シオミズツボワムシ Brachionus plicatilis ノ ハイセツリツ

The excretion rates and excreted components of the rotifer, Brachionus plicatilis, cultured on the Chlorophycean, Chlorella saccharophila, were measured under constant conditions of: 20°C, 20 ppt salinity, and 1 klux light intensity. Analyses for: NH_4-N, urea-N, total persulfate nitrogen, and PO_4-P were carried out on the resulting experimental water. Rotifer density, fecundity, and algal density were examined as dependent variables. The uptake kinetics of dissolved nutrients by C. saccharophila were also determined as a control. Under the above conditions, B. plicatilis excretes the majority of its dissolved nitrogen as ammonium and urea, with urea comprising almost an equal amount of the total nitrogen as NH_4-N. The rates of excretion by B. plicatilis were found to be high in comparison to other zooplankton excretion rates, and dependent on all the tested variables. Thus, B. plicatilis most likely plays a very important role in the cycling of nutrients in both natural and artificial ecosystems