Jeanna Bryner at LiveScience:
Ocean currents can whisk tiny larval fish a long way from home. Turns out, the little ones follow their noses back to their native reefs.
Jelle Atema, a sensory biologist at Boston University, and Gabriele Gerlach of the Marine Biological Laboratory in Woods Hole, Mass., analyzed small gene units called microsatellite markers in three species of reef fish, including the cardinal fish, spiny damsel fish and the neon damsel fish, living on five reefs within Australia’s Great Barrier Reef.
The markers indicated that more returned to their home reef than random chance would predict. The most obvious was the cardinal fish [image], which showed clear genetic differences from one reef to another.
“Even though the [cardinal fish] larvae are dispersing out in the ocean, there are distinct differences between reefs as if they were not dispersing,” Atema explained. “That means they either have to, by great majority, all go home every generation, or those that do go to other reefs die off and they don’t reproduce.”
To find out what was steering the cardinal fish home, the scientists placed individual fish larvae into a flume containing “lanes” of water samples collected from different reefs. The cardinal fish larvae preferred water from their home reefs and spent more time in that part of the flume compared with water from other reefs [video].
The researchers suggest the young creatures sniffed out familiar scents dispersed in the water to guide them home.