diving physiology and behavior - division of physical...

4/18/2012

1

Northern Fur Seal Three Foraging Patterns

Thermocline

Diving Physiology and

Behavior

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2

Fundamental Constraint on Foraging Behavior

Return to Surface to Breathe

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Studies of Dive Behavior

• Dive depths from entanglements

• Observations

• Electronic developments

– instruments to measure diving

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4

Marine Mammal Publications

Year

1970 1980 1990 2000

No.

of P

ublic

atio

ns

0

10

20

30

40

50

Diving N = 381Tracking N = 66

Why Marine Mammals Dive?

1) To find food

2) To avoid predators

3) Energy efficient

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Marine Mammal Diving Depths

Div

e d

ep

th (

m)

-2500

-2000

-1500

-1000

-500

0

Average Depth

Max Depth

Sea otte

r

Walru

s Otariids Phocids Odontocetes

Mys

ticete

s

Figure 1:


Div

e d

ep

th (

m)

-2500

-2000

-1500

-1000

-500

0

Average Depth

Max Depth

Sea otte

r

Walru


Mys

ticete

s

Figure 1:

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Div

e d

ep

th (

m)

-2500

-2000

-1500

-1000

-500

0

Average Depth

Max Depth

Sea otte

r

Walru


Mys

ticete

s

Figure 1:

I. Pressure effects

II. Pressure diseases

III. Breath hold diving

Diving Physiology

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7

Pressure Effects

• Hydrostatic pressure

– pressure at depth due to weight

of water column

Hydrostatic Pressure

Depth (m) Pressure (Atms)

Surface 1

10 2

20 3

30 4

40 5

50 6

100 11

500 51

1000 101

3000 301

Harbor seals,

CA sea lions

Elephant seals

Sperm whales,

beaked whales

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Pressure Effects

• Hydrostatic pressure

– pressure at depth due to weight

of water column

• Boyle's Law

– How pressure changes as

function of depth

• Lung Collapse

Boyle’s Law

P V

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Change in Volume with Pressure

1/2

1/3 1/4

Lung Collapse

• Graded process

• 25 – 100m in all marine mammals

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Alveoli

Bronchus

Bronchioles

Trachea

Lung collapse begins at alveoli

and works up

How Do Marine Mammals Deal

With Lung Collapse?

1) Reinforced terminal airways &

trachea

- cartilage and muscle reinforcement

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Phocid Otariid Odobenid

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How Do Marine Mammals Deal

With Lung Collapse?

1) Reinforced terminal airways &

trachea

- cartilage and muscle reinforcement

2) Lung surfactants

- reduces surface tension

- produced in alveoli

I. Pressure effects



Diving Physiology

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13

Pressure Diseases

1) N2 narcosis

– Narcotic affect on CNS

– Humans: onset ~30m, loss of

consciousness ~ 100m

2) O2 toxicity

- Toxic at high pressures

- Causes: nausea, convulsion, death

Henry’s law: pressure = solubility of gas in blood & tissues

Alveoli

Bronchus

Bronchioles

Trachea

Gas exchange occurs at alveoli

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Nitrogen Absorption

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• Dolphins trained

to do repetitive

dives

• Sampled blood

• Build up of N2

occurred

Pressure Diseases

3) Decompression sickness

– Increase solubility at depth

– Gasses saturated in tissues

– Form bubbles in tissue/joints on ascent

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Pressure Diseases

3) Decompression sickness

– Increase solubility at depth

– Gasses saturated in tissues

– Form bubbles in tissue/joints on ascent

4) High pressure nervous syndrome

(HPNS)

– Pressure causes changes in nerve function

– Cause tremors, seizures, and death

Pressure & Temperature

1) Pressure may change protein

structure and function

2) Pressure may influence viscosity of

cell membranes

3) Temperature may influence enzyme

functions

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Adaptations to Pressure

Deep Divers

– Dive on exhalation

– Lung collapse

• Avoid O2 toxicity &

N2 narcosis

– HPNS??

• N2 retention

– Pressure Squeeze

• Eliminate air spaces

Shallow Divers

– Dive on inhalation

– Dive repetitively

– Decompression

sickness

• Possible, Avoidance?

– Pressure Squeeze

• Eliminate air space

Table 1

I. Pressure effects



Diving Physiology

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Marine Mammal Dive Duration

Div

e d

ura

tion

(m

inu

tes)

1

10

100

Average

Maximum

MysticetesOdontocetesPhocidsOtariidsW

alrus

Sirenia

Sea otte

r

Figure 2:


Div

e d

ura

tion

(m

inu

tes)

1

10

100

Average

Maximum


alrus

Sirenia

Sea otte

r

Figure 2:

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20


Div

e d

ura

tion

(m

inu

tes)

1

10

100

Average

Maximum


alrus

Sirenia

Sea otte

r

Figure 2:

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Breath Hold Diving

• Storing oxygen “on board”

– Lungs

– Muscle

– Blood

• Reduce oxygen usage

• Aerobic vs. Anaerobic metabolism

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Diving Physiology –

The Early Years

• Studies of forced submersion

– Ducks vs. chickens (1800’s)

Early Studies

Forced breath-hold experiments

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• A dramatic set of physiological changes

that occur upon submergence

• “Master Switch” of life

Dive Response

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Dive Response

• Extreme bradycardia

– Few beats per min

– Cardiac Output by up 90%

• Dramatic peripheral vasoconstriction

– Flow to heart and vital organs

– Muscles, skin, and other organs reduced

• Hypometabolism

(End of dive spike of lactic acid)

Physiological Changes from Forced Dive

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Physiological Changes from Forced Dive

Is The Dive Response Real?

