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Throughout the ages

Marine ecology project unites four generations of scientists to search out lost experiments

 

Paul Dayton remembers climbing up the ladder with only his elbows, his hands numbed and useless after diving in the subfreezing waters of McMurdo Sound. Tears of pain poured down his cheeks.

The wetsuits and gloves he and dive partner Gordy Robilliard used to keep warm in the minus 1.8 degrees Celsius water were inadequate to the task. This was the 1960s. Dive equipment was still primitive.

But the men were making two dives a day, setting out cages for various experiments to learn more about the bizarre world that existed underneath the ice.

Once out of the dive hole, teeth chattering, the men excitedly relived the experience on the surface. “The things we would talk about were the wonderful things we had seen. We were never moaning about the tears running down our cheeks,” Dayton said.

The 71-year-old professor from Scripps Institution of Oceanography is heading back to Antarctica this year to revisit those wonderful things. The experiments — many cages or floats designed to see how the marine community on the seafloor interacted — are now artificial reefs.

All sorts of coral and critters that live on the seafloor have taken up residence over the decades on these long-abandoned experiments. It’s like a timeline of benthic succession, according to Stacy Kim, a researcher at Moss Landing Marine Labs in California.

“From an ecological perspective, there’re very few places where we have a dataset that extends back that far. When you go into marine ecology, it becomes even fewer. And when you go into polar marine ecology, it goes into way fewer,” explained Kim, the project manager for the nearly three-month field study, dubbed Investigating Change in Ecology in Antarctica by Gizmologists, Educators and Divers (ICE AGED).

“This is a really rare opportunity to get a look at how an ecosystem has changed and developed over that long a time period,” she added.

Setting the standard

Dayton’s first trip to Antarctica was a long one — a winter-over in 1963 working as a science technician at McMurdo Station. He didn’t dive that year, though he had taught himself scuba in the 1950s, inspired like many of his generation by the exploits of French marine naturalist Jacques Cousteau.

“In the ‘50s, it was very different. The ocean was very different. All the predators were still there. It was relatively still pristine when I [started diving],” said Dayton, who grew up in the dry desert climate of Tucson, Ariz., and had to travel Mexico to snorkel and dive.

He built his own dive equipment in those early days. The tanks were scavenged from a junkyard where the fire department discarded the ones they believed might explode. The regulator he bought for $1 from the Army surplus store and rebuilt leaked constantly.

“It probably should have killed me. It almost did,” Dayton mused. “It was a fascination from a very early age.”

By the time Dayton visited the Ice, he was an experienced diver and a budding marine ecologist who recognized that the Antarctic ecosystem offered a unique opportunity.

The deep-freeze that persisted in the marine environment is stable and predictable, Dayton realized. He wondered how such an ecosystem that evolved in relative climactic stability differed from those that underwent disturbances and changes. What was happening with the polar food web? Who were the winners and losers in the competition for resources and space?

He wrote a proposal to the biology program manager at the National Science Foundation, George Llano, as a first-year graduate student after leaving Antarctica — and got the funding to begin testing some of his ideas.

That first field plan evolved as Dayton recognized what would and wouldn’t work as he came to understand the marine ecosystem. The experiments, some designed to cage out predators like ravenous sea stars that feasted on sponges, were set up to define competition.

No one was doing those sorts of subtidal experiments at depths of up to 60 meters on the seafloor at the time.

“That part was creative and novel, I think,” he said. “I put together an ecosystem story that was really contrived from a lot of different approaches. I think it’s pretty good,”

It’s a story he followed and wrote about for the next 25 years, until his last trip to the Ice in 1989. The scientific papers that resulted from some 500 dives and countless hours underwater largely set the standard for Antarctic marine ecology.

Changes through time

Always central to that story was succession — how the different marine communities develop and change over time.

Dayton has a record of when each experiment was set up over the course of more than two decades. The ICE AGED team will return to each of those artificial substrates, spread across McMurdo Sound, with divers and a special robot designed to work deeper under the ice to access and re-sample all the sites.

“We’re not going to be so interested in what’s under the cages as what’s on the cages,” Kim said.

