Science and signs of climate change in Antarctica hit home for Palmer Station physician
Posted July 1, 2011
I jumped into the Zodiac with my dry bag: an impermeable sack containing a bottle of fresh water, my camera and a set of dry clothes to change into in case I somehow ended up in the subfreezing sea.
Two graduate students from the University of Alabama at Birmingham, Ruth McDowell and Kate Schoenrock, and their dissertation advisor, Chuck Amsler, were waiting for me after I had been delayed getting back from the glacier that morning. Chuck (wearing a dry suit for diving), Ruth (also suited up) and Kate needed to collect some red seaweed.
Kate backed the boat away from its mooring into Hero Inlet, and then asked if I would “drive.” Enthusiastically, I made my way back to the tiller, trying not to stumble over all of the diving and other equipment occupying most of the 17-foot pontoon around my feet, and slowly turned up the throttle.
“We’re going to Spume,” said Kate, referring to an island two nautical miles to the southwest of Palmer Station, the U.S. Antarctic Program’s smallest research base. I’m the station physician. But on this excursion, I was a volunteer dive tender. I spend as much time as I can with the scientists, because science is Antarctica’s culture.
I eased the boat past Bonaparte Point, the tip of the peninsula on the other side of Hero Inlet. Spume Island came into view — way out on the horizon, all by itself, surrounded by uninviting gray sky and deserted sea. It seemed halfway to New Zealand. From the bow, Kate signaled our heading. Chuck, seated midway up to my left, scanned the island then turned to me and said, “Now speed it way up, Steve. We’re in 200-foot water and there’s nothing around.”
Suddenly I longed for places more familiar, like the operating room … or the slope of the slippery glacier where I spent the morning.
Marr Ice Piedmont occupies almost all of Anvers Island, except for small rocky outcroppings like Gamage Point where Palmer Station is located. A swath of the ice rising up behind Palmer had been found free of crevasses and safe for hiking.
I had headed out to the glacier right after Sunday breakfast. My cleats crunched into the icy incline as I trudged my way up into the howling winds, closing in on the clouds, feeling the strain in my lungs and fighting the fatigue in my legs to get just a little higher where space and time all but disappear.
The exhilaration of reaching the crest soon gave way to a surreal, calm sense of being part of this mystical place, as if eons ago I calved off this very glacier, just another blue iceberg floating out into the world. Slowly, peacefully, I scanned the mountaintops, then the endless sea and then, in the other direction, four miles away and 500 feet below, the islands of Arthur Harbor.
Suddenly, I realized: I’m late!
I scurried back down, my progress impeded by the 500 yards of bare rock and boulders splayed out in peaks and valleys between the foot of the glacier and the station. When Palmer Station was built, the glacier began immediately to its rear, but over the last 43 years, it has receded to its present location, exposing an ever-lengthening stretch of desolation and serving up the only tedious part of its friendship.
Out of breath, I made it to the boathouse just in time to go out with the dive team. I had taken Palmer’s boating classes, including the island survival session, but I was still inexperienced at the helm. Now in open water, staring at the distant speck that was Spume Island, I did my best to ignore the cramp in my throttle hand and cranked it up until my knees started shaking.
Notwithstanding my trepidation, the Zodiac gained adequate headway and for a spell even skimmed the water’s surface. Halfway to Spume we came upon a field of brash ice, the small bits floating on the surface. Mercifully, I needed to slow way down so as not to damage the propeller on the frozen chunks. We could feel and hear ice grinding the undersurface of the boat. The tiller suddenly jolted to the right as a piece of ice locked noisily in the prop blades, as if some fun-loving fur seal had yanked the propeller shaft the other way.
“Rock the tiller sideways a bit,” advised Chuck, who has made more than a dozen expeditions to Antarctica.
