Krill in this food web is the primary consumer. Since the producer of the food web is the phytoplankton. Removing them from the food chain cuts the supply of food for secondary consumers such as seals, and whales. This disrupts the whole Antartic ecosystem since there will be a large amount of phytoplankton but not enough food for secondary consumers. This because secondary consumers are not able to eat phytoplankton due to their microscopic size. Only krill are able to feed on them and have the maximum energy gain from them.
