( Marine scientists working on Australia'...)Baby fish 'smell their way home'

Remarkable in itself, the discovery by a team including Professor Mike Kingsford of the ARC Centre of Excellence for Coral Reef Studies and James Cook University and colleagues from Woods Hole, USA, also shines a new light on how the breathtaking diversity of fish on coral reefs has arisen. This has major implications for how reefs are managed.

"The babies of many coral fish species are swept off their home reef by ocean currents within days of hatching. Ordinarily you'd expect them to be thoroughly mixed up and this would mean the population of one reef would be pretty much the same, genetically, as another," he says.

"But that is not the case. There are major genetic differences between fish of the same species on reefs only a few kilometres or even hundreds of metres apart."

This diversity between populations of the same fish species is what drives evolution on the Reef and underpins the spectacular richness of its sea life, Prof. Kingsford says. "This genetic separation between reefs may be what gives rise to so many different species in coral reef systems."

The researchers were intrigued how tiny damsel and cardinal fish, born on one reef, managed to find their way back home to preserve such remarkable population differences, braving strong currents and ferocious predators in their 20 days at sea ?all when only a centimeter or so in size.

"We tested several ideas, but the most attractive seemed to be that they could smell the unique trace of their home reef ?rather like salmon can smell the home river.

"We know these late stage fish larvae, generally between about 9 and 14mm long, already have developed noses ?but the question was whether they could use them to recogni
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Source:James Cook University