Kaikoura’s alien landscapes: Once lively seabeds now a wasteland

[New Zealand] Not far from the buried roads and twisted railway tracks that blemish its coastline, parts of Kaikoura look like an alien landscape.

While last year’s 7.8 earthquake had a severe impact on land, its power had a greater influence on the world beneath.

Marine scientists discussed their findings from Kaikoura at the New Zealand Marine Sciences conference in Christchurch this week.

REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
Uplift at ward beach. The area would have been covered in algae, but is now bare.

They described vibrant ecosystems lost in one fell swoop, leaving an empty canvas for a new world to develop.

“It’s a big physical event, but I would say it’s an even bigger ecological event,” NIWA marine ecologist Dr David Bowden said.

It was clear deep beneath the coastline in the Kaikoura canyon, an underwater chasm hundreds of metres deep.

REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
Limpets line up to feed on an algal bloom.

The canyon was home to one of the world’s most significant benthic ecosystems, research had showed.

The earthquake collapsed the head of the canyon, triggering underwater avalanches that flushed about 100,000 swimming pools of sediment into deep seas.

Billions of vertebrates would have died, turning the once lively seabed into a wasteland.

REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
Eggs caught on a dying plant.

Photo: REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
Stumps of kelp in an area once below the water.

A decade of seabed imagery before the earthquake showed abundant life; now there was nothing.

“We’ve never got more than a few metres on the seabed without seeing some sign of living animals,” Bowden said.

“In 6km of seabed here, there was nothing living.”

REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
The green algae shows where the tide now reaches.

Closer to the surface, coastal reefs permanently thrust above the surface had become stripped of life under the sun.

Researchers documented the changes on a Facebook page, the Reef Uplift Research Consortium.

At Ward beach, north of Kaikoura, lies an immense, flat platform that used to be a reef.

REEF UPLIFT RESEARCH CONSORTIUM/FACEBOOK
Limestone boulders.

“The scale of it is amazing, it’s probably over a square kilometre of subtidal and intertidal reef that’s lifted,” researcher Shawn Gerrity said.

Nearer the water, where the tide still reached, some algae survived and there were signs of recovery.

Where the uplift was severe – in some cases, upwards of six metres – the ecosystems would likely never bounce back.

PIPPA BROWN
A Hutton’s Shearwater chick. Tens of thousands of the birds likely died in the November earthquake.

How the death of these ecosystems impact others in the habitat remains to be seen.

For the region’s famous sperm whales, which forage in the Kaikoura canyon, there was no significant displacement so far.

“The abundance calculated for the season just after the earthquake was the lowest we’ve ever recorded, so we’re definitely not ruling out any influence of the earthquake yet,” whale researcher Marta Guerra said.

“This winter we’re very lucky to have seen a similar abundance to previous years.”

More research was needed to see if there would be significant long-term changes, she said.

High up in the mountains, the endangered bird species Hutton’s Shearwater was in the middle of nesting season when the earthquake hit.

About 15 per cent of mountain slopes failed, burying parts of the endemic species’ habitat under rivers of sediment.

Much of the area remained inaccessible, but a crude estimate indicated between 65,000 and 109,000 birds died out of a total population of about 600,000.

“We’ve lost a big number of this year’s chicks,” colony manager Lindsay Rowe said.

“It’s going to take a long time for those remaining breeding birds to bring that back up.”

While many species faced enormous stress, a few were withstanding the changes.

Seals had adapted well, finding new playing spots on the soft sediment away from their destroyed sanctuary at Ohau Point.

The earthquake proved to be positive for one species – the red-billed gull.

“The krill hadn’t showed up this year and the birds and the chicks were starving,” Ted Howard of the Kaikoura Coastal Guardians said.

“Then the quake came along and the birds suddenly had this amazing source of food, all the limpids that were exposed and fell off. What looked like a complete disaster of a breeding season has turned into the best fledging they’ve had in many years.

“So it hasn’t all been bad for animal life.”

 

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