Australia’s worst-ever coral bleaching event is endangering the lives of reef fish who are unable to identify new predators.
Researchers in Australia and Sweden found that the damage to corals from bleaching prevents the common damselfish from responding to the telltale chemicals that indicate hungry predators are approaching.
“Baby fish use chemical alarm signals released from the skin of attacked individuals to learn the identity of new predators,” says Professor Mark McCormick from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.
“They mix the alarm cue from their wounded buddy with the smell or sight of the responsible predator, allowing them to learn which individuals are dangerous and should be avoided in the future.
“We found that the chemical alarm only worked on damselfish on live coral.
“Their counterparts on dead coral failed to pick up the scent.”
Dr. Oona Lönnstedt from Uppsala University in Sweden explains, “We found that when corals die and become covered in algae the olfactory landscape of the reef seems to change, which affects this crucial learning mechanism used by fish.”
“If the process of cataloguing and avoiding predators is hindered in some species by coral degradation and loss, then much of the diversity of reef fish could be lost too,” she says.
“Many reef fish need specific habitats that only healthy coral reefs can provide.”
“The Great Barrier Reef is currently experiencing the worst mass coral bleaching event in its history and coral cover on the majority of reefs is declining sharply,” says Prof. McCormick.
“If dead coral masks key chemical signals used to learn new predators, the replenishment of reefs could be seriously threatened.”
The study by Professor McCormick and Dr. Oona Lönnstedt has been published today in the journal Proceedings of the Royal Society B.
McCormick M.I., Lönnstedt O.M. 2016 Disrupted learning: habitat degradation impairs crucial antipredator responses in naïve prey. Proceedings of the Royal Society B 20160441. (doi:10.1098/rspb.2016.0441)
Professor Mark McCormick, ARC Centre of Excellence for Coral Reef Studies, James Cook University
Mobile: +61 (0) 409 371 015
Dr Oona Lönnstedt, University of Uppsala
Mobile: +46 700 218346