Deck 19: Polar Marine Biology

Question 1

Antarctic and arctic environments have the following in common:

A) Very-large-bodied invertebrates in bottom communities
B) Very high phytoplankton productivity
C) Ice as a source of algal production and deposition on the sea floor
D) Dominance of penguins

Answer 1

C

Question 2

The reduction of floating ice cover has affected penguins because

A) Killer whales now can hunt them more effectively
B) Leopard seals can leap out of the water and raid nests
C) Krill, the food of penguins, grows better under the floating ice
D) All of the above

Answer 2

C

Question 3

Which of these statements characterizes Arctic food webs?

A) Arctic primary productivity is very low and benthic abundance is comparable to the deep-sea soft bottoms
B) Arctic food webs are characterized by few large carnivores
C) Unlike the Antarctic, ice algae has no role in flow through food webs
D) Arctic primary productivity is much higher than that which is typical of the Antarctic

Answer 3

D

Question 4

When polar floating ice melts back in the spring,

A) The sea surface becomes colder as heat is lost to the atmosphere
B) Melting ice releases high amounts of nutrients that fuel phytoplankton blooms
C) Krill suddenly becomes more abundant
D) The ice tends never to return the next winter

Question 5

Which of these statements is supported by current evidence?

A) The Arctic is already showing evidence of major species movements owing to climate change
B) The Antarctic has witnessed no change of summer sea ice changes
C) The Antarctic food web is not affected strongly by the presence of krill
D) Feeding by baleen whales is only of importance in the Arctic

Question 6

Abundant Antarctic Adelie and Chinstrap penguins

A) Have been steadily increasing in recent years, owing to increased conservation measures
B) Are not heavily dependent on krill and therefore can survive on diverse food sources
C) Are confined to small areas in the Ross Sea
D) Are both in steep decline since the 1970s

Question 7

Crabeater seals have which of the following main food in their diet?

A) Krill
B) Juvenile penguins that move toward the ice edge
C) Spider crabs
D) All of the above

Question 8

Why might krill be more abundant now than 100 years ago?

A) Fishing for krill has been declared illegal and has ceased recently
B) Krill may have been exploited by baleen whales, which were severely overfished
C) Krill used to be eaten for health food reasons but that is no longer true
D) All of the above

Question 9

Shell-crushing predators

A) Are abundant on the Antarctic shallow shelf and suppress shell bearing benthos
B) Are generally absent from the Antarctic shelf
C) Are common in the Antarctic shelf and have selected for a benthic fauna of thick-shelled mollusks
D) Have recently invaded the Antarctic shelf and have eliminated shell bearing local benthos