JOURNAL OF PLANKTON RESEARCH | VOLUME 16 | NUMBER 8 | PAGES 1021-1038 | 1994
© Oxford University Press
research-article |
Experimental studies into the feeding biology of rotifers in brackish water
Universität Rostock, Fachbereich Biologie, WB Experimentelle Ökologie Freiligrathstraße 718, D-18055 Rostock, FRG
Received on October 10, 1992; accepted on March 20, 1994 Mass developments of rotifers of the genus Brachionus, and especially of B.quadridentatus, occur regularly in the largely hypertrophic chain of shallow waters (‘boddens’) south of the Darss-Zingst peninsula (Southern Baltic). Interest in the autecology of the species is, therefore, considerable. Various food sources were used in laboratory experiments to ascertain the food requirements of B.quadridentatus, determine its filtration and ingestion rates, and assess its food particle size-selection ability. Growth experiments showed that the chlorophyceans Nannochloris sp. and Chlorella vulgaris possess considerable nutritional value for the species, whereas abundances declined when Microcystis firma, detritus from Enteromorpha sp. and only bacteria (Pseudomonas), respectively, were provided as food sources. Filtration rates varied between 0.02 and 1.73 µl ind.–1 h–1, and ingestion rates between 121 and 5560 cells ind.–1 h–1, depending on the filtration rate and algal concentration. Investigations into food particle size selection using fluorescent latex particles revealed that particle size influences food particle intake. When particles of different sizes were mixed, the animals showed a preference for the larger particles and ingested the smaller ones with a diameter of 1–2 µm less efficiently. The brackish water species Brachionus plicatilis was studied besides B.quadridentatus in all experiments. The former species proved to be superior both in its range of utilizable particle sizes and its growth rate. The experiments with laboratory cultures were backed up by studies performed with various rotifer species taken from natural populations.