Penguins can suffer dramatically from the effects of oil pollution even
if their feathers are only lightly contaminated, according to new research.
Compared to clean penguins, oiled birds work harder in water and slow down
bodily activities in order to keep warm out of the water.
Ultimately, this means they are unable to forage properly which, in
breeding birds, could mean reproductive failure and death of young penguins,
says a group led by Boris Culik of the Institute of Marine Studies in Kiel,
Culik and colleagues examined the behaviour of Adelie penguins (Pygoscelis
adeliae) lightly covered by oil. They studied the birds in a specially designed
pool, and compared their results with those from experiments on clean birds.
Culik and colleagues report in the August issue of the Marine Pollution
Bulletin that in air, the oiled penguins had average heart rates of 90 beats
a minute, against 98 beats for clean birds. Also, their metabolism was lower
– 4.7 watts per kilogram of body weight against 5.2 – and they were half
a degree cooler. Culik and colleagues suggest that oiled birds suppress
body movements to reduce heat loss.
The effects were even more dramatic in water, where the oiled birds
showed erratic swimming behaviour. They swam more slowly, averaging speeds
of 1.6 metres a second compared to 1.8 metres a second for controls.
The metabolic rate of oiled birds was 50 per cent higher than that of
controls, and average heartbeat rose to 321 beats a minute against 252 for
controls. Culik argues that heartbeat and metabolism increased because the
birds were unable to control them while swimming.
On the surface of the water, the birds shivered between activity bouts
and their feathers were wet through, Culik says. He argues that these observations
prove that the birds were suffering from heat loss.
‘Penguins are more vulnerable to oil spills than flying birds, since
they must swim through oil that occurs between their breeding colonies and
feeding grounds. Oil and other surface active agents such as detergents
and fecal matter destroy the waterproofing quality of the feathers and cause
loss of buoyancy and insulation,’ he says. Culik concludes that for penguins,
the impact of oil spills in the Antarctic may be much greater than had previously