Kaikōura Canyon seabed recovering faster than expected after 2016 earthquake

After the 2016 earthquake nearly wiped out all of the Kaikōura Canyon’s seabed ecosystems, scientists say it is showing promising signs of recovery.

A recent study found that just four years after the 7.8 magnitude earthquake, parts of the seabed had returned to it’s pre-earthquake state. Scientists earlier predicted it would take up to 12 years to fully recover.

NIWA and Te Herenga Waka Victoria University of Wellington PhD student Katie Bigham said the area is showing “astonishing resilience to the physical and biogeochemical disturbance caused by the earthquake”.

The earthquake caused a “full canyon flushing event” that reshaped the seabed floor and carried 850 metric megatons of sediment out of the Hikurangi Channel, Bigham said.

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The event was “devastating” for marine life in New Zealand’s only deep-sea marine reserve.

However devastating the earthquake was, it provided scientists with the opportunity to study the impacts of an underwater earthquake on seabed communities, Bigham said.

“Encouragingly, the ecosystem is showing great resilience. Many of the marine organisms have returned, with some parts well on the way to being fully recovered.”

Images of the seabed taken shortly after the earthquake showed that the earthquake had been “catastrophic” for the once productive marine community, but within months scientists discovered a noticeable increase in some species.

Within four years the seabed community appeared similar to what it was before the earthquake.

NIWA principal scientist of marine ecology and Professor of marine biology at Victoria University, Dr Ashley Rowden said it was the “very nature” of the volatile environment that made it such a resilient ecosystem.

“We think this habitat can so easily recover because it’s an area often at the mercy of mother nature,” Rowden said.

The earthquake was a 1 in 140 year event, Rowden explained, which may seem infrequent but in evolutionary terms was a “blink of an eye”.

Rowden said this meant species in the area regularly experienced stressors, such as earthquakes, and species have adapted to it.

Results of the study were “encouraging” for showing the long-term efficiency of the marine reserve, but scientists still have questions.

Bigham said questions remain around how humans interact with these environments and how surrounding deep-sea fisheries were impacted by the earthquake.

So, while initial research was promising, more research was needed.