 kme.g. New Brunswick to NYC(area 10,000 km2)

Bluewhale

Can use transmission-loss curves to calculate the effective communication range

Range of effective communication for blue whale singing at 20 Hz and 155 dB

Range before mid-1800s

Current range

Noise-induced mass strandings

Mass strandings associated with Navy sonar activity The Bahamas (2000):14 beaked whales, 1 spotted dolphin, 2 minke whalesCranial Bleeding

Naval Training Exercise: SONARThe Canary Islands (2002):14 beaked whalesGas bubbles and bleeding in multiple organs, likely from surfacing too quickly

Noise-induced mass strandings

Mass strandings associated with air gunsTasmania and New Zealand (2004): 208 whales and dolphins

Mass Stranding: ExxonMobile Seismic TestingSenegal and Madagascar (2008): 200 pilot whales and melon-head whales

Mass Stranging: Dolphins & Seismic TestingNorthern 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