Osmotic regulation of the krill Meganyctiphanes norvegica
1. 1. The krill Meganyctiphanes norvegica is an osmoconformer in salinities from 24 to 40 ppt, with the lower lethal limit probably occurring between 20 and 24 ppt at 3-7°C. 2. 2. Haemolymph osmolality and Na+ concentration are close to those of the ambient seawater, while Cl- concentration is consistently 50-70 mM lower. 3. 3. Upon acclimation to a range of salinities, cell volume regulation probably occurs in the abdominal flexor muscle with proline regulated at salinities from 35 to 28 ppt, and glycine from 32 to 24 ppt. 4. 4. Haemolymph osmolality and Na+ and Cl- concentrations equilibrate within 2 hr to a 5 ppt decrease in salinity which implies haemolymph osmolality and ionic concentrations will change during vertical migration. © 1983.