• Forced dives – No control over duration

– Maximum response (Fear)

• Natural dives – Animals control duration, effort, oxygen

use

– Graded response

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Breath Hold Diving


– Lungs

– Muscle

– Blood



Humans (20ml O2/kg)

Lungs: 24%

Blood: 57%

Muscle: 15%

Figure 3

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Odontocetes (35ml O2/kg)

Lungs: 22%

Blood: 30%

Muscle: 48%

Figure 3

Otariids (40ml O2/kg)

Lungs: 13%

Blood: 54%

Muscle: 33%

Figure 3

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Phocids (60ml O2/kg)

Lungs: 7%

Blood: 65%

Muscle: 28%

Figure 3

Increased O2 Stores

• Lung O2 stores

– Reduced in deep divers

– Important in shallow divers

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Increased O2 Stores

• Lung O2 stores



• Higher muscle O2

– Myoglobin: oxygen binding protein in

muscle, similar to hemoglobin

Myoglobin in relation to dive times

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Increased O2 Stores

• Lung O2 stores



• Higher muscle O2

– Myoglobin

• Higher Blood O2

– Larger blood volume

– Higher hematocrit

– Higher blood hemoglobin

Blo

od

vo

lum

e (

% b

od

y m

as

s)

0

5

10

15

20

Se

a o

tter

Wa

lru

s

N.

fur

sea

l

Ca

lif.

se

a l

ion

N.

Z.

se

a l

ion

Ha

rbo

r s

ea

l

N.

ele

se

al

We

dd

ell

sea

l

Bo

ttle

no

se d

olp

hin

Kil

ler

wh

ale

P.

wh

ite

sid

ed

do

lph

in

Be

lug

ha

wh

ale

Da

ll's

po

rpo

ise

Au

str

ali

an

sea

lio

n

Rib

bo

n s

eal

Rin

g s

eal

Otariids Phocids Odontocetes

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Spleen

contraction

• Increases

circulating red

blood cells

(hematocrit)

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Breath Hold Diving


– Lungs

– Muscle

– Blood



1) body size

Decrease Metabolism

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Mass (kg)

1 10 100 1000 10000 100000

Meta

bo

lic r

ate

(W

att

s)

1

10

100

1000

Oxygen stores kg 1.0

Metabolic rate kg 0.75

Ox

yg

en

sto

res (

Lit

ers

)

0

100

200

300

400

500

600

700

Larger animals use less energy per unit mass

1:1 ratio

Oxygen stores

scale to 1.0

1) body size

2) Swim efficiently, streamlining

Decrease Metabolism

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1) body size


3) Hypometabolism

• Vasoconstriction & redistribution of blood

• 50% of resting metabolism costs due to

organs

Decrease Metabolism

Redistribute Blood Flow

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1) body size


3) Hypometabolism

• Vasoconstriction & redistribution of blood

• 50% of resting metabolism costs due to

organs

• Increased tolerance to hypoxia

• Bradycardia

Decrease Metabolism

Bradycardia

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Breath Hold Diving


– Lungs

– Muscle

– Blood



Biochemical Pathway of

Metabolism

Aerobic

- Oxygen present

- Produces 36-38 ATP

Anaerobic

- No oxygen

- Produces only 2 ATP

- Lactic acid produced

Figure 4

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cADL (min) =

O2 stores (mL O2 kg-1)

Metabolic Rate (mL O2 kg -1 min -1)

Aerobic Dive Limit (ADL):

Amount of time an animal can hold its

breath without an increase in lactic acid

Aerobic Dive Limit

Phylogenetic differences:

• O2 stores

• Diving Metabolic Rate

• Dive depths & durations

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40

Aerobic Dive Limit Phylogenetic Differences

• Phocids

– Superb O2 stores (60 ml O2 kg-1)

– Low diving metabolic rate (1-2 x BMR)

• Otariids & Dolphins

– Good O2 stores (40 ml O2 kg -1)

– High diving metabolic rate (4-7 x BMR)

Role of Body Mass on Dive Time

Body mass (kg)

0 200 400 600 800 1000

Aero

bic

div

e lim

it (

min

ute

s)

0

5

10

15

20

25 Phocids 1.4 x BMR

Phocids 2 x BMR

Otariids 5 x BMR

Dolphins 5 x BMR

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Weddell Seals on Fast Ice

Repeated blood, heart-rate, &

metabolism measurements

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ADL

90-95% of all

dives < 20 min

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Ice Hole Experiments

• Dive response is graded

• Estimates of O2 stores & cADL

matched lactate measurements

• Most animals dive within estimated

ADL

– More efficient diving strategy

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Decrease in Lactic Acid with Time at

Surface

20 40 60

20 min aerobic dive with 2 minute surface interval

80 100 120

2 4 6 8 10 12

140 160

14

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20 40 60

60

20 min aerobic dive with 2 minute surface interval

80 100 120

2 4 6 8 10 12

60 min anaerobic dive with 100 minute surface interval

100

140 160

14

Why Dive

Anaerobically?

• Can reach deeper depths

– Untapped resources

– Larger prey

• More continuous time at depth

– More time for pursuit

– Handling time

diving physiology and behavior - division of physical...

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