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See detailFeeding of planktonic rotifers on ciliates: a method using natural ciliate assemblages labelled with fluorescent microparticles
Joaquim-Justo, Célia ULg; Detry, Cédric ULg; Caufman, F. et al

in Journal of Plankton Research (2004), 26(11), 1289-1299

A method was developed to allow direct measurements of predation exerted by metazooplankton on ciliates. The method relied on the use of ciliates labelled with fluorescent microparticles (FMP). Optimal ... [more ▼]

A method was developed to allow direct measurements of predation exerted by metazooplankton on ciliates. The method relied on the use of ciliates labelled with fluorescent microparticles (FMP). Optimal labelling conditions were determined with ciliates from cultures (Tetrahymena pyriformis) and with natural ciliate assemblages sampled in a river. Labelled T. pyriformis were used as tracer food to determine gut passage time (GPT) and ingestion rates of the rotifer Brachionus calyciflorus in the laboratory. Predation of metazooplankton from the lowland river Meuse (Belgium) was determined by labelling natural assemblages of ciliates and using them as tracer food for metazooplankters sampled in the river. Optimal labels of ciliates, i.e. sharp distribution of FMP in cells, were obtained with short incubations (10 min) and low FMP concentrations (1 x 10(5) mL(-1)). GPT varied between 30 and 45 min for B. calyciflorus and from 25 up to >35 min for rotifers from the river. The ingestion rate of B. calyciflorus fed with T. pyriformis was 3.3 +/- 0.6 ciliate rot(-1) h(-1), i.e. 1.4 +/- 0.3 ngC rot(-1) h(-1). Metazooplankton species for which the ingestion of ciliates could be measured were the rotifers Keratella cochlearis, Euchlanis dilatata and Synchaeta spp. Ingestion rates measured ranged from 0.4 to 12.5 ngC rot(-1) h(-1). The method proposed proved to be useful in estimating the predation of microplankton on ciliates in semi- in situ conditions; in further developments, labelled natural assemblages of ciliates could be used for in situ incubations with the Haney chamber. [less ▲]

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See detailIN SITU MEASUREMENTS OF METAZOOPLANKTON PREDATION ON PROTOZOOPLANKTON: USE OF FLUORESCENTLY LABELLED PROTISTS.
Joaquim-Justo, Célia ULg; Caufman, F; Thomé, Jean-Pierre ULg

Poster (2001, February 04)

The importance of trophic relationships between metazooplankton and protozoans in rivers are not yet well known, but as some authors have shown during the last decade, the predation exerted by ... [more ▼]

The importance of trophic relationships between metazooplankton and protozoans in rivers are not yet well known, but as some authors have shown during the last decade, the predation exerted by metazooplankton on these organisms might be of importance in the transfer of energy from the pico- and nanoplankton to the metazooplankton. Fluorescent carboxylate microspheres of 0.5 µm in diameter were used to label natural protozooplankton. Different combinations of labelling times and concentrations of microspheres were tested to achieve an optimal labelling of the protists (i.e. a maximal proportion of individuals labelled with an identical number of microspheres); the most appropriate labelling conditions were with short incubations (10 minutes) and relatively low microsphere concentrations (1.105 FMP/ml). Live labelled protozooplankton was used to determine ingestion rates of the natural metazooplankton of the river Meuse (Belgium). It could be showed for all abundant species (i.e. the rotifers Brachionus calyciflorus, Brachionus angularis and Keratella cochlearis) that the predation exerted on protozooplankton was high (from 34 to 182 protists.rotifer-1.h-1) in in situ conditions. [less ▲]

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