Saving Nemo: Bleaching threatens clownfish

Study reveals clownfish, the star Disney fish, and their sea anemone homes are at risk

Date: May 25, 2016

Source: University of Delaware

Clownfish became a household name over a decade ago when Disney released the movie "Finding Nemo."

Found exclusively in the Indo-Pacific, clownfish are symbiotic animals that only live in sea anemones, a close relative of corals that don't have a hard outer shell. The anemone provides a home and protection for the clownfish, while the clownfish provides food for the anemone.

As global concern grows for Australia's Great Barrier Reef -- which is experiencing the worst bleaching event in its history due to sustained high ocean temperatures amid a strong El Nino weather pattern -- University of Delaware researcher Danielle Dixson has co-authored a paper demonstrating how vulnerable clownfish are to the increased frequency of bleaching events.

Published today in Proceedings of the Royal Society B: Biological Sciences and co-authored with Anna Scott, a researcher at Southern Cross University in Australia, the paper illustrates that while clownfish can identify -- through smell alone -- if their potential home is bleached or healthy, they are inflexible in selecting a habitat.

"Unfortunately, our research has shown that bleaching does not break the symbiotic relationship between the anemone and clownfish. Clownfish are so behaviorally linked to one or a few particular anemone species for a home, that it limits their ability to acclimate if an entire reef bleaches," explained Dixson, an assistant professor of marine science and policy in UD's College of Earth, Ocean, and Environment.

"This means that clownfish are setting themselves up for bigger risk because we know that fish that go to bleached coral or anemones have an increased predation risk."

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