Answer:
the antarctic krill, the emperor penguins, and the leopard seals.
Explanation:
The passage says that Antarctic Krill eats up the algae in the underside of sea ice in the Southern Ocean. This means that the Antarctic Krill itself can be found in the Sothern Ocean.
The Emperor penguins and the leopard seals also feed on the Antarctic Krill in the Southern Ocean. This means that both the predators and the prey make up the community in the Southern Ocean.
