A Scripps Institution of Oceanography at UC San Diego graduate student is part of a research team calling attention to climate change and connections to the dwindling supply of food available to plunging penguin populations at the bottom of the world.
Based on 30 years of data and recent field expeditions, researchers from NOAA's Southwest Fisheries Science Center as well as Scripps graduate student Jefferson Hinke believe the declining availability of tiny crustaceans called krill is responsible for steady drops in Antarctic chinstrap and AdÃ©lie penguins.
Populations of those penguins rose in the 19th and 20thcenturies when fur seals, baleen whales, and certain fishes-competitors for krill, the penguin's primary food supply-were decimated by human hunting. But since the 1980s the numbers of chinstraps and AdÃ©lies began plunging. Today, the West Antarctic Peninsula and adjacent Scotia Sea is one of the planet's fastest warming areas. Rising temperatures and a reduction of sea ice, combined with recoveries of whale and seal populations, has resulted in less krill and, as a result the authors say, fewer numbers of chinstraps and AdÃ©lies. In one study site at South Shetland Islands their numbers have declined by more than 50 percent.
"Long thought to be ecological winners in the climate-warming scenario, the chinstrap penguin instead may be among the most vulnerable species affected by a warming climate," the authors write in their paper, published in theProceedings of the National Academy of Sciences.
Because penguins are a dominant consumer of krill and fish in the Southern Ocean, their population fluctuations can provide key information about the entire state of the Antarctic ecosystem. Based on their findings, the researchers have called for increased monitoring and status reviews of the penguin populations in the area.
For Hinke, who has participated in six expeditions to Antarctica, the most interesting aspect of the research was the team's ability to use details of their focused studies in Antarctica's Admiralty Bay and, in conjunction with data collected across a wider scale, make broader conclusions across the penguin habitat.
When you study a small colony, there's always some doubt whether it is representative of the wider population," said Hinke, who is a NOAA employee studying at Scripps under the Student Career Experience Program (SCEP)."I was pleased to see that our ideas from a small colony could be translated across the region."
Hinke's southward travels have taken him to the Falklands, South Georgia, and into the Weddell Sea. During Antarctic expeditions he spends up to three months at a time in the field.
"The most rewarding aspect is the solitude and simplicity of life in a small field camp," said Hinke. "Being surrounded by glaciers, thousands of penguins, and beautiful, icy seas doesn't hurt either."
Hinke's research interests in biology started with fish and lake studies at the University of Wisconsin. After funding for research on Pacific salmon dried up, an opportunity arose to work on a long-term penguin data set.
"During my first trip to Antarctica in 2005 I got hooked," said Hinke. "I haven't looked back."
"This is an important paper that required the long-term study and exceptional persistence of the scientists that conducted the work. Jefferson Hinke, a graduate student and critical part of the team, represents a new generation that will continue this ecological study of population trends of chinstrap and AdÃ©lie penguins," said Jerry Kooyman Emeritus Professor of Biology at Scripps and Hinke's advisor. "The project covers a decisive period in the region of warming of the climate, decrease in sea ice distribution and increase in competitors for krill, the basic protein resource of the West Antarctic Peninsula food web."
Coauthors of the PNAS study include: Wayne Trivelpiece, Aileen Miller, Christian Reiss, Susan Trivelpiece, and George Watters of the Southwest Fisheries Science Center, part of NOAA's National Marine Fisheries Service.
The research was funded by NOAA, the National Science Foundation, the Pew Charitable Trusts, and the Oceanites Foundation.