Turbulent Times

This month, a story from a COA alum who has gone on to research marine ecology beyond Frenchman Bay. Eliza Oldach (class of 2015) has recently returned from a Fulbright project in New Zealand, where she studied coastal ecology with the Marine Ecology Research Group at University of Canterbury. For more of her stories on science and New Zealand, check out her blog, Zeacology.


The shaking woke me up, as it did everyone.

In the early hours of November 14th, New Zealand was rocked by a 7.8 magnitude quake, the biggest felt in the country since 1855. It caused serious damage across a swathe of the country from Wellington to Kaikoura, and serious alarm for the rest. In the days and weeks following the quake, national attention was fixed on the areas with the most extreme damage and the greatest need for emergency aid.

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Faults ruptured in November quake (credit: GNS Science).

Biological and geological systems were just as disrupted as human ones. The emergency scientific response followed closely on the heels of humanitarian aid, as biologists and geologists hurried to impacted areas to document the quake’s effect on natural systems.

One of the most immediately obvious effects was a significant amount of coastal uplift. Shifting fault lines had pushed rock above the ocean, lifting areas that were previously underwater and visibly altering coastlines. The University of Canterbury’s Marine Ecology Research Group (MERG), my host for the year, followed these updates closely. Some of our field sites were in the center of the uplifted zones, and we hurried to get to those sites and record the changes to coastal ecology as soon as possible.

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’d sampled before. Over twenty years ago, researchers from MERG had established long-term monitoring sites at three sites along the coast— Cape Campbell, Kaikoura, and Moeraki. By returning to these sites and repeating sampling every season for several decades, MERG had established a robust baseline of the seaweed community. We knew that severe uplift along the coast would impact seaweeds, and by returning to areas where we had baseline data we’d be able to provide detailed evidence of those changes.

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The Kaikoura coast, pre- and post-quake (credit: NASA Earth Observatory Images by Joshua Stevens)

In the week following the earthquake, I joined the sampling trip to our site at Cape Campbell (north of Kaikoura– see map, above) . With the roads south of the Cape closed, the normal route from Christchurch was impassable. Instead, I hopped on a puddle jumper to Blenheim, and was met by my labmate Shawn to drive to the Cape from the north.

Changes to the coastline were visible even on our drive out to the field site. 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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Stark changes in the reef community (credit: EO).

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 Durvilleae changing from golden to dark brown, the Carpophyllum 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.

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Paul amidst bleached corallines and blackened Durv (credit: EO).

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 were chased back to land by the rising tide before we’ve finished all of our surveys.

No longer. On the post-quake visit, 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.

Small wonder, then, that the seaweeds were stressed and the invertebrates had 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 of even 30 centimeters increases the amount of time intertidal organisms have to withstand heat and desiccation stress. At Cape Campbell, the amount of lift was estimated to be closer to two meters.

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Shawn and Paul survey the dying Durv zone (credit: EO).

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 aficionado, 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 was a grim image, this decline of seaweed communities that were once rich with life.

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The reef, as of January. Lots of Ulva, but no canopy species (credit: Shawn Gerrity).

Since I’ve returned to the States, MERG researchers have continued their sampling trips out to the reefs at Cape Campbell and Kaikoura.  I’ve been following along, taking breaks from the upended politics in this country to check in on the upended reefs in New Zealand. Intertidal communities are still in a state of flux. By now, most of the large canopy-forming seaweeds like Hormosira, Durvilleae, and Carpophyllum have died off completely in the zones they used to dominate. They’ve been replaced by large swathes of weedy Ulva. Bleached coralline turfs are beginning now to break off of the mudstone substrate of the rocky reefs, and the exposed stone is increasingly eroding into a fine silt that coats the intertidal zone. Dead algae is washing up in mats of wrack along the coastline. And the invertebrates? Some limpets remain, and feast readily on the abundant Ulva, but the highly diverse invertebrate communities that existed pre-quake have disappeared— after all, there’s no habitat for them to recolonize. In the most recent update, MERG researchers put it this way: “no obvious ‘recovery’ is happening anywhere so far.”

The changes that have occurred in the seaweed communities are troubling in their own right, but also have consequences for the related human communities, and particularly for the communities of Kaikoura. Kaikoura’s economy rests largely on fishing and tourism, and the uplift throws the future of these industries into question. Key fishery species, like paua (abalone) and crayfish, relied on healthy seaweed forests that have disappeared. Now these species’ populations are at risk. Tourism was hampered on land by the damage to roads into and out of Kaikoura, but it’s been threatened at sea, too: uplift in Kaikoura’s harbor has made it impossible for the popular whale watch boats to access the marina except at high tide. Since the quakes, some progress has been made. Fishery closures are beginning to lift, roads are opening for traffic at specific times of day, and the whale watch is operating tours on a limited basis. Still, the dramatic change to the coastline has been sorely felt by local communities.

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Dredging Kaikoura’s harbor to allow ship passage (credit: Shawn Gerrity).

According to ecological theory, the new intertidal zone will develop again into stable, diverse seaweed communities if given enough time. Human infrastructure, too, will likely be rebuilt to a functional state, if given enough funding. One could predict that, in a few years or decades, the coastal communities of Kaikoura and Cape Campbell will have fully “recovered”.

But in observing the earthquake and its impacts, it’s impossible not to be reminded of the future facing our coastlines. In the coming decades, coastal communities will be subject to an unrelenting slew of physical changes just as stressful as the uplift— sea level rise, sea temperature warming, stronger hurricanes, lengthier droughts, and on and on and on. And I think, just as with the earthquake, we’ll see those changes reverberate back and forth between ecological communities and human ones. In a point of crisis, those connections will become more evident than ever.

But maybe there’s a role for human ecologists to identify those links before the crisis point is reached, and start now to provide data and policy and communication and art to reveal and strengthen them. And maybe that knowledge will help contribute to resilience when these crises arrive. I really don’t know— but maybe.

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