emirates7 - A new study from NYU Abu Dhabi has found that small coral reef fish in the Arabian Gulf are facing a hidden but growing source of stress.

When oxygen levels at night, a common occurrence on some of the world’s hottest reefs, these fish must use extra energy just to recover the next day. Over time, this additional strain could impact their growth, survival, and the overall balance of reef ecosystems.

This work was conducted at NYU Abu Dhabi’s Marine Biology Lab and led by Postdoctoral Associate at NYU Abu Dhabi Daniel Ripley.

To understand how fish respond to these conditions, the researchers recreated real nighttime low-oxygen events in the laboratory. They observed how much the fish moved, how much energy they used and how their bodies reacted at a cellular level. The results showed that the fish reduced their energy use when oxygen levels fell, but once oxygen returned to normal, their bodies worked harder than usual for several hours to recover.

The study also found that during low oxygen the fish activated biological pathways that help them sense and respond to oxygen shortage. However, this response faded quickly once oxygen levels increased. When the researchers compared their findings with real oxygen data from reefs in the Arabian Gulf, they discovered that these stressful low-oxygen events occur on more than half of all summer days.

“These fish are already coping with some of the warmest ocean conditions on Earth,” said Ripley. “Our findings that repeated nighttime drops in oxygen add a hidden layer of stress that could make it harder for them to grow and survive in the long term. Understanding this is important because small fish play a crucial role in keeping coral reef ecosystems healthy.”