It’s October - springtime in the Antarctic. And on the Ross Sea, it’s pupping season. The world’s southernmost-breeding mammals, the Weddell seals, are hauled out on the fast ice of McMurdo Sound. The temperature hovers near zero degrees Fahrenheit. The surface of the sea remains frozen for miles. The only breaks in the ice are tidal cracks and breathing holes that the seals have carved out with their teeth. As the summer progresses and brings with it continuous daylight, the sea ice covering this area will begin to fracture and melt. For now, though, the ice is solid and the frozen landscape is dotted with female seals and their pups.
Weddell seals are uniquely adapted to survive life in this polar habitat. Just like their phocid (seal) relatives in the Arctic, these seals have thick blubber that insulates their bodies from the frigid climate. Still, life in this extreme environment isn’t easy!
VIDEO: LIFE IN THE ANTARCTIC
Learn about the extreme Antarctic conditions Weddell seals are adapted to live in. (2:20)
Measuring over 10 feet (3 meters) from head to flippers and weighing in at more than 1,000 pounds (450 kilograms), Weddell seals are a hardy bunch. And it’s a good thing! These marine mammals live in one of the world’s harshest environments: the Antarctic.
Antarctica is often described as seeming like an alien planet. It certainly isn’t like anywhere else on Earth! 98% of the Antarctic continent is covered with ice, but the ice doesn’t stop at the land’s edge.
Winter conditions in this area are severe enough that the sea surface freezes solid over much of the Southern Ocean.
This sea ice is important habitat for wildlife, including Weddell seals. During the austral spring and summer it provides a safe place for the seals to haul out of the near-freezing water to rest and give birth to their pups.
Although Antarctica receives 24-hour daylight in the summertime, it is definitely not a warm place to relax! Summer air temperatures in McMurdo Sound average about 26° Fahrenheit (-3° Celsius).
In the winter, air temperatures can be as low as -58°F (-50°C). During these months, seals migrate out to sea where they forage near the ice edge. Because of the extreme air temperatures, seals spend all winter in the water, only surfacing to breathe.
Recently, many people living and working in the Arctic have observed significant and measureable changes in the region’s climate. Because Antarctica has no permanent human population, far fewer people are aware that similar dramatic changes have been recorded in the Antarctic as well.
Around Antarctica temperatures are warming. Coastal ice shelves have lost huge volumes of ice as massive pieces have broken away and melted. At the same time, some areas of the continent have been experiencing increased winter sea ice extent.
Researchers hope to learn more about the lives of Weddell seals in Antarctica so they can gain a better understanding of how ice seals in both the Antarctic and Arctic might adapt to their changing environments.
While environmental changes have presented themselves differently in the Arctic and Antarctic, one common theme is that conditions have become less predictable. Just as dealing with an unpredictable situation can be hard for a person, adapting to an unpredictable environment can be challenging for an animal. For Weddell seals, whose migration, foraging habits, and breeding activities are dependent on specific sea ice conditions, such unpredictable conditions could have negative impacts.
Dr. Jo-Ann Mellish is a Marine Mammal Scientist. She and her research team want to understand how hard it is to be a polar seal. In particular, they're curious to know how seals stay warm in such cold environments. Understanding how Weddell seals are able to survive in their environment will help the scientists begin to predict how seals at both poles may be impacted by changing environmental conditions.
VIDEO: INTRODUCTION TO THE RESEARCH PROJECT
Dr. Jo-Ann Mellish explains why the team is interested in studying polar seals. (1:56)
Jo-Ann Mellish: “It was one of those cases where one question leads to another question. I was on a previous project on McMurdo Sound, with Weddell seals. We were down there for a couple years, and as we were there there were a lot of issues with the sea ice. There was some very thick, very old, multi-year sea ice. There were some icebergs around and it was impacting water patterns and ice patterns. In addition to that, everywhere in the news it’s ice change in the Arctic.
“So you’ve got ice changing in very different ways at either end of the Earth, but the common factor is that you’ve got these seals that depend on the ice for where they breed; where it impacts very strongly, how they get to their breeding sites. These ice-obligate seals are at both poles, there’s ice changing at both poles, but nobody has ever looked at how much energy it costs just to be a seal in these environments.
“One of the common themes in biology is that if an animal lives in a place, you assume that it’s adapted. But what happens if that habitat that the animal lives in starts to change? How much flexibility does that animal have to adapt to the change? Maybe there’s a lot, maybe there’s this huge buffer zone. Maybe there’s a teeny-tiny buffer zone. You kind of assume that these animals at the ends of the earth might have a teeny-tiny buffer zone.
“Nobody knows what that buffer zone is. So what we wanted to do was actually document the cost of living in a polar seal. “
The research described in Southern Exposure was funded by the Office of Polar Programs, Antarctic Organisms and Ecosystems, National Science Foundation, Award #1043779.
All research was conducted under National Marine Fisheries Service Marine Mammal Protection Act authorization 15748 and Antarctic Conservation Act permit 2012-003.
Unless otherwise noted, the videos in this virtual field trip are courtesy of Jo-Ann Mellish, John Skinner, Henry Kaiser, or the Alaska SeaLife Center.
WHO IS STUDYING SEALS?
FAST ICE (n) - sea ice that is attached to the shore
TIDAL CRACK (n) - a broken area of sea ice caused by movement of the tides
ADAPT (v) - to change behaviors or physical traits to survive in a specific environment
POLAR (n) - describing the area of the Earth’s surface around the north and south poles
PHOCID (n) - the scientific family name for true (earless) seals
ICE SHELF (n) - a floating sheet of ice, attached to a landmass
AUSTRAL (adj) - of or relating to the southern hemisphere
MIGRATION (n) - movement from one area to another
FORAGE (v) - to search for and collect food
THERMOREGULATION (n) - the ability to maintain a constant body temperature under changing conditions
HYPOTHESIS (n) - a proposed explanation to a question that must be tested
PHYSIOLOGY (n) - a branch of biology dealing with the study of how living things function