Free of the ice field, I picked up speed once more and finally reached the southern shore of Spume Island. Kate then relieved me of the tiller so we could survey the area for leopard seals, which would have made diving unsafe. We didn’t spot any of the large predators, but Chuck felt that the surf was too strong for his liking, so we headed back halfway to Janus Island, where the waters were a little less rough.
Chuck and Ruth began donning the rest of their diving equipment with the boat now stationary at Janus, except for riding up and down the swells. Kate and I helped them with their heavy gear, and before long, I found myself feeling like I did on the research vessel Laurence M. Gould in the middle of the Drake Passage on the way down here two weeks earlier. I was glad that I didn’t have time for lunch before jumping on the Zodiac.
Chuck and Ruth disappeared into the water, and Kate and I concentrated on following the course of their bubbles as they met the surface.
“They’re hoping to collect some Myriogramme smithii,” said Kate, referring to a particular species of red seaweed — called “macroalgae” by scientists — which amphipods won’t eat.
The amphipods will devour other types of red seaweed such as Palmaria decipiens. But amphipods and their predator fish downright refuse so much as a nibble from the most common macroalgae in the waters around Anvers Island, the brown Desmarestia anceps and D. antarctica. That’s not only good for the Desmarestia, perhaps explaining why they’re the most abundant marine plant here, but it also makes this algal foliage a convenient place for amphipods to hang out and not get eaten. Live-and-let-live ecology.
The surface bubbles now passed in tandem to the other side of the boat, farther from shore, and then slowly back. Chuck and Ruth remained underwater for nearly 30 minutes before resurfacing, each with a sack full of algae. Kate and I helped Chuck and Ruth back into the Zodiac, along with their weighty tanks and the precious foliage. We then headed straight back to Palmer Station, where grad student Julie Schram and Chuck’s research colleague and spouse Maggie were preparing the lab, so that they could all get right to work on the specimens, as they do after every dive.
In the lab, Chuck and his co-workers prepare extracts of the algae and identify which ones drive amphipods away from foods they otherwise scarf down. Those samples go to Tampa to Chuck’s co-principal investigator, Bill Baker, another veteran of numerous diving expeditions in Antarctica and for whom McMurdo Sound’s Baker Point is named.
Baker, who was at Palmer earlier this season before my arrival, is professor of chemistry at the University of South Florida, specializing in the organic chemistry of natural products that algae and sedentary invertebrates produce to defend themselves chemically from potential predators. From some of those same molecules we get many of our most important antibiotics, which protect us from predacious microbes.
Through such studies of the algae and invertebrates in the waters around Palmer Station, Amsler, Baker and James McClintock, a zoologist at the University of Alabama at Birmingham and the third and founding principal investigator of the chemical ecology team — and the scores of scientists working with them — have identified at least a dozen fat-soluble, predator-repellant organic molecules.
One of them, a polyketide macrolide isolated from the tunicate Synoicum adareanum named Palmerolide A (in honor of Palmer Station), has been found by colleagues at the National Institutes of Health to show selective, potent cytotoxic activity against a particularly lethal cancer, one that I sometimes diagnose and treat: malignant melanoma.
Ten days after my vertiginous voyage, I had another chance at the helm. We headed west, around Torgersen Island to Norsel Point, at the western tip of Amsler Island, named for Chuck and Maggie, who have done extensive ecological research here over the last 30 years.
Chuck had me cruise up the south shore of the island to recon for leopard seals. No leps, but we spotted a fur seal rolling through the water contentedly. Maggie and Ruth dove there for about 25 minutes to retrieve some of the benthic (bottom-dwelling) sponge Dendrilla membranosa, which Chuck placed in liquid nitrogen immediately after Maggie and Ruth were back in the Zodiac for later chemical analysis.
I drove the Zodiac back toward the station as a cormorant soared overhead. Along the way, we encountered another labyrinth of brash ice and blue icebergs that had calved from the glacier over the preceding week. I meandered through it, at home now on the water, at the tiller and among the ice.
