Final answer:
There is no animal whose urination has formed a significant part of the ocean's ice; this appears to be a myth. Regarding the impact of melting sea ice in Alaska, polar bears would be most affected due to their reliance on sea ice for hunting.
Step-by-step explanation:
The question is regarding which animal contributed to the ice composition in the Southern Ocean by urination. However, this sounds like a myth and there's no scientific evidence to support the claim that any animal's urine could form a significant part of the ocean's ice. Therefore, there's no correct answer to this part of the question.
For the factual part of the question related to sea ice melting in Alaska, the polar bears would be most affected. This is because polar bears are highly dependent on sea ice for hunting seals, their primary prey. With the ice melting, their hunting grounds are drastically reduced which negatively impacts their ability to feed and survive.