Scientists study penguin body clocks

Press, 23 February 1987, Page 5

Scientists study penguin body clocks

By

GRAEME WIX

NZPA Scott Base The Cape Royds Adelie Penguin colony has been the subject of scientific study for the last month. A scientist, John Cockrem, and a technician, Don Waddington, have taken about . 5000 blood samples from the penguins to measure the level of a hormone called melatonin. This hormone is responsible for control of the body clock. Melatonin levels in the blood of penguins and humans rise at night. Antarctica’s 24-hour summer daylight and 24hour winter night tends to upset the natural clock in humans but not penguins. “It seems the light intensity rises to 70,000 lux about midday and drops to 10,000 lux about midnight and penguins seem

to be able to detect that,” said Mr Cockrem, of the D.S.I.R. Ecology Division. The level of melatonin controls the amount of time that penguins forage for food and when they lay eggs. Scientists want to establish how the penguins maintain a sense of time. “If you take away the normal nine to five things from a human their body reverts to a 25-hour clock” Mr Cockrem said. “It seems the penguins can latch on to the change in light intensity.” Melatonin has been used to control jet lag in humans. A pill is taken at dusk in the new time zone to boost the level of melatonin. An Australian scientist, Brian Green, is measuring the energy requirements of the penguins during the breeding season.

He injects isotopes of sodium water and oxygen into the birds and a few hours later a blood sample is taken to measure the isotope level. The main food source for Adelie penguins is krill. The tiny shrimp-like creatures flourish in Antarctic waters. Krill are burned in a laboratory and the amount of sodium water and oxygen is measured. The figures are compared ; and scientists will be able to establish the amount of krill required to maintain i the penguins. i Krill is being fished from the Antarctic but the : effect on penguins is unknown. “We don’t know how , much krill the penguins ; eat near their breeding ; ground,” Mr Green said. > “It may be 1 per cent — it may be much more.”