The significance of some methodological effects on filtration and ingestion rates of the rotifer Brachionus plicatilis

Filtration rate (F) and ingestion rate (I) were measured in the rotifer B. plicatilis feeding on the flagellate Dunaliella spec. and on yeast cells (Saccharomyces cerevisiae ). 60-min experiments in rotating bottles servedas a standard for testing methodological effects on levels of F and I. A lack of rotation reduced F values by 40%, and a rise in temperature from 18 degree to 23.5 degree C increased them by 42%. Ingestion rates increased significantly up to a particle (yeast) concentration of ca. 600-800 cells/µl; then they remained constant, whereas filtration rates decreased beyond this threshold. Elemental analyses ofrotifers and their food suggest that B. plicatilis can ingest up to 0.6 mJ or ca. 14% of its own body carbon within 15 min. The long term average was estimated as 3.4 m/ind or ca. 75% of body carbon/d.