The University of Manchester

Gulf fish more resilient to climate change than thought, study finds

Some fish species in the Arabian Gulf’s coral reefs are more resilient to climate change than previously thought, an international team of scientists has found.

The study, published in Nature Communications, challenges current scientific models which argue that by 2050, coral reef fish could shrink by 14-39 percent in size due to increasing temperatures under climate change.

The researchers from NYU Abu Dhabi, the Hawaii Institute of Marine Biology and The University of Manchester, identified how coral reef fish living in the Arabian Gulf – the warmest waters on earth – have adapted to survive extreme temperatures.

It was led by John Burt, co-principal Investigator at The Mubadala Arabian Center for Climate and Environmental Sciences (ACCESS) at NYU Abu Dhabi and Jacob Johansen, Associate Research  Professor at the  Hawaii Institute of Marine Biology.

Though they studied two kinds of fish the findings are likely to be relevant to other species.

Professor Holly Shiels was also on the team, along with her PhD students Dan Ripley and Grace Vaughan.

She said: “The Arabian/Persian Gulf is a window to future ocean conditions and working together with colleagues in the region we have used this natural laboratory to provide new insight into impact of rising water temperatures on fish.

“Our study offers hope for some marine species in a continuously warming world.”

According to the researchers, adaptations in both metabolism and swimming abilities helped the fish to survive extreme conditions in the Arabian Gulf.

The warming of our oceans is anticipated to drastically affect marine life and the fishing industry, potentially upsetting entire ecosystems and economic structures reliant on these habitats.

However, the study’s findings challenge the prevailing view that oxygen supply limitations in larger fishes are the main reason for smaller fish in warmer waters – known as the “shrinking fish phenomenon.”

The researchers instead argue the decrease in fish size and their survival in increasingly warm oceans might be more closely related to an imbalance between how much energy fish species can obtain and how much they need to sustain themselves.

The researchers compared two species of fish, the Blackspot snapper and the Arabian monocle bream, surviving under the elevated temperatures within the Arabian Gulf to those of similar age living in the cooler, more benign conditions in the nearby Gulf of Oman.

They determined the qualities reef fish in the Arabian Gulf have that enable them to survive there, where typical summer water temperatures are comparable to worst-case ocean warming projections for many tropical coral reefs globally by 2100.

John Burt said: “The hottest coral reefs in the world are an ideal natural laboratory to explore the future impact of rising water temperatures on fishes.

“Our findings indicate that some fish species are more resilient to climate change than previously understood and help explain why smaller individuals are evolutionarily favored at high temperatures.

This has significant implications for our understanding of the future of marine biodiversity in a continuously warming world.”

  • “Causes and consequences of ocean warming on fish size reductions on the world’s hottest coral reefs” is published in the journal Nature Communications.

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