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Introduction to Marine Ecology > Polar Regions > Flashcards

Polar Regions Flashcards

1
Q

What are the consequences of climate change in polar regions?

A

+Collapse of ice shelves.
+Less sea ice.
+Increased melt conditions

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2
Q

What are the geological features of the Arctic?

A

+Ice covered ocean + surrounding land.

+14.5 sq million km.

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3
Q

What is the boundary of the Arctic defined by?

A

The treeline, 10 deg.C July Isotherm, or the Arctic circle (66 deg, 33’ 44”)

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4
Q

What are the names of the two basins that form the Arctic?

A

The Eurasian basin and the Amerasian basin.

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5
Q

When was the Eurasian basin formed?

A

During the cenozoic era (~56Mya)

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6
Q

When was the Amerasian basin formed?

A

During the Mesozoic (250-65Mya).

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7
Q

What are the geological features of Antarctica?

A

+Ice covered continent, geographically isolated.
+14 million sq km.
+Mountainous: transantarctic chain
+Land to east higher than land to west.

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8
Q

When did Antarctica form?

A

+Breakup of Gondwana: 180 Mya

+Oceanographic isolation: 40 Mya

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9
Q

What are the depths of the Antarctic and Arctic continental shelves?

A

Arctic: 100-200m
Antarctic: 400-500m.

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10
Q

What is the average summer and winter temperatures for the Arctic?

A

Winter temperatures can drop -50 deg.C and summer temperatures from -10 to 10 deg.C.

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11
Q

What are the average winter and summer temperatures of the Antarctic.

A

Winter: -49 deg.C. Summer: -20 deg.C

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12
Q

What are the two main types of ice?

A

+Glacier ice (glaciers + icebergs)

+Sea ice (pack ice +multiyear ice)

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13
Q

What is glacier ice formed from?

A

Compacted snow/frozen fresh water.

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14
Q

What is sea ice formed from?

A

Freezing of seawater. Frazil ice –> grease ice –> sea ice.

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15
Q

What is multiyear ice?

A

Persists over melt seasons - more common in arctic.

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16
Q

Why are there such drastic differences in sea ice in the two poles?

A

Different geography - landmass surrounded by ocean + semi-enclosed ocean.

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17
Q

Why is there more sea ice in the arctic?

A

+Lots of freshwater input.
+Reduced ice flow.
+Build up o thick ridges: 3-8m - greater longevity.
+7 million sq km multiyear.

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18
Q

Why is there less sea ice in the antarctic?

A

Lots of drift to warmer water - more annual ice. Longevity and thickness less in antarctica.

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19
Q

What is the difference in geographic distribution?

A

Arctic: asymmetric - due to ocean currents.
Antarctic: symmetric - due to circumpolar flow.

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20
Q

What is the difference in snow thickness?

A

Arctic: thinner.
Antarctic: thicker due to surrounded ocean - more precipitation.

21
Q

What is the circulation of the arctic like?

A

Unique: ice covered + relatively isolated. Contains bering strait, chukchi sea, beaufort gyre, transpolar current & north atlantic current.

22
Q

What is the circulation of the antarctic ocean like?

A

+Antarctic circumpolar current (ACC) W-E c/w.

  • Largest wind driven current.
  • Coincident with Antarctic Convergence Barrier seperating SO from north oceans.
  • Extends to 4000m, -1 - 5 deg.C, fast (2 knots)
23
Q

What are the plants of the Antarctic and Arctic like?

A

Antarctic: NO tundra/tree lines.
Arctic: Tundra well developed + marked by tree shrubline.

24
Q

What are the mammals of the arctic/antarctic like?

A

Antarctic: No terrestrial mammals.
Arctic: Many terrestrial mammals.
Both: Several marine mammals, w/ exception of polar bears in Antarctica.

25
Q

What is the food web of the arctic like?

A

+Unique, complex ecosystem.
+Sea-ice biota.
+Ice algae and phytoplankton.
+Climate change - cascading effects.

26
Q

What is the food web of the antarctic like? (4pt)

A

+Can be relatively simple.
+Very productive - phytoplankton underpin food web.
+Krill are key.
+Ice is important component.

27
Q

What are the human impacts of antarctica?

A

+No government/belongs to no country.
+No permanent residents, sparse scientific population.
+First crossing of A. circle James Cook, jan 17, 1773.

28
Q

What are the human interactions in the Arctic?

A

+Nations include russia, canada, greenland, USA, iceland, norway, sweden, finland.
+Population 60 deg. North >4 million.
+First crossing prehistoric.

