[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.
Adrian, R. and Schneider-Olt, B. (1999) Top-down effects of crustacean zooplankton on pelagic microorganisms in a mesotrophic lake. J. Plankton Res., 21, 2175-2190.
Andrew, T. E. and Fitzsimons, A. G. (1992) Seasonality, population dynamics and production of planktonic rotifers in Lough Neagh, Northern Ireland. Hydrobiologia, 246, 147-164.
Arndt, H. (1993) Rotifers as predators on components of the microbial web (bacteria, heterotrophic flagellates, ciliates) - a review. Hydrobiologia, 255/256, 231-246.
Arndt, H., Dietrich, D., Auer, B. et al. (2000) Functional diversity of heterotrophic flagellates in aquatic ecosystems. In Leadbeater, B. S. C. and Green, L. C. (eds), The Flagellates. Taylor & Francis, London, pp. 241-268.
Baranyi, C., Hein, T., Holarek, C. et al. (2002) Zooplankton biomass and community structure in a Danube River floodplain system: effects of hydrology. Freshw. Biol., 47, 473-482.
Boëchat, I. G., Schuran, S. and Adrian, R. (2005) Supplementation of the protist Chilomonas paramecium with a highly unsaturated fatty acid enhances its nutritional quality for the rotifer Keratella quadrata. J. Plankton Res., 27, 663-670.
Boenigk, J., Arndt, H. and Cleven, E.-J. (2001a) The problematic nature of fluorescently labeled bacteria (FLB) in Spumella feeding experiments - an explanation by using video microscopy. Arch. Hydrobiol., 152, 338-341.
Boenigk, J., Matz, C., Jürgens, K. et al. (2001b) Confusing selective feeding with differential digestion in bacterivorous nanoflagellates. J. Eukaryot. Microbiol., 48, 425-432.
Boersma, M. and Stelzer, C.-P. (2000) Response of a zooplankton community to the addition of unsaturated fatty acids: an enclosure study. Freshw. Biol., 45, 179-188.
Bogdan, K. G. and Gilbert, J. J. (1984) Body size and food size in freshwater zooplankton. Proc. Natl. Acad. Sci. USA, 81, 6427-6431.
Bogdan, K. G., Gilbert, J. J. and Starkweather, P. L. (1980) In situ clearance rates of planktonic rotifers. Hydrobiologia, 73, 73-77.
Børsheim, K. Y. and Bratbak, G. (1987) Cell volume to carbon conversion factors for a bacterivorous Monas sp. enriched from seawater. Mar. Ecol. Prog. Ser., 36, 171-175.
Cajander, V.-R. (1983) Production of planktonic Rotatoria in Ormajärvi, an eutrophicated lake in southern Finland. Hydrobiologia, 104, 329-333.
Callieri, C., Karjalainen, S. M. and Passoni, S. (2002) Grazing by ciliates and heterotrophic nanoflagellates on picocyanobacteria in Lago Maggiore, Italy. J. Plankton Res., 24, 785-796.
Carlough, L. A. and Meyer, J. L. (1989) Protozoans in two southeastern blackwater rivers and their importance to trophic transfer. Limnol. Oceanogr., 34, 163-177.
Carrick, H. J., Fahnenstiel, G. L., Stoermer, E. F. et al. (1991) The importance of zooplankton-protozoan trophic couplings in lake Michigan. Limnol. Oceanogr., 36, 1335-1345.
Descy, J.-P. and Gosselain, V. (1994) Development and ecological importance of phytoplankton in a large lowland river (River Meuse, Belgium). Hydrobiologia, 289, 139-155.
Descy, J.-P. and Métens, A. (1996) Biomass-pigment relationships in potamoplankton. J. Plankton Res., 18, 1557-1566.
Dolan, J. R., Gallegos, C. L. and Moigis, A. (2000) Dilution effects on microzooplankton in dilution grazing experiments. Mar. Ecol. Prog. Ser., 200, 127-139.
Dumont, H. J., Van de Velde, I. and Dumont, S. (1975) The dry weight estimate of biomass in a selection of Cladocera, Copepoda and Rotifera from the plankton, periphyton and benthos of continental waters. Oecologia, 19, 75-97.
Everbecq, E., Gosselain, V., Viroux, L. and Descy, J.-P. (2001) Potamon: a dynamic model for predicting phytoplankton composition and biomass in lowland rivers. Wat. Res., 35, 901-912.
Fernández-Reiriz, M. J. and Labarta, U. (1996) Lipid classes and fatty acid composition of rotifers (Brachionus plicatilis) fed two algal diets. Hydrobiologia, 330, 73-79.
Gilbert, J. J. and Jack, J. D. (1993) Rotifers as predators on small ciliates. Hydrobiologia, 255/256, 247-253.
