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 Brachionus rotundiformis in the same way as live cells. B. plicatilis can daily ingest 60-90% of their dry weight, while B. rotundiformis can daily ingest 160% of their dry weight. In B, plicatilis, the relationship between cell concentration and filtration and ingestion rates follows the criterion of energy maximization. As food concentration increases from very low values, both rates rise until an inflexion point is reached. Above this point, the maximum food processing rate could be maintained with filtration rates that decrease progressively, and with ingestion rates that maintain the maximum value reached. In B. rotundiformis, filtration rates decrease steadily while ingestion rates increase rapidly as food concentration increases. Once an inflexion point is reached, further increases in food processing are very slow. Experiment duration is also a factor which significantly influences feeding rates, so that after the first hour filtration and ingestion rates are lower and remain almost constant. (C) 1999 Elsevier Science B.V. All rights reserved.