DRY-WEIGHT AND CHEMICAL-COMPOSITION (CHN) IN RELATION TO POPULATION-DENSITY OF CULTIVATED TISBE-HOLOTHURIAE (COPEPODA, HARPACTICOIDA)

The harpacticoid copepod Tisbe holothuriae was cultivated at different densities in a running-water system. Dry weight and chemical composit ion (CHN) of both females and egg-sacs have been determined. Dry weigh t decreased significantly with increasing density from 3.48 to 1.94 mu g in egg-sacs, and from 10.80 to 6.58 mug in females. Increasing densi ty in both egg-sacs and females results in decrease of carbon, nitroge n and hydrogen contents, expressed as a percentage of dry weight of eg g-sacs and females, respectively. Carbon decreases from 52.56 to 50.57 % (egg-sacs) and 45.80 to 39.95 % (female), nitrogen from 12.63 to 11 .94 % and 10.72 to 9.73 % and hydrogen from 9.08 to 7.78 % and 7.47 to 6.17 %. The dry weight and elemental compositions of the egg-sacs var ied in accordance with that of the females, however, a higher percenta ge of elemental content was observed in egg-sacs. The energy equivalen ts were calculated from the carbon content. This indicates that more e nergy was transferred from the maternal body into egg-sacs. The ratio of carbon to nitrogen did not show any marked variations; no clear rel ation appeared between C:N and density, indicating a relatively consta nt chemical composition in both females and egg-sacs.