Chapter 12: Polar Regions

Question 1

what percent of the earth’s surface is made up of pack ice at its maxium extent?

Answer 1

13%

Question 2

how are people able to research polar regions?

Answer 2

by setting up ice camps and drift stations

Question 3

where do icebergs originate from?

Answer 3

broken-off pieces of FW glaciers and ice shelves

Question 4

what is pack ice?

Answer 4

formed from the freezing seawater in autumn

• ice crystals form to GREASE ICE
• form ICE PANCAKES
• form SUPER PANCAKES
• raft together from wind and waves, freeze.

Question 5

how cold does the water have to be to form pack ice?

Answer 5

-1.8*C

Question 6

how big are ice pancakes?

Answer 6

5-10cm in dia

Question 7

what are the differences btwn arctic and Antarctic pack ice?

Answer 7

• arctic ocean has more ice
• arctic basin is almost enclosed entirely
• southern ocean is circumpolar
• arctic ice last for up to 10 years
• arctic ocean only has a mean depth of 1800m
• Antarctic pack ice zone range between 4000-6500m deep
• lots of FW rivers run-off in the arctic basin

Question 8

what percentage of the total southern ocean primary productivity occurs in the sea ice?

Answer 8

up to 5%

Question 9

what is the main microbiota found?

Answer 9

pennate diatoms

Question 10

how do microbes survive in the ice sheets?

Answer 10

brine channels within ice creates refuges

Question 11

what are physiological pre-requisites for survival in a block of ice?

Answer 11

adaptations to low light, low temp and high salinities

Question 12

what important nutrient source does bacteria and microalgae produce?

Answer 12

PUFAs

-poly unsaccharied fatty acids

Question 13

what happens when sea ice melts?

Answer 13

• FW release lowers salinity levels
• stabelizes upper water column
• creates frontal system
• algal blooms
• higher rates of grazing

Question 14

how does the algal blooms influence other habitats?

Answer 14

• feeding ground for entire food webs

- faecal pellet production results in a large downward flux of biogenic material to the underlying sediments

Question 15

strong ________ in the open arctic waters

Answer 15

pynocline

Question 16

high concentrations of _____ ____ in the southern ocean

Answer 16

inorganic nutrients

Question 17

large variation in ____ _______ in the arctic

Answer 17

latitudinal gradients

Question 18

what is the relationship between krill, whales, iron, and ocean productivity?

Answer 18

if whales are able to recover, the result will be an increase of iron in the ocean, therefore increasing ocean’s productivity. The amount of iron in krill is so high that the fecal matter of whales are particularily iron-rich.

Question 19

what occurs with the grounding of icebergs?

Answer 19

• considerable damage to the benthic communities
• scour
• sessile species eradicated and pioneer spp grow in high abundances

Question 20

the largest proportion

of the Antarctic shelf benthos is made up of what?

Answer 20

sessile suspension-feeders (sponges, cniderians, bryozoans, echninoderms)

Question 21

how do organisms feed during winter months when there is no primary productivity?

Answer 21

• resuspension of sediments

- lateral advection of organic rich material

Question 22

what percentage of fish genera and species are endemic in the antarctic?

Answer 22

70% fish genera

95% fish spp

Question 23

why are there so many endemic spp in the arctic, Antarctic?

Answer 23

• greater age

- longer isolation

Question 24

why gigantism in polar regions?

Answer 24

• low water temp = low metabolic rates
• growth rates slow enough to enable them to live longer
• higher DO concentration in water

Question 25

what importance is sea ice to birds and mammals?

Answer 25

• haul out area
• reproduction
• raising young
• major feeding area (under ice)