On our final approach, looming up before us was the Gould, which minutes earlier had just returned to Palmer’s pier after a three-day fishing trip. Kristin O’Brien and Elizabeth (Lisa) Crockett, comparative physiologists and biochemists from University of Alaska at Fairbanks and Ohio University, respectively, are collaborating on a multiyear study of notothenioid fishes, which dominate the freezing, isolated waters surrounding Antarctica.
When Antarctica and Australia split up 38 million years ago and went their separate ways, the waters around Antarctica cooled to the freezing point as the new continent drifted south. Its gargantuan ice sheet began to take shape and the Antarctic Circumpolar Current formed. Into this extreme, foreboding environment swam the notothenioids, which now comprise half of all fish species that live on Antarctica’s continental shelf.
Their success stems from many elegant adaptations to the cold, foremost among them being their antifreeze glycoproteins that evolved from pancreatic enzymes to bind nascent ice crystals and keep their blood and other tissues fluid in frigid waters. These amazing creatures have gotten so good at thriving in the cold that their very existence may now hinge on it.
Climate change could turn these icefish into the proverbial canary in the coalmine, so Kristen, Lisa and their colleagues want to learn as much as they can about how notothenioids may respond to a warming ocean. It’s easy to understand why Lisa chose this for her life’s work. From 1928 until 1930, a young Harvard student, who many years later became her father, served with geologist Laurence M. Gould as a key member of the Antarctica team in the South Pole expedition of Adm. Richard E. Byrd.
Behind Bio Lab stands a series of cylindrical aquaria that resemble backyard swimming pools, each pumped with fresh seawater from Arthur Harbor a few yards away. In the first of these were the newly arrived Notothenia coriiceps, a common species in this group, their camouflage-khaki skin making them hard to pick out amidst the brown algae of their habitat. Swimming nonchalantly one tank over were their flamboyant cousins in the Nototheniidae family, Gobionotothen gibberifrons, or gibbies, with their spotted blonde coats and extra-big, protruding eyes.
In the third and largest tank were two species of their slightly more distant relatives from the Channichthyidae family that I heard so much about and was excited to meet — the icefish.
In a molecular mishap between 5.5 and 2 million years ago, the icefish lost the ability to manufacture hemoglobin, and some species have since also lost their ability to produce myoglobin, giving them blood as clear as mineral oil and muscles as white as candle wax. Yet they prosper in the frigid, oxygen-rich waters of the Southern Ocean.
On approaching their tank I was instantly captivated. They swim with the grace of ballerinas, twirling, rather than flapping, their fanlike pectoral fins. Seconds after I began watching them, a group gathered at my edge of the tank, bobbing halfway out of the water at me, like puppy dogs at a pet shop. I locked eyes with several, who gaped their huge jaws into a magnetic greeting, a friendly fish smile, as if to say, “Look, I couldn’t bite you even if I wanted to. I have no teeth!” (They do, but they’re very fine, harmless cartilaginous bristles.)
Just off the rear deck, inside Bio Lab, first-year grad student Devin Devor was checking the temperature of the seawater in the experimental tank. Zero-point-five degrees centigrade, just right for the baseline studies of the icefish (in this case a species called Chaenocephalus aceratus) and the N. coriiceps, the red-blooded animals.
One by one, as each fish equilibrates in the tank, Devin removes it into a bucket of anesthetic and takes it next door to Lab 1, where Kristen swiftly withdraws a sample of arterial blood from the dorsal aorta and Lisa draws a sample of mixed venous blood from the two-chambered heart. Devin then takes the fish down the hall to Lab 10, where he and senior Fairbanks, Alaska, grad student Irina Müeller collect tissues surgically for analysis back home, using some of the same instruments that have served me for decades in the operating room.
