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0 - Boreal Ecology > Midterm 3 (20% of exam) > Flashcards

Midterm 3 (20% of exam) Flashcards

1
Q

*L1: Define boreal ecology.

A

Boreal ecology = ecology of the North

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2
Q

*L1: Define boreal regions.

A

Boreal regions = where snow cover affects animals and plants, or where living organisms have evolved adaptations to snow and ice

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3
Q

List some examples of arctic stressors

A
  • Climate change
  • Shipping
  • Mining
  • Fishing
  • Oil and gas exploration and exploitation
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4
Q

__% of global MPA’s implemented.

__% is the global goal for MPA’s by 2020.

A

3.7% of global MPA’s implemented.

10% is the global goal for MPA’s by 2020.

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5
Q

T or F - most protected areas are terrestrial, not marine.

A

True

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6
Q

Dave’s research

Baffinland shipping is proposed to increase (+ice breaking to allow for more ships passing through each summer).

  • What was done to research the effects on ring seals?
  • What were the threats?
  • How could this be done safely?
A
  • Hotspots identified using aerial surveys
  • Ice breaking would go right through hotspots
Threats:
- Non consumptive effects (stress on mom's and pups during nursing time)
• Displacement of individuals
• Separation of mothers and pups
• Destroy subnivean lairs
• Vessel-seal collisions

Mitigation measures:
• Safe distance of ≥ 250 m from seals – based on smaller Caspian Sea vessels (would likely need more distance here)
• Ringed seal hotspot is unavoidable

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7
Q

How are marine mammals responding to vessel presence (Narwhals)?

A
  • Narwhals: 70% found to swim away in summer, 80% in fall.
  • Quantify a movement score; moving towards, moving away, moving parallel, moving perpendicular (same as moving away)
  • Data was presented in an (intentionally?) misleading way
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8
Q

How sensitive are marine mammals to ships during ice-free seasons?

  • What were some of the most sensitive animals, and where?
A

Looked at 6 variables (DNM):

  1. Behaviour disturbance
  2. Injury or mortality
  3. Acoustic impacts
  4. Frequency of vessel traffic
  5. Sensitivity to ice loss
  6. Abundance of population
  • Most sensitive: Beluga, Narwhal, also cetaceans, pinnipeds (mostly aquatic animals who can’t hide out on land).
  • Most vulnerable in Lancaster sound.
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9
Q

T or F - Arctic mammals that are aquatic and live in Lancaster sound are most sensitive to ships during ice free seasons.

A

True

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10
Q

What species was determined to be most vulnerable to ships?

A

Narwhals

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11
Q

How much do hotspots overlap with protected areas in the arctic (%)?
Is the east or west better protected (%)?

A
  • Total protected area overlap of only 5-7%.

- East is 15% protected, West and South is <1%.

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12
Q

Seismic surveys

A
  • Oil and gas exploration and exploitation
  • Uses air and seismic guns to find oil, resulting in ecosystem disruption, increase in zooplankton mortality
  • Supreme Court of Canada + Clyde River community overturned a decision to allow oil exploration without government consultation
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13
Q

Exploitative competition

A
  • 2 competitors directly competing for the same prey
  • Has a negative effect on both of them (competition, conflict) and the prey too
  • Indirect
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14
Q

Interference competition

A
  • A result of exploitative competition
  • If the competitor is eating all the food, one predator may try to remove the other
  • Common in canids (wolves, red foxes, coyotes)
  • Indirect
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15
Q

Apparent competition

A
  • 2 species share a predator
  • If one species increases, then the predator increases and the second prey species experiences more predation
  • No competition for resources, but still affects each other
  • Indirect
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16
Q

How have wolves changed the greater Yellowstone ecosystem?

A
  • Gray wolves reintroduced
  • Elk foraging patterns changed
  • Modified forest structure

combined effects of a behaviorally- mediated and density-mediated trophic cascade

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17
Q

Define: Density mediated effects (+ is it direct or indirect?).

A
  • predators reduce prey numbers

- Indirect

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18
Q

Define: Trait mediated effects (+ is it direct or indirect?).

A
  • predators affect prey phenotype (e.g., behavior or physiology)
    • effect of the risk of predation
  • Indirect
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19
Q

predators reduce prey numbers

A

Density-mediated

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20
Q

predators affect prey phenotype (e.g., behavior or physiology)

A

Trait-mediated

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21
Q

T or F - Shorebird nest predation rates vary hugely, from nest success rates of 80% vs 2%.

