Reference : Trophic links in the lowland River Meuse (Belgium): assessing the role of bacteria an...
Scientific journals : Article
Life sciences : Aquatic sciences & oceanology
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/8668
Trophic links in the lowland River Meuse (Belgium): assessing the role of bacteria and protozoans in planktonic food webs
English
Joaquim-Justo, Célia mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Ecologie animale et écotoxicologie >]
Pirlot, S. [Facultés Universitaires Notre-Dame de la Paix - Namur - FUNDP > > > > > >]
Viroux, L. [Facultés Universitaires Notre-Dame de la Paix - Namur - FUNDP > > > > > >]
Servais, Pierre [Université Libre de Bruxelles - ULB > > > >]
Thomé, Jean-Pierre mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Ecologie animale et écotoxicologie >]
Sep-2006
Journal of Plankton Research
Oxford Univ Press
28
9
857-870
Yes (verified by ORBi)
International
0142-7873
Oxford
[en] Trophic interactions within the plankton of the lowland River Meuse (Belgium) were measured in spring and summer 2001. Consumption of bacteria by protozoa was measured by monitoring the disappearance of H-3-thymidine-labelled bacteria. Metazooplankton bacterivory was assessed using 0.5-mu m fluorescent microparticles (FMPs), and predation of metazooplankton on ciliates was measured using natural ciliate assemblages labelled with FMPs as tracer food. Grazing of metazooplanklon on flagellates was determined through in situ incubations with manipulated metazooplankton densities. Protozooplankton bacterivory varied between 6.08 and 53.90 mg C m(-3) day(-1) (i.e. from 0.12 to 0.86 g C-1 bacteria g C-1 protozoa day(-1)). Metazooplankton, essentially rotfiers, grazing on bacteria was negligible compared with grazing by protozoa (similar to 1000 times lower). Predation of rotfiers on heterotrophic flagellates (HFs) was generally low (on average 1.77 mg C m(-3) day(-1), i.e. 0.084 g C-1 flagellates g C-1 rotfiers day(-1)), the higher contribution of HF in the diet of rotfiers being observed when Keratella cochlearis was the dominant metazooplankter. Predation of rotfiers on ciliates was low in spring samples (0.56 mg C m(-3) day(-1), i.e. 0.014 g C-1 ciliates g C-1 rotfiers day(-1)) in contrast to measurements performed in July (8.72 mg C m(-3) day(-1), i.e. 0.242 g C-1 ciliates g C-1 rotfiers day(-1)). The proportion of protozoa in the diet of rotfiers was low compared with that of phytoplankton (< 30% of total carbon ingestion) except when phytoplankton biomass decreased below the incipient limiting level (ILL) of the main metazooplantonic species. In such conditions, protozoa (mainly ciliates) constituted similar to 50% of total rotfier diet These results give evidence that microbial organisms play a significant role within the planktonic food web of a eutrophic lowland river, ciliates providing an alternative food for metazooplankton when phytoplankton becomes scarce.
Researchers ; Professionals ; Students ; General public
http://hdl.handle.net/2268/8668

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