Diet and distribution of seals in the Canadian Arctic
Climate change is warming the Arctic three times faster than the global average and causing a rapid loss of sea ice that Arctic species depend on.
Ringed seals are vulnerable to the loss of sea-ice as they depend on it for habitat to give birth to pups and for food that comes from sea-ice environments. They also experience very different sea-ice conditions from the low Arctic to the high Arctic. Changes in their abundance and diet across these sea-ice conditions make them a great indicator of how the Arctic marine ecosystem will respond to continued loss of sea ice in the future. Polar bears vulnerability to climate change is also tied to their heavy dependence on ringed seals in their diet. Ringed seals are also important to culture of Arctic communities and their food security through annual subsistence hunts.
Ringed seal (Pusa hispida) Photo: Pascal Tremblay
During my MSc research at the University of Manitoba, I looked at how the density and diet of ringed seals changed with the different sea-ice conditions they experienced from low to high Arctic.
We found that the density of ringed seals density were similar in the low and intermediate Arctic with lots of first-year sea ice but density was low in the high Arctic with less first-year ice and more thick multiyear sea ice. This is likely due to first-year ice being preferred habitat for ringed seals to make breathing holes and lairs to birth their pups and also due to less productivity for food in areas with thick multiyear ice coverage. Less multiyear ice in the high Arctic could help ringed seals in the high Arctic in the near future, but ringed seals of the low Arctic will be hurt by continued loss of necessary first-year ice habitat.
We also found a shift in ringed seal diets from primarily pelagic phytoplankton carbon in the low Arctic to a high amount of ice-algal carbon in the high Arctic. We also saw an increase in the trophic position of ringed seals from the low to high Arctic. Ringed seal diets show a change in the primary producers at the base of food webs and the trophic dynamics of food webs that ringed seals feed in linked to sea-ice conditions. High Arctic ringed seals may continue to have sea-ice based diets at high latitudes as sea-ice production is expected to increase but in the intermediate Arctic ringed seal diets may shift to more phytoplankton based diets like the low Arctic with continued sea ice loss expected to impact sea ice algae growth during the spring bloom.
Graphical depiction of findings on changes in ringed seal diet with latitude from Carlyle et al. (2022). Ecological Indicators. https://doi.org/10.1016/j.ecolind.2022.109746
Overall, we show that ringed seal density and diet can reflect large scale changes to the Arctic environment and Arctic food webs. We also provide insight into how ringed seals may respond to continued sea-ice loss and changes to Arctic ecosystems. This information is important for understanding the impacts of climate change in the Arctic and effective comanagement with Arctic communities that rely on the ringed seal.
