NYUAD RESEARCHERS SPOT RARE BRAMBLE SHARK IN UAE WATERS
▶ Endangered species surprises biologists surveying coral reef off coast of Fujairah, writes John Dennehy
Arare bramble shark has been seen in UAE waters for the first time, after the sea floor-dwelling fish swam over to a submersible with researchers on board.
The species, Echinorhinus brucus, is listed as endangered, but this shark was seen at a depth of about 850 metres off the east coast during an expedition led by scientists from New York University Abu Dhabi.
Experts hailed the sighting, saying it shows how much remains to be learnt about the UAE’s marine environment.
John Burt, an associate professor of biology at NYUAD, told how the fish approached the team’s submersible on the seabed about 80km from the shore.
“Almost as soon as we landed, this massive shark swam up to look at us,” said Prof Burt.
“Because it’s pitch black, if there’s any light down there, any organism can see it from a long distance away.
“They’re curious. They popped up to see what we were doing.”
Bramble sharks are quiet creatures and typically live close to the sea floor at depths of up to 900 metres. This one was recorded off the edge of the continental shelf. Harmless to humans, they are usually black or brown and can grow to more than three metres long. They have two small dorsal fins at the back, and are covered with sharp toothlike structures called denticles.
In 2020, the International Union for Conservation of Nature, a global authority on the status of the natural world, classified the bramble shark as endangered, due in part to intentional and incidental catches.
Footage from the submersible shows the bramble shark moving slowly across the sea floor.
“What’s really exciting about that shark is that it has never been recorded in the UAE before,” said Prof Burt.
He said it was not surprising they had not been seen before, as the east coast is very shallow. However, they are present in the Arabian Sea.
“It’s not just an individual,” he said. “It is a population of them that occur out there that we didn’t even know existed.”
The discovery came during an expedition on the OceanX research vessel, OceanXplorer, in December. It is equipped with underwater submersible craft, acoustic mapping sonars and remotely operated vehicles capable of exploring depths up to 6,000 metres.
Prof Burt and his team from the NYUAD marine biology lab were there to study a mysterious 144 metre deep reef discovered about 30km off Fujairah in 2022.
The reef was first explored by Simon Nadim, a Fujairah-based technical diver. Technical divers explore deeper waters than scuba divers.
Initially, Mr Nadim thought it was a wreck. Instead, he found a remarkable formation of coral not typically encountered at that depth in these waters.
This is known as the mesophotic zone, and it is thought to be home to unique species.
Mr Nadim also took part in the OceanX expedition.
“We call it the twilight zone, because it is very much like the sun has just set, and there’s just enough light there,” said Prof Burt.
Footage shows how the submersible was lowered off the OceanXplorer, before slowly descending and using its powerful lights to penetrate the darkness as the reef looms ahead.
“You can see rocks actually appearing out of the sea bottom. And on those rocks, you start to see the corals appearing,” said Prof Burt.
It covers an area of about 100 metres by 50 metres, with a ridge of rock that rises to four metres above the sea floor before tapering back down. Fish use the reef as a habitat for shelter and food.
“That large rocky ridge had a tonne of stuff growing on it,” said Prof Burt. More than 80 coral specimens were collected. These included rare black corals, soft corals and hard corals – the colourful ones people typically think of.
“Many are believed to be new for the UAE, and some are thought to be new to science and perhaps even endemic – meaning they are found nowhere else.
“It is amazing for me, as a scientist, to be able to get down there and not only see it with my own eyes as the second person in the world to see this, but rather to be able to spend six hours doing detailed surveys of the site. We literally saw every coral that was on that reef.”
Coral reefs are crucial ecosystems and a lifeline for many species. But they are under pressure from a variety of issues, from warming seas to pollution.
Prof Burt said it had initially been thought that these deeper reefs could provide support to corals in shallow waters as a sort of “refuge from climate change”, but they are now believed to be separate ecosystems. “We didn’t even know these existed [in UAE waters] until November 2022,” he said.
“If you have a unique ecosystem, you should be protecting it, but you cannot manage something that you don’t understand.
“Much more remains to be discovered about the reef, such as why the colonies are smaller when compared to similar reefs in other parts of the world. Was there a past disturbance event? Why is the temperature warmer by the reef? Do marine conditions play a role, such as hot salty water that comes from the Gulf?
“These are unexplored questions that we’re going to start looking into.”
The site is also close to port anchorages, while dredging work has cut a channel very close to the reef, showing how vulnerable it is.
“It’s eerie how much it came to impacting that reef,” said Prof Burt.
“But what I can say is that this is a highly vulnerable site … and important ecosystem. This is very significant.”
The team scoured the area looking for other reefs during the 10-day expedition, completing several missions in the submersibles. Prof Burt said the sea floor has ridges and rises that take time to chart.
Other finds included the fossilised remains of “many thousands” of mangrove roots.
Prof Burt said these are believed to be the “remnants of mangrove populations” at the mouth of the Gulf of Oman during the last ice age, when there was no Arabian Gulf. This could shed light on where the coast was then.
Mr Nadim said it was a “mind-blowing experience” to be on the OceanX vessel, and was grateful his dive in 2022 had helped open new gateways of scientific exploration.
He is now using his diving experience to try to pinpoint more deepwater reefs, showing how academics, researchers and divers can combine knowledge.
Prof Burt’s team was just one of several on board the OceanX vessel, with others conducting separate studies of the UAE’s environment.
OceanX is supported by Dalio Philanthropies, which in November last year granted $1 million in funding to researchers at NYUAD in support of efforts to protect the Arabian Gulf’s coral reefs against rising ocean temperatures.
OceanX science programme director Mattie Rodrigue said the OceanX team was responsible for high-resolution mapping of more than 1,250 square kilometres.
She also highlighted the significance of Prof Burt’s work. “For the first time, mesophotic and deep sea corals were discovered and studied in the UAE,” said Ms Rodrigue.
“This tremendous achievement, we hope, will inspire research for NYUAD and the Burt lab for years to come, especially given the unique warm, saline conditions of UAE waters and the ability for these corals to survive and thrive in that extreme environment.”
It’s not just an individual. It is a population of them that occur out there that we didn’t even know existed
JOHN BURT
Associate professor, NYUAD