Environmental indicators link prey and predator body condition of two Arctic marine predators

Many Arctic marine predators are experiencing sustained changes in foraging success and body condition, likely driven by reduced sea ice and associated shifts in prey distribution, including the northward retraction of energy-rich, ice-adapted species. For ringed seals ( Pusa hispida ) – an opportunistic mesopredator and primary prey of polar bears ( Ursus maritimus ) – the links between diet, environmental conditions, and body condition remain poorly characterized. We assessed the body condition and dietary indicators (blubber fatty acid composition) of 236 ringed seals harvested during the ice-covered period in 1996, 1999, 2001, and 2012-2015 from Amundsen Gulf, Canada. We explored relationships between ringed seal body condition, diet, winter environmental metrics (Arctic Oscillation Index [AOI], regional sea ice drift, and local thin sea ice accessibility), and their correlation with the body condition of 108 polar bears. Our results suggest that ringed seal body condition increased with dietary indicators of sea ice algae-associated prey, negative phases of AOI, thin sea ice accessibility, and sea ice drift, which creates pressure ridges and leads that enhance foraging habitat. Higher polar bear body condition was associated with higher ringed seal body condition in years with corresponding data. This study provides insights into the complex and cascading effects of environmental conditions on the foraging outcomes of Arctic marine predators. We suggest that shifts in marine predator foraging ecology will continue with climate warming, consistent with recent forecasts of sea ice and primary production, although the mechanisms and potential consequences for Arctic predators will depend on species-specific ecological plasticity and the magnitude of warming.