Meanwhile, across the building in Lab 1, Kristin determines the oxygen tension in the arterial blood and Lisa uses an analyzer and reagent cartridges from the station’s clinic to record some of the same blood parameters that I measure routinely in critically ill patients, including pH, oxygen and carbon dioxide gas pressures, bicarbonate level, base excess and accumulated lactic acid.
They repeat the same process over and over again, methodically increasing seawater temperatures, first with N. coriiceps and then icefish, with and without supplemental oxygen in the water. From the clockwork to the chemistry, their operation feels like an acute-care surgery center. I am very much at home. I can relate to their long hours and to the physiology of their fish.
As the seawater heats up ands carries progressively less oxygen, the N. coriiceps do fine until 17 degrees Celsius, when they lose their balance, wobble sideways and occasionally swim upside-down. They become, as I do on occasion, seasick. As expected, much the same happens with icefish, albeit at a lower temperature of 13 degrees Celsius.
But the notothenioids fight back. The blood tests confirm that they hyperventilate, just like the occasional newbie, fresh off the plane at South Pole, laboring to breathe in the meager high-altitude atmosphere. And just like a patient who struggles against dyspnea (shortness of breath), giving the hypoxic notothenioids supplemental oxygen, by bubbling it into the water they breathe, causes them to stop gasping.
The blood chemistry also reveals striking metabolic derangement in the hyperthermic fish of both species. By the time the fish start wobbling in the water, the syndrome is full-blown and severe. To me, after 30 years of medical experience with Homo sapiens, these findings are not at all fishy. They denote clinical shock, a condition resulting from the heart’s inability to deliver adequate oxygen to the body’s organs, or the inability of those organs to utilize the oxygen that comes their way, or both.
At the higher temperatures, hemoglobin loses some of its affinity for oxygen, and blood plasma, like seawater, can dissolve less of it. Not surprisingly, supplemental oxygen mitigates the signs of shock in both species, so at least some of the effects of heat likely stem from problems with oxygen delivery in the fishes.
Once Kristin, Lisa and their teams complete their analysis of the experimental tissues and the reams of data they collected during their time at Palmer Station this year, perhaps we will learn to what extent warmth diminishes the notothenioids’ ability to carry oxygen to its tissues and to what extent it interferes with its tissues’ ability to utilize oxygen.
What is certain is that the waters around Antarctica’s peninsula have warmed by 1 degree centigrade during my lifetime alone. If continued unchecked, that rate portends doom for these enchanting creatures long before the end of this millennium.
Jeffrey Grim, Lisa’s former student and now a new postdoctoral fellow at Boston’s Northeastern University, ponders these fishes’ next turn on their journey through time. “Survival of Antarctic notothenioid fishes will depend on the impact of rising oceanic temperatures on their embryonic development,” he says.
Jeff studies molecular signaling in the genes of notothenioid embryos as they develop in the egg under conditions potentially mimicking a warming ocean, where oxygen is scarcer but reactive oxygen species may be more abundant. In such an environment different genes might be activated, or the same genes might be regulated differently, and produce a different kind of fish, one with a more buoyant, cartilaginous skeleton in the case of the N. coriiceps, for example.
Maybe, just maybe, Antarctica’s fishes will reinvent themselves as their world — and ours — changes.
For my part, it’s hard not to take all of this just a little bit personally. Having kept company with the glacier on its own terms and exchanged smiles of delight with the icefish, I suffer pangs of sadness that after millions of years both are now fleeting.
But that’s Antarctica — a place where under the next rock or in the next plant frond or sea star might be hiding the next wonder drug. Where every day begins with excitement and ends with new understandings about oneself and the world, learned only by trekking to the ends of the Earth.
Dr. Untracht is a surgeon who also holds a Ph.D. in biophysics and theoretical biology from the University of Chicago. He devotes a substantial portion of his clinical activities to remote parts of developing countries, including those in south Asia, Africa, the Caribbean and Central America. Immediately before going to Antarctica, he served six months as a doctor to the Iñupiat people of Alaska’s Arctic Slope.
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