Clownfish spend their entire lives nestling in the protective tentacles of host anemones, but new research shows that as babies they sometimes travel hundreds of kilometres across the open ocean. Although the process of long-distance dispersal by reef fish has been predicted, this is the first time that the high level exchange of offspring between distant populations has been observed. Dr Steve Simpson, Senior Lecturer in Marine Biology and Global Change in Biosciences at the University of Exeter, and colleagues from the Australian Research Council Centre of Excellence for Coral Reef Studies (ARC COE CRS), Sultan Qaboos University (Oman) and the Centre National de la Recherche Scientifique (France) have published their findings on the dispersal of Omani clownfish larvae in the journal PLOS ONE.
Clownfish spend their entire lives nestling in the protective tentacles of host anemones, but new research shows that as babies they sometimes travel hundreds of kilometres across the open ocean. Although the process of long-distance dispersal by reef fish has been predicted, this is the first time that the high level exchange of offspring between distant populations has been observed.
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Dr Steve Simpson, Senior Lecturer in Marine Biology and Global Change in Biosciences at the University of Exeter, and colleagues from the Australian Research Council Centre of Excellence for Coral Reef Studies (ARC COE CRS), Sultan Qaboos University (Oman) and the Centre National de la Recherche Scientifique (France) have published their findings on the dispersal of Omani clownfish larvae in the journal PLOS ONE.
The study found that six percent of the fish sampled had migrated over 400 km from one population to the other, which, contrary to the film Finding Nemo, is a process that only occurs during the ocean-going larval stage.
"This is an epic journey for these tiny week-old fish. When they arrive at the reef, they are less than a centimetre long, and only a few days old, so to travel hundreds of kilometres they must be riding ocean currents to assist their migration," said Dr Simpson.
Dr Simpson led a team of undergraduate and postgraduate students from the University of Edinburgh to collect the clownfish samples from throughout southern Oman.
"The southern coast of Oman is relatively isolated from the rest of the Arabian Peninsula so you find a lot of species there that you wouldn't find anywhere else in the world," said Dr Simpson. "There are only two coral reef systems along this coast, and they are separated by 400 km of surf beaches. In order to persist as a single species, we know Omani clownfish fish must occasionally migrate between these two populations."
The team used DNA fingerprinting to identify local, long-distant migrant, and hybrid individuals from populations throughout the entire Omani clownfish (Amphiprion omanensis) species range. Around 400 fish were harmlessly caught during 92 dives, and a small fin clip taken for DNA analysis before releasing fish back to their colonies.
"Just like accents that allow us to tell an Englishman from an American, fish populations develop their own genetic signatures," said co-author Hugo Harrison from the ARC COE CRS. "By looking at the signature of each fish we can tell whether it originated there or not. It's like finding an Englishman in New York, they stand out."
Continue reading at The University of Exeter.
Clownfish image via Shutterstock.
