caa a22 4500 465790658 CHVBK 20180323112023.0 cr unu---uuuuu 170327e19901201xx s 000 0 eng 10.1007/BF02543881 doi (NATIONALLICENCE)springer-10.1007/BF02543881 Qualitative importance of the microbial loop and plankton community structure in a eutrophic lake during a bloom of cyanobacteria [Elektronische Daten] [Kirsten Christoffersen, Bo Riemann, Lone Hansen, Annette Klysner, Helle Sørensen] Plankton community structure and major pools and fluxes of carbon were observed before and after culmination of a bloom of cyanobacteria in eutrophic Frederiksborg Slotssø, Denmark. Biomass changes of heterotrophic nanoflagellates, ciliates, microzooplankton (50 to 140 μm), and macrozooplankton (larger than 140 μm) were compared to phytoplankton and bacterial production as well as micro- and macrozooplankton ingestion rates of phytoplankton and bacteria. The carbon budget was used as a means to examine causal relationships in the plankton community. Phytoplankton biomass decreased and algae smaller than 20 μm replacedAphanizomenon after the culmination of cyanobacteria. Bacterial net production peaked shortly after the culmination of the bloom (510 μg C liter−1 d−1 and decreased thereafter to a level of approximately 124 μg C liter−1 d−1. Phytoplankton extracellular release of organic carbon accounted for only 4-9% of bacterial carbon demand. Cyclopoid copepods and small-sized cladocerans started to grow after the culmination, but food limitation probably controlled the biomass after the collapse of the bloom. Grazing of micro- and macrozooplankton were estimated from in situ experiments using labeled bacteria and algae. Macrozooplankton grazed 22% of bacterial net production during the bloom and 86% after the bloom, while microzooplankton (nauplii, rotifers and ciliates larger than 50 μm) ingested low amounts of bacteria and removed 10-16% of bacterial carbon. Both macro-and microzooplankton grazed algae smaller than 20 μm, although they did not control algal biomass. From calculated clearance rates it was found that heterotrophic nanoflagellates (40-440 ml−1) grazed 3-4% of the bacterial production, while ciliates smaller than 50 μm removed 19-39% of bacterial production, supporting the idea that ciliates are an important link between bacteria and higher trophic levels. During and after the bloom ofAphanizomenon, major fluxes of carbon between bacteria, ciliates and crustaceans were observed, and heterotrophic nanoflagellates played a minor role in the pelagic food web. Springer-Verlag New York Inc., 1990 Christoffersen Kirsten The International Agency for 14C Determination, The Water Quality Institute, 11 Agern Allè, DK-2970, Hørsholm, Denmark aut Riemann Bo The International Agency for 14C Determination, The Water Quality Institute, 11 Agern Allè, DK-2970, Hørsholm, Denmark aut Hansen Lone Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut Klysner Annette Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut Sørensen Helle Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut Microbial Ecology Springer-Verlag 20/1(1990-12-01), 253-272 0095-3628 20:1<253 1990 20 248 https://doi.org/10.1007/BF02543881 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02543881 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Christoffersen Kirsten The International Agency for 14C Determination, The Water Quality Institute, 11 Agern Allè, DK-2970, Hørsholm, Denmark aut NATIONALLICENCE 700 1- Riemann Bo The International Agency for 14C Determination, The Water Quality Institute, 11 Agern Allè, DK-2970, Hørsholm, Denmark aut NATIONALLICENCE 700 1- Hansen Lone Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut NATIONALLICENCE 700 1- Klysner Annette Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut NATIONALLICENCE 700 1- Sørensen Helle Freshwater Biological Laboratory, University of Copenhagen, 51 Helsingørsgade, DK-3400, Hillerød, Denmark aut NATIONALLICENCE 773 0- Microbial Ecology Springer-Verlag 20/1(1990-12-01), 253-272 0095-3628 20:1<253 1990 20 248 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer