For Endangered Galápagos Penguins, Climate Change May Come With Benefits
The Galápagos penguin—the only penguin native to the northern hemisphere—may be one of the few species experiencing benefits from climate change.
Shifting equatorial winds and water temperatures, possibly related to climate change, have caused an important undersea river called the Equatorial Undercurrent to rise up and hit the Galápagos Islands a bit farther north of its historic course, according to a new study led by researchers at the Woods Hole Oceanographic Institution.
The steady supply of cold ocean water has rejuvenated the marine food web on the western side of the Galápagos archipelago, where a vast majority of the Galápagos penguin population resides.
With more fish to eat, adult Galápagos penguins have hatched and reared more baby penguins to adulthood, more than tripling their numbers from just a few hundred 15 years ago to more than 1,000 today. It’s also been good news for fur seals and iguanas native to the region.
“When you see a cold pool of water where you’d expect to see warm water, that indicates something is mixing that water up from below,” said Kristopher B. Karnauskas, an associate scientist with Woods Hole and lead author of the study. “That water is feeding everything from plankton on up. It has been strengthening in the past 30 years and expanding northward.”
Karnauskas and his colleagues found the connection between the Equatorial Undercurrent’s shift and penguin population growth by comparing satellite data on sea surface temperatures in the Galápagos with year-on-year census counts of the Galápagos penguin.
An estimated 2,000 penguins once roamed the islands, but by the early 1980s, fewer than 500 remained. Introduced predators such as cats, dogs, and rats had long weakened their health and numbers, leaving the species especially vulnerable to depleted food supplies during El Niño weather cycles. “The penguins tend to die off during El Niño events, which are a massive sweeping circulation in the whole ocean” that warms sea surface waters and drives away fish, Karnauskas said.
The Galápagos penguin gained U.S. endangered species status in 2000 and is classified as “endangered”—just two steps away from extinct—on the International Union for Conservation of Nature Red List.
Karnauskas believes his study’s findings suggest strategies that could help the penguins’ numbers continue to grow.
“The sea surface temperature trend shows that just to the north of where most of the penguins are has become more of a suitable environment than it was in the past,” he said. “If that continues, I would cautiously draw a box around the north part of the island and say, ‘If there’s any place conservation can help the penguins, that’s where I would do it.’ ”
Karnauskas is only cautiously optimistic, however, because for most of the world, rising ocean temperatures and shifting chemistry owing to greenhouse gas pollution are degrading marine habitats.
“This could be interpreted as ‘Global warming is good for penguins.’ I think that’s glossing over the details too much,” he said. “The Galápagos happens to be this little outpost that, at least in the near term, is benefiting from changes in ocean circulation that could be driven by anthropogenic climate change. But I wouldn’t necessarily count on this saving them forever.”