It's difficult to determine the exact amount of energy the crustaceans would have without more specific information about their feeding habits and trophic level in the food chain. However, on average, only about 10% of energy is transferred from one trophic level to the next. This means that if phytoplankton have 1,000 Kcal of energy, the crustaceans would likely have around 100 Kcal of energy.
