In an Antarctic pelagic community, the primary producers are phytoplankton, which serve as food for the dominant grazing zooplankton, especially krill and copepods, both of which are crustaceans. These zooplankton species are in turn eaten by various carnivores, including other plankton, penguins, seals, fish, and baleen whales. Squids, which are carnivores that feed on fish and zooplankton, are another important link in these food webs, as they are in turn eaten by seals and toothed whales (Figure 1).

Figure 1: Arrows follow the transfer of food from the producers (phytoplankton) up through the trophic levels. For simplicity, this diagram omits decomposers.

Antarctic krill (Euphausia superba) is an important source of food for whales, seals, squid, fish, and many species of birds. Its abundant biomass is one of the largest on Earth. Figure 2 compares the effects of krill harvesting on species richness within two small sections of the Antarctic region; one section was subject to krill harvesting and the other section was not.

Describe how the autotrophs facilitates the flow of energy through the Antarctic ecosystem. In the Antarctic pelagic community, there are three types of seals. The leopard seals eat birds, but the crabeater and elephant seals do not. Explain how the interactions between seals and other species may affect their food sources.
Identify the independent variable of the data graphed in Figure 2. Explain one way this variable is affecting the biodiversity of the Antarctic food web.
Analyze the change in species richness with or without krill harvesting. Predict how the removal of krill from the Antarctic ecosystem will affect its long-term structure.
Justify the claim that the Antarctic krill is a foundation species, not a keystone species. Provide evidence to support your claim.