Young fish can't learn to tell friend from foe
The current spate of coral bleaching in Australian waters is preventing baby common damselfish from learning how to identify which fish species are predatory towards them, according to researchers in Australia and Sweden.
"Baby fish use chemical alarm signals released from the skin of attacked individuals to learn the identity of new predators. 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,” said Professor Mark McCormick, from the ARC Centre of Excellence for Coral Reef Studies at James Cook University.
This natural learning process works only within the environment of living corals. If the surrounding corals are dead, the fish cannot detect the alarm signals.
Dr Oona Lönnstedt of Uppsala University in Sweden explained that when corals died and become covered in algae, the olfactory landscape of the reef seemed to change, and this affected this learning mechanism.
“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. Many reef fish need specific habitats that only healthy coral reefs can provide,” she added.
Baby fish less stressed when large predators are around
Fish distracted by motorboat noise become easy prey