2 weeks Ago By Gavin McGrath
Four thousand metres below the Southern Ocean surface lies a mysterious and alien world. Deep within the Bass Canyon — an 80-kilometre-long yawning gash in the sea floor — is a place of near complete darkness and crushing pressures. The temperature in the canyon is barely above freezing, and the conditions are seemingly incompatible for life.
But the Bass Canyon is far from lifeless. There is a staggering diversity of strange creatures, the likes of which rarely see the light of day. A tripod fish on the Bass Canyon floor, as seen through the CSIRO's camera.
The CSIRO's Research Vessel Investigator explored this submarine crevice with a combination of multi-beam sonar and visual camera photography during its autumn cruise off the Tasmanian coast. RV Investigator's chief science officer Georgia Nester said it was a rare opportunity to peer into a part of the planet few have seen. "We were lucky enough to do a deployment at 3,000m and have a look at what's down there," Dr Nester said.
"We did a drop-tow camera, we did a CTD [conductivity, temperature, and depth measurement] and hopefully we'll be able to analyse that data and figure out all of the weird and wacky creatures living down there." Georgia Nester says few have seen this part of the planet. Freaky creatures While many of these creatures would not look out of place in some deep-sea horror film, Dr Nester said few were as fearsome as they appeared.
"I think the deep-sea creatures, they're always a little bit freakier than their shallow water counterparts," she said. "We did find a really cute octopus, but we also see sharks which have freaky little pointy noses and teeth all over their face. "A lot of the time, especially in deeper water, we have these fish that'll be a little bit gelatinous like those blob fish many people think of.
So they're a bit squishy. Dr Nester said the deep ocean was often associated with scary predators, but the reality was quite different. "The deep sea has a bit of a bad reputation in the sense that everyone thinks it's a little bit frightening, but many are scavengers," Dr Nester said.
Bass Canyon can reach depths of 4,500m. Exploring the depths The first steps in exploring the canyon were several passes over it using Investigator's permanent sonar system. "It allows us to get good, high-resolution mapping of the lay of the land underneath the vessel on the sea floor," marine biologist and RV Investigator CAPSTAN voyage manager Dr Arthur explained.
"It's the equivalent of a very powerful, very fancy fish finder." Ben Arthur has been exploring the dark deep. Dr Arthur said sonar mapping was just the first stage, and allowed the team to gain insights into the canyon before deploying additional equipment.
"It's sending out sound waves into the water and hitting something, in this case the sea floor; it bounces back so we can listen for it," Dr Arthur said. "Through some complicated data processing, you can determine the depth and how steep the slope is, because that will determine the speed we will be towing equipment through that canyon system. "We then deploy the deep-tow camera, which uses a high-resolution camera in a titanium housing we've engineered here to cope with the pressure.
He said the camera also had a powered frame for lights and for enabling images to be sent back in real time. The camera can send images back in real time. Discovering and cataloguing the inhabitants of the canyon was only one element of the ship's voyage to the west of Tasmania.
It primary function was as CAPSTAN (Collaborative Australian Postgraduate Sea Training Alliance Network) training cruise. CAPSTAN is a maritime education and training initiative of CSIRO. The voyage enabled 21 postgraduate students from 16 universities to be introduced to life aboard the research vessel and to get the opportunity to operate the equipment.
CSIRO's Research Vessel (RV) Investigator. Dr Nester said the Bass Canyon tour was one perk of the tour, which included a circumnavigation of Tasmania. "I guess it's knowing that the parts of the sea floor that you're watching, no-one else has seen before," Dr Nester said.
.
