First video: Australian deep sea canyon
A DEEP SEA CANYON off the coast of Western Australia has been filmed for the first time, revealing the habitat of some of Australia’s rarest marine life, including the blue whale and a fish that lives for 70 years.
The Perth Canyon is roughly the same size as the Grand Canyon in the US, and is Australia’s largest deep-sea canyon at 15 km wide and 1500 m at its deepest point. It was videoed in March by scientists from the University of Western Australia (UWA) and the CSIRO who released the footage today. The team lowered robotic cameras hundreds of metres below sea level to produce the stunning images.
Deep-sea canyons, immense valleys carved over great period of time by erosion, are generally areas that contain an abundance of varied marine life. Professor Jessica Meeuwig, from the UWA’s Centre for Marine Futures, says visual documentation of life in the Perth Canyon – which is 22 km west of Rottnest Island and was carved by erosion from Perth’s Swan River – is both very exciting and fundamentally important in understanding the entire region of the west coast.
Surprise underwater finds
“We saw unexpected things,” Jessica told Australian Geographic. “The pink snapper was recorded at 250 m; the previous depth they have been reported to is 200 m.” The footage also depicts sharks, a rocket squid shooting past the camera and squirting ink, as well as the elusive Bight redfish, a southern Australian species vulnerable to overfishing, which has an average lifespan of more than 70 years.
“One day, it’d be amazing to see a blue whale swim past our cameras,” says Jessica. The incredibly diverse region is one of two Australian feeding places of the elusive blue whale, the largest animal ever known to have lived.
Deep-sea canyons, hidden and hard to reach, are often productivity hotspots for marine-life. Professor Charitha Pattiaratchi of the UWA Oceans Institute says the Perth Canyon is the most productive region along the entire coast, from Kangaroo Island in the south to Shark Bay in the north.
Marine productivity hotspot
“The interaction between the subsurface currents and canyons brings higher nutrient water to the surface which we call ‘upwelling’,” Charitha says. It is this upwelling that sustains high levels of biodiversity – and these levels must be monitored into the future.
Jessica says the footage is valuable for scientists to study changes in population in WA’s unique marine ecosystem. “One of the biggest challenges of this environment is we don’t know what’s down there. We’re trying to establish a benchmark that will help us understand change due to ocean warming and overfishing.”
The team produced the footage by lowering two stereo cameras, angled to face a bag of bait, between 100 and 500 m below sea surface. A blue light provided illumination as the cameras sat dormant on the seabed for three hours, photographing animals as they approached.
Next on the agenda for the team of oceanographers is to send the cameras deeper into the 1.5-km-deep canyon. “We want to continue documenting the fish assemblages in the Perth region, and the next step is to go deeper,” Jessica says.