Marine Mammal Sensory

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Marine Mammal Sensory Sound Production
Systems MARE 390 Dr. Turner
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Sound
Production, transmission, reception of sounds
produced by marine mammals unique airborne
waterborne Manner differs between taxa
media Purposes Communication within species to
location of unseen targets with echolocation
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Sound Propagation
Acoustic energy characterized by velocity,
frequency, wavelength, amplitude Human hearing
18 Hz to 15kHz Marine mammal vocalizations above
below lt 18 Hz (infrasonic) gt 20 kHz
(ultrasonic)
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Sound in Air Water
Sound travels 5X faster in water (1550m/s) than
air (340m/s) depending upon temperature
salinity (depth) Why increased capacity for
sound production? Poor light transmission
vision in water
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Functions of Sound
Dolphins large variety of whistle-like sounds
can understand complex linguistics Many sounds
used for communication Signature calls identify
individuals Loud impulse sounds debilitation
of prey, self-defense, intimidation of
conspecifics Echolocation active detection
identification of a target with sound
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Acoustic Signal
Frequency, duration, energy level are portrayed
as Spectrogram (frequency with time) Power
spectrum (sound pressure levels with
time) Frequency spectrum (sound pressure levels
with frequency)
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Acoustic Signal
Spectrogram (frequency with time) Power
spectrogram (sound pressure levels with
time) Frequency spectrum (sound pressure levels
with frequency)
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Use of Sounds
Low frequency sounds attenuate more slowly so
good for long distance communication High
frequency sounds attenuate more quickly but
have the potential to provide more information on
target resolution
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Mammalian Ear
Evolved for detection of sound vibrations in
air Amplitude (loudness) determined by the
number of hair cells stimulated Frequency
(pitch) depends upon the distribution pattern of
stimulated hair cells
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Pinniped Sounds
Sounds produced 1 with larynx 2 - teeth
pharyngeal pouches Typical mammalian ear with
modifications amplify sound reception engorged
with blood during diving
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Cetacean Sounds
Nasal sacs ventral to blowhole produce sounds
including whistles echolocation Monkey-lips or
Phonic lips produce sounds as air is forced
through them tweaking end of air-filled balloon
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Cetacean Sounds
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Sperm Whale Head
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Sound Propagation
Melon contains low-density lipids which serve as
an acoustic lens to create focused directional
sound beams
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Mysticete Rhythms
Mysticete larynx possesses structures homologous
to vocal folds - are capable of sound generation
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Mysticete Rhythms
(U-fold) in the lumen of the larynx - vibration
of edges may generate sounds - walls of the
laryngeal sac can serve as a resonant space
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Sound Reception
All cetaceans have good hearing Auditory canal
narrow in odontocetes plugged in
mysticetes Glove finger projection of eardrum
into ear canal
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Odontocete Reception
Unique sound reception pathway jaw Pan Bones -
Posterior portions of mandibles, flared, thin to
transparency Filled with low density lipid
similar to melon Directly connects with the
auditory bulla of the middle ear
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Odontocete Reception
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Other Marine Mammals
Sea Otters Polar Bears no special
adaptations similar to terrestrial
mammals Sirenians have lipid filled zygomatic
process (skull bone) connects to ear
analogous to pan bone in odontocetes Poor
directionality and lack of high frequency sound
reception reason for high number of boat
strikes
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Pinniped Sounds
In air vocalizations classified by species,
age, sex Otariids more vocal than
phocids Male calls barks, roars,
grunts Mother-pup calls used specifically for
recognizing locating each other Underwater
vocalizations typically male songs
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Pinniped Sounds
Weddell seal
N. Elephant seal
California sea lion
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Other Marine Mammal Sounds
Walruses males produce a series of knocking
