Another thought came to mind. If it is indeed a warm-water plume related to volcanic activity, that could also mean that it's pumping all kind of minerals into the upper layers of the ocean. If the previously colder waters and ice dampened this effect, keeping those minerals in deeper waters, this could be dramatically changing the ocean chemistry. And how might that effect life and the food chain in those waters?

My best guess would be a warm-water plume. Which leads to the question of what the volcanic nature of the sea floor is like at that location, taking into account any drift of the ice that might have occurred.

Already saw it in the X Files.

Rapture!