The thawing of the fabled Northwest Passage on Canada's north coast isn't just an opportunity for humans to cut shipping times between Asia, Europe and North America—or squabble over oil. It's also an opportunity for the tough shellfish species that thrive in the northern Pacific to colonize the gentler environs of the northern Atlantic, according to new research in Science.

Last year—thanks to global warming—said passage cleared for the first time in recorded history as the ice that covers the Arctic Ocean dwindled to a record minimum. This year is shaping up to be another low and scientists project that the Arctic could be ice free by the summer of 2050--or sooner.

Warmer waters (and water that is not beneath an ice sheet) means plankton—food for these mollusks—enabling them to slowly spread across the Arctic Ocean and into the Atlantic. They've done it before. The fossil record shows that a similar invasion of clams, oysters, snails and slugs took place in the Pliocene era (roughly 3.5 million years ago)—the last time the Arctic was ice free.

This doesn't mean that unassuming northern Atlantic species, including the Malpeques beloved by oyster connoisseurs, will disappear. It just means they may have to defend their undersea turf against their brethren from the Bering and Chukchi Seas by 2050 or so. "The composition and dynamics of north Atlantic communities will change," said geologist Peter Roopnarine of the California Academy of Sciences in a press release. "Whether that will help or harm local fisheries is an open question."

Credit: Dr. Sebastian Holmes (published on the MarLIN Web site)