sounds Sirenians chirp-squeaks little
geographic variation key in keeping calves with
mothers Sea otters above water low-frequency
sounds similar to sea lions Polar bears
females defensive growls males - chuffs
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Other Marine Mammal Sounds
Walrus Manatee Sea Otter Polar Bear
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Cetacean Sounds
Echolocation projecting short-duration sounds
and listening for reflected echoes Signature
whistles narrow band frequency modulated (FM)
sound with harmonic structure specific to
individuals Mysticete sounds low-frequency
sounds used for long distance communication Prey
stunning sounds loud blasts of sound called
bangs to debilitate prey
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Echolocation
Used by about 20 of mammals (bats
odontocetes Evolved independently in 5 mammalian
lineages (bats, shrews, hamsters,
lemurs) Dolphins may use successive echolocation
clicks followed by multiclick processing
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Echolocation
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Echolocation
Bottlenose dolphin Rissos dolphin Beluga
whale Sperm whale
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Signature Whistles
Hypothesized that whistle broadcasts identity of
the animal other information (state of arousal,
fear, food, etc) More social animals whistle
more often Often different dialects representing
regional distributions
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Vocal Clans
Killer whales Sperm whales Pods share calls
including calls specific to individuals Pods are
loosely associated into clans share clan
specific calls as well some but not all calls
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Vocal Clans
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Prey Stunning Sounds
Blasts of sounds called bangs used to stun or
debilitate prey First identified in sperm whales
jaw claps Energetics of sperm whale feeding
ecology Evidence difficult to collect 240-250
db of sound required for stunning
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Empirical Evidence
Empirical studies suggest that sounds not enough
to debilitate playback experiments conducted
with live fish but not live dolphins/porpoises
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Mysticete Sounds
Hypothesized to have some form of echolocation
never substantiated Different equipment
form/function of sounds production in
odontocetes Most well known sound production
from humpbacks- male songs
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Mysticete Sounds
Broad system clicks pulses Low frequency whale
tones with very long wavelengths Humpbacks sing
long complex songs
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Humpback Songs
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Mysticete Sounds
Blue whale Humpback whale Bowhead whale
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Sound in the Ocean
Sound pollution thought to be as detrimental to
marine mammals as chemical, thermal,
physical NATO Navy Sonar war games ATOC
Acoustic Thermometry of Ocean Climate 260 watt
low frequency sounds
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Sound in the Ocean
Sound pollution thought to be as detrimental to
marine mammals as chemical, thermal,
physical NATO Navy Sonar war games ATOC
Acoustic Thermometry of Ocean Climate 260 watt
low frequency sounds
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Sound in the Ocean
Sources of Human-Generated Ocean
Noise Transportation Aircraft, ships and boats,
icebreakers, hovercrafts and vehicles on
ice Dredging and Construction Dredging, tunnel
boring, other operations. Oil Drilling and
Production Drilling from islands and caissons,
bottom-mounted platforms, and vessels
and offshore oil and gas production. Geophysical
Surveys Air-guns, sleeve exploders, and gas
guns. Sonars Fish finders, depth sounders, and
military systems. Explosions Ocean Research
Seismology, acoustic propagation, acoustic
tomography, acoustic thermometry
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Sound in the Ocean
Ocean Acoustic Tomography (Acoustic Thermometry)
- technique used to measure temperatures across
large distances in the ocean Sounds travel
between transmitter and receiver of known
distance (typically 100-5000km) time for sound
to reach received depends upon temperature of
water (and other variables)
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Sound in the Ocean
ATOC - Acoustic Thermometry of Ocean
Climate Most infamous regarding marine
mammals Public outrage and political reaction
primarily caused by misinformation
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Sound in the Ocean
AMODE (Acoustic Mid-Ocean Dynamics Experiment)
SYNOP (Synoptic Ocean Prediction) most recent
versions
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Workshop Navy Sonar and Cetaceans Why Does
RIMPAC have us on High Alert?
