Underwater Robot Getting Close-up Look At Kaikōura Canyon
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.