Phosphorus distribution in three crustacean zooplankton species

The distribution of phosphorus (P) was assessed in homogeneously P-33-label ed Daphnia magna, Daphnia galeata and Eudiaptomus gracilis. The specific P contents were 1.48, 1.41, and 0.50% of dry weight (DW), respectively. The r esults support the view of low intraspecific variability in P: DW ratios in crustacean zooplankton. The fraction of P allocated to nucleic acids, phos pholipids, and other P compounds was assessed in D. galeata and E. gracilis . In both species, the major pool, 35-69% of the total P content, was assoc iated with nucleic acids. This fraction decreased with both body size (age) of D. galeata and E. gracilis and with the reproductive rate of D. galeata . D. magna and D. galeata revealed similar patterns of P allocation between body, carapace, and eggs. The carapace contained approximately 14% of the total P content. If most P is not reabsorbed from the exoskeleton prior to molting, the molting will result in a substantial P drain both from the ind ividual and, at times, from the entire planktonic system.