Allocation strategies in crustacean stoichiometry: the potential role of phosphorus in the limitation of reproduction

Abstract

Summary 1. Elemental composition (carbon : nitrogen : phosphorus, C : N : P) was analysed in eggs and juveniles of two crustaceans, Daphnia magna (Cladocera) and the crayfish Astacus astacus (Decapoda). Stoichiometry was also analysed for the carapace, muscle tissue, hepatopanchreas and gills of Astacus. 2. For both species the C : P ratio was significantly higher in eggs than juveniles, but there was a constant, homeostatic elemental ratio in eggs during embryogenesis (Astacus) and with different C : N : P in maternal food (Daphnia). 3. Differences in the stoichiometry of major tissue categories in Astacus suggest that there are distinct allocation strategies of elements to various somatic tissues as well as to reproduction versus somatic tissues overall. 4. There are strong ontogenetic shifts in the allocation of energy and elements in both species, as for crustaceans in general. During maturity there may be a trade‐off with regard to the allocation of C, N or P to somatic or reproductive tissue, and poor food quality (high C : P in food) could pose other constraints on reproductive capacity than does food shortage (low C). 5. Egg production may be at least as sensitive to low P as is somatic growth and could result in a marked decrease in overall population growth rate more severe than would be expected from individual growth rate alone.

Reproduction as one of the main causes of temporal variability in the elemental composition of zooplankton

“…In contrast, the C : P ratio of Daphnia females was only slightly smaller than that of their eggs; being their N : P much smaller and the C : N much higher because of a higher N content in the eggs. A higher C : P ratio in Daphnia eggs than juveniles was found by Faerøvig and Hessen (2003); however, the C : P ratios were substantially lower for both Daphnia magna and Astracus (120 for both species) than in our study. The C : P ratios measured in this study are closer to those found by Sterner and Schulz (1998), who reported egg C : P ratios for Daphnia magna and Daphnia obtusa of 192 and 310, respectively, D. magna eggs having almost twice the C : P ratio of adult females (83).…”

Sex and size matter: ontogenetic patterns of nutrient content of aquatic insects

“…Nutrient ratios also are important because growth requires different relative amounts of C, N, and P, and other elements (Elser et al 1996, Sterner and. Furthermore, somatic growth may have different elemental requirements than gamete production, especially with reference to P (Vrede et al 1999, Faerøvig andHessen 2003). Because %C and %N did not vary markedly across ontogeny, the C:N ratio also did not vary much for the 8 taxa examined in our study.…”

“…For P measurement, individual insects were weighed as above, placed in 22-mL glass scintillation vials, pulverized with a metal spatula, capped with a lid containing a Teflon septum, and chemically digested in an autoclave for 1 h at 120uC by the method of Faerøvig and Hessen (2003). The minimum mass required for P measurement was 10 mg (assuming 1% P content).…”

Strong relationship between elemental stoichiometry and metabolome in plants

“…Low ratios of environmental N/P and C/P favor species with very high rates of growth (5) and may induce shifts in species communities (6,7). The GRH has strong experimental support in freshwater ecosystems (2), with a few exceptions related to the allocation of nutrients to functions other than growth (8)(9)(10). In terrestrial ecosystems, however, the direct application of the GRH frequently fails or is accomplished incompletely (2,11).…”