marine mammal respiration & diving physiology mare 390 dr. turner
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Marine Mammal Respiration & Diving Physiology MARE 390 Dr. Turner. Diving. Most marine mammals spend a significant potion of their time underwater Foraging for food Increase swimming efficiency Reducing metabolic costs Minimizing risk of predation during sleep. Diving Capabilities. - PowerPoint PPT PresentationTRANSCRIPT
Marine Mammal Respiration & Diving
Physiology
MARE 390Dr. Turner
Diving
Most marine mammals spend a significant potion of their time underwater
Foraging for foodIncrease swimming efficiencyReducing metabolic costsMinimizing risk of predation during sleep
Diving Capabilities
Measured as maximum depth or durationPhocid N. elephant seal 1530(m) 77(min) S. elephant seal 1430(m) 120(min)Otariid Cal. sea lion 482(m) 15(min)Odobenid Walrus 300(m) 13(min)
Diving Capabilities
Odontocete Sperm whale 3000(m) 138(min)Mysticete Fin whale 500(m) 30(min) Bowhead 352(m) 80(min)Sirenian W.I. manatee 600(m) 6(min) Dugong 400(m) 8(min)Sea otter 100(m)
Diving Capabilities
Diving Capabilities
Diving Capabilities
Diving Adaptations
Cease breathing during diving events apneic conditions – conflicting conditions1. O2 stores ↓ with ↑ activity (O2 demand)2. CO2 & lactate ↑ in blood & muscle
During hypoxic events, muscle activity is maintained anaerobically
results in ↑ accumulation of lactate
Low-Impact Aerobics
In the past 10-20 yrs – research emphasis on anaerobic dive physiology
Recent on aerobic dive limits and how animals stay within these limits
Know that aerobic diving is the only way to facilitate multiple sequential dives over a short period of time
Under Pressure
Tolerate ↑ in water pressure
1 atmosphere (atm) for each 10mSperm whale – 3000m (300atm)
Squeezes air-filled spaces
Absorbing gases at high pressure can be toxic – damage from bubbles
Effect upon central nervous system
Out of Circulation
Heart similar to other mammals – few adaptations
Retia mirabilia – (wonderful net) tissue masses containing extensive spirals of blood vessels (mainly arteries)
“red muscle”
Total Body Oxygen Stores
Largest O2 stores in diving marine mammals Hemoglobin – O2 binding molecule of
red blood cells; can deliver O2 where needed
Myoglobin – O2 binding molecule of muscle cells; delivers O2 directly to muscles
Hematocrit – packed red blood cell volume; hemoglobin volume – higher in mammals with increased diving capacity
Total Body Oxygen StoresResp – Cardio – Cellular = All EqualFewer mitochondria
Cellular dominantMore mitochondria
Total Body Oxygen Stores
Total Body Oxygen Stores
Total Body Oxygen Stores
Total (L, M, B)
Respiratory System
Deep diving marine mammals have flexible chest walls – allow for collapse; lungs airless
Trachea supported by cartilaginous ringsmaintains rigidity while alveoli collapse
Lungs not larger than terrestrial mammals but important adaptations
Pinniped Lungs
Multiple alveolar sacs in deep diving phocids
Phocid Otariid Odobenid
Cetacean Lungs
Cetacean lungs – greater elasticity
Volume lower in deeper diving species
Inability of respiratory tract to store gasWHY?Risks of embolism; bends
Efficient air renewal - > 90% in single breathSirenians – similarHumans – 10%
Total Body Oxygen Stores
Cetacean Lungs
Oblique position – empties more completelyefficient gas exchange
MysticeteOdonticete
Da Bends!
Neither pinnipeds or cetaceans use lung volume to supply O2 during dive
Pinnipeds – exhale before dive
Cetaceans – inhale before diveAir pushed out of lungs at depth into
trachea, bronchi
Helps to stave off both bends (gas bubbles in blood) & nitrgogen narcosis (euphoria)
“Mini-Ditka, Tirty-tree, New York Giants, Twenty eight” – Bill Swerski
Dugongs & Otters & Bears (Oh My!)
Sirenians – long, extend posteriorly to kidneys - 2° buoyancy control
Otters – 2.5 times terrestrial mammals; buoyancy control
Polar Bear – little to no adaptations
Aerobic Dive Limit
Longest dive that does not lead to an increase in blood lactate concentration
If dive within ADL, can dive again immediately without recovery period
If dive exceeds ADL and accumulate lactate; surface recovery period is
required to “burn-off” (remove) lactic acid from the body
Aerobic Dive Limit
ADL = Total O2 store (mLO2 ) / (Metabolic rate during dive (mL O2 x min-1)
Total O2 store = O2 in blood, muscle, lungs
↑ ADL = longer and / or deeper the dive
Foraging capacity related to the balance b/w total O2 store and metabolic rate
Dive Response
During dive, available O2 ↓ (hypoxia) and CO2 ↑ (hypercapnia)
Together create asphyxia
Counteract with several adaptations:Anaerobic diving – no O2; lactic acid & H+ ions accumulateBradycardia – decline in heart rateIschemia – preferential distribution of blood to O2 sensitive organs;
temperature & metabolic rate
BradycardiaDecreased heart rate - modest (sirenians), moderate (cetaceans) extreme (phocids)
Measured in diving mammals, birds, and reptiles
Ringed Seal
IschemiaA decrease in the blood supply to a bodily organ, tissue, or part caused by constriction of blood vessels
Preferentially to “core” organs – Brain, heart
Away from skin, muscles, lungs
Aerobic Dive Limit
BrainAbdomenDorsal muscle
Declining metabolism during dive
Aerobic Dive LimitDuring a dive, lactic acid accumulates as a waste product in the muscles; depletes O2 stores from myoglobin due to ↓ pH
Aerobic Dive Limit
O2Lactate
Heart
Aerobic Dive LimitInformation from archival tag recorders greatly expanded information regarding ADL and dive routine
Aerobic Dive Limit
Aerobic Dive Limit
Aerobic Dive Limit
Aerobic Dive Limit
Aerobic Dive Limit
Aerobic Dive Limit
Aerobic Dive Limit
My Seal Is Broken!
Phocids – correlation between body size & dive behavior (larger – longer)
Hawaiian monk – typically shallow; deep diving recently identified (550m)
Otariids – not as much time divingfew minutes,shallow depths
Pinniped Diving Strategy
1. Apnea with exhalation (phocids) or inhalation (otariids)2. Bradycardia3. Peripheral vasoconstriction & hypoperfusion4. Hypometabolism in ischemic tissues5. Enhance O2 carrying capacity6. Spleen for regulating hematocrit (large-phocids; typical - otariids)