Polar ice caps are melting and opening the way between oceans. (Photo: Clamer.eu/NOAA)
Melting Arctic ice spawns mass oceanic migrations
Friday, July 01, 2011, 23:30 (GMT + 9)
Vast migrations of marine species are taking place thanks to melting polar ice caps opening the way between oceans. Species unseen for centuries or longer are crossing over from the Pacific to the North Atlantic Ocean though a new Northwest Passage, a phenomenon which scientists warn could endanger North Atlantic ecosystem.
"Such a geographical shift could transform the biodiversity and functioning of the Arctic and North Atlantic marine ecosystems," the Sir Alister Hardy Foundation for Ocean Science (SAHFOS) presaged, reports TG Daily.
After disappearing from the North Atlantic 800,000 years ago, a minuscule species of plankton called Neodenticula seminae has reappeared, likely having travelled from the Pacific through the Arctic Ocean. This constitutes “the first evidence of a trans-Arctic migration in modern times,” SAHFOS explained.
Last year, despite having been hunted to extinction in the Atlantic Ocean by the mid-1700s, a Pacific gray whale was observed off the coasts of Spain and Israel, reports Associated Press.
The findings appear in a new catalog by project Climate Change and European Marine Ecosystem Research (CLAMER), a collaboration of 17 institutes on climate change and the oceans in 10 European countries combining the results of almost 300 climate change-related research projects funded by the European Union (EU) over 13 years.
"The migrations are an example of how changing climate conditions cause species to move or change their behaviour, leading to shifts in ecosystems that are clearly visible today," stated Carlo Heip, director general of the NIOZ Royal Netherlands Institute for Sea Research, which heads the CLAMER project.
As it documents the change in plankton through the Continuous Plankton Recorder Survey -- the longest and most geographically extensive marine biological survey ever done -- SAHFOS has found that populations of tiny animals called copepods are also changing, jeopardising the food supply of fish including cod, herring and mackerel and their predators.
As climate change progresses and the Atlantic and the North Sea get warmer, the copepod Calanus finmarchicus is being replaced by smaller and less nutritious varieties and has led to the collapse of certain fish stocks, the researchers report.
"The major issue about this climate change is the rate at which things are happening at this moment. … We had change, we had warming, we had cooling, we had ice ages, but it was always slower than things are going now," said Katja Philippart, a marine biologist with the Royal Netherlands Institute and a coordinator for CLAMER, reports CBS News. "The rate is unprecedented."
Among many other species shifting northward, harbour porpoises migrated from the northern North Sea when sand eels, a favourite prey, moved north.
"The predictions of higher average temperatures and milder winters in the North Sea make it likely that these species will increase further in abundance and move northward," said scientists from the Netherlands Institute for Ecology (NIOO). "This will affect the North Sea food web and therefore commercial species by predation on juveniles and competition for food resources."
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By Natalia Real