Vadstein, O., Y. Olsen
Abstract:
The carbon (C), nitrogen (N) and phosphorus (P) content and ratios between these elements were measured in the rotifer Brachionus plicatilis. Experiments were run to investigate the influence of specific growth rate on the composition of the rotifers. Analyses of lipid and protein content were used to provide biochemical explanations for the observed variation in C, N and P content.
For a variation in specific growth rate from 0.13 to 0.39 day^-1, the range in C, N and P content was 50-53, 9.1-11 and 1.1-1.6 % of ash free dry weight, respectively. Whereas the C content decreased with increasing growth rate, both the N:C and the P:C ratio increased with growth rate. Because the variation was higher for N than for P, the N:P ratio of the rotifers decreased with increasing growth rate.
N content was linearly related to the protein content of the rotifer, particularly on a per individual basis. As expected the relationship between C and lipid was more obscure, whereas a good linear relationship was observed between the N:C-ratio and the Protein:Lipid-ratio.
Our experiments suggest that elemental compositions may be a good predictor of gross chemical composition under specific conditions.
(SINTEF Applied Chemistry, Center of Aquaculture, 7034 Trondheim, Norway)
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