NSS Home Page  Nature Sounds Newsletter Spring 1998 Sound Recording Adventures in Antarctica (3)
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Sound Recording Adventures in Antarctica (3): Recording at the Sea-Ice Edge
by Douglas Quin I had just returned to McMurdo from Cape Royds, and that evening talk had turned to a possible trip to the sea-ice edge. Buck Tilley, experienced at making this challenging and potentially dangerous trip, had agreed to be my guide. For all its possible problems, a trip to the sea ice edge holds the potential of capturing the voices of Killer Whales, Minke Whales, and Leopard Seals. Recording these large Antarctic predators can be a hit or miss proposition, however; one never quiet knows what might be active out along the sea-ice edge. The following morning looked promising; temperatures were in the mid-20s, with an onshore breeze. Even though wind chill put a bite in the air, our trip definitely was on! By chance, I had breakfast with Samantha Tisdel, a fire house dispatcher taking her day off. I invited Samantha to join our trip and, since her day otherwise promised nothing more exciting than doing laundry, she readily accepted. Samantha is a writer and journalist from Ouray, Colorado. She is bright, inquisitive, and has a nice way of framing her experiences in words. I particularly came to appreciate this skill when she wrote up my sound recording work for the weekly "Antarctic Times." An adventuresome spirit, Samantha taught English in Tsing Tao Province in China for a year, and then traveled extensively throughout China and Southeast Asia. Among her journalistic works: a Seattle Times article describing her culinary experiences eating fried grasshoppers! After breakfast we packed and repacked gear, obtained food from A. C. Hitch at the Berg Field Center, and hauled out a Jiffy Ice Auger at the Mechanical Equipment Center. By 9:30, we were ready! We picked up Buck at the Field Training Center, and dropped our equipment and survival bags off at the ice transition, where snowmobiles were parked and fueled. We decided to take two ski-doos, one with a sled in tow to haul out our gear. Air temperature had been rising, and the snow had become a bit heavy and slushy. Big caterpillar rigs had plowed and resurfaced a smooth path out to the ice runway, however. Cloud formations of different denominations stretched across the sound. Cirrus wisps contrasted sharply with the deep blue of the sky, and a muddy yellow cumulus front rose before us. Brooding Mount Erebus steamed from its volcanic vent, and a shaft of sunlight forced its crevasse field to glow golden on the slopes below. We made for Penguin Ranch, where Gerry and Carsten Kooyman still held forth. The rest of their research group had recently pulled up stakes (literally!) and left for the States. We arrived to a scene I hardly recognized. Recent storms had drifted snow all around the huts, and the penguin corral. All tents had been taken down. The excessive snow had been so weighty it had depressed the surrounding ice, causing the dive hole in the main hut to overflow. "We had to have someone come out and clear out the area." Gerry explained. "It cost us a couple days of work." Gerry gave us some final advice on sea ice condition beyond the ranch. "There are some dangerously thin and slushy stretches about 5 kilometres in the direction of Cape Royds." he warned. Finally, he looked up some Global Positioning System (GPS) longitude and latitude numbers for us, wished us luck, and we were off for the sea-ice edge. Buck had decided to aim for the edge in another direction, to a place near where the Nathanial B. Palmer research ship (the "Natty B.," in McMurdo lingo) had anchored several weeks before. We edged out over the frozen expanse, and Buck stopped periodically to get GPS readings. About five kilometres out, in flat light, horizon and ice seemed to merge, not unlike in a whiteout. It was fairly overcast, and the wind had died to an occasional gust. Suddenly, Buck's snowmobile skidded to a halt. He stood up and waved frantically for us to stop! Samantha and I, following at about 100 metres, did just that. Buck then motioned for us to approach -- slowly! The sea ice edge was just 150 metres beyond. In the filtered, yellowish light, we simply could not see it! At times like these, I thought, one really appreciates the value of experience. The sea was like glass, and our only real clue that an icy-cold, salt water bath lay just beyond was a broken line of Adelie Penguins; adelies and a single curious emperor, who immediately waddled over to make friends. Buck pulled his ice auger and a throw rope off the equipment sled, and we slowly walked, about 15 metres apart, toward the edge. Buck drilled every 20 metres or so, to check ice thickness, and the shelf shrank rather quickly from two metres thick to just one. After scouting the site, Buck determined we could approach to within about six metres of the actual edge. With Samantha's help, I assembled hydrophones and other gear. We bored two 10-centimeter holes about 60 metres apart in the ice, parallel to the water-ice boundary, and dunked our hydrophones. I was curious to listen to the sounds of the sea- ice edge, since wildlife there is different from that under the fast ice. Under the fast ice, Weddell Seals roam about with relative ease and safety, and I had been recording their wondrous sounds over the past two weeks. In the more open waters beyond the edge, Leopard Seals and Killer Whales patrol, looking for prey. With hydrophones lowered to 15 metres, I could hear the telltale whistles, trills, and chirps of far-off Weddell Seals. But also there was another sound, lower in frequency, and one that I never had heard before. It was modulated, pulsed, and pitched, like a muted steam whistle with rounded, booming chugs. I never had heard Killer Whales make such sounds, and I guessed they were, perhaps, from minkes. Knowing I later would have ample opportunity for repeated listening and scrutiny of my tapes, I let Samantha slide the headphones onto her ears. While Buck videotaped, a look of wonderful surprise came over her face. An hour later Samantha had eased back on the ice, and was grinning and humming along with her eyes closed. "She is gone," commented Buck. Indeed, Samantha was hooked on the sounds of the Antarctic sea-ice edge. With Samantha lost in her private world of underwater sound, Buck and I talked in whispers about the Adelie Penguins. They swam in groups along the ice edge, porpoising in and out of the water. One especially curious fellow, dressed in his (actually, it could have been a her) spiffy, black-and-white tuxedo plumage, ambled over to check us out, and to inspect our hydrophone cables. The bird paused, stooped, and inched in with reserve -- they are a bit more shy than the emperors. Its wings were flushed pink on the inside, and its plumage still glistened with sea water. The bird lingered a moment, looking us up and down, then abruptly turned and waddled off in response to a flourish of calling from a passing group of adelies at the ice edge. Thereafter, my thoughts wandered, and I was asking myself "What had been that mysterious, deep, new sound I had heard through my hydrophones?" Only later, after our return to McMurdo, did Gerry Kooyman identify the sound for me. It was a Leopard Seal. He had heard them through the ice, from a distance of nearly five kilometres, when he was out at Cape Washington. Suddenly, through the headphones, and all around us, a resounding, booming crack! Samantha levitated from her lotus position. Buck and I reeled around and stared toward shore. It was cracking ice -- a large fissure for sure! We looked at our throw rope, tied to the snowmobile so we could tell if we were drifting. Buck did a quick check of the GPS. Relief! We were not moving! The last thing we wanted was to drift off on a broken floe, into the pack ice, never to be seen again. It would have ruined our whole recording trip. As if the cracking of ice weren't ample warning, the wind started to pick up, and change to an offshore direction. We could discern a layer of grease ice just beyond the sea-ice edge, and the water seemed to boil beneath us; the effect of current and wind cavitating. Perhaps nature was trying to tell us something. We quickly packed our gear and headed for the safety of shore. In hindsight, in spite of its dangers (or maybe partly because of them), our recording trip to the sea-ice edge will remain one of my more memorable and exhilarating experiences. |
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