Calcium uptake by juvenile western rock lobster,Panulirus cygnus George,from dietary coralline algae

Foliose coralline algae form a large proportion of the diet of juvenile Panulirus cygnus George at some locations but its rôle in the diet is not clear. In the laboratory, early post-moult rock lobsters fed Corallina cuvieri Lamouroux, labelled with ⁴⁵Ca primarily in the algal skeleton showed significant uptake of calcium compared with lobsters maintained in sea water containing dissolved ⁴⁵Ca. Shortly after ingestion by the rock lobsters the isotopic calcium was distributed through all the soft tissues examined and the exoskeleton. After a 5-day period isotopic calcium levels had fallen in most soft tissues but were not significantly lower in the digestive gland, the mid-gut or the exoskeleton. The data indicate that calcium in the algal skeleton of dietary C. cuvieri is absorbed by the digestive system and may be important in the postmoult re-mineralization of the exoskeleton.