Coral reef bleaching apparently emits a stench of death, that apparently also hides the scent of predators from small reef fish, making them vulnerable, according to a new study.

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Researchers and scientists from James Cook University in Australia and Uppsala University in Sweden carried out two months of field study across the northern area of the Great Barrier Reef last year, for them to determine if coral bleaching hindered the small reef fishes' ability to sniff out their predators.  

These tiny reef fish known as damselfish were studied buy scientists where they discovered that when they dwell in dying and damaged coral reefs, it becomes difficult for them to detect nearby predators, therefore making them vulnerable to danger.

According to lead author of the study, Mark McCormick from the JCU College of Marine and Environmental Sciences, damselfish use their taste buds that are located in front of their bodies to identify which predators to keep away from. They have the ability to smell skin cells from a similar species that have been damaged, emitting chemical alarms. This serve as a crucial warning for the small fish to stop foraging and hide immediately.

In the presence of healthy reefs, damselfish possess a sort of database for these chemical alarm signals to keep them safe. In this new study however, researchers were able to discover that these fish now live in bleached and degraded coral, making it difficult and even dangerous for them to spot potential predators.

McCormick says that when the reef is entering its dying stages, the coral becomes covered in sponges and algae and similar organisms. This can cause the scent landscape to change dramatically, where the damselfish can no longer use their chemical alarm signals. 

Usually, when the fish is around live coral sitting on a bed of living coral, chemical alarm signals can effectively work. On dead corals, the fish can no longer distinguish that the new smells are now dangerous for their survival.

Researchers say that even if this is already occurring, some fish species managed to adapt to this new scent of bleached coral reefs. However, the team is still not certain if this can be taught among different fish species for their own protection and survival, or how they can quickly recover or respond to this environmental disaster caused by the degraded reef.

To date, the northern half area of the Great Barrier Reef is affected by coral bleaching, where scientists predict that up to 90 percent of it will die in the near future.

This new study is published in the journal, Proceedings of the Royal Society B.

Tagsdamselfish, Coral bleaching, Great Barrier Reef, Australia, coral reefs, bleaching event