Cape Quake

They say good things come in threes, and that’s certainly been true for my experience with Cape Campbell this year. I’ve traveled to the Cape for research on three occasions this year (ones that stack up neatly in the first weekend, midway point, and last weekend of my fellowship).  I’ve gone on these trips to help the Marine Ecology Research Group (MERG) maintain longterm monitoring of the seaweed and invertebrate communities along the Cape’s intertidal reefs. Each time I’ve visited, I’ve gotten to know the reefs a bit better. And each time, I’ve been more convinced that, to me, Cape Campbell is the most beautiful of coastlines, the most dazzling of intertidal reefs, the most perfect of field sites.

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Hello, beautiful field site.

But this last time, the Cape was dramatically changed.

It all started with the earthquake. In the early hours of the morning of November 14th, New Zealand was rocked by the biggest earthquake felt here since 1855.  It was a 7.8 magnitude quake, and it shook people awake across the country. For days and weeks afterwards, the country was focused on supplying immediate aid to most affected areas. A town called Kaikoura was the most impacted, with access completely cut off from both northern and southern roads and hundreds of people forced to evacuate by air and sea.

Biological and geological systems were just as disrupted as human structures and society. In the midst of the emergency aid response came an emergency scientific response, one that mobilized biologists and geologists to document quake disruptions to natural systems.

One of the most immediately obvious effects of the quake was a significant amount of coastal uplift. Shifting fault lines had pushed rock above the ocean, lifting areas that were previously underwater. Some of MERG’s long-term research sites—like those at Cape Campbell—were smack dab in the center of the uplifted areas. We heard these reports in Christchurch, and felt the strong need to visit the sites and see the impacts on reef communities as soon as possible.

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NASA Earth Observatory imagery of coastal uplift. (Courtesy of geographical.co.uk.)

It didn’t take long before reports of drying seaweeds and dying invertebrates reached Christchurch. University of Canterbury biologist Dr. Sharyn Goldstein quickly organized a helicopter survey of the area, and invited my coworker Shawn to join. He jumped on board the helicopter with a camera and a quadrat, and came back with reports of dramatic uplift visible along the coast from the bays south of Kaikoura all the way to northern Cape Campbell.

Back at MERG, we started organizing methods for studying these changes. We mapped out points along the coast to visit, choosing bays that had experienced a range of uplift intensity to understand responses to varying levels of disturbance. In addition to establishing new plots in these areas, however, we also wanted to return to the places where we’ve conducted research for the past several decades. We had more than twenty years of data from Cape Campbell and Kaikoura reefs—how would those reefs respond to this change?

Later that week, I joined the sampling trip to Cape Campbell. With the roads south of the Cape closed, our normal drive north from Christchurch was impossible. Instead, I hopped on a puddle jumper to Blenheim, and was met by Shawn to drive to the Cape from the north.

Changes to the coastline were visible even on our drive out to our sites. Rock platforms usually tucked below tide were well above water. When we ventured out onto those platforms, gumboots on and quadrats in hand, the changes were even more dramatic.

The reef had lost its color. The dominant seaweed, Hormosira, usually forms an olive-hued cover over much of the rock, interspersed with purple Lophothamnion, bright green Ulva, and ruby-brown Champia. This time, the Hormosira was brown and crisped from sun exposure. The Lophothamnion was dark and scraggly, and the Champia had gone completely clear. Underlying turfs and encrusting corallines, usually a healthy pink crust beneath the seaweed canopies, had bleached to a sickly white. It looked like a seaweed graveyard.

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The reef as seen on September 2016 and December 2016.

We continued out along the rock platforms, traveling from the Hormosira zone to lower elevations. Here, Hormosira should be replaced by subtidal seaweed species, the massive Durvilleae and Carpophyllum. This time, those subtidal seaweeds were still present, but ailing—the Durv changing from golden to dark brown, the Carp blackened and crisped.

