Presence and significance of lithium in the brown shrimp, Crangon crangon (L.).

1. In female (non-ovigerous and ovigerous) brown shrimps, Crangon crangon, whole animal lithium levels are about 20% higher than in males, which indicates that lithium has a special function in the female reproductive system. 2. Decreasing lithium levels in larger males suggest that with males a substantial part of the lithium present may be passively absorbed to the exoskeleton. 3. At low temperatures internal lithium concentrations are strongly increased. In response to external salinity the internal lithium concentrations show a typical regulation pattern. The effects of temperature and salinity clarify that lithium must be involved in metabolic processes. 4. Apart from a special function in the reproductive system, lithium can probably replace other ions in their function, e.g. in regulating the activity of enzymatic processes.