Gosselain, V. (1998) Phytoplancton de la Meuse et de la Moselle et impact du broutage par le zooplancton. PhD Thesis. University of Namur, Presses Universitaires de Namur, pp. 1-459.
Gosselain, V., Descy, J.-P. and Everbecq, E. (1994) The phytoplankton community of the River Meuse, Belgium: seasonal dynamics (year 1992) and the possible incidence of zooplankton grazing. Hydrobiologia, 289, 179-191.
Gosselain, V., Joaquim-Justo, C., Viroux, L. et al. (1996) Laboratory and in situ grazing rates of freshwater rotifers and their contribution to community grazing rates. Arch. Hydrobiol. Suppl., 113 (Large Rivers 10), 353-361.
Hansen, A.-M. (2000) Response of ciliates and Cryptomonas to the spring cohort of a cyclopoid copepod in a shallow hypertrophic lake. J. Plankton Res., 22, 185-203.
Hart, R. C. and Jarvis, A. C. (1993) In situ determinations of bacterial selectivity and filtration rates by five cladoceran zooplankters in a hypertrophic subtropical reservoir. J. Plankton Res., 15, 295-315.
Hwang, S.-J. and Heath, R. T. (1999) Zooplankton bacterivory at coastal offshore sites of lake Erie. J. Plankton Res., 21, 699-719.
Iriberri, J., Ayo, B., Unanue, M. et al. (1993) Channeling of bacterioplanktonic production toward phagotrophic flagellates and ciliates under different seasonal conditions in a river. Microb. Ecol., 26, 111-124.
Jack, J. D. and Gilbert, J. J. (1997) Effects of metazoan predators on ciliates in freshwater plankton communities. J. Eukaryot. Microbiol., 44, 194-199.
Jacquet, V. (2003) Structure et dynamique des communautés de protistes flagellés et ciliés dans un lac méso-eutrophe (Esch-sur-SÛre, Luxembourg), et détermination de leur rôle dans la boucle microbienne. PhD Thesis. University of Liège, pp. 1-285.
Jacquet, S., Domaizon, I., Personnic, S. et al. (2005) Estimates of protozoan- and viral-mediated mortality of bacterioplankton in Lake Bourget (France). Freshw. Biol., 50, 627-645.
Joaquim-Justo, C., Detry, C., Caufman, F. et al. (2004) Feeding of planktonic rotifers on ciliates: a method using natural ciliate assemblages labelled with fluorescent microparticles. J. Plankton Res., 26, 1289-1299.
Jürgens, K., Arndt, H. and Zimmermann, H. (1997) Impact of metazoan and protozoan grazers on bacterial biomass distribution in microcosm experiments. Aquat. Microb. Ecol., 12, 131-138.
Jürgens, K., Wickham, S. A., Rothhaupt, K. O. et al. (1996) Feeding rates of macro- and microzooplankton on heterotrophic nanoflagellates. Limnol. Oceanogr., 41, 1833-1839.
Kim, H.-W., Hwang, S.-J. and Joo, G.-J. (2000) Zooplankton grazing on bacteria and phytoplankton in a regulated large river (Nakdong River, Korea). J. Plankton Res., 22, 1559-1577.
Kim, H. W., Joo, G. J. and Walz, N. (2001) Zooplankton dynamics in the hyper-eutrophic Nakdong river system (Korea) regulated by an estuary dam and side channels. Internat. Rev. Hydrobiol., 86, 127-143.
Kobayashi, T. (1997) Associations between environmental variables and zooplankton body masses in a regulated Australian river. Mar. Freshw. Res., 48, 523-529.
Lair, N., Jacquet, V. and Reyes-Marchant, P. (1999) Factors related to autotrophic potamoplankton, heterotrophic protists and micrometazoan abundances, at two sites in a lowland temperate river during low water flow. Hydrobiologia, 394, 13-28.
Leimeroth, N. (1980) Respiration of different stages and energy budgets of juvenile Brachionus calyciflorus. Hydrobiologia, 73, 195-197.
Levine, S. N., Borchardt, M. A., Shambaugh, A. D. et al. (1999) Lower trophic level interactions in pelagic Lake Champlain. In Manley, T. and Manley, P. (eds), Lake Champlain in Transition: From Research Towards Restoration. Water Science Application. Vol. 1, American Geophysical Union, Washington, DC, pp. 301-321.
Liu, H. B., Dagg, M. J., Wu, C. J. and Chiang, K. P. (2005) Mesozooplankton consumption of microplankton in the Mississippi River plume, with special emphasis on planktonic ciliates. Mar. Ecol. Prog. Ser., 286, 133-144.
Lubzens, E., Marko, A. and Tietz, A. (1985) De novo synthesis of fatty acids in the rotifer Brachionus plicatilis. Aquaculture, 47, 27-37.
