Abstract:

The effect of temperature on the chemical composition (carbon, nitrogen and ash content) and the energy content of the rotifers Brachionus plicatilis and Brachionus rotundiformis (formerly B. plicatilis L- and S-type respectively) was examined in experimental populations. Dry weight and carbon, nitrogen and hydrogen content remained practically unchanged in the 20-35 degrees C range in B. rotundiformis, while in B. plicatilis the dry weight decreased slightly with increasing temperature from 15 degrees to 35 degrees C. Nevertheless, the major source of variation was the fecundity status of the populations. On the other hand, B. rotundiformis showed higher energy content (joules per mg of dry matter) than B. plicatilis. This difference in energy content was due to the different ash content because the organic matter of both species had the same energy content, as well as the same basic biomass composition.
(CSIC, Inst. Ciencias Marinas Andalucia, Apartado Oficial, Puerto Real 11510, Cadiz, Spain)
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