If this is true, why?

A

True - lemmings are the cause. Their opulation cycles influence other species, when they change in abundance, this influences predator abundance and thus their predation rates on other species.

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22
Q

T or F - for arctic nesting birds, nest predation varies with lemming abundance.

A

True - lemmings can increase predator abundance.

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23
Q

How do lemmings affect birds?

A

High lemming populations increase predators (foxes) which predate on lemmings and other species, like birds.

Other influences also - less space to nest.

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24
Q

Functional vs numerical response

which one causes more apparent competition?

A

Functional: consumption is related to prey abundance.

Numerical: The more prey, the more predators.

In numerical response, you get more apparent competition.

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25
Q

T or F - lemmings have the largest litters of any arctic animal.

A

True - Up to 20 young per litter.

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26
Q

T or F - Lemming cycles are increasing in frequency.

A

False - they’re decreasing.

27
Q

Why are lemming cycles decrease in frequency?

A

Warming affects snow cover, depth, and quality:

  • Melt-frost events affect thermal insulation
  • Lower reproduction
  • Higher juvenile mortality
  • Exposed to predators earlier in summer

*use subnivean layer and need a blanket of snow for insulation.

28
Q

T or F - Lemmings use the subnivean layer.

A

True

29
Q

Why are snow geese number changing, and what are the implications of this? What has been the response of other animals?

A
  • Dramatic increase in numbers
  • Likely due to feeding on waste grains from agriculture, eat their way up to breeding grounds and then breed in tundra
  • Feed through grubbing (rip out plants by their roots, turning coastal areas into barren ground)
  • In a vegetated salt marsh, the annual inputs of sea water salts are leached downward by spring floods and summer rains.
    When the vegetation is removed, evaporation brings these salts to the surface and concentrates them, killing root systems.
  • Quantified diet of foxes and found a functional (consumption related to prey abundance) response, but not a numerical one (more prey = more predators)
  • No increase in reproduction despite huge increase in geese
  • Why? Geese fly south in the winter, not around year round so winter food abundance likely plays a big role in this
30
Q

What salt tolerant plant indicates degraded and hyper saline soil (perhaps through snow geese grazing)?

A

Salicornia

31
Q

T or F - Snow geese and arctic foxes have displayed a positive correlation when it comes to their population abundance in the arctic.

A

False - no increase in foxes despite huge increase in geese.

32
Q

T or F - Lack of prey abundance is responsible for the lack of population increase in arctic foxes.

A

False - it’s due to a lack of winter food (still caching eggs but not enough food to stimulate reproduction)

33
Q

How do arctic foxes affect ringed seals?

A
  • Consume ~25% of their young from dens

- But most of their feeding is from scavenging on leftovers from polar bears

34
Q

Allochthonous resource

A 
Allochthonous resources (spatial subsidies)
• food sources from other habitats or ecosystems
• donor controlled (renewal unaffected by consumption)
35
Q

What 3 biomes intersect in Churchill?

A

boreal forest, tundra, and marine

36
Q

Describe fox dens

A
  • easy to locate fox dens because the vegetation differs greatly on top of them.
  • the ones with pups can also be easily identified due to prey remains, tracks, and digging.
  • mostly <10km of the coast, on relic beach ridges
37
Q

T or F - There is a strong numerical response between fox reproductive success and lemming populations.

A

True

38
Q

T or F - Fatter polar bears correlates with arctic fox populations.

A

True - they follow polar bears and eat their scraps.

39
Q

Northern borders of animal distributions are often determined by ______

A

Northern borders of animal distributions are often determined by temperatures lower
than species-specific tolerance limits

40
Q

T or F - Red fox density increases with warmer temperatures.

A

True - red not arctic fox

41
Q

Southern borders of Arctic animal distributions are often determined by ______

A

Southern borders of Arctic animal distributions are often determined by biotic factors (competitors & natural enemies)

42
Q

T or F - red fox abundance is increasing but arctic foxes are decreasing.

A

False - no trend for red foxes but arctic foxes are decreasing

43
Q

The “Green World” Hypothesis

A

By controlling herbivores, predators allow plants to thrive

44
Q

By controlling herbivores, predators allow plants to thrive

A

The “Green World” Hypothesis

45
Q

How are arctic foxes ecosystem engineers?

