Harbor locks along the Alaskan coast select the glaciers they ride on depending on the season, according to new research presented today at the annual meeting of the American Geophysical Union.
The study focused on the properties of the lagoon in Alaska’s Glacier Bay National Park, where the Johns Hopkins glacier is at its peak—one of the few in the world that does so, according to an AGU release. Due to the conditions of its development, the ice does not destroy many icebergs in the fjord area, reducing the habitat of the seals. A recent study investigated the types of icebergs the harbor seal (Poca vitulina) chose to date (no pun intended) during the year.
“Icebergs are found throughout the fjord in areas of fast flow, within eddies, and near the glacier,” said Lynn Kaluzienski, a University of Alaska Southeast researcher and lead author of the study, in a release. “We wanted to understand which of these habitats the seals use and how this habitat is changing due to the advance of the ice front and the reduction in iceberg numbers.”
The researchers found that the seals tended to set up shop on slow-moving ice bergs during the budding season (June) and on fast-moving bergs during the melting season (August). The team classified slow-moving icebergs as those moving at a speed of 7 to 8 inches (0.2 meters) per second. During the melting season, the seals were often on the mountaintops near the flowing water formed by the ocean currents and ice flow, called the plume. The plue is over plankton and fish, according to the AGU release, offering a feast for the seals.
The team suggests that the slow-moving bergs provide more stability for older seals caring for their pups in early summer. During molting that stability is less important, and fast bergs provide easy feeding opportunities.
“Our work provides a direct link between ice development and the distribution and behavior of seals,” said Kaluzienski. “Differential studies like this one coupled with long-term monitoring campaigns will be important to understand how climate change will affect tidewater glacier fjord ecosystems in the future.”
Climate change can significantly alter the habitats of seals; An AI-driven analysis of 10 climate models released today found that 34 regions defined by the International Panel on Climate Change (IPCC) have a 50/50 chance of warming by 3.6 degrees Fahrenheit (2 degrees Celsius) compared to levels they are pre-industrial.
It’s been a busy year for seals in general. In February, a male elephant seal caused a stir when it rescued a drowning pup, pushing it back to shore with its head. Not all the news was so good: In July, nine seals off the coast of South Africa were found to have rabies, after months of reports of seals attacking people.
Seals from Alaska are cooler than their South African counterparts. The reduction in iceberg numbers isn’t good for them, but at least they don’t have rabies. There is always a silver lining!
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