Download Polar Ecosystems: The Arctic

Polar Ecosystems: The Arctic
 The Arctic is a deep basin & much of this sea is a
permanently frozen ice cap.
 Marine ecosystems in the Arctic face the challenges of
reduced sunlight under the ice & water that’s barely
above freezing.
 For these reasons, diversity of organisms is limited under
the permanent ice cap.
 Species that do live in these conditions have special
adaptations. These include antifreezing compounds in their
blood & extremely low metabolisms.
Polar Ecosystems: The Arctic
 At the edge of the ice cap, however, life intensifies especially
between March & September.
 As the sun melts ice in the spring, water flows off the ice,
sinking into deep water.
 Warm currents from the south interact with the cold water
at the continental shelf edges.
 This process churns up nutrients from the shelf bottom.
 This ecosystem flourishes from the churned up
nutrients.
Polar Ecosystems: The Arctic
 Extremely high productivity occurs along an arc in the North
Pacific & across the North Atlantic from April to August.
 These waters support massive fisheries, marine mammals,
& other organisms.
Polar Ecosystems: The Antarctic
 Antarctica has a more extreme climate than the Arctic.
 Also, the Antarctic differs geographically from the Arctic.
Antarctica, is a continent, not a frozen sea.
 It’s also not enclosed by the continental shelves of other
continents. Instead, it has its own continental shelf.
 The deepest & broadest ocean ring surrounds the Antarctic.
For these reasons, the Antarctic ecosystem has differences
& similarities compared to the Arctic.
Polar Ecosystems: The Antarctic
 During the winter, sea ice surrounding Antarctica freezes,
adding an area about the size of North America.
 When summer comes, the melting of this sheet sets off an
explosion of bioproductivity.
 Winds blowing along the coast result in Ekman Transport,
which moves water away from the continent at the surface,
causing upwelling in the area.
Polar Ecosystems: The Antarctic
 This nutrient-rich deep water reaches the surface at the
Antarctic Divergence.
 This is the largest nutrient-rich area on Earth.
 The Antarctic Divergence supports massive phytoplankton
blooms from November through the southern summer.
 The copepod & krill populations are larger than any
other species population found in any other ecosystem.
 Single krill swarms have been estimated as exceeding 100
million tons, which is more than the world’s annual
commercial fish catch.
Polar Ecosystems: The Antarctic
 The productive water zone extends northward until it meets
the warm Atlantic, Indian, & Pacific waters.
 As in the Arctic, organisms living in the coldest Antarctic
ecosystems have special adaptations.
 Because the Antarctic is a relatively isolated ecosystem,
most species are specialized & found only in the Antarctic.