December 4, 2018
Day 12: Onboard videographer, Andrew Terhell
Ever tried hanging a camera a few thousand metres off the back of a ship, to film and photograph the ocean floor more than 1500 metres underwater? Neither have I, and after watching the scientists and crew onboard Investigator perform this task over parts of the South-east Marine Parks Network, I can see that this is far more complicated than strapping a GoPro to some lead and cranking the outboard.
The deep-tow camera system has been designed and fabricated by CSIRO engineers specially for this voyage. It has two video cameras that feed a livestream through fibre optic cable back to the ship. This enables the 'pilot' to position the camera system, and gives scientists a real-time view of the seafloor habitats and marine life beneath them. Televisions around the ship are tuned into this feed and people are watching with excitement from the mess, the operations room, control room and all over the vessel. It creates a real buzz, particularly when interesting transects are being sampled (crossings of the seamounts with the camera system in the water).
The camera platform also holds two DSLR still cameras and two strobes, one for each camera. These all fire at the same time, meaning that the two images have enough light and the two photos can be used together to provide a stereo, similar to 3D, image of the seafloor and the species and specimens sighted. This provides a greater understanding of the size of the objects seen by the camera system.
Karl Forcey and Aaron Tyndall of CSIRO have been taking shifts in ‘flying’ the camera at depths of around 1700 m. This is a challenging role requiring deep concentration for up to an hour, constantly adjusting the length of released cable (of which there is about 3000 m on the winch) to ensure the camera platform is close enough to the bottom without hitting it, and the acquired imagery is in focus. But the camera operators love their job. Karl says that “to fly the camera along the sea floor is pretty cool, you know you’re a kilometre deep, you’re looking at things that no one has ever seen before . . . it’s a really good feeling”.
Karl is also the expert onboard when it comes to the towed camera. In addition to piloting the camera, he has had to make adjustments to the strobe light, the calibration of the two cameras and many other quick fixes on the fly.
Members of the ship’s crew are responsible for deployment and retrieval of the deep-tow camera platform. Deployment is pretty efficient, but retrieval can be challenging. Crew members need to hook ropes onto the platform before raising it out of the water, and this is done with a pole almost three metres long. Two crew members are responsible for securing these hooks and there’s quite a lot of friendly banter among them about who manages to secure their hook first.
Watching scientists getting excited about the live footage is great! It’s cool to see their passion for their respective areas. The conversations on the ship are really inspiring. Sometimes I’m working on my computer and someone will jump out of their chair and yell a word I haven’t heard before, which is followed by a description of what that is and why it is so amazing. It’s like the science equivalent of an Ashes Test Match, it’s always on in the background, there’s a lot of random excitement, and it provides a great amount of water cooler conversation.
Notes on today's activities from Marine Biodiversity Hub Director, Nic Bax . . .
We started the day hove to waiting for conditions to improve. By 6 am waves had diminished sufficiently to drop the conductivity, temperature, depth (CTD) profiler for a water column profile above Main Maat seamount. This was quickly followed by a beam trawl at 1500 metres to collect specimens for the biologists. There was severe pinup on this operation. We could not see this happen and the ship did not falter in its progress, but the load on the winch increased suddenly from two to eight tons, returning to two tons quickly once the bolts holding the replaceable beam had sheared. The beam trawl was retrieved immediately, reaching the surface some 30 minutes later with a small catch.
We then conducted five towed camera transects on Main Matt, noteworthy for the large schools of orange roughy seen on the camera between 800 and 950 m on some but not all of the transects. The schools were also picked up on the single beam acoustics.
Towards the end of the day we started steaming back towards Southport where a small boat transfer will be used to swap half of the scientific crew and pick up some spare parts, mostly for the towed video cameras. Over the last 12 days we have undertaken 79 operations from the Investigator: 54 towed video transects, seven beam trawls, eight CTDs, deployed four BRUVs and undertaken two acoustic experiments. And the bird and mammal observers have been adding to their tally of species sighted every day. We have been able to make use of the scientists and park managers on board, annotating 43 of the videos and processing 2576 still images from 27 operations, leading to 1288 spatially rendered images available for quantitative processing.
While we have a few transects to return to on Main Matt, and one on Hill K1, we are close to completing our eight transects from top to base of six seamounts with varying fishing histories and depths. This will provide the basis for a comprehensive description of the vertical biogeography of seamounts in this area, describing how individual species abundances and ranges differ between seamounts and hopefully identify some of the factors causing those differences. On the next leg of this survey we will be expanding our effort to sample the continental slope and the area between seamounts to identify where and how much deep-water coral is found away from the seamounts, and estimate how much deep water coral there is the Huon and Tasman Fracture Marine Parks.
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