Fish learn how to survive in warming Arabian Gulf

Abu Dhabi scientists find coral reef fish showing higher ‘thermal tolerance’

Scientists say fish living in the Arabian Gulf have developed a higher 'thermal tolerance' than in the Gulf of Oman. Photo: Rebekka Pentti / NYUAD

The warming waters of the Arabian Gulf mean fish must adapt to survive – but new research suggests local marine life might be particularly good at it.

Scientists at NYU Abu Dhabi found reef fish in the harsh Arabian Gulf conditions had developed a higher "thermal tolerance" than in the milder Gulf of Oman. However, the Arabian Gulf had fewer fish species overall, suggesting those unable to adapt had been lost.

Already the world's hottest sea, the Arabian Gulf is expected to become warmer still due to climate change, altering a marine ecosystem that supports tourism and fishing in the UAE. Temperatures approaching 40°C have been recorded in waters off the Emirates, even at depths of six metres.

Rising temperatures in the Arabian Gulf mean fish must adapt or die out. Photo: Oliver Farrell

"The increased thermal tolerance observed in fish from the Arabian Gulf suggests an adaptive response to years of extreme temperatures," said Daniel Ripley, one of the leaders of the Mubadala Arabian Centre for Climate and Environmental Sciences research team.

"However, the noticeably lower fish diversity in the Arabian Gulf compared to the Gulf of Oman indicates that only certain species can physiologically adjust to temperature changes, meaning fewer species will survive as the climate continues to warm.”

Scientists tested one theory that fish might be able to adjust their heart rate or metabolism to survive in warmer waters. However, there was no difference between the Arabian Gulf and Gulf of Oman on that score, suggesting the theory does not hold true for tropical fish.

The Arabian Gulf is expected to become warmer still due to climate change, altering a marine ecosystem that supports tourism and fishing. Photo: Oliver Farrell

Dubai last year installed 1,000 artificial "reef modules" in its waters to provide food and shelter for marine life, making good on a Dubai Reef project unveiled at the Cop28 climate summit. The reefs are designed to last more than 100 years, providing long-term ecological benefits.

“While some coral reef fish in the Arabian Gulf show slight adaptability to increasing temperatures, many do not,” said biology professor John Burt, a second leader of the research. “This suggests that as global temperatures rise, fish biodiversity is likely to decline in many ecosystems. Our findings highlight the need to further investigate existing theories of thermal tolerance across different environments to better predict the long-term impacts of climate change.”

The study Narrow Margins: Aerobic Performance and Temperature Tolerance of Coral Reef Fishes Facing Extreme Thermal Variability is published in the journal Global Change Biology.