Leaping into new territory
Palmer LTER adds whales to marine ecosystem study of Antarctic Peninsula
Posted July 25, 2014
Once upon a time – but not so long ago – humpback whales in the Southern Ocean around Antarctica and elsewhere were heavily exploited, decimating populations before a hunting ban was put into effect in the 1986.
Today, this baleen whale species is making a comeback, with estimates from the International Whaling Commission (IWC) saying that humpbacks are approaching pre-commercial whaling populations. The IWC reports there are at least 60,000 humpbacks in the Southern Hemisphere.
Their return as one of the main predators in the polar food web has prompted researchers with the Palmer Long Term Ecological Research (LTER) program to add yet another level of sophistication to the National Science Foundation -funded project.
“We now cover the polar marine ecosystem from bacteria to whales,” said Hugh Ducklow , principal investigator (PI) for the Palmer LTER and a professor at Columbia University’s Lamont-Doherty Earth Observatory .
Photo Credit: Janice O'Reilly/Antarctic Photo Library
An Adélie penguin near Palmer Station.
Begun in 1990, the Palmer LTER program is a comprehensive ecosystem study of the western side of the Antarctic Peninsula, one of the fastest warming regions on the planet. Average temperatures have increased by a half-degree Celsius per decade since the 1950s. Winter sea ice duration has decreased by an average of three months during that time.
The project is interdisciplinary, with scientists studying everything from physical ocean processes like sea-ice formation to bacteria and small crustaceans called krill to predators such as the iconic Adélie penguin .
Now scientists will attempt to understand how humpback whales and other cetaceans fit into the regional picture, where local Adélie populations are in steep decline as a subantarctic climate pushes inexorably south.
“The opportunity was there to get up to speed with whales and how they function as part of the Antarctic ecosystem around the peninsula,” explained Ari Friedlaender , an associate professor at Oregon State University’s Marine Mammal Institute . Friedlaender is the newest co-PI on the Palmer LTER, leading the study of humpback whales in the Antarctic.
It’s a research field he knows well, dating back to the early 2000s during the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, one of several regional initiatives of the international GLOBEC project to understand the world’s ocean ecosystem. His work with SO GLOBEC analyzing the spatial distribution of whales.
Photo Credit: Kyle Hoppe/Antarctic Photo Library
More recently, with colleagues from Duke University , where he was a postdoctoral researcher, Friedlaender spent the last several seasons learning about the feeding and diving behavior of humpbacks, including an effort to quantify how much krill the whales may be consuming. [See previous article — Tagged: Technology to help scientists measure krill consumption by humpbacks.] Krill is also the primary prey of Adélie penguins, whose populations in the northern end of the LTER study site have dropped by 85 percent since 1974.
“Estimating the consumption rate of an individual whale is a challenging process,” Friedlaender noted, because of uncertainties around how many krill are able to escape each whale-sized gulp from the humpbacks, which can grow to 16 meters in length.
The researchers are particularly interested in hotspots of biological activity where penguins and whales both compete for krill.
“As an open ocean, polar project, we have always felt that we were on the margins of the LTER Network with regard to the central field of ecology, and also direct human impacts on ecosystems,” Ducklow said. “Our new focus on competition between whales and Adélies allows us to test fundamental ecological hypotheses. And we can study the long-term recovery of whales from human exploitation.”
Noted Friedlaender of what appears to be a lopsided contest for prey between the two species: “Penguins are more at risk of conditions changing locally and affecting them, while whales can move around and find conditions that suit them best.”