Comparative aspects of the biology of the Arctic and Antarctic marine ecosystems
The Arctic is an ocean surrounded by land. The Antarctic is a continent surrounded by ocean.
High Arctic Shallow High Arctic Abyssal High Arctic brackishBoreal littoral Zones of the High Arctic Marine Ecosystem
Characteristics of the Arctic Marine Ecosystem: million years old - marine fauna mainly derived from N. Atlantic - low degree of endemism (no endemic genera) - absence of intertidal fauna - reduction in productivity away from continental shelf - ice-covered, stratified layers, reduced mixing - long circulation time - important factors influencing life processes - light: cyclical availability - importance of euphotic zone - nutrients: phosphates, silicates, nitrates - rivers refurbish nutrients coastally in summer - critical importance of epontic (subice) productivity % of total productivity - protracted phytoplankton “bloom” - influenced by snow cover & multiyear ice - terrestrial predators, diversity of birds and mammals
The importance of epontic (subice) productivity to pagophilic species and to those that feed near the ice edge Ambio 1989
Key species in the Arctic marine food web
Typical coastal shore lead in the Beaufort Sea Winds that alternate between “onshore” and “offshore” maintain coastal shorelead polynya systems along the coastlines of the mainland, Hudson Bay, and high arctic archipelagos.
Distribution of arctic seabird colonies in relation to recurring polynyas and shoreleads M. Mallory
Characteristics of the Antarctic Marine Ecosystem: - coldest, driest, windiest and least accessible area - I/10 th of earth’s surface, 98% ice-covered o C, coldest temperature on polar plateau - ice in middle of continent 3 km thick million years old, many different species - high degree of endemism (70-90% in various groups) - absence of intertidal fauna - most ocean north of 70 o N - ice cover much more variable, 90%annual change - 50% annual change in the Arctic - prevailing winds from south stimulate ice production and sinking of cold water along coast, and coastal polynyas - no terrestrial predators, replaced by marine predators - must swim or fly to reach continent - low diversity of birds and mammals - feed from the sea at some level
Maximum ice Cover – October Minimum ice Cover – February
Euphausia superba The Antarctic krill
Key species in the Antarctic marine food web
Weddell seal feeding on an Antarctic tooth fish – Dissostichus mawsoni
Emperor penguins “flying” underwater as they search for food