Researchers at the Mubadala Arabian Centre for Climate and Environmental Sciences (Mubadala ACCESS) at NYU Abu Dhabi have made significant discoveries about how reef fish in the Arabian Gulf, the world’s hottest sea, cope with extreme temperature fluctuations.
The study found that fish in the Arabian Gulf have a higher tolerance to temperature changes compared to those living in more stable coral reef environments. However, despite this increased adaptability, the Arabian Gulf has fewer fish species overall, suggesting that only certain species are able to withstand the rising global temperatures.
The Arabian Gulf's extreme and highly variable thermal conditions provide a unique setting for studying how reef fish might adapt to climate change. By comparing fish from this harsh environment to those in the more temperate Gulf of Oman, the research team, led by Dr Grace Vaughan, postdoctoral associate Daniel Ripley, and professor of Biology John Burt, found that the fish in the Arabian Gulf showed a slight increase in temperature tolerance.
However, overall biodiversity is lower. This suggests that while some species can adapt to environmental variability, the difference in thermal tolerance between the two regions was minimal.
A key part of the research tested the “plastic floors and concrete ceilings” hypothesis. This theory suggests that fish can adjust their physiological rates, such as metabolism and heart rate, to adapt to warmer climates. The researchers were the first to apply this hypothesis to a coral reef ecosystem experiencing increasing thermal variability rather than just rising average temperatures.
By comparing the metabolic rates of three reef fish species in the Arabian Gulf with the same species in the Gulf of Oman, the team found no significant difference in the metabolic rates between the two regions. This suggests that the "plastic floors and concrete ceilings" principle, which was originally developed in colder-water species, does not hold for tropical fish dealing with shifting temperature variability.
“The increased thermal tolerance observed in fish from the Arabian Gulf suggests an adaptive response to years of extreme temperatures,” said Ripley. “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.”
“While some coral reef fish in the Arabian Gulf show slight adaptability to increasing temperatures, many do not,” added Burt, who is also the co-principal investigator at the Mubadala ACCESS Centre. “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 team's findings were published in the paper Narrow Margins: Aerobic Performance and Temperature Tolerance of Coral Reef Fishes Facing Extreme Thermal Variability in the journal Global Change Biology.
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