Friday, December 19, 2008

Does 'junk food' threaten marine predators in northern seas?

I've got a piece in today's Science looking at what's called the junk-food hypothesis. This is the idea that climate driven changes to food webs are hurting marine predators either by causing their preferred prey to be replaced by less nutritious species, or by causing those prey species to become less nutritious themselves.

Here's the intro...

In 2004, ecologist Sarah Wanless was observing a colony of guillemots on the Isle of May off the coast of southeast Scotland. These diving seabirds were having a terrible breeding season in the United Kingdom, and some colonies hatched no chicks at all. But Wanless could see that parent birds were catching as many fish as ever, if not more. "We couldn't work out what was going wrong," she said. The light dawned when she and her colleagues measured the fat and protein in the fish being caught, mostly sprat, a member of the herring family. Compared with previous years, the amount of energy a hungry guillemot received from a 10-centimeter sprat plunged in 2004, dropping from 55 kilojoules to 12 kilojoules. "They were largely water," Wanless says.

And for keenies, and because Science's News Foci don't have reference lists, here, in no particular order, is some further reading. All free unless otherwise stated.

Low energy values of fish as a probable cause of a major seabird breeding failure in the North Sea

Community reorganization in the Gulf of Alaska following ocean climate regime shift

Junk food in marine ecosystems (not free, but there's a press release).

Pollock and the decline of Steller sea lions: testing the junk-food hypothesis

A Critical Review of the Regime Shift-“Junk Food”-Nutritional Stress Hypothesis for the Decline of the Western Stock of Steller Sea Lion


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