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Butterflyfish are fighting more often due to coral bleaching.
Nationalgeographic.co.id—A new study reveals that fish-fish that lose food due to coral bleaching mass involved fight which is more unnecessary. This causes them to expend precious energy and potentially threatens their survival.
With the future Coral reefs a world threatened by climate changethe research team studied how mass bleaching events affected 38 species of butterflyfish.
The reef fish with the colorful patterns were the first to feel the effects of bleaching because they were eating coral, so “their food source was depleting very quickly”, said Sally Keith, a marine ecologist at Lancaster University.
Keith and his colleagues had no idea a mass bleaching event was coming when they first studied fish on 17 coral reefs off the coasts of Japan, the Philippines, Indonesia and Christmas Island.
However, when one of the worst global bleaching events in history occurred in 2016, it offered the “perfect opportunity” to study how it affected fish behavior, Keith said.
The researchers returned in a year and were “shocked” to see the destruction of the once beautiful coral reef, he said.
Wearing snorkels or scuba gear, the team observed fish “swimming around looking for food that was no longer there,” added Keith as quoted from AFP.
The bleaching especially affected Acropora coral, the main food source for the butterflyfish. This “changes the playing field of who eats what,” says Keith.
When the butterflyfish wants to signal to its rival that a certain section of the reef is its own, it turns its nose down and raises its spiny dorsal fin.
Failing that, one fish will chase the other, usually until the other gives up. “I did one run for about 50 metres, it was quite tiring, they were really fast,” said Keith.
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The team observed 3,700 encounters between butterflyfish.
Prior to the coral bleaching event, different species of butterflyfish were able to resolve about 28 percent of disputes using signaling.
However, that figure drops to just 10 percent after bleaching. That represents a lot of “unnecessary attacks,” according to a new study in the journal Proceedings of the Royal Society B.
It’s not clear whether fish can adapt to the changes caused by coral bleaching quickly enough, the researchers warn.
Human-driven climate change has fueled mass coral bleaching as the world’s oceans get warmer.
Modeling research last year found that even if the Paris climate goal of holding global warming to 1.5 degrees Celsius is achieved, 99 percent of the world’s coral reefs will not be able to recover.
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