THE ENERGETIC COST OF EGG-PRODUCTION IN ANTARCTIC KRILL (EUPHAUSIA-SUPERBA DANA)

A female Antarctic krill loses 34% of its body mass when it lays a batch of eggs. This represents a considerable input of energy which was estimated using a combination of measured mass and energy differences in female krill and from the measured energetic content of ovarian tissue. Large (c. 50 mm) female krill lose 2.9-3.8 kJ each time a batch of eggs is laid. Calculations using this figure indicate that multiple spawning by Antarctic krill in a season would require above average phytoplankton concentrations (> 0.5 mu g chl a 1(-1)) and filtration rates which are close to the maximum reported (> 101 h(-1)).