Research Highlight: The Beat Goes On... Barely

The emperor penguin has become a key source of knowledge about the changing environment of Antarctica. Scripps Institution of Oceanography at UC San Diego scientist Jerry Kooyman is studying how the emperor’s habitats are changing as the landscape of the continent transforms under warming climate conditions.

And now the emperor penguin is providing fresh information about how the birds survive and thrive in the harsh conditions of the Antarctic, including clues about their amazing diving capabilities.

A new study led by Scripps graduate student researcher Jessica Meir, research physiologist Paul Ponganis of the Scripps Center for Marine Biotechnology and Biomedicine, and their colleagues has broken fresh ground in understanding how the emperor penguin has adapted its bodily functions to become the deepest diving bird on the planet, logging dives of more than 500 meters (1,640 feet).

Meir and her colleagues studied the penguins’ diving heart rate—specifically bradycardia, or slowing of the heart rate, that emperors employ in order to stay underwater for amazingly long blocks of time.

The study was the first in which researchers utilized a digital electrocardiogram recorder on any penguin species to document beat-by-beat heart rate data. Advancing from previous instruments that provided generalized heart rate averages, this technology allowed them to secure the complete heart beat profile, including some remarkable highs and lows.

During one penguin’s astonishing 18-minute dive, for example, the researchers recorded a span in which a penguin’s heart beat only six times per minute over a five-minute period. They also documented the penguin’s heart rate at the surface before and after dives. One recording taken just after an emperor reached the surface was the highest heart rate ever recorded in an emperor penguin at 256 beats per minute. For comparison, a penguin’s resting heart beat average is 70 beats per minute, a human averages 60 to 80 beats per minute at rest.

The team’s research paper about the results was featured as the cover story of the Journal of Experimental Biology.

Meir’s years prior to joining Scripps were spent at the International Space University in France and NASA’s Johnson Space Center in Houston. Switching from outer space to the South Pole might seem far flung, but the distance between the two was bridged by her interests in biology and physiology. In each case she has investigated how bodies respond to extreme environments, whether studying how a human body performs in space or how a penguin functions in the frigid extremes of Antarctic waters.

The latest results regarding penguin heart rate and oxygen depletion during diving are helping to provide clues about the bird’s physiological adaptations that may benefit humans down the road.

“When humans experience heart attacks and strokes, they undergo low levels of oxygen,” said Meir. “If we can figure out how these animals can tolerate these extremely low levels, that might help us figure out how to prevent human tissues from being damaged during low levels of oxygen,” said Meir.

The studies might also advance knowledge about stress to human organs and blood flow in cases of transplants and during surgeries.

Meir says insights of the emperor’s diving ability will also help scientists further define the role of the animal in an ecosystem facing global change on several fronts.

“To understand what’s really going on in the Antarctic ecosystem, I think understanding more about the emperor penguin’s diving ability is crucial, particularly in the face of global climate change,” she said.

The research was supported by the National Science Foundation’s Office of Polar Programs, a National Defense Science and Engineering Graduate (NDSEG) Fellowship, a Los Angeles Achievement Rewards for College Scientists (ARCS) Fellowship, and the Scripps Education Department.

-- Mario C. Aguilera