General Characteristics

Transcription

1 Polar Seas

2 General Characteristics Seasonal Sea ice can cover up to 13% of Earth s surface Arctic 5% of the world ocean Mostly north of the Arctic Circle Antarctic 10% of the world ocean

3 General Characteristics Deep water and Bottom water currents Due to the sinking of cold/dense saline waters near Greenland, and the Antarctic Convergence, among other sites, the global ocean circulation is maintained Sunlight and Primary Productivity Winter: months of darkness Summer: months of sunlight However, due to angle of the sun, reflection by sea ice, and salinity of the water, less light penetrates the water than in other seas

4 General Characteristics Antarctic Convergence a curve continuously encircling Antarctica, varying in latitude seasonally, where cold, northward-flowing Antarctic waters meet the relatively warmer waters of the subantarctic

5 Arctic Surrounded by continents Relatively shallow basin due to the world s largest continental shelves extending from Siberia and Alaska (>1000 km) Contains the deepest, slowest spreading mid ocean ridge Rich nutrient runoff and freshwater influx from Siberian rivers + upwelling = rich waters vital for abundant phytoplankton

6 Arctic Important waterways Northwest Passage Northern Sea Route Bering Strait Sea ice Winter: covers 80% Summer: covers 60% Coverage area and thickness are declining as a result of climate change

7 Arctic Ecosystem: Polar Bears Weigh up to 1500 pounds Thick white coat aids in camouflage and heat retention Excellent swimmers but need to rest/mate on ice Feed on ringed seals primarily Can also eat fish, birds, and in summer vegetation

8 Arctic Ecosystem: Seals Permanent residents: Bearded Seal, Ringed Seal Bearded seals are the largest Arctic seal and most closely related to the walrus Ringed seal is smallest and most common Arctic seal Seasonal residents (summer): Harp Seal, Hooded Seal Occasional visitors: Harbor Seal

9 Arctic Ecosystem: Seals

10 Arctic Ecosystem: Walruses Atlantic and Pacific subspecies Pacific are larger (1.3 tons) compared to Atlantic (0.75 tons) Live in shallow icy seas; rely on ice to mate, birth, rest Very social; protective moms Use whiskers to find clams and mussels Both sexes grow large tusks which are helpful in hauling out onto the ice

11 Arctic Ecosystem: Whales Many whales visit the Arctic Bowheads Feed on krill and small fish Unique V-shaped mouth Can live to be 200 years old! Inuits are allowed to hunt a limited number, as the spring whale hunt traditionally supplies most of their food needs for the year

12 Arctic Ecosystem: Fish Many species have antifreeze compounds in their blood Feed on krill, smaller fish, crustaceans and other invertebrates. Are food to squid, polar bears, seals, and whales. Arctic cod has been fished extensively

13 Arctic Ecosystem: Bottom Dwellers Starfish, Sea Urchins, Brittle Stars, Sea Cucumbers, Mussels Rely on detritus

14 Arctic Ecosystem: Zooplankton, Phytoplankton, Ice Algae Phytoplankton in surface layers help form base of Arctic food web Diatoms, dinoflagellates Ice Algae supplement the base of the food web Grow on underside of sea ice Grow in pockets of water between ice crystals in pack ice

15 Arctic Ecosystem: Detritus Older ice algae, dead organisms, fecal pellets Eaten by bottom dwellers such as urchins, sea stars, and mussels Most in suspension, eventually settling

16 Antarctica & the Southern Ocean Antarctica Covered by ice Highest, driest, windiest, coldest continent on Earth No riverine input into the Southern Ocean Few species live permanently here The Southern Ocean Low DOM In additional to sea ice (relatively thin, ~2m) there are also Ice Shelves (ie. floating Glaciers!)

17 Antarctica & the Southern Ocean Interesting research Ice cores contain gas bubbles that scientists examine to study changes in Earth s atmosphere over millennia Lake Vostok, buried under ice Early studies suggest it has been isolated from the atmosphere for millennia No life has yet to be found

18 Antarctica & the Southern Ocean Interesting research

19 Antarctica Ecosystem: Whales Both toothed and baleen Orcas Hunt fish, squid, seals, and other small whales Very abundant in Antarctic Sperm Whales Dive very deep Feed on squid and fish Numbers severely declined due to whaling Fin, Minke, Humpback, Blue, Southern Right, Sei Feed on Krill

20 Antarctica Ecosystem: Whales

21 Antarctica Ecosystem: Whales

22 Antarctica Ecosystem: Seals Crabeater Seals Prey on fish and krill Leopard Seals Feed on crabeater seals and penguins

23 Antarctica Ecosystem: Birds Petrels Albatross and Terns take extremely long migrations looking for food and can be found in the Antarctic in the summers. Both species can stay in air for months or years Penguins Adelie Emperor Other species

24 Antarctica Ecosystem: Fish Only 120 species are known to be able to live in Antarctic Convergence Have antifreeze compounds Live in midwaters to surface Eaten by most large predators

25 Antarctica Ecosystem: Jellyfish & Squid Jellyfish live in all the world s oceans Polar species can get quite large Feed on zooplankton or small fish Squid are found in all the world s oceans Common squid range in size from very small to over 4 feet Giant Squid can be many meters Feed on zooplankton, fish, even other squid Food for penguins, whales, and Albatross

26 Antarctica Ecosystem: Zooplankton & Phytoplankton Phytoplankton blooms in spring and summer form the base of Antarctic food web Many species of zooplankton feed on phytoplankton Krill, copepods, salps, amphipods Krill are vital to Antarctic ecosystem Huge blooms feed fish, whales, penguins, seals, birds, and larger zooplankton

27 Issues that Affect Polar Seas Stable ecosystems; slow to recover from damage Industrial fishing altering polar food webs Climate change is rapidly reducing the amount of sea ice Loss of habitat for polar species Loss of ice s ability to reflect solar energy speeds up climate change TED Talk about melting glaciers

28 Polar Seas Food Web Create a food web of either antarctic or arctic ecosystem At least 30 things (both biotic and abiotic) Be specific!