Marine Vertebrate Foraging Ecology Flashcards

(54 cards)

1
Q

what are the 2 scales of foraging ecology ?

A

Ranging behaviour - where they go to forage as seen from above, their range
Foraging itself - what they do when they go down

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2
Q

What are the problems associated with foraging in the sea?

A
  • navigation in a featureless environment
  • spatial distribution of prey
  • environmental factors eg. Tide
  • prey are not normally visible from the surface
  • physiological limitations
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3
Q

What is primary productivity a helpful tool for?

A

Predicting where populations of marine vertebrates will be

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4
Q

What determines the location of food?

A

Sunlight

Nutrients

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5
Q

What affects major surface currents

A

Gyres

Wind patterns

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6
Q

What are the oceanographic features?

A

Coastal upwelling
Bathymetry
Fronts
Eddies

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7
Q

Where do upwelling occur and why?

A

The coast

Wind and tides

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8
Q

What are fronts and eddies?

A

Patterns in water movements on smaller scales (still over 100’s of km)
Caused by flow of water over topographical features
Affect food distribution

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9
Q

What do all these different oceanic movements mean?

A

That the ocean isn’t so featureless, as there are predictable aggregations of foods near water movements that increase primary productivity

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10
Q

Where is productivity highest?

A

Higher latitudes and cooler waters

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11
Q

Give an example of the effects ocean movements can have

A

El Niño and La Niña

Last year La Niña happened, gave us harsh winter, on other side of world

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12
Q

What is the difference between El Niño and La Niña

A

El Niño causes warm water tongue in equatorial Pacific

La Niña causes cold water tongue in equatorial Pacific

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13
Q

What happened to California sea lions in 2004/5

A

They had to move out to forage much further at sea because of El Niño

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14
Q

What is the TOPP scheme

A

Top Predators being tagged in the Pacific and finding out where they move and aggregations
Including fish seals sharks tuna birds turtles

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15
Q

What is a dive cycle

A

Time of dive
+
Time at surface between dives (recovery and preparation)

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16
Q

What is a dive bout?

A

A group of dives

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17
Q

What affects foraging behaviour?

A
Prey species
Prey movements + location
Bathymetry
Time of year
Sex of animal
Time of day
Physical state of animal
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18
Q

What can constrain diving behaviour?

A

Light levels
Predators
Diving ability

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19
Q

What do pinnipeds eat?

A
  • primarily fish or squid
  • some crustacean specialists
  • some eat other pinnipeds and birds
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20
Q

What do Cetacea eat?

A
  • krill & invertebrates
  • fish or squid
  • other marine vertebrates
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21
Q

What do seabirds eat?

A
  • fish or squid
  • plankton
  • crustaceans
  • molluscs
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22
Q

What do Dugong and manatee eat?

A

They are herbivores

23
Q

What do polar bears eat?

A
  • pinnipeds

- an increasing number of birds

24
Q

What do sea otters eat?

A
  • Echinoderms
  • bivalves
  • Crustacea
25
What morphological feature can help indicate what food marine vertebrates eat?
Dentition | Eg. Crab eater seal has specialised teeth for sieving krill from water
26
What pinniped teeth types are there?
Peircing - fish catching | Cage like - sieving
27
How do they measure foraging activity?
Time death recorder - measures pressure at set time intervals
28
What is epipelagic diving?
Foraging in the upper layer of the ocean also known as the epipelagic zone or water column
29
What’s benthic diving?
Foraging down to the sea floor ‘square diving’ eg. Sea otters
30
What is mesopelagic diving?
Diving deep into the sea off of the continental shelf
31
When does most fur seal diving take place?
Night time
32
Which marine vertebrate spends the most time at depthV
Elephant seal, 85% of time submerged
33
Because elephant seals spend so little time at the surface with oxygen, what do they do about digestion etc
They do processing dives where they use the oxygen to process instead of foraging
34
What does pressure do to marine vertebrates in water?
Can change nervous system function, chemical reactions | But most importantly on lungs, air spaces get compressed and lungs begin to collapse
35
How do marine vertebrates avoid permanent lung collapse?
Produce a detergent that reduces the surface tension, allowing the collapsed lung to separate Also have rings of cartilaginous support all the way down to the alveoli (but not the alveoli)
36
Why do a lot of marine vertebrates breathe out before diving?
1. Because the alveoli collapse shortly after beginning the dive, so no gas exchange will be taking place from the last gulp of air 2. Reduces buoyancy so easier to dive
37
How do marine vertebrates store/preserve oxygen for dives if they don’t take the last breath
- lungs, will be available for first 10’s of metres (very small component of oxygen stores) - muscle, attached to myoglobin - blood, - reduce oxygen usage, restricting blood flow to vital organs and muscles
38
Does higher percentage blood volume mean longer dive duration
Yes
39
How is the stellate plexus different in diving animals?
It is bigger and has better blood supply because it is acting as a store of oxygenated red blood cells, acting as a scuba tank
40
What does the caval sphincter do?
It controls the release of the store of oxygenated blood during the dive
41
What happens to the spleen during a dive?
It contracts forcing the oxygenated blood into the blood stream giving extra oxygen
42
How can marine divers reduce metabolic rate?
- increase body size, bigger you are, more efficiently you metabolise - swim efficiently, streamlining - vasoconstriction - increase tolerance to hypoxia - bradycardia
43
Dive response was measured in diving animals by ‘force diving’ them, why do this not reliable
``` Forced dive: - no control over duration - maximum response (fear) Natural dive - animals control duration, effort, oxygen use - graded response ```
44
What is the ADL?
Aerobic dive limit The maximum duration an animal can sustain aerobic metabolism, after this point an animal would have to rely exclusively on anaerobic metabolism
45
What is ADL calculated from?
- the useable oxygen stores | - the metabolic rate of the animal during submersion
46
What is the problem with the ADL?
It suggests a sudden switch from aerobic to anaerobic respiration when ALL oxygen is run out But this would be death, as there always has to be SOME oxygen for the brain to function, cannot Work anaerobically
47
Where would the ADL actually be?
When anaerobic respiration really starts to increase in use, possibly in inactive tissues, and eventually the active ones
48
Why does lactic acid levels shoot up after the dive ends?
Because during the dive the blood supply to the muscles that are respiring anaerobically is shut off, so it builds up in the muscle, then when it flushes everything with blood once back at surface, the lactic acid enters the blood
49
What is the surge in lactic acid after a dive called?
The lactic acid flush out
50
What 4 ways can the animal deal with the lactic acid flush out?
``` Oxidise lactate: - at surface -> increase recovery time - during dive -> reduce dive duration Recycle lactate back to glucose - at surface -> increase recovery time - during dive -> reduce dive duration ```
51
Why are weddel seals and emperor penguins commonly used to investigate diving?
Because they dive from ice holes, so can make them use your hole because so far away from others, so they are free diving but able to measure them
52
What was the first every ADL measured for an animal?
20 minutes for a weddell seal
53
What 3 animals have had ADL measured?
Emperor penguin Baikal seal Weddell seal
54
Which way of diving (dive for 60 mins recover for 100 OR dive for 20 recover for 2 mins) is more efficient?
Shorter dives, much more efficient to maintain their body within the aerobic capacity