Underwater robot getting close-up look at Kaikōura Canyon

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A six-metre long orange underwater robot is flying through the Kaikōura Canyon for the next month collecting information on how the canyon has changed since the 2016 earthquake.

The technology-laden AUV – or autonomous underwater vehicle – is being deployed from NIWA research vessel Tangaroa with the information collected expected to shed light on what happens to marine areas like this.

Voyage leader and NIWA marine geologist Dr Joshu Mountjoy says this is the first time this technology has been used to survey submarine canyons in New Zealand waters and information collected will lead to new understanding relevant to many of the world’s continental margins.

“Submarine canyons are the bridge between the land and the deep ocean, connecting sedimentary systems, capturing carbon and supporting rich ecosystems."

“We have little knowledge of what happens to these marine hotspots after massive disturbances like the Kaikōura Earthquake and so we need to make the most of this opportunity.”

The AUV is programmed from the ship and then carries out its surveys while the team on board can resume other scientific work. The focus so far has been on the middle to lower canyon, about 20km off the Kaikōura coast.

It is flying at 50m above the seafloor sending back data in higher resolution than has ever previously been possible. “Our earlier surveys were conducted from the ship which is 2000m away from the seafloor. We have never collected AUV data or deployed sediment traps in our canyons, so this is a first. But we hope the start of a new era of high-resolution canyon observations.”

Two NIWA surveys since the earthquake discovered large areas of the Kaikōura Canyon drastically changed. An enormous amount of mud and sediment – estimated to be about 850 million metric tonnes –  was shaken off the canyon rim and then flowed down into the canyon channel causing a powerful “flushing” of sediment out to the deep ocean.

“We are mostly interested in understanding the physical process that has removed such a huge amount of sediment and rock from the canyon. This is a rare opportunity because we know from our previous work that there has a been a very large change recently and this is unusual in the deep ocean,” Dr Mountjoy says.

This flushing immediately turned the canyon from a biodiversity hotspot full of dense populations of large invertebrates and abundant fish species into a barren, almost uninhabited landscape.  But a NIWA survey 10 months after the earthquake found signs of early recovery.

On this voyage NIWA Is also taking underwater video footage of the canyon and early indications show the ecosystem is now recovering well.

The AUV is on loan from Sweden’s Gothenburg University in an international sharing arrangement of scientific equipment brokered by marine research alliance Eurofleets+.

Dr Mountjoy has spent several anxious months negotiating COVID-19 restrictions to get the AUV to New Zealand. It comes with two technicians from Swedish company MMT who had to undergo quarantine on arrival but plans for scientists from several other countries to join the voyage had to be cancelled.

Some modifications have been made to Tangaroa to enable the AUV to be deployed which will be at work until the end of the month.

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Related information:

The AUV on loan from Gothenburg University in Sweden can dive to 3000m and has an inbuilt multibeam echosounder used for seafloor mapping. [Photo: Lana Young, NIWA]
The 'RAN' at the end of '3000 AUV Ran' refers to 'Rán' – the Norse goddess of the sea. [Photo: Lana Young, NIWA]
The AUV onboard RV Tangaroa, ready for deployment. [Photo: Lana Young, NIWA]