Feeding behaviour of the rotifers Brachionus plicatilis and Brachionus rotundiformis with two types of food: live and freeze-dried microalgae

Freeze-dried cells are accepted and ingested by Brachionus plicatilis and B rachionus rotundiformis in the same way as live cells. B. plicatilis can da ily ingest 60-90% of their dry weight, while B. rotundiformis can daily ing est 160% of their dry weight. In B, plicatilis, the relationship between ce ll concentration and filtration and ingestion rates follows the criterion o f energy maximization. As food concentration increases from very low values , both rates rise until an inflexion point is reached. Above this point, th e maximum food processing rate could be maintained with filtration rates th at decrease progressively, and with ingestion rates that maintain the maxim um value reached. In B. rotundiformis, filtration rates decrease steadily w hile ingestion rates increase rapidly as food concentration increases. Once an inflexion point is reached, further increases in food processing are ve ry slow. Experiment duration is also a factor which significantly influence s feeding rates, so that after the first hour filtration and ingestion rate s are lower and remain almost constant. (C) 1999 Elsevier Science B.V. All rights reserved.