A new study finds that there's a lot more to coral bleaching than had been thought.
A disturbing new study finds that the destruction of coral reefs has an additional negative effect on the fish that live there.
The study, published in the journal Proceedings of the Royal Society B, found that coral bleaching can affect how small reef fish learn about and avoid predators, according to a James Cook University statement.
Reefs tend to have very rich and tightly interconnected ecosystems, housing many types of animals, and stresses on these reefs globally can result in lots of dead corals that are covered in algae. The study found that coral death and degradation affects how the damselfish responds to chemicals given off by predators.
These small fish use chemical alarm signals to learn the identity of new predators, allowing them to better avoid individuals in the future. But when corals die and get covered in algae, it changes the “smell” of the reef, and disrupts this learning mechanism.
The scientists worry that this shows that we could lose some crucial diversity in reef fish if there is continued coral bleaching due to global warming. Many fish rely on reef habitats, so the loss of those habitats could be devastating to those species, upsetting a delicate ecosystem. The Great Barrier Reef in particular is undergoing its worst mass coral bleaching in history.
“Baby fish use chemical alarm signals released from the skin of attacked individuals to learn the identity of new predators,” Professor Mark McCormick from the ARC Centre of Excellence for Coral Reef Studies at James Cook University said in the statement. “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.”