Duke Travel Journal: Bubble-Net Feeding and Charismatic Penguins

Fragile beauty: hiking across the volcanic soils from Neptune’s Window to Whalers Bay inside the caldera of Deception Island
Dave Johnston Ph.D. ’04

For two weeks this past January, we took an intrepid group of Duke alumni on board the 290-foot-long, ice-strengthened ship Clelia II to explore and learn about Antarctica. Our research at Duke focuses on the marine ecosystem around Antarctica, specifically how whales and other animals are being affected by rapid and dramatic climate change. The most obvious manifestation is the lack of winter sea ice around the Antarctic Peninsula. This has severe consequences for animals like penguins and seals that require ice not only to rest and breed on but also for the staple of their diet, Antarctic krill, which require sea ice in order to grow and survive.

During our trip, we were able to teach the alumni firsthand about the places, processes, and inhabitants that make up this unique part of our planet. Above all else, Antarctica is a place that gets your attention. Visually, the landscape of the Antarctic Peninsula is unrivaled, with craggy peaks and serpentine glaciers framing every vista. The icebergs are as varied as snowflakes in their size, shape, and color. And nobody can deny the charisma of the penguins, which are so indifferent to humans that you can sit outside a colony to watch and have one walk within inches of you. Oh, yeah, it is darn cold as well.

To us as teachers and scientists, this trip was particularly fruitful. There is no better classroom in which to talk about current research and threats to an ecosystem. This part of the world is experiencing dramatic and frightening changes at a pace that is approaching out of control—something we could illustrate by showing people, for example, how far a particular glacier has retreated in recent times. Likewise, visiting the rookeries of different penguin species offered the opportunity to teach about the requirements of each and demonstrate how in a changing environment, with more snow and warmer temperatures, some will thrive while others will be decimated.

The other wonderful thing about this trip was that it gave us the opportunity to see new things and formulate new ideas for future work. The most striking example of this came on our last day in the region, when we visited Wilhelmina Bay, the site of our current research on the feeding behavior of humpback whales and how this relates to changes in the environment in Antarctica.

Waterfront property: (from left to right) crabeater seals resting on ice floes in Pleneau Bay; expedition leader Ignacio Rojas amid Paradise Bay icebergs; Adélie penguins on Peterman Island rookery with Clelia II anchored off shore.
Ari Friedlaender Ph.D. '06/Dave Johnston Ph.D. '04

We entered the bay under bluer-than-blue skies, without a lick of wind, and in the arms of spectacular mountains and glaciers that make keeping an eye on the water a difficult task. It was late in the evening, yet the sun was still high above and circling around us. The only sounds came from a quartet of humpback whales feeding in a small cove. We eased toward them to get a better look.

No sooner had we arrived than we started to see something spectacular. The whales would dive in synchrony, and soon thereafter a spiraling series of bubbles would rise to the surface. Your eyes followed the bubbles as they got closer and closer together until all of a sudden the whales would rupture the surface in the middle of it all, mouths sometimes agape and full of water and krill. Over and over the bubbles would form on the glassy water, and the whales would charge through the center, corralling prey and feeding heartily.

This is a behavior unique to humpback whales called bubble-net feeding. It is a strategy that the whales use to keep their prey contained and make feeding more efficient. We have seen the behavior among whales in the waters around Cape Cod and Alaska but never in the Antarctic. As we steamed away from the whales, their heaving breaths suspended in the air like geysers,we couldn’t help wondering what could have prompted the whales to create such a complex feeding behavior. We also couldn’t help pondering whether the changes in ocean conditions from climate warming had forced these whales to adopt new and more complicated means of feed ing because it is becoming harder for them to find enough food.

Every person who visits Antarctica is touched by the place and comes to realize that despite its rough and impenetrable exterior, it is fragile and in need of protection. As scientists, we want to learn about these threats—what can be done to thwart them and to communicate this knowledge to others. As leaders in our communities, Duke alumni have the privilege of going to places like Antarctica and sharing these experiences of a magical place with others. But we also share the responsibility to tell others about the threats to this far-off part of our planet and to promote its conservation.

—Ari Friedlaender and Dave Johnston

Friedlaender Ph.D. ’06 and Johnston Ph.D. ’04 are research scientists at the Duke Marine Lab.

Watch Friendlaender talk about his research during an "Office Hours" from February 5, 2011.
See additional photos and video from Friedlaender in Antartica.