How is a polar bear beneficial to the biome?

Sea ice is critical to the polar bear because these bears hunt from this ice.

As the north warms in spring, the bears wait for the ice to begin to break up as they begin to venture out on it. There on the ice they will try to take seals, walrus, or anything else they might catch. Even the mothers take their cubs out on this ice as seals use it to den and can be hunted from the frozen platform.