What would happen if krill became extinct (Antarctica)?

Question

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Answer 1

Krill are at the bottom of the food chain in Antarctica. If they die out everything else above them in the food chain will be adversely affected.

Krill is a general term used to describe about 85 species of open-ocean crustaceans known as euphausiids. They are prey for myriads of surface feeding predators such as seabirds, squid, fish and whales.

More than anything else, krill are the engine that powers the Antarctic ecosystem. Krill are unusual in that they are so super-abundant and large when compared to other phytoplankton feeders in other oceans. This means that many large animals such as seals, penguins, whales and myriad birds are able to tap the food chain close to the production of the phytoplankton before energy is lost, so the Antarctic supports a large population of large animals.

Recent studies (November 2004) have shown that stocks of krill in Antarctica have declined dramatically in recent years. The reason for this is likely to be a fall in the amount of sea ice in the winter months particularly in the Antarctic Peninsula region.

Krill numbers may have dropped by as much as 80% since the 1970's - so today's stocks are a mere 1/5th of what they were only 30 years ago. The decline in krill may  in turn account for the decline in the numbers of some penguin species.

This decline in krill will also make it more difficult for the great baleen whales to return to pre-exploitation levels following their decimation in numbers during the years from approximately 1925-1975.