University of Western Australia: Survey documents loss of globally unique kelp forest in Oman

A new study from The University of Western Australia has discovered the only confirmed northern hemisphere population of golden kelp can no longer be found in Oman.

The expedition was led by Adjunct Professor Melinda Coleman and Professor Thomas Wernberg, from the Oceans Institute and School of Biological Sciences at The University of Western Australia, and the findings were published in Scientific Reports.

“Marginal kelp populations at warm, equatorward range edges are often among the most vulnerable to climate change because they experience temperatures near or exceeding their thermal thresholds and may lack the genetic diversity to respond,” Adjunct Professor Coleman said.

“Significant ocean warming trends punctuated by periods of suppressed upwelling that previously supported the existence of this kelp in a shallow, low latitude seascape, are likely to have driven the local extinction of this kelp population.”

Forty years ago forests of golden kelp (Ecklonia radiata) were reported in abundance in Sadah on the Dhofar coast but a recent survey in 2019 failed to find any signs of the species.

“We did not find any evidence of the kelp in Oman following five days of intensive searching off Sadah in the peak post-monsoon season, the period it was reported to be abundant in all surveys from the 1980s,” Professor Wernberg said.

“This included 57 towed video surveys and ten SCUBA dives across many kilometres of coastline at sites and depths where it was reported to be historically abundant. Video surveys at deeper depths and additional beach wrack inspections – where washed up kelp plants could have accumulated from previous seasons or years – also failed to find any evidence of the species.”

Adjunct Professor Coleman said the loss was a concern as these marginal populations often harbour unique or functional genetic diversity.