Energy available to krill is 1500 calories
Step-by-step explanation:
Energy produced by phytoplankton = 15,000 calories
Energy available to krill = ?
Along the food chain, only 10% of energy is transferred to the organism of higher trophic level.
Thus,
energy available to krill =

= 1500 calories
Energy available to small fish =

= 150 calories
Energy available to medium fish =

= 15 calories
Energy available to large fish =

= 1.5 calories