Coral in the Northern Red Sea might bleach if the temperature of the water drops, a new research claims. Researchers from Bar-Ilan University’s Mina and Everard Goodman Faculty of Life Sciences and the Interuniversity Institute for Marine Science, examined coral in controlled low temperatures to see whether they would be affected by the temperature change.

Coral is one of the most diverse ecosystems on Earth, and by bleaching, a process in which coral is affected due to temperature change and throw out alga present in their tissue, it will white in color.

A previous experiment from Professor Maoz Fine of Bar-Ilan University showed that coral reefs of Israel’s shores had a higher level of tolerance to the high temperature of the seawater when compared to other reefs across the globe.

The team also found out that the coral copes well with warmer temperatures, which is expected to happen with global warming. The team used a Red Sea Simulator System to raise the temperature around the coral. However, with experts suggesting the Red Sea is moving towards a cooler period, the results show how much damage a slight drop in temperature can cause to a vast ecosystem.

“Whilst we have repeatedly demonstrated the high-temperature tolerance of coral on the shallow reefs in Eilat, we wanted to test the possibility that this exceptional heat tolerance comes with the trade-off of being cold-sensitive,” said Dr. Jessica Bellworthy. “Indeed we found that exposure to cold water periods causes a physiological response akin to bleaching.”

The team demonstrated that even a 1°C temperature drop can trigger a physiological stress response, seen on other coral when exposed to high temperatures. However, the research also showed that the damaged coral did not die and returned to its previous state.

“It was an important discovery for us to understand that even those individuals that suffered the cold winter stress, still did not bleach at the high temperatures,” Bellworthy said.