A third of marine species could become extinct in the Arabian Gulf by 2090 unless immediate action is taken, a study from the University of British Columbia has found, with Abu Dhabi expected to be worst hit.

Rising water temperature, changing salinity and oxygen levels, and human activity, are all adding to the strain on sea life, with the report claiming that 35 per cent of the fauna found here in 2010 will become extinct over the next 62 years, and this is a conservative estimate.

The study was led by Colette Wabnitz, a research associate at the Institute for the Oceans and Fisheries at UBC, and published in the peer-reviewed, open-access PLOS One journal.

It found that “multiple human stressors, such as habitat destruction and overfishing, are likely to exacerbate this vulnerability”.

“Indeed, the region’s ecosystems are under the more immediate and ever-increasing pressures associated with the rapid development of economic, social and industrial activities, making the Gulf one of the highest anthropogenically impacted regions in the world.”

Researchers at UBC projected the future habitat suitability of the Gulf for 55 priority marine species, 47 of which are commercially important, and found that by 2050, the highest species loss will be along the north-west coast of Bahrain and the UAE.

The impact of climate change on these species is indicative of what could happen to other marine species in the Gulf, where climate-driven changes will make most of the southern area uninhabitable for current species.

Abu Dhabi will be in the hardest hit area, and the UAE will have a catch decline of more than 40 per cent.

Given that local species are either highly adapted to extreme temperatures or migratory species living at the limit of their environmental range, they are expected to be sensitive to changes in temperatures or salinity.

As species tend to head towards the poles, when the south of the Gulf warms up, fish are likely to move north towards Iraq and Kuwait. In the Gulf, this creates a cul-de-sac effect. Species cannot adapt by moving to deeper waters. The Gulf is just too shallow and with nowhere to go, many species will die out.

Climate change is expected to have a stronger impact on the Gulf relative to other regions due to its unique environmental conditions. The study considered the rate of species invasion, the rate of species extinction and changing habitat conditions that included salinity, oxygen levels and water temperature.

“We did not consider the interactions between other human activities in addition to climate change,” said William Cheung, an associate professor at UBC and author of the study. “Thus, considering the rapid development of marine environment in the region, it may be worst. I think besides mitigating the damage, there is an urgent need to reduce carbon emission. In the longer term, this will be the ultimate solution to the problem.”

The study notes that there are some species that could genetically adapt to rising temperatures, but this is a best case scenario. Water temperatures have reached between 35 and 37 degrees Celsius at least five times since the late 1990s, causing coral bleaching and the loss of coral essential to breeding fish.

The environmental loss will carry a heavy economic impact as fishing industries collapse. The fisheries of Bahrain and Iran are most vulnerable — Bahrain for its comparatively larger economic dependence on fisheries, and Iran because it has the highest catch and fewer employment alternatives.

Overfishing, shoreline development, dredging and oil extraction are “likely to represent more imminent and dangerous threats to these species’ survival than climate change”.

“For example, it is expected that the expansion of desalination plants would significantly increase average and maximum surface and bottom temperatures as well as average and maximum salinity throughout the Gulf, further exacerbating the impact of climate change on marine species.”

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The study notes that widespread degradation of coral reefs, which are used as foraging sites and nursery habitats, will further accelerate local extinction rates.

John Burt, an associate professor of biology at New York University - Abu Dhabi, said that 23 coral-dependent species in the Gulf are at high risk of regional extinction as corals die off.

“Coral reefs in the southern Gulf have undergone considerable degradation in the past three decades as a result of coastal development and increasing sea temperatures, and it is projected that we will continue to see the loss of these important habitats in the future if active restoration and reef management efforts are not put in place immediately,” said Dr Burt, who researches coral ecology in extreme environments.

Last summer was unusually hot and more than 85 per cent of coral was lost from most reefs in Abu Dhabi.

“There is incredible need for more applied research on how future climate conditions are likely to affect fish, particularly given that fisheries represent the second largest economic resource sector after oil,” said Dr Burt.