Monday, 14 May 2012

Just back again – and friends are there too

Gray whale
Some 800,000 years ago - about the time early human tribes were learning to make fire – a tiny species of plankton called Neodenticula seminae went extinct in the North Atlantic. Now, that microscopic plant has come back again. It drifted into North Atlantic from the Pacific through the Arctic Ocean.

The melting Arctic has opened a passage across the Pole for the tiny algae. And while it's a food source, it isn't being welcomed because it could change the marine food web.

The tiny marine plant's migration is paired with the arrival of a Pacific gray whale, spotted last year off the coasts of Spain and Israel. Gray whale vanished from the Atlantic three centuries ago, likely because of over-hunting.  

Neodenticula seminae off  Iceland
Other phytoplankton species, known as dinoflagellates, are moving steadily eastward across the Atlantic towards Scandinavia. That is looking less innocent then Neodenticula seminae because many dinoflagellates are harmful. Their bloom affects other marine creatures.

Jellyfish too are increasing in the northeast Atlantic, often forming massive blooms. Outbreaks of venomous warm-water jellyfish, Pelagia noctiluca a gluttonous predator of juvenile fish, have become an annual event, forcing the closing of beaches.

Rootmouth jellyfish
Simple changes in temperature mean some species are no longer available when their predators need them. Off Northwest Europe, the warming trend has led to earlier spawning of cod, while phytoplankton have kept their traditional biological schedule. The result is a mismatch between the cod's larval and its food. The impacts of such changes remain difficult to assess. The web of life in the oceans is complex. Some impacts will combine to magnify their effects on ocean life; others might neutralize each other; or marine life might alter abruptly. [*]

[*] after press release of project “Climate Change and European Marine Ecosystem Research”

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