Carbon, nitrogen, and phosphorus content of freshwater zooplankton

Abstract

The amounts of C, N, and P in relation to dry weight were measured in natural populations of crustacean zooplankton from a humic lake. The elemental composition within a given species showed little seasonal variation, and experimental starvation or feeding did not cause any significant changes in the P content. C constituted 48±1% of dry weight with only minor variation among species. The mean C : N : P atomic ratios reflected large interspecific differences in P and N content and ranged from 212 : 39 : 1 in Acanthodiaptomus denticornis to 85 : 14 : 1 in Daphnia longispina. Comparisons with published measurements indicate that this pattern is quite general and probably constitutional. These findings suggest that the species composition of the zooplankton community can have strong influence on the N : P ratio of recycled nutrients and thereby affect resource competition between phytoplankton species.

Modelling the plankton groups of the deep, peri-alpine Lake Bourget

“…Conversion of the phytoplankton species counts to carbon biomass was based on biovolume of each species (Druart and Rimet, 2008), and assuming 0.2 pgC/µm 3 . Zooplankton counts were rst converted into wet weight, 10% of which was assumed to be dry weight (Dumont et al, 1975), from which the carbon biomasses were calculated assuming that carbon constitutes 48% of dry weight (Andersen and Hessen, 1991).…”

“…The plankton model described above acts homeostatically when Qmin= Qmax, values of which, for herbivores and carnivores are respectively based on D. longispina and as an approximate average of Heterocope and Acanthodiaptomus (Andersen and Hessen, 1991).…”

Competition and stoichiometry: coexistence of two predators on one prey

“…On the other hand, in animals P:C varies much less within a species (Sterner and Elser, 2002). For example, the zooplankton Daphnia's P:C stays within relatively narrow bounds around 31 Â 10 À3 by mass, decreasing only by around 30% when food P:C is more than 20-times lower than Daphnia's P:C (Andersen and Hessen, 1991;Sterner and Hessen, 1994;DeMott, 1998). Using only two elements is a gross simplification of reality, but it is a qualitative step forward from conventional ''chemically homogeneous'' models like model (1).…”

Coupling of growth rate and body stoichiometry in Daphnia: a role for maintenance processes?

“…While variation in C : N : P ratios in the photoautotrophic organisms that make up the base of pelagic food webs is generally understood as being driven by physiological plasticity associated with the severity of phytoplankton nutrient limitation (Sterner & Elser, 2002), variation also exists in the C : P and N : P ratios of animal biomass (Andersen & Hessen, 1991). These variations have been viewed primarily as taxon-or stage-specific differences, as it has commonly been observed, for example, that the taxon Daphnia has consistently lower C : P and N : P ratios than other crustacean zooplankton species.…”