Polar Ecosystems

1. Polar Ecosystems • The Arctic Marine Ecosystem: the Arctic Ocean is relatively small and shallow; much of area includes continental shelves; high productivity in N. Pacific and N. Atlantic • Greenland Sharks: large shark, scavenger; high amount of pollutants in blood (incl. PCBs, Agent Orange) • Arctic Cod: relative of true cod; main prey of seals and dolphins • Cetaceans • Narwal: males with single long tusk, used in male battles for dominance • Beluga: gregarious white whale; high-frequency vocalizations • Bowhead whale: eats copepods; remains in polynyas through winter • Pinnipeds • Several species, including Ringed, Harp, Bearded, Ribbon, and Spotted seals • Walrus: males with pair of long tusks; haul-outs along rocky shores • Polar Bear: catch ringed seal pups on the ice during two-week period between birth of pups and ice break-up; global warming has led to earlier ice break-ups (threatened listing, United States E.S.A.)

2. Figure 14-29

3. Polar Ecosystems • The Antarctic Marine Ecosystem: the Southern Ocean surrounds the continent of Antarctica; nutrients churned up from the melting of ice in southern Spring (cold, dense water sinks)  high productivity; krill most important zooplankton • Invertebrates: echinoderms, sponges, cnidarians dominate seafloor coverage; sea spiders common • Antarctic Icefishes (Notothenioids): possess anti-freeze proteins in blood; important food source for penguins, Weddell seals • Cetaceans: Blue, humpback, minke, and killer whales • Pinnipeds • Leopard seal: large, powerful predator (of penguins) • Crabeater seal: teeth modified for straining krill • Weddell seal: southernmost seal; remains through winter and grinds down teeth maintaining breathing hole • Southern elephant seal: males fight for dominance ( “beachmaster”) • Birds: male emperor penguins balance egg on feet through winter, other species (ex. chinstrap penguin) breed in summer; skuas

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