A
In the last 50 years, sea surface temperatures around Antarctica have risen by 1—2°C, which is more than twice the global average.
Loss of species
Global warming could basically change the ecosystem, leading to the loss of some species. Sharks are going to arrive in Antarctica as long as the warming trend continues, a bit more slowly than crabs—crabs are going to get there first, but once they do get there they are able to eat the organisms that live there.
Professor Wilga said the arrival of sharks and shell-crushing bony fishes would lead to great changes in the number and proportions (比例)of species found there.
Shrimp, ribbon worms and brittle stars are likely to be the most attackable to population declines. Animals living in shallow waters in Antarctica are unique on Earth today because they evolved (进化) in a very cold environment over tens of millions of years.
Extreme conditions
In the course of a process we call Antarctic cooling that started about 40 million years ago, all major seafloor predators such as sharks and crabs went extinct in Antarctica because they were not able to deal with these extreme conditions.
However, today global warming is removing barriers to invasions and we've seen recently that crabs, especially king crabs, are on the doorstep of Antarctica—they can potentially re-invade the shallow waters if warming continues.
Urgent local and global actions are needed to protect this last environment and measures are needed to stop alien species being brought in through ships.
Strange creatures
Animals that live on the seafloor of Antarctica are some of the strangest creatures on Earth. The extreme cold and darkness has presented huge challenges to marine life over the passage of time, leading to the evolution of fish equipped with anti-freeze proteins in their blood.
1. How will these alien species affect the ecosystem in Antarctica?
A. They will change the extremely cold conditions in Antarctica.
B. They will change the numbers and proportions of species in Antarctica.
C. The sea surface temperature of Antarctica will rise more quickly.
D. The number of shrimp and ribbon worms will increase in Antarctica.
2. How does the author feel about the alien species' invasion to Antarctica?
A. Worried.
B. Doubtful.
C. Satisfied.
D. Excited.
3. Which is the best title of this passage?
A. Creatures in Antarctica Are Unique
B. The Extreme Conditions in Antarctica
C. Alien Species Are Not Found in Antarctica
D. Alien Species May Change Antarctic Ecosystem
