Spotlight

Ice Angler

Tim Higham

In New Zealand, John Macdonald is not much of a fisherman, but in Antarctica he is an inspirational angler.

John Macdonald is an Antarctican comfortable with his environment. Unlike most New Zealanders, who wrap in layers of specially designed cold-climate fabrics, Macdonald has a black singlet-and-gumboots look about his garb. He prefers to work in woollen trousers and bush shirt covered by red overalls into which he has stitched a hood. In temperatures well below zero, such choices are important. Macdonald works slowly and deliberately, tying fishing lures onto thin monofilament with bare fingers while there is a wind chill factor of -20^oC.

Patience, though, brings rewards, and fish are regularly pulled through a hole in the sea ice and transferred to a chilly bin nearby. When the bin is full, an ice auger, fishing rod and the catch are loaded onto a snow mobile and Macdonald returns to his kerosene-heated hut.

Antarctic fish have been Macdonald's research passion for over 20 years. He first visited the ice in 1963, while a student at Stanford University, then returned in 1974 after a doctorate at the University of Texas and a shift to Auckland to take up a university lecturing post. He has been back about every second season since.

Macdonald's research has been motivated by one simple question. How do fish in Antarctica survive in water temperatures less than zero? Most other animals would freeze solid if held at the -2^oC which Antarctic sea water stays close to throughout the year. Like most scientific questions though, Macdonald has found the answer is not so easy.

"It's not one thing that makes it possible, but a complex of features."

American colleagues of Macdonald's have found that the fish possess an antifreeze in their blood -- a glycoprotein which prevents the build-up of ice crystals which would otherwise wreck living cells. The fish also show differences in the behaviour of proteins, enzymes and other cell components. In general, Macdonald has discovered that Antarctic fish are able to survive the cold by having body compounds that are more fluid than those found in other species.

In the case of blood, it is thinner because it contains less red blood cells, and one species -- the icefish -- has no red blood cells at all. Macdonald says these fish can survive because cold seawater contains relatively high concentrations of dissolved oxygen. If Antarctica ever warmed up again the fish -- because of their unstable cell components -- would be doomed.

Most Antarctic fish are members of the same super-family -- the notothenioids -- and its 100 species are found throughout the south polar seas. They range in size from the common, herring-like borks to Mawson's cod, which can weigh over 100 kg. Members of the same family occur around the coasts of southern latitude countries, and include New Zealand's black cod. Macdonald says these fish evolved during the period Antarctica split away from other southern lands and developed its ice-clogged seas.

He is now looking at matching the adaptations within the family with major geological events. Why did the notothenioids make the adjustment and not others?

"There are still many big maybes'," Macdonald says.

Recently Macdonald received a polar medal -- a royal honour -- for his contributions to Antarctic science. He admits to being "chuffed" -- because he admires everyone else who has received one . His contribution, he says modestly, has been to "harass, interest and encourage" others into Antarctic fish research. One of Macdonald's colleagues, Auckland University biologist Clive Evans, believes there are potentially huge benefits from Antarctic fish research.

"Any fish that can survive at freezing temperatures is an invaluable mine of information on how best to apply cold-temperature technology to biomedical problems," Evans says. "The field of organ transplantation, in which body components can be transported around the world packed in ice, could benefit from understanding how functional organs survive at low temperatures."

Macdonald is more cautious about prophesying applications from the work and emphasises instead the value of pure science -- increasing our knowledge about the way the planet works.

"Intrinsically Antarctica is no more important than the Sahara Desert or the Waitemata Harbour," he muses. "But when you focus on particular aspects, then it becomes fascinating in a subjective way."

His Antarctic research has become the catalyst for related work on insects: comparing the physiology of alpine wetas with tree wetas, and Australian Snowy Mountain grasshoppers with those found in the Northern Territories. He has discovered that they mirror the pattern in fish, with body fluids in mountain species tending to be runnier.

Antarctica though will continue to draw Macdonald back for some years yet. Scott Base, he says, always invokes a feeling of home coming.

"It's like living in a city for a few years, then going back to the farm."

Tim Higham is with the New Zealand Antarctic Programme.