New Zealand mudslide wipes out sea life in precious marine reserve

While earthquakes cause damage on the surface, we often don't pay attention to the havoc played out under the sea.

Back in November, earthquakes with a magnitude of up to 7.8 hit Kaikōura in the north-east of New Zealand's South Island.

There was significant damage to major roads, as well as nine faults discovered in the area.

But scientists have recently discovered that the earthquakes also unleashed underwater mudslides in Kaikōura Canyon, wiping out all life living in its sea bed.

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The Kaikōura Canyon is an undersea canyon which stretches for over 60 kilometres (37 miles) and reaches depths of more than 1,200 metres (1,312 yards), according to Whale Watch NZ.

Ten years ago, Kaikōura Canyon was found to have the highest volumes of invertebrate biomass living in mud anywhere in the world.

"It was about 100 times higher than anything reported anywhere else for that kind of seabed," Dr Joshu Mountjoy, a marine geologist from New Zealand's National Institute of Water and Atmospheric Research (NIWA), said in a statement.

That survey, conducted by NIWA and the U.S., contributed to the area becoming a protected marine reserve.

"There was an extraordinary amount of life living in the bottom of the canyon which we think was a consequence of the very high marine productivity of the whole region," Mountjoy added.

The earthquake emptied out the mud which filled ridges and valleys in the upper slope of the canyon, where it cascaded to the deep seafloor to devastating effect.

"We surveyed exactly the same area we did in 2006 and, while fish were still found in the area, this time didn’t record evidence of a single organism living on or in the seabed over a stretch of nearly six kilometres of seabed. Nothing," NIWA marine ecologist Dr Dave Bowden said in a statement.

"It was quite sobering, and a catastrophic event for the ecology of the canyon."

What was previously a seabed covered with burrows, tracks, pits and mounds is now smooth and barren. While the discovery is disheartening, it also paves the way for important research to be conducted.

"We suspect that events like this might happen every few hundred years in the Kaikōura Canyon. It will be very interesting to follow what happens from here, and I will be highly surprised if it doesn’t regenerate," Bowden said.