Polar Regions

Question 1

Arctic Geography

Answer 1

Ice covered ocean and surrounding land
Boundaries:
- Tree line, Mean July 10 Degree isotherm, Arctic circle
14.5 million km2 ocean basin, same size as Antarctic continent

Question 2

Arctic geological history

Answer 2

Divided into 2 basins:
- Eurasian basin
- Amerasian basin
Eurasian basin formed during the Cenozoic era (began 65 Mya)
Amerasian basin formed earlier during Mesozoic (250-65 mya)
Opening of Fram Strait, 17.5 Mya, opened North Atlantic to the Arctic

Question 3

Antarctica

Answer 3

Ice-covered continent, geographically isolated.
14 million km2
Mountainous, transantarctic mountain chain
break up of Gondwana 180 Mya
Oceanographic isolation 40 Mya

Question 4

Differences in physical features

Answer 4

Continental shelf:
- Arctic, 200m
- Antarctic: 500m

Question 5

Temperature

Answer 5

Both v cold
Annual mean temp in S pole winter is -60 and N pole is -40.
Antarctic is colder due to elevation and being drier
As it is a continent parts of it are very far from ocean so doesn’t have a climate moderating effect

Question 6

Ice

Answer 6

Glacier ice and sea ice
Arctic is semi-enclosed so sea ice is trapped in ice basins and can build up
Antarctic ice reaches out until it melts, longevity and thickness of ice is less in Antarctica
2m thickness in arctic and 1m in ant
Antarctic retreats and extends further

Question 7

Arctic ocean circulation

Answer 7

Unique
Bering strait
Chukchi sea
Beaufort gyre
Transpolar current
Various exit gateways
north Atlantic current

Question 8

Southern Ocean Circulation

Answer 8

Antarctic Circumpolar Current, clockwise
Largest wind driven current
Coincident with Antarctic convergence
Barrier separating Southern Ocean from Northern Ocean
Extend to 4000m depth, cold (-1 to +5 deg) and fast ( 2 knots)
Deep water formation at continental shelf of Ross and Weddell seas

Question 9

Plants and animals

Answer 9

Plants:
- Antarctic, no tundra or tree lines. Only two flowering plant species.
- Arctic, tundra well developed and marked by a tree shrubline
mammals:
- Antarctic: no terrestrial
- Arctic: many terrestrial mammals
Antarctic and arctic, several marine mammals

Question 10

Arctic Ocean Food Web

Answer 10

Unique complex ecosystem
- Phyto and ice algae
- Micro-zoo
- Meso-zoo
- Larger zoo
- Detritus
- Seals, walrus and polar bears

Question 11

Southern Ocean food web

Answer 11

Very productive
Krill is keystone
Phytoplankton at base of food web

Question 12

Human Presence

Answer 12

Antarctic governed by Antarctic Treaty System.
Arctic states
No residents at Antarctic
4 million in Arctic
First crossing of Antarctic circle in 1773
Arctic first crossing was prehistoric

Question 13

Climate warming

Answer 13

Both poles warming
Fossil fuels less of an impact on Southern Ocean
Reducing sea ice and glacier stores

Question 14

Antarctic seafloor community

Answer 14

Relict fauna, deep ocean derived and migrants, 8200 benthic species
High species richness:
- Pycnogonids, echinoderms, polychaetes, gastropods, amphipods.
Low species richness:
- Bivalves, crawling decapods, many fishes

Question 15

Antarctic sea floor

Answer 15

Origins:
- cooling, 40 Mya drop of 9 to 4 deg
-Isolation, opening of drake passage, establishment of ACC.
- Long history of evolution in situ
Unique:
- Strict physiological limits, stenothermal (-1.85 to +2)
- Slow physiological rates
- Growth, embryonic development, metabolism, benthic activity levels and longevity.
- Metabolic rates in Antarctic are very low, slow, except sustained swimming in fish, temperature compensated so have more mitochondria

Question 16

Under represented groups in Antarctic

Answer 16

Teleost fishes, muscle output 1/10 at 0 than 225
Crawling decapods, inefficient Mg regulation at low temps.
Sharks, active lifestyle, expensive
No predators which consume hard organisms
Coincident with global cooling trend, late Eocene 40 Mya
These groups couldn’t survive

Question 17

Why is Antarctic interesting and important

Answer 17

Decadal means of summer surface temp anomalies for the 2nd half of 20th century
Glaciers, predominantly decreasing at accelerating rates
Precipitation increased over last century
Sea ice is retreating and length of sea-ice season shortening

Question 18

Why study Antarctic benthos

Answer 18

Comprise vast majority of of biodiversity known in this area, ~80%
Extremely vulnerable to warming.
- Strict physiological limits.
- Slow physiological rates and impaired fundamental biological functions
- Limited intrinsic physiological flexibility to cope with change.

Question 19

Effect of increasing temp

Answer 19

IPCC predicts global sea water temp may rise 2-4 deg in next 100 years.
Acclimation to a new temp, ability to cope.
Inability to perform fundamental biological functions at critical temperature.

Question 20

Will ice melt be significant

Answer 20

Melting conditions accelerating on the Antarctic Peninsula.
- Retreating glaciers.
- Increased flow rate.
- Ice sheet collapse
- Changes in productivity
More icebergs
Scour the seafloor:
- Promote biodiversity over large areas
- Catastrophic effects on local biodiversity if persistent.

Question 21

Alien species

Answer 21

Lithodid crabs excluded from cold Antarctic continental shelf waters for 40 mya.
Large populations of predatory king crabs in the deep water of W Antarctic Peninsula
14 species now known in Southern Ocean
Slow growth and developent
Longevity
SST has risen by a degree in last 50 years, shelf waters show increase of 0.01 deg per year.