Animals that were oceans apart are now together, due to melting Arctic ice

By Washington Post, adapted by Newsela staff

12.21.15

Animals have been showing up in strange places lately.

Gray whales live in the Pacific Ocean. In the spring of 2010, though, a single gray whale was spotted in the Mediterranean Sea. It was the first time a gray whale was seen in the North Atlantic in about 200 years. 

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Other animals that live in the Pacific have been appearing in the Atlantic as well. Likewise, creatures that live in the Atlantic Ocean have been seen in the Pacific. 

What is going on? A group of scientists, led by a scientist named Seabird McKeon, published a paper about the strange pattern. The paper was released on Nov. 30 in the magazine Global Biology. It said that the reason animals are moving between the Atlantic and the Pacific may have to do with climate change. 

Between the Atlantic and Pacific are giant continents. Sea creatures cannot cross them. Connecting the two oceans to the north is the Arctic Ocean. The Arctic is one of the coldest places on earth. Because of how cold it is, big parts of the Arctic Ocean are covered in ice. 

Melting Ice Makes Travel Easier

The ice usually keeps animals from using the Arctic to move between the Atlantic and Pacific oceans. Animals like whales and seals have difficulty getting through the ice. It gets in the way of their swimming and can block them from coming up to breathe. Birds can fly over the frozen ocean, but the ice prevents them from diving for fish.

These days, however, the ice is starting to melt. The climate is changing. Each year, the earth is getting a little warmer. As the Arctic has warmed, ice has started melting. As a result, passageways have opened up in the ice. 

McKeon and his team believe that this has allowed certain animals to cross through the Arctic, letting them move between the Atlantic and the Pacific. It is like a bridge has opened up between two oceans that used to be separate. Animals that used to always be apart can now mix. Scientists call this mixing "faunal exchange."

Studying "Faunal Exchange"

Many animals could become part of the faunal exchange. Birds such as Arctic terns, common eiders, Atlantic puffins and short-tailed shearwaters may start to move between the Atlantic and the Pacific. Beluga whales, ringed seals and Atlantic white-sided dolphins may do so as well.

No one can say for sure what effects the faunal exchange will have. To get some idea, though, McKeon and his team examined past examples of faunal exchange.

The Great American Biotic Interchange was a large faunal exchange. Several million years ago a thin strip of land called the Isthmus of Panama formed between North and South America. The new bridge allowed land animals to cross between the two continents for the first time. As a result, animals from North America invaded South America. They beat out many of the native animals there for food. 

Watch Out For Killer Whales!

McKeon and his team also looked at what happened when killer whales moved into Hudson Bay, a large body of water in Canada. As their name suggests, killer whales are hunters. All of the sudden, the animals in Hudson Bay had to be on the lookout for a new predator. Faunal exchange, in that case, altered the delicate balance of predators and prey.

McKeon and his team argue that the current exchange between the Pacific and Atlantic may have the same kinds of effects. It may lead to genetic changes as well. As animals move to new territories, they mix with different kinds of animals. Sometimes these new neighbors interbreed. New kinds of animals might be born as a result.

What Next?

At this point, scientists can only wait and see, and study. Most scientists seem to agree that faunal exchange between the Pacific and Atlantic is already occurring. It seems like it will only increase as more passages open up in the Arctic. The effects of faunal exchange, however, remain to be seen.

Questions:

1. Where do gray whales live in and where were they found in now?

2. Why the animals are moving between the Atlantic and the Pacific?

3. Why do animals cannot cross between the Atlantic and Pacific?

4. Why does the ice keeps animals from using the Arctic to move between the Atlantic and Pacific oceans?

5. What does "faunal exchange" mean?

6. What are the effects of current exchange between the Pacific and Atlantic?