During the three previous years in Antarctica, Kim and her team of scientists and engineers developed and tested a new kind of remotely operated vehicle, Submersible Capable of Under Ice Navigation and Imaging (SCINI). Tethered and operated by remote control from the surface, SCINI is easy to deploy down a hole in the sea ice without the use of heavy equipment.

In its first season of operation, SCINI located many of Dayton’s “lost experiments,” some at depths well beyond today’s safety limit of 40 meters. The sites were photographed and marked with GPS, as opposed to Dayton’s method of lining up landmarks to find sites before the age of satellites.

“It’s a record of succession that’s better than anywhere else,” noted John Oliver, a research professor at Moss Landing Marine Labs and principal investigator on ICE AGED with Dayton.

Oliver knows a bit about some of those experiments: Dayton was his greatest mentor, and Oliver helped set up some of those cages and substrates. He’s made about 10 trips to the Ice himself. His interests these days mostly focus on human impacts to marine ecosystems and habitat restoration.

But his motivation for doing the ICE AGED expedition is pretty simple: “If Paul dies tomorrow, 40 years is gone. We’ve saving a time series,” he said. “Every year that goes by, those data become more valuable.”

The scientists are interested in not only comparing the past to the present, but also creating a baseline against which future changes can be measured, according to Kim.

“The biggest thing that will come out of this is that we will take all of the information and all of this data into a big database that will be available to anybody internationally,” Kim explained. The data will be fed to the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCARMarBIN), which provides information for a global marine survey that ends later this year.

The temporal and spatial comparisons of the different sites should give the ICE AGED researchers a better understanding of succession in an ice-covered environment, Kim noted. For example, do species compete and reproduce on an annual basis, or are there periodic booms and busts based on environmental conditions that occur over the longer time scale of decades?

“If there are abrupt jumps and breaks in the colonization sequence between one year and the next year between the different substrates, then we can say something happened there in that particular year,” Kim said.

In addition to photographing the environment, project divers will collect plenty of organisms for morphological and taxonomic studies back at Scripps, Kim said. It turns out the sea star in McMurdo Sound and the one found off the Antarctic Peninsula may look alike but could turn out to be different species.

“What we’ve been finding is that there are far more species in Antarctica than we have described from just a morphological perspective,” she said. “Molecular taxonomy can allow you to look into that in greater detail.”

Over the generations

While always interested in the details, Dayton built his reputation on being able to see the big picture. One of the world’s preeminent marine ecologists today, Dayton still conducts research into coastal and estuarine habitats around the world, including benthic and kelp communities. His studies also include the impact of overfishing on marine ecosystems.

“To me he is the Charles Darwin of marine ecology. To spend three months with him in Antarctica is something I couldn’t pass up,” said Jennifer Fisher, a larval ecologist at the University of Oregon who will be one of the project’s divers.

In fact, Fisher represents the latest generation of the Dayton legacy in Antarctica. Dayton mentored Oliver, who was an advisor to Kim. Fisher worked in Kim’s lab at Moss Landing and made two previous trips to the Ice.

“We’re going to have four scientific generations that are going to be on this project, and that’s a thrilling thing,” Kim said. “That’s the sort of continuity you need across these long timescales.”

The connections don’t end there. Kevin O’Connor is another diver and research technician on the project. His father, Ed O’Connor, dived in McMurdo Sound with Dayton and Oliver in the 1970s.

“It’s just fun as hell to have the next generation come through,” Oliver said.

Scientists build reputations on scientific papers. It’s what they do for a living. Dayton’s seminal work, a paper published in 1971 titled “Competition, disturbance and community organization: The provision and subsequent utilization of space in a rocky intertidal community” has been cited more than 1,400 times, a remarkable number.

That seems less important to Dayton than a different number — the more than 30 students he’s worked with and tutored over the years.

“Even the best papers should go extinct. Science moves on,” he said. “If you’ve done a good job of mentoring students, that doesn’t go extinct. It continues, and they mentor more students. If there’s anything I would take pride in, it’s my students.”

NSF-funded research in this story: Paul Dayton, University of California-San Diego Scripps Institution of Oceanography, Award No. 0841538; and John Oliver, San Jose State University Foundation, Award No. 0842064.

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs