Ecological consequences of sea ice decline Flashcards
What is the cryosphere?
The cryosphere is the frozen water part of the Earth system
Difference between Antarctic and Arctic
Antarctica:
Land mass surrounded by ocean- can move freely = high drift speeds, tends to be covered in snow.
Arctic:
Semi-enclosed ocean almost completely surrounded by land, low snowfall
Loss of summer sea ice has accelerated in the past four decades
When will arctic be ice free?
At the current rate of 12% per decade, Arctic will be 95% ice-free by 2100.
Sea ice extent has declined dramatically during the 20th century in both hemispheres.
Where has the trend been more obvious?
The Arctic
Impacts of sea ice decline on fauna?
Pagophilic species (dependent on ice)
Sea ice as a feeding ground
Sea ice as a substitute to land for reproduction
Ecological consequences of sea ice decline
1) Alteration of food web
2) Habitat loss
3) Extinctions?
Sea ice decline and alteration of food web
Simplified trophic levels
Photosynthetic algae, sea ice algae and phytoplankton
Zooplankton (krill)
Ice-associated vertebrates
Other than phytoplankton, what acts as a key part of the Arctic food web?
Polar cod
Cascade effect through the food chain
Decrease in the extent and duration of ice cover
Perturbations of the food web at different levels
Bottom-up impact: perturbations work their way up through the food chains
Earlier retreat of sea ice and reduction of sea ice cover equals decline in ice algae production which means…
Shortening of the time for growth and reproduction
Greater exposure to predators
Food shortage
What will sea ice decline mean for walruses?
Females feed on benthic prey in shallow waters when nursing their young
Sea ice provides walruses with a resting platform, access to offshore feeding areas
Are emperor penguin (Aptenodytes forsteri) facing extinction ?
The emperor penguin life cycle depends on sea ice.
Low sea ice concentration reduces adult survival through its effect on the food web (low food resources and/or high pre- dation)
