Suddenly, reef fish lose the ability to recognize the intruder and then respond accordingly.
When coral reefs are destroyed by large-scale bleaching, the consequences are dire. Not just for coral reefs, but also for the fish that depend on them A new study on. Coral fish generally have a certain pattern of behavior. However, when corals are exposed to bleaching, the impact is great, causing sudden amnesia in fish.
Butterfly fish
The scientists visited five different coral reefs in the Indo-Pacific for their study. This zone includes the tropical waters of the Indian Ocean, the western and central Pacific Oceans, as well as the connecting seas around Indonesia. In particular, the researchers here studied one of the inhabitants of the coral reef, the butterflyfish – a striking, tropical and brightly colored fish.
Read more about butterfly fish
Kepe-kepe are a family of beautifully colored, perch-like marine fish. They live mainly on coral reefs in the Atlantic, Indian and Pacific oceans. Most butterflyfish are small. Its dimensions are usually from 12 to 22 centimeters. The largest species of Chaetodon lineolatus could reach 30 centimeters. There are a total of 127 species, grouped into 11 genera. The butterflyfish nickname is associated with bright colors and shades of colors such as black, white, blue, red, yellow and orange.
Butterflyfish are known to follow certain “rules of conduct”. This allows them to recognize competing species and respond accordingly. “This ability allows the fish to decide whether or not to escalate the situation,” said lead researcher Sally Keith. “As a result, they not only conserve valuable energy, but also prevent injury.”
Forget it
The researchers analyzed a total of 3,700 observations from a total of 38 different butterfly species. The team compared the behavior of the butterflyfish before and after severe bleaching on the coral reefs where they lived. And it shows something extraordinary. Fish, seeing their refuge disappear, suddenly forget the rules of their behavior. This means that they suddenly find it very difficult to identify competitors. And it has a long-lasting effect. As a result, they could not decide whether they wanted to interfere or not. This leads them to suddenly end up in pointless fights where they consume precious and limited energy.
The results show that butterflyfish recognize other species much worse after the bleaching period. The encounter then spiraled out of control at over 90 percent and resulted in a heated chase. By comparison, before the bleaching era, this was only 72% of the time. The researchers also found that the chases lasted longer, with the fish expending more energy chasing the intruder than before.
Nuisance
The team believes the bleaching period is responsible for this change in behavior. As many corals died, the fish were forced to change and diversify their diets and territories. Thus, large-scale environmental change effectively disrupts the established and mutually developed relationships that previously allowed different fish species to coexist peacefully. “The rules of conduct are designed for a specific playing field,” says Keith. “But the industry is changing. Periods of mass bleaching follow each other quickly. This results in less coral, the butterflyfish’s food source. At this point, we don’t know if these fish can update their “rulebook” quickly enough to reconsider their decision.
In the worst case, it could even impact their survival, researchers warn. As the Earth continues to warm, more corals are likely to die. And it is increasingly grappling with the fish of the coral reef. “We now know how butterflies respond to changes in their environment,” Keith said. “They could make seemingly relatively minor mistakes about where to spend their precious energy. But that will eventually put them on the sword.
