marine mammal sensory & sound production systems mare 390 dr. turner
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Marine Mammal Sensory & Sound Production Systems MARE 390 Dr. Turner. Sound. Production, transmission, & reception of sounds produced by marine mammals unique – airborne & waterborne Manner differs between taxa & media - PowerPoint PPT PresentationTRANSCRIPT
Marine Mammal Sensory & Sound Production
Systems
MARE 390Dr. Turner
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
Sound Propagation
Acoustic energy characterized by velocity, frequency, wavelength, & amplitude
Human hearing 18 Hz to 15kHzMarine mammal vocalizations above & below
< 18 Hz (infrasonic)> 20 kHz (ultrasonic)
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
Functions of Sound
Dolphins – large variety of whistle-like sounds; can understand complex linguistics
Many sounds used for communicationSignature calls identify individuals
Loud impulse sounds – debilitation of prey, self-defense, intimidation of conspecifics
Echolocation – active detection & identification of a target with sound
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)
Acoustic Signal
Spectrogram (frequency with time)
Power spectrogram(sound pressure levels with time)
Frequency spectrum (sound pressure levels with frequency)
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
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
Pinniped Sounds
Sounds produced 1° with larynx
2° - teeth & pharyngeal pouches
Typical mammalian ear with modificationsamplify sound receptionengorged with blood during diving
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
Cetacean Sounds
Sperm Whale Head
Sound Propagation
Melon contains low-density lipids which serve as an acoustic lens to create focused directional sound beams
Mysticete Rhythms
Mysticete larynx possesses structures homologous to vocal folds - are capable of sound generation
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
Sound ReceptionAll cetaceans have good hearing
Auditory canal narrow in odontocetes; plugged in mysticetesGlove finger – projection of eardrum into ear canal
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
Odontocete Reception
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
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”
Pinniped SoundsWeddell seal
N. Elephant seal
California sea lion
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
Other Marine Mammal SoundsWalrus
Manatee
Sea Otter
Polar Bear
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
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
Echolocation
Echolocation
Bottlenose dolphin
Risso’s dolphin
Beluga whale
Sperm whale
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
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
Vocal Clans
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
Empirical Evidence
Empirical studies suggest that sounds not enough to debilitate – playback experiments; conducted with live fish but not live dolphins/porpoises
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
Mysticete Sounds
Broad system clicks & pulses
Low frequency whale tones with very long wavelengths
Humpbacks sing long complex songs
Humpback Songs
Mysticete Sounds
Blue whale
Humpback whale
Bowhead whale
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
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
Sound in the OceanSources of Human-Generated Ocean NoiseTransportation: Aircraft, ships and boats, icebreakers, hovercrafts and vehicles on iceDredging and Construction: Dredging, tunnel boring, other operations.Oil Drilling and Production: Drilling from islands and caissons, bottom-mounted platforms, and vessels; andoffshore oil and gas production.Geophysical Surveys: Air-guns, sleeve exploders, and gas guns.Sonars: Fish finders, depth sounders, and military systems.ExplosionsOcean Research: Seismology, acoustic propagation, acoustic tomography, acoustic thermometry
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)
Sound in the OceanATOC - Acoustic Thermometry of Ocean Climate
Most infamous regarding marine mammals
Public outrage and political reaction primarily caused by misinformation
Sound in the OceanAMODE (Acoustic Mid-Ocean Dynamics Experiment) & SYNOP (Synoptic Ocean Prediction) – most recent versions
Workshop: Navy Sonar and Cetaceans:Why Does RIMPAC have us on High Alert?
What Is RIMPACRim 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
ParticipantsAlways: 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
PurposeEnhance coordination armed forces in Pacific
Key to military readiness; conflict "hot spots“China & Taiwan North Korea & South Korea, US, Japan
Conduct ship-sinking & torpedo exercises Test new naval vessels and technology
Exercises
Marine Mammals and Sound
Patterns of ConcernGreece, May 1996‘atypical’ mass stranding of 12 Cuvier’s beaked whales associated with acoustic trials by vessels from NATO
Bahamas, March 200016 whales (14 beaked, 2 minke) stranded over 2 daysUS Navy vessels were using active high intensity sonar
Madeira, May 20003 Cuvier’s beaked whales over 4 days NATO naval exercises involving multiple ships
Patterns of ConcernCanary Islands, September 200214 beaked whales (4 species) on same day as nearby International naval exercise (Neo-Tapon 2002)
Gulf of California, September 20022 Cuvier’s beaked whales near research vessel conducting seismic surveys
Canary Islands, July 20044 Cuvier’s beaked whales, coincided with the naval exercise ‘‘Majestic Eagle”, conducted 100 km to the north
Patterns of ConcernHonshu Japan, 1950s until 2004 11 reported mass strandings (total of 51 beaked whales ) Adjacent base for operations; US Navy’s Pacific 7th Fleet
Taiwan, February-March 2004 several cetacean strandings; including a beaked whaleCoincided with a joint US/Philippine military exercise
Almería, Spain 2006 ‘atypical” mass stranding of Cuvier’s beaked whalescoincident with a NATO naval exercise
Patterns of ConcernScotland, 2008Cuvier’s beaked whales, dying at sea and washing ashoreResearchers 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
In Hawaii3 species of beaked whales
Highest sightings – West side Hawaii Island
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
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
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
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 byacoustic exposure
Necropy FindingsEar 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
Why do we think they Strand?
What is the Government’s RoleUS 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
How it worksUS 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
In ConclusionConclusive 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 beforewe act?
Marine Pollution Bulletin 56 (2008) 1248–1257