Arctic Ecosystems

Unique organisms

Polar sea ice is essential for the survival of many polar ecosystems. Sea ice is frozen seawater that moves with oceanic currents, and it provides important habitats as well as a resting place for animals.
CAFF Assessment Series No. 10: Life Linked to Ice

Due to seasonal warming, Arctic sea ice covers less area in the summer than in the winter. Some sea ice persists year-round, creating a unique ecosystem. The Arctic has many endemic species- meaning species that are not found anywhere else- most of which rely on the year-round ice cover for their survival.

Species Group: Present in Arctic % of Worldwide Mainly in Arctic Threatened
Terrestrial mammals: 67 1% 18 1
Marine mammals: 35 27% 11 13
Terrestrial and freshwater birds: 154 2% 81 17
Marine birds: 45 15% 24 3
Amphibians and reptiles: 6 <1% 0 0
Freshwater and diadromous fishes: 128 <1% 19
Marine fishes: 250 <1% 63 4
Terrestrial and freshwater invertebrates: >4750
Marine invertebrates: ~5,000
Vascular plants: 2,218 <1% 106 0
Bryophytes: ~900 6%
Terrestrial and freshwater algae: >1700
Marine algae: >2300
Non-lichenized fungi: ~2030 4% <2%
Lichens: ~1750 10% ~350
Lichenoculous fungi: 363 >20%

CAFF Arctic Biodiversity Assessment 2013: Synthesis

Fragile phytoplankton

Organisms that live within and under the sea ice tend to be small- bacteria, algae, larvae, unicellular organisms, and different types of phytoplankton. Diatoms, a type of algae, are considered the most important primary producers inside the sea ice. With recent Arctic sea ice levels have dropped, massive phytoplankton blooms have been occurring in the areas. The food chains of the Arctic begin under the sea ice with these small organisms- they occupy the lowest trophic level.

CAFF Assessment Series No. 10: Life Linked to Ice

As sea ice decreases, the annual primary productivity bloom timing is shortened, leading to reduced levels of zooplankton. As the zooplankton levels are decreased, marine life that depends on it for food will also become reduced, causing a trophic cascade. Loss of ice will create large dispersals between the sea ice, isolate terrestrial populations, and restrict the gene flow of marine populations. Less sea ice will also limit foraging days for polar bears, causing tremendous decline in their populations.