Melting Glaciers Threaten Harbor Seal Havens on Icebergs

Harbour Seals Adapt Their Habitat Preferences as Glacier Changes Transform Iceberg Availability

Harbor seals rely heavily on icebergs for survival. These icy platforms serve as important locations for giving birth, raising pups, and molting. Recent research sheds light on how climate change, specifically changes in glaciers, is impacting the seals’ essential habitat.

**Iceberg Preferences Shift with the Seasons**

A new study reveals that harbor seals exhibit fascinating habitat preferences depending on the time of year.

“Stable, slow-moving icebergs are preferred by mother seals for pupping and nurturing their young, while during the molting season, seals favor faster-moving icebergs closer to productive feeding areas,” explains Lynn Kaluzienski, a postdoctoral fellow at the University of Alaska Southeast who led the study.

**Unveiling the Link Between Glacier Advance and Seal Behavior**

The research, conducted in Johns Hopkins Inlet and Glacier in Alaska’s Glacier Bay National Park, focused on the relationship between glacier movement and harbor seal distribution. Johns Hopkins Glacier, unusually, is advancing rather than retreating due to a natural barrier at its front. This barrier, although protecting the glacier, limits the number of icebergs released into the fjord, making it crucial to understand how seals utilize the available ice.

“Our work provides a direct link between a glacier’s advance and seals’ distribution and behavior,” says Kaluzienski. “Interdisciplinary studies like this one coupled with long-term monitoring campaigns will be important to understand how climate change will influence tidewater glacier fjord ecosystems in the future.”

**Foraging Success and Iceberg Movement**

The study revealed a clear connection between iceberg movement and foraging opportunities. When an iceberg breaks away from a glacier, its speed and path are influenced by wind, ocean currents, and freshwater runoff, known as a plume. This plume brings plankton and fish to the surface, creating a natural buffet for seals. The research found that during the molting season, seals actively sought out faster-moving icebergs near the plume, likely to capitalize on the increased foraging opportunities.

Meeting: AGU Annual Meeting 2024

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