A
  • return to dens for generations
  • nutrient input
  • defecation
  • decomposing prey
  • disturbance (digging)

Promotes plant colonization

Result:

  • Higher soil nutrients on dens
  • More grass and shrubs on dens than in adjacent tundra
46
Q

Why do lemmings nest on arctic fox dens?

A 
Grass &amp; willows on dens (food)
- nesting material &amp; forage
- Greater plant productivity on dens
- Vegetation on dens is more nutritious
- Plants trap snow
• much thicker on dens
- Warmer subnivean temperature on fox dens (lemming activity increases with subnivian temp increase)
- More reproduction on fox dens
- Foxes are out on ice hunting when lemming population is low so they're relatively safe on low density years
47
Q

T or F - Herbivore like the Canada goose, snow goose, arctic hare, and caribou in addition to lemmings use fox dens.

A

True - more vegetation + more nutritious vegetation.

48
Q

T or F - Scavenger species like polar bears use fox dens.

A

True - possibly because foxes leave scavenged carcasses if they have pups.

49
Q

T or F - Canada has 1/3 of all polar bears in the world.

A

False - 2/3

50
Q

How many cubs do most polar bears have? What kind of maternal care exists?

A
  • most cubs are born late December through early January weighing < 1 kg (2.2 lb)
  • twin and single litters most common, triplets much rarer
  • one quadruplet litter in 27 years of research in Churchill area
  • 10 cases of cub adoption and 1 case of monozygotic twins

Extended maternal care - 2.5 years

51
Q

When do polar bears hunt the most seals? Why?

A

Mid-april, peak of reproduction and pup births so bears are most successful

52
Q

What did Serum urea/creatinine ratios in the Beaufort Sea reveal about polar bears?

A

Since 2005 (vs 1985), there was increased bear fasting, they were catching less seals, they were thinner, and population declined by over 50% - likely related to changing sea ice conditions and lack of prey availability.

53
Q

T or F - polar bears have a home range of about 50,000km.

A

False - 300,000km

54
Q

How much earlier is ice breaking up now? How much later is it freezing?

A
  • 3 week earlier break up
  • 2 week later freeze up

= longer fasting times for polar bears

55
Q

T or F - Every 10 years, the polar bears will have to go an extra 30 days without food.

A

True

56
Q

What is an issue with fasting in female polar bears?

A

When they have cubs - if females become too skinny, they stop producing milk for her cubs, it’s extremely hard on them because they’ll continue to use energy reserves to grow but don’t have food now.

57
Q

In a 25 year study in Hudson’s bay, there’s been a __% decline in the size of the polar bear population.

A

In a 25 year study in Hudson’s bay, there’s been a 30% decline in the size of the polar bear population.

58
Q

Why are some male polar bears having 0 reproductive success?

A
  • Some males can sire 13 cubs, but there’s a lot having 0. Huge variation - but why are some having way more?
  • Females have relatively stable reproductive output but males have a peak time where their body size/strength is best for defending females.
  • Selection intensity on morphometric traits: There’s similar selection on body size in polar bears as for other secondary sexual characteristic (horn size, antler size in other organisms) - there’s sexual selection for these traits over time that have an effect on breeding/mating success.
  • The males who had 12+ cubs were on the high end of body length (“monster bears” never have to fight, other bears wont even try to compete for females), the small ones may never get to breed. Over time, adult males are getting smaller, and they’re less competitive in the mating system - this is very evident in Hudson’s bay where the males have a poor start and can’t grow much, and then the bears from the north are so large that only they get to breed.
59
Q

__% decline in male lifetime productive success in Churchill.

A

50% decline in male lifetime productive success in Churchill.

60
Q

How are natural selection and sexual selection acting in polar bear populations?

A

Male bears are preprogrammed to grow fast and large, but when the mother stops lactating early, the male can’t grow… sexual selection selects for large males, but natural selection is selecting for smaller bears who can survive.

61
Q

In what area are arctic marine mammals most sensitive to shipping?

A

Lancaster sound

62
Q

Functional response

A

Functional: consumption is related to prey abundance.

63
Q

Numerical response

A

Numerical: The more prey, the more predators.

0 - Boreal Ecology (4 decks)

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