Ch 23: Polar Ecosystems

Polar Circles

lines encompassing regions that experiences at least one 24 hour period when the sun remains below the horizon and another 24 hour period where the sun never drops below the horizon

Gondwanaland

the ancient super continent that incorporated present day South America, Africa, Arabia, Madagascar, India, Australia, and Antarctica

Polynyas / polynias

persistent open waters surrounded by sea ice in polar regions

What Causes Polynyas

1. Warmer waters rising from depth maintian open surface water above freezing point

2. Strong dry katabatic winds cause formed ice to drift from the coast

Katabatic Wind

a wind that carries high-density air from a higher elevation down a slope under the force of gravity

Key Characteristics of Arctic Environments

1. Langley ice covered with winds and currents driving ice movements

2. Relative isolation form other oceans or other semi-enclosed basins

multi-year ice

ice that persists through the year into the following winter

North Atlantic Deep Water

a large, dense water mass that originates largely from Gulf Stream waters that cool and sink in the Arctic

Sympagic Communities

communities associated with sea ice

Brine

seawater with particularly high salt content and high concentrations of inorganic nutrients

Phytoplankton Production in Arctic Environments

Limited due to snow/ice cover, low sun angle, short growing season

Most Arctic Fish are _____

benthic or demersal

Antarctic Bottom Water (ADW)

a large, dense water mass formed from the cooling and sinking of waters around Antarctica

Roaring Forties

area of strong winds formed from atmospheric perturbations at latitudes between 40 and 50 degrees

Furious Fifties

area of strong winds formed from atmospheric perturbations at latitudes between 50 and 65 degrees

Land Fast Ice / Fast Ice

the progressive freezing of the water layer at the sea-ice interface to form a coastal ice shelf

Pack Ice

a large floating mass of drifting ice formed largely from convergence of fast ice

Ice-Foot

land fast ice that remains attached to the shore and potentially gives rise to multi-year ice

floes

ice islands ranging in size between hundreds of meters up to 10Km in diameter that drift on the ocean during the summer

Grease Ice

“oily’’ ice formed when ice crystals develop into needles or small plates of ice

frazil ice

waxes and wanes from grease ice as slush

Pancake Ice

round plates up to meters in diameter that develop from grease to ice

young ice

initial ice formed by the freezing of seawater from the bottom of new surface ice

Gray Ice

ice formed as young ice progressively thickens from below

Young Ice / First Year Ice

thickness can attain thickness ranging from 120-180 cm

Brown Ice

ice that forms near the water-ice interface during antarctic spring, supporting abundant life and partially primary producers

Ice Edge Bloom

blooms at the edge of sea ice

Ice melt POM

particulate organic material previously trapped within the ice that sinks through the water column to enrich the benthic community

Bottom ice

the lower 10 cm of the sea ice column

Key Physical Factors of Antarctic Biodiversity

sea ice, substrate, light, oceanic fronts, depth, emperature, isolation, geomorphy, seasonality, currents, iceberg disturbance

Key Biological Factors of Antarctic Biodiversity

primary production, biological substrate, dispersal ability, and community interactions

big ass table on slide 43 I aint doing today lol