The parasites that like it hot

Posted by fi17 at Dec 14, 2011 04:14 PM |
Worms infecting fish grow four times faster in warmer waters, and can even control the host's behaviour, new study finds
The parasites that like it hot

Three infected stickleback

Parasitic worms that infect stickleback fish prefer warm temperatures, according to a study carried out by Dr Iain Barber and doctoral student Vicki Macnab of our Department of Biology. They compared infected fish living at 20°C to those living at 15°C, and found that in warmer water the worms grew four times faster whilst the fish growth slowed. The worms like it warm - but the effect on fish is devastating, reducing their size and interfering with reproduction.

Those pesky parasites can also manipulate their hosts. A follow-up study found evidence that fish infected with the worms changed their behaviour and showed a preference for warmer temperatures. This trickery allows the worm to enjoy balmy temperatures and rapid growth - all at the expense of its poor host.

The research shows how global warming could potentially affect the balance between parasite and host. As global temperatures rise, the warm water benefits parasites, but the knock-on effects on fish populations could be serious and devastating. The worms' increased growth rate and size also means they go on to lay more eggs, further increasing the parasite population.

The research has been published in the journal Global Change Biology.

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