We started looking for our historic survey sites, unsure whether the marker bolts had survived the quakes. A few moments of searching revealed them, completely intact, their pink zip ties a bright marker against the new brown and white cast of the reef. We threw down a quadrat, and knelt to assess the scene in more detail. Some water was held in the cracks and pits of the rock, and in those places the seaweeds maintained their structure and color. Predominantly, though, they were out of any water cover, left to dry and wither in the sun. We also noticed a lack of invertebrates in the plots. Usually, the seaweed is crawling with Lunella and Melagraphia snails, a smattering of crabs, perhaps the odd sea slug. Now, A few limpets held on to areas protected by seaweed canopy, and anemones hunkered down in pits in the rock, but other than that it was an empty scene.

There was another obvious change, too. Normally, our trips to Cape Campbell have to be carefully timed. The species we study exist in a narrow slice of time and space between high tide and low. More often than not, we’re chased back to land by the rising tide before we’ve finished all of our surveys. Cape Campbell is an especially notorious site, one that involves hip-deep wades through rising tides at the end of every surveying day.

No longer. This time, we spent hours on the reef. We finished our surveys for the day, moved on to collect more data and set up new permanent plots, messed about with oxygen probes and temperature loggers, stopped to share coffee from a thermos—and still the rising tide hadn’t covered our sites.

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Paul in the Durvilleae zone, which is normally inaccessible without a wetsuit and snorkel.

It’s small wonder, then, that the seaweeds are stressed and the invertebrates have vanished. These species have adapted to life in specific conditions—they can handle a moderate amount of sun and wind exposure, but they’re already on the physiological brink. A lift in reef of even 30 centimeters increases the amount of time these organisms have to withstand heat and desiccation stress. At Cape Campbell, the amount of lift was estimated to be closer to two meters.

I thought I’d be prepared for these changes, but I wasn’t. Seeing the Cape, changed as it was, was shocking. My research mates agreed. Paul South, seaweed afficianado, had travelled from Nelson to help Shawn and I for the day. He was surprised by the state of the reef, too, comparing it to an atmosphere that’s suddenly lost most of its oxygen.
“Which would you prefer?” he asked us. “To lose 100% of the atmosphere’s oxygen all at once and be dead immediately, or to be down to 40% oxygen and hang on for a slow decline?”

Looking at the stressed reef around us, the metaphor struck home. It’s a grim image, this gradual decline of seaweed communities that were once rich with life.

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Shawn and Paul identify seaweed remnants in the Durvillaea and Carpophyllum zone.

The question, then, is: what comes next? Almost certainly, the old intertidal seaweeds will die off completely. The blackened Hormosira and bleached corallines don’t have much of a chance to persist at this new tidal elevation, especially given the increasing temperatures and sun hours of the austral summer. We expect, perhaps, to see a gradual replacement of zones as seaweeds recolonize closer to the new low tide mark. But it’s unclear how long it will take for these communities to become established, or if other factors will impede their return to a highly-diverse state. Until the seaweeds do return, the invertebrates that rely on seaweed habitats will be missing the food, oxygen, and predator protection the seaweeds used to provide. That’s ecologically important, but it directly impacts human economy as well. Paua (abalone) and crayfish rely on these intertidal seaweed communities, and the uplift throws the future of these fisheries into question. In short, the extent of the changes is largely unknown, but the immediate effects are not looking good. To understand how these effects will develop, more research into the ecology, geology, and economy of these areas will be sorely needed.

For now, we know at least this: Cape Campbell and other areas of the New Zealand coast have been changed, and changed irreversibly.

Until next time,
E

PS: I can’t really leave this post on such a dispirited note. And besides, there are heartening aspects to these changes, too. For one thing, the community and scientific response has been thoughtful and supportive. The turmoil has been managed with a lot of collaboration, a lot of support, and a lot of conversation, and that’s been reassuring. Another aspect of this entire situation that soothes a bit is that—for once—this ecological disturbance is not caused by the actions of humans. So much of ecology centers on studying environments in light of human-caused degradation, but in this case the changes were completely and utterly beyond us. All we can do now is understand the change and how to respond, and that is a humbling and refreshing place to be.

Anyways: learn more and follow our work at the Reef Uplift Research Consortium page.

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