Autonomous robots that follow the routes of swimming penguins are collecting information that could help scientists understand why the birds’ populations are dropping rapidly.
Researcher Alex Kahl with a glider off of Antarctica. (Elizabeth Leonardis)
The underwater robots, called gliders, are programmed to record ocean conditions as they follow the tracks of Adelie penguins swimming in the Southern Ocean surrounding Antarctica.
The penguins have been dying off in large numbers for decades, and scientists suspect that warming of the seawater could be to blame. Part of the problem may be disappearing sea ice, which grows algae that attracts the krill the birds prefer to eat. “They’re probably starving to death,” said Bill Fraser, a penguin biologist and president of the Polar Oceans Research Group.
Adelie penguins spend hours, and even days, on feeding trips. But once they dive below the surface, it’s hard to know what the birds are dealing with. So Fraser and oceanographers Alex Kahl and Oscar Schofield, both of Rutgers University, turned to robots to find out what ocean conditions are like when Adelie penguins are in the water.
Fraser has been sticking radio tags on the penguins for a decade to keep track of where they go. But the equipment that could tell researchers whether there is krill or algae in the water with the penguins is still too big to put on a 9-to-10-pound bird.
Research ships have sampled areas over deep underwater canyons where Adelies hang out, but this only yielded snippets of what was going on. The gliders can provide a potentially continuous stream of information.
Schofield has been using gliders all over the world for years to gather data on ocean physics and chemistry to study plankton ecology.
Fraser and Schofield got together in 2008 to test whether they could program the gliders to collect information on the presence or absence of algae and krill in the the underwater canyons. The gliders discovered blooms of microscopic algae, which krill eat. And because Adelies eat krill, this supported the scientists’ hypothesis that the penguins were feeding in these areas. “With the radio tags on the penguins, we could see where they foraged and how deep they were,” said Schofield. But with the addition of the gliders, “for the first time, now we know why they’re there,” he said.
In subsequent studies, the researchers started using near real-time penguin-location data to direct the gliders. “We can get location data on the penguin in the evening and design a mission for the glider for the next day,” said Schofield. In January, Schofield and Fraser used acoustic sensors on the glider to map the patches of krill that Adelies were eating.
“The concept of using animals to study oceanographic features isn’t new,” said Dan Costa, a marine-mammal and seabird researcher at the University of California–Santa Cruz, who wasn’t involved in the research. “But this is 9,000 times better than what we’ve been able to do” in the past. The next step is to eliminate the middleman. “My goal in five years is to have an automated network where you have penguins foraging, and my gliders are adjusting their tracks automatically,” said Schofield.
|Author:||Jane J. Lee|