Expedition reveals deep sea coral gardens

Astonishing ‘gardens’ of deep-sea corals have been discovered by Australian and international scientists in the Bremer Canyon Marine Park in the Southern Ocean.

Bremer Canyon Marine Park is approximately half-way between Albany and Esperance, offshore from Fitzgerald River National Park. It covers 4472 square kilometres, with depths from 15 metres to 5000 metres.

It is already well recognised as a biodiversity hotspot for marine species such as whales and orcas. The recent oceanographic expedition has now revealed rich and diverse ecosystems inhabiting the cold waters deep within the canyon.

Led by researchers from The University of Western Australia, these discoveries were made possible by the philanthropic Schmidt Ocean Institute’s deep-sea remotely operated vehicle, SuBastian, which is capable of sampling depths to 4,500m. The team collected deep-sea corals, associated fauna, seawater and geological samples from the abyssal depths (about 4,000m) to the continental shelf (about 200m).

Expedition leader Dr Julie Trotter, from UWA’s School of Earth Sciences and Oceans Institute, said they had already made a number of remarkable discoveries from the Bremer Canyon.

“The vertical cliffs and ridges support a stunning array of deep-sea corals that often host a range of organisms and form numerous mini-ecosystems,” Dr Trotter said.

“Such rare records of these deep-sea habitats are a new and very important contribution to the Marine Parks, which will help managers as well as the broader community to better understand and protect these previously unknown ecosystems. “

The expedition explored the Bremer, Leeuwin and Perth canyons, all of which have extensive fossil coral deposits, with the Leeuwin especially notable for a massive pedestal-like coral graveyard.

Professor Malcolm McCulloch, also from UWA’s Oceans Institute, said the discovery had global implications given these waters originate from around Antarctica and feed all of the major oceans and regulate our climate system.