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What Is RIMPAC
Rim of the Pacific Exercise since 1971 World's
largest international maritime exercise Hosted
and administered by the US Navy, US Marine Corps,
US Coast Guard Hawaii National Guard Held
biennially in June and July in Hawaii
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Participants
Always United States, Canada, and Australia,
Sometimes United Kingdom, Japan, Republic of
Korea, Chile, and Peru Observers France,
Singapore, Malaysia, the Philippines, Thailand,
Colombia, Mexico, India, Ecuador, Indonesia,
China and Russia
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Purpose
Enhance coordination armed forces in Pacific Key
to military readiness conflict "hot
spots China Taiwan North Korea South
Korea, US, Japan
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Exercises
Conduct ship-sinking torpedo exercises Test new
naval vessels and technology
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Marine Mammals and Sound
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Patterns of Concern
Greece, May 1996 atypical mass stranding of 12
Cuviers beaked whales associated with acoustic
trials by vessels from NATO Bahamas, March
2000 16 whales (14 beaked, 2 minke) stranded over
2 days US Navy vessels were using active high
intensity sonar Madeira, May 2000 3 Cuviers
beaked whales over 4 days NATO naval exercises
involving multiple ships
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Patterns of Concern
Canary Islands, September 2002 14 beaked whales
(4 species) on same day as nearby International
naval exercise (Neo-Tapon 2002) Gulf of
California, September 2002 2 Cuviers beaked
whales near research vessel conducting seismic
surveys Canary Islands, July 2004 4 Cuviers
beaked whales, coincided with the naval exercise
Majestic Eagle, conducted 100 km to the north
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Patterns of Concern
Honshu Japan, 1950s until 2004 11 reported mass
strandings (total of 51 beaked whales ) Adjacent
base for operations US Navys Pacific 7th
Fleet Taiwan, February-March 2004 several
cetacean strandings including a beaked
whale Coincided with a joint US/Philippine
military exercise Almería, Spain 2006
atypical mass stranding of Cuviers beaked
whales coincident with a NATO naval exercise
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Patterns of Concern
Scotland, 2008 Cuviers beaked whales, dying at
sea and washing ashore Researchers are
investigating potential naval activities Other
species Minke, pilot (long short finned),
pygmy sperm, pygmy killer, other smaller
dolphins During RIMPAC Oahu, 2006 Pygmy Killer
Whale Molokai, 2008 Beaked Whale
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In Hawaii
3 species of beaked whales Highest sightings
West side Hawaii Island
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Why do we think they Strand?
Gas and fat emboli Acoustically mediated bubble
growth Dysbaric Osteotrauma (DOT) Behavioural
alterations Resonance Disseminated
Intravascular Coagulation (DIC) - coagulopathy,
bleeding diathesis
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Why do we think they Strand?
Gas and fat emboli - essentially the bends -
gases forced out of solution during rapid ascent
- causes clots, tissues damage, fractured
bones Acoustically mediated bubble growth -
although marine mammals protected from the
bends - sound waves cause gases to come out of
solution - exaggerates nitrogen effects
especially in deep divers
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Why do we think they Strand?
Dysbaric Osteotrauma (DOT) - produces chronic
lesions in bones - damage to marrow - long-term
effects of gas bubbles in fat/blood Behavioural
alterations - acoustic exposure is not the
primary cause - mechanism that causes a
behavioural response that induces beaked whales
to forgo natural diving protocols - animal with
nitrogen in blood could be frightened by sonar -
forced to alter its dive profile ascend faster
than normal
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Why do we think they Strand?
Resonance - Air-containing spaces in diving
mammals resonate sound - energy reflected or
absorbed damaging tissues Disseminated
Intravascular Coagulation (DIC) - coagulopathy,
bleeding diathesis - diathetic fragility, or the
tendency to bleed - may occur in concert with
resonance - bleeding becomes associated with
the tissues of resonating structures or air
spaces - may also result from a stress response
initiated by acoustic exposure
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Necropy Findings
Ear damage - massive ear damage and blood clots
along auditory nerve Acute systemic
haemorrhages - within the lungs, CNS,
kidneys Fat Gas emboli - in vessels from
brain, choroid plexus, visceral/parietal serosa,
kidneys
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Why do we think they Strand?
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What is the Governments Role
US Navy and NOAA (Oceanic Atmospheric
Admin) Working under National Defense
Exemption of the Marine Mammal Protection
Act Means Navy can take animals under MMPA for
purposes of Military Readiness - have to report
after - must take steps to reduce take
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How it works
US Navy contacts NOAA notifies about RIMPAC -
when takes place (July 6-30, 2010) - where takes
place Main Hawaiian Islands - supports
research before, during, after - reports out
afterwards After Action Report
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In Conclusion
Conclusive evidence is still lacking Many
scientists feel enough evidence to act Public
Scientific opinion Government has evidence
but afraid to act Navy sonar and cetaceans Just
how much does the gun need to smoke before we
act?
Marine Pollution Bulletin 56 (2008) 12481257