Arctic Warming May Allow Pacific Mollusks to Spread into the Atlantic
15.12.2009 - Water & Oceans, Flora & Fauna, Arctic
Researchers in California believe that the melting Arctic sea ice may allow mollusks from the Pacific to make their way into the Atlantic. But in order for mollusks to pass, there would have to be at least 125 consecutive days of less than 75% sea ice cover - something that could happen by 2050 according to the IPCC's Fourth Assessment Report, although some researchers such as Peter Roopnarine, Curator of Geology and Paleontology at the California Academy of Sciences in San Francisco, believe such ice conditions could exist as early as 2020 or 2030.
A lot of this migration theory is derived from fossil records of the last time such an event occurred some 3.5 million years ago, when there was a sudden shift in climate, allowing the Bering Strait to remain open long enough to allow hundreds of species including mollusks, cod and herring to reach the Atlantic via the ice-free Arctic. Although some species became extinct, others species thrived and slowly colonized the Atlantic - many of which are still there today.
The same kind of phenomenon might have already started in our times. A microscopic plant native to the Pacific called Neodentacula seminae was found in the Atlantic as early as 1999 after the retreat of the ice from the Arctic in 1998. However another theory suggests that the diatom might have been carried along with a ship's ballast water - although this is quite improbable since ships do usually not discharge their ballast water in the middle of the ocean, which is where the tiny plant was found at the time.
It is important to note that while species crossing the Pacific to the Atlantic may once again occur, it is unlikely that the invasive mollusks will displace the native species of the Atlantic Ocean.
