Population dynamics of rotifers (Brachionus plicatilis and Brachionus rotundiformis) in semicontinuous culture fed freeze- dried microalgae: influence of dilution rate

Freeze-dried microalgae can be used in establishing semicontinuous cultures for rotifers with high efficiency. The populations reach a quasi-steady state as the result of a process of regulation by means of exchanging material and energy between the population and their food, giving that at the beginning of each dilution, rotifer density is always the same, since population growth rate balances dilution losses. At this state, the specific growth rate (r) is constant and independent of time. The control of the semicontinuous production is obtained by the dilution rate (D). Several dilution rates were tested and those that resulted in the best productions (mg rotifer day(-1)) and food conversion efficiencies (mg rotifer developed per mg microalgae consumed) were D = 0.3 day(-1) for Brachionus plicatilis and D = 0.2 day(-1) for Brachionus rotundiformis. (C) 1998 Elsevier Science B.V. All rights reserved.