For centuries，fishers in Narrangansett have fished in the waters of the northwestern Atlantic for herrings（鯡魚）.But as climate change warms the world's seas，the herrings are disappearing at the southern end of their range and turning up more often at its northern edges.A study shows that concentrations of marine（海洋的）species populations have been shifting away from the equator （赤道） and toward the poles during the course of the past century.These movements could wreak havoc on food webs and endanger the livelihoods（生計） of fishers.
   The tropical （熱帶的）water at the equator is well-known for having the richest diversity of marine life on Earth.The number of marine species naturally decreases gradually as you head towards the poles.Ecologists have assumed this global pattern has remained stable over recent centuries until now.Our recent study found the ocean around the equator has already become too hot for many species to survive，and that global warming is responsible.And as species flee to cooler water towards the poles，it's likely to have deep impacts on marine ecosystems.
   Losing species in tropical ecosystems means ecological adaptation to environmental changes is reduced，potentially damage ecosystem persistence.In subtropical ecosystems，species richness is increasing.This means there'll be species invaders，and new competitive relationships.This could result in ecosystem collapse in which species go extinct and ecosystem services（such as food supplies） are permanently changed.
   One way is to reduce our emissions aggressively.Other opportunities could also help safeguard biodiversity and hopefully minimize the worst impacts of it shifting away from the equator.Designing climate-smart reserves could further protect biodiversity from future changes.For example，reserves for marine life could be placed where the climate will be stable over the foreseeable future.We should take action without delay.

（1）What does the underlined phrase "wreak havoc on" probably mean in Paragraph 1？

C

C

A．Clarify.
B．Classify.
C．Destroy.
D．Purify.
（2）What can be learnt from the second paragraph？

A

A

A．Some species move to water in lower temperature.
B．More marine species exist at the poles than the equator.
C．The subtropical water has the most diverse marine species.
D．The global pattern of the ecosystem remains unchanged now.
（3）What is the main idea of the third paragraph？

D

D

A．The increase of species in subtropical ecosystem.
B．The decline of ecological changes in the ocean.
C．The temporary changes in ecosystem services.
D．The effects of species' immigration on marine ecosystem.
（4）What is the author's purpose in writing this article？

B

B

A．To inform readers of the reduction of marine species.
B．To appeal to readers to protect marine biodiversity.
C．To predict the future of the marine ecosystem.
D．To explain the reasons for global warming.