Marneffe, Y., Descy, J. P. and Thomé, J. P. (1996) The zooplankton of the lower river Meuse, Belgium: seasonal changes and impact of industrial and municipal discharges. Hydrobiologia, 319, 1-13.
Menon, P., Billen, G. and Servais, P. (2003) Mortality rates of autochthonous and fecal bacteria in natural aquatic ecosystems. Water Res., 37, 4151-4158.
Mohr, S. and Adrian, R. (2000) Functional responses of the rotifers Brachionus calyciflorus and Brachionus rubens feeding on armored and unarmored ciliates. Limnol. Oceanogr., 45, 1175-1180.
Mohr, S. and Adrian, R. (2002) Reproductive success of the rotifer Brachionus calyciflorus feeding on ciliates and flagellates of different trophic modes. Freshw. Biol., 47, 1832-1839.
Ooms-Wilms, A. L. (1997) Are bacteria an important food source for rotifers in eutrophic lakes? J. Plankton Res., 19, 1125-1141.
Ooms-Wilms, A. L., Postema, G. and Gulati, R. D. (1995) Evaluation of bacterivory of Rotifera based on measurements of in situ ingestion of fluorescent particles, including some comparisons with Cladocera. J. Plankton Res., 17, 1057-1077.
Paffenhöfer, G.-A. (1998) Heterotrophic protozoa and small metazoa: feeding rates and prey-consumer interactions. J. Plankton Res., 20, 121-133.
Pontin, R. M. (1978) A Key to British Planktonic Rotifera. Scientific Publication 38. Freshwater Biological Association, Titus Wilson & Son Ltd., Kendal, 178 pp.
Porter, K. G. and Feig, Y. S. (1980) The use of DAPI for identifying and counting aquatic microflora. Limnol. Oceanogr., 25, 943-948.
Pourriot, R. (1977) Food and feeding habits of Rotifera. Arch. Hydrobiol. Beih. Ergebn. Limnol., 8, 243-260.
Pourriot, R. and Francez, A.-J. (1986) Rotifères. Introduction À la Systématique Des Organismes Des Eaux Continentales Françaises. Vol. 8. Extrait du Bulletin mensuel de la Société Linnéenne de Lyon 55, pp. 37.
Ronneberger, D. (1998) Uptake of latex beads as size-model for food of planktonic rotifers. Hydrobiologia, 387/388, 445-449.
Rothhaupt, K. O. (1990) Differences in particle size-dependent feeding efficiencies of closely related rotifer species. Limnol. Oceanogr., 35, 16-23.
Ruttner-Kolisko, A. (1974) Plankton Rotifers. Biology and Taxonomy. Die Binnengewässer, Supplementary edn, English translation of Vol. 26. E. Schweizerbart'sche-Verlagsbuchhandlung, Stuttgart, 146 pp.
Sanders, R. W., Porter, K. G., Bennett, S. J. et al. (1989) Seasonal patterns of bacterivory by flagellates, ciliates, rotifers, and cladocerans in a freshwater planktonic community. Limnol. Oceanogr., 34, 673-687.
Scherwab, A. (2001) Seasonal dynamics and mechanisms of control of ciliated potamoplankton in the river Rhine. PhD Thesis. University of Cologne, pp. 1-121.
Servais, P., Becquevort, S. and Vandevelde, F. (1998) Comparaison de deux méthodes d'estimation du broutage des bactéries par les protozoaires en milieux aquatiques. Rev. Sci. Eau, 4, 631-639.
Servais, P., Billen, G., Martinez, J. et al. (1989) Estimating bacterial mortality by the disappearance of 3H-labeled intracellular DNA. FEMS Microbiol. Ecol., 62, 119-126.
Servais, P., Billen, G. and Vives-Rego, J. (1985) Rate of bacterial mortality in aquatic environments. Appl. Environ. Microbiol., 49, 1448-1454.
Servais, P., Gosselain, V., Joaquim-Justo, C. et al. (2000) Trophic relationships between planktonic micro-organisms in the river Meuse (Belgium): a carbon budget. Arch. Hydrobiol., 149, 625-653.
Sherr, B. F., Sherr, E. B., Andrew, T. L. et al. (1986) Trophic interactions between heterotrophic Protozoa and bacterioplankton in estuarine water analysed with selective metabolic inhibitors. Mar. Ecol. Prog. Ser., 32, 169-179.
Simon, M. and Azam, F. (1989) Protein content and protein synthesis rates of planktonic marine bacteria. Mar. Ecol. Prog. Ser., 51, 201-213.
Starkweather, P. L., Gilbert, J. J. and Frost, T. M. (1979) Bacterial feeding by the rotifer Brachionus calyciflorus: clearance and ingestion rates, behavior and population dynamics. Oecologia, 44, 26-30.