29
Q

Why are polar regions important? (4pt)

A

+Cornerstones of global ecosystem.
+Barometers of planet health.
+Messengers of global processes.
+Regulators & drivers of world climate.

30
Q

What are the effects of climate change in the Arctic?

A

Rapid rise in air temp (x2 global average), reduction in sea ice + faster flowing glaciers.

31
Q

What are the effects of climate change in the Antarctic?

A

Increase in sea ice, receding glaciers + change in ocean productivity.

32
Q

What drives both polar food webs?

A

Ice biota and krill.

33
Q

What are the characteristics of the Southern ocean?

A

All water south of polar front, with Clockwise surface currents from W-E (ACC). Unique:
+Low stable temperatures.
+Seasonal signal in production.
+Deep continental shelf (Weight of ice cap + erosion).

34
Q

What are the organisms with high species richness in the southern ocean? (7pt)

A 
\+Pycnogonids
\+Sponges
\+Echinoderms
\+Tunicates
\+Polychaetes
\+Gastropods
\+Amphipods and isopods.
35
Q

What are organisms in the southern ocean with low species richness?

A

+Bivalves
+Reptant (crawling) decapods.
+Many fishes e.g. Teleosts

36
Q

What are the origins of the southern ocean benthic community?

A

+Cooling (40 Mya, 4 - 9 deg.C)
+Isolation - opening Drake’s passage (Polar front, ACC)
+Long history of evoltion in situ, elevated endemism.

37
Q

Why is the southern ocean benthic community unique?

A

+Strict physiological limits - stenothermal (-1.85 - +2 deg.C)
+Slow physological rates - growth, embryonic development, metabolism, benthic activity levels and longevity.
+Underrepresented e.g. durophagous predators in Antarctica.

38
Q

Why are there no durophagous predators in Antarctica?

A

+Teleostean fish: muscle power at 0 deg.C 1/10th than at 25 deg.C
+Reptant decapods: inefficient ion regulation at low temps, narcotic effect.
+Sharks: active lifestyle prohibitively expensive.

39
Q

Why study Antarctic benthos?

A

+Comprise vat majority of biodiversity known around Antarctica (~80%)
+Antarctic benthos extremely vulnerable to climate warming.

40
Q

Why are Antarctic benthos so vulnerable to global warming?

A

+Strict physiological limits, i.e. Stenothermy.
+Slow physiological rates + impaired fundamental biological functions.
+Limited intrinsic physiological flexibility to cope with change.

41
Q

What will accelerated melt conditions on the antarctic peninsula cause?

A

+Retreating glaciers.
+Increased flow rate
+Ice sheet collapse.

42
Q

What will the effects of more ice bergs be?

A

Scour the seafloor:
+Promote biodiversity over large areas
+Catastrophic effects on local biodiversity.

43
Q

What is the relationship between the surface ocean and seafloor?

A

Seafloor organisms are reliant upon export flux of carbon from surface ocean for food (pelagic-benthic coupling)
Seafloor organisms are vital for healthy marine ecosystems.

44
Q

What drives ecological processes under a climate change scenario from October to November (late spring)?

A

+Sea ice cover breaking up - nearing 24hr daylight.

+Ice-algae released by melting ice and melt-water induced stratification of water column begins.

45
Q

What drives ecological processes under a climate change scenario from January to March (Austral summer)?

A

Sea ice over receded and phytoplankton bloom fully developed, sedimentation of organic material can produce thick phytodetrital carpet.

46
Q

What drives ecological processes under a climate change scenario from May to July (late autumn)?

A

Nearly 24hr darkness, sea ice forms, low phytoplankton biomass.

47
Q

What drives ecological processes under a climate change scenario from August to September (late winter)?

A

Period of maximum sea ice coverage, short but lengthening daylight hours.
Relatively harsh winter.
Expect to see strong seasonality in food availability at seafloor.

48
Q

What is the FOODBANCS hypothesis?

A

Sea ice retreat and intense summer phytoplankton blooms yield substantial summer deposition of algal detritus onto the WAP shelf floor, deposited bloom material then provides a sustained source of food (“food bank”) for seafloor animals during winter months.

49
Q

Will environmental change introduce alien species?

A

yes. Lithodid (king) crabs have been excluded from cold antarctic continental shelf waters for Mya, but now large populations discovered in deep water off west antarctic peninsula.
Slow growth and development - longevity.

Introduction to Marine Ecology (7 decks)

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