A gray whale apparently made the voyage from the North Pacific to just off Israel last year by wandering through the normally ice-bound route through Arctic Canada.
Plankton not found in the North Atlantic for at least 800,000 years seem to have taken the same path.
“The implications are enormous. It’s a threshold that has been crossed,” said Philip C. Reid, of the Alister Hardy Foundation for Ocean Science in Plymouth, England.
Reid told The Associated Press that the last time such a major incursion occurred from the Pacific was 2 million years ago, when it had “a huge impact on the North Atlantic.”
It drove some species to extinction as the newcomers won out in the competition for food.