Stemberger, R. S. (1981) A general approach to the culture of planktonic rotifers. Can. J. Fish. Aquat. Sci., 38, 721-724.
Thouvenot, A., Debroas, D., Richardot, M. et al. (1999b) Impact of natural metazooplankton assemblage on planktonic microbial communities in a newly flooded reservoir. J. Plankton Res., 21, 179-199.
Thouvenot, A., Richardot, M., Debroas, D. et al. (1999a) Bacterivory of metazooplankton, ciliates and flagellates in a newly flooded reservoir. J. Plankton Res., 21, 1659-1679.
Turley, C. M., Newell, R. C. and Robins, D. B. (1986) Survival strategies of two small marine ciliates and their role in regulating bacterial community structure under experimental conditions. Mar. Ecol. Prog. Ser., 33, 59-70.
Urabe, J. and Wanatabe, Y. (1990) Difference in the bacterial utilization ability of four cladoceran plankton (Crustacea: Cladocera). Nat. Hist. Res., 1, 85-92.
Vancil, J. E. (1983) A method for the laboratory culture of the planktonic rotifer Keratella cochlearis (Gosse). Hydrobiologia, 107, 47-50.
Vanderploeg, H. A., Liebig, J. R. and Gluck, A. A. (1996) Evaluation of different phytoplankton for supporting development of Zebra Mussel larvae (Dreissena polymorpha): the importance of size and polyunsaturated fatty acid content. J. Gt. Lakes Res., 22, 36-45.
Verity, P. G. (1991) Measurement and simulation of prey uptake by marine planktonic ciliates fed plastidic and aplastidic nanoplankton. Limnol. Oceanogr., 36, 729-750.
Viroux, L. (1999) Zooplankton distribution in flowing waters and its implications for sampling: case studies in the River Meuse (Belgium) and the River Moselle (France, Luxembourg). J. Plankton Res., 21, 1231-1248.
Viroux, L. (2000) Dynamique du métazooplancton en milieu fluvial [Metazooplankton dynamics in a large lowland river]. PhD Thesis. University of Namur, Presses Universitaires de Namur, 309 pp.
Von Elert, E. and Stampfl, P. (2000) Food quality for Eudiaptomus gracilis: the importance of particular highly unsaturated fatty acids. Freshw. Biol., 45, 189-200.
Vörös, L., Balogh, K., Herodek, S. et al. (2000) Underwater light conditions, phytoplankton photosynthesis and bacterioplankton production in the Hungarian section of the River Danube. Arch. Hydrobiol. Suppl., 115, 511-532.
Walz, N. (1983) Continuous culture of the pelagic rotifers Keratella cochlearis and Brachionus angularis. Arch. Hydrobiol., 98, 70-92.
Walz, N. (1997) Rotifer life history strategies and evolution in freshwater plankton communities. In Streit, B., Städler, T. and Lively, C. M. (eds), Evolutionary Ecology of Freshwater Animals. Verlag Basel, Basel, Switzerland, pp. 119-149.
Weisse, T. and Frahm, A. (2002) Direct and indirect impact of two common rotifer species (Keratella spp.) on two abundant ciliate species (Urotricha furcata, Balanion planctonicum). Freshw. Biol., 47, 53-64.
Weitere, M. (2001) The heterotrophic nanoflagellates in the water column of the river Rhine: seasonal and spatial dynamics and their position in the food web. PhD Thesis. University of Cologne, pp. 1-133.
Weitere, M. and Arndt, H. (2002a) Water discharge-regulated bacteriaheterotrophic nanoflagellate (HNF) interactions in the water column of the river Rhine. Microb. Ecol., 44, 19-29.
Weitere, M. and Arndt, H. (2002b) Top-down effects on pelagic heterotrophic nanoflagellates (HNF) in a large river (River Rhine): do losses to the benthos play a role? Freshw. Biol., 47, 1437-1450.
Weitere, M., Scherwass, A., Sieben, K.-T. et al. (2005) Planktonic food web structure and potential carbon flow in the lower river Rhine with a focus on the role of protozoans. River Res. Appl., 21, 535-549.
Work, K., Havens, K., Sharfstein, B. et al. (2005) How important is bacterial carbon to planktonic grazers in a turbid, subtropical lake? J. Plankton Res., 27, 357-372.
Wylie, J. L. and Currie, D. J. (1991) The relative importance of bacteria and algae as food sources for crustacean zooplankton. Limnol. Oceanogr., 36, 708-728.
Zimmermann, H. (1996) Interactions between planktonic protozoans and metazoans after the spring bloom of phytoplankton in a eutrophic lake, the Belauer See, in the Bornhöveder Seenkette, North Germany. Acta Protozool., 35, 215-221.