'Nemo' Travels Across the Open Ocean
Clownfish spend their entire lives nestled
within the protective tentacles of anemones, using them as a shield against
predators. Yet now, scientists have found that these fish may be a bit more
adventurous in their youth. They've discovered that baby clownfish may travel
hundreds of kilometers across the open ocean before settling down in an anemone
of their own.
"This is an epic journey for these tiny week-old fish," said
Steve Simpson, one of the researchers, in a
news release. "When they arrive at the reef, they are less than a
centimeter long, and only a few days old, so to travel hundreds of kilometers
they must be riding ocean currents to assist their migration."
The researchers made the discovery after using DNA fingerprinting to
identify local, long-distant migrants and hybrid individuals from populations
throughout the entire Omani clownfish species range. In all, the scientists
examined 400 fish, which were harmlessly caught during 92 dives. By examining
the genetic signature of each fish, the scientists could tell where it came
from.
In the end, the DNA evidence showed that the majority of migrant fish
travelled from north to south. In order to test whether this was due to
prevailing currents or not, the scientists then created an oceanographic model
for the region. In the end, they found that the migration pattern did
correspond to the dominant ocean currents in the area.
"This study is furthest anyone has tracked the dispersal of coral
reef fish, and it demonstrates that distant populations in the marine
environment can be well connected," said Simpson. "Our ability to
predict how far fish larvae disperse helps us to manage coral reef ecosystems.
Understanding connectivity means we can protect populations that are most
sensitive, harvest from populations that have a regular and consistent
turn-over, and design coherent networks of marine protected areas."
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