title: Structure and seasonal dynamics of the protozoan community (heterotrophic flagellates, ciliates, amoeboid protozoa) in the plankton of a large river (River Danube, Hungary).
abstract: Seasonal dynamics of all major protozoan groups were investigated in the plankton of the River Danube, upstream of Budapest (Hungary), by bi-weekly sampling over a 1-year long period. Sixty-one heterotrophic flagellate, 14 naked amoeba, 50 testate amoeba, 4 heliozoan and 83 ciliate morphospecies were identified. The estimated abundance ranges of major groups throughout the year were as follows: heterotrophic flagellates, 0.27-7.8 x 10(6)ind.l(-1); naked amoebae, max. 3300ind.l(-1); testaceans, max. 1600ind.l(-1); heliozoans, max. 8500ind.l(-1); ciliates, 132-34,000ind.l(-1). In terms of biovolume, heterotrophic flagellates dominated throughout the year (max. 0.58mm(3)l(-1)), and ciliates only exceeded their biovolume in summer (max. 0.76mm(3)l(-1)). Naked amoeba and heliozoan biovolume was about one, and testacean biovolume 1-3, orders of magnitude lower than that of ciliates. In winter, flagellates, mainly chrysomonads, had the highest biomass, whilst ciliates were dominated by peritrichs. In 2005 from April to July a long spring/summer peak occurred for all protozoan groups. Beside chrysomonads typical flagellates were choanoflagellates, bicosoecids and abundant microflagellates (large chrysomonads and Collodictyon). Most abundant ciliates were oligotrichs, while Phascolodon, Urotricha, Vorticella, haptorids, Suctoria, Climacostomum and Stokesia also contributed significantly to biovolume during rapid succession processes. In October and November a second high protozoan peak occurred, with flagellate dominance, and slightly different taxonomic composition.
authors.affiliation: Institute of Ecology and Botany of the Hungarian Academy of Sciences, Hungarian Danube Research Station, Jávorka, Hungary. aronkevekiss@yahoo.co.uk
authors.forename: Aron Keve
authors.initials: AK
authors.lastname: Kiss
authors.forename: Eva
authors.initials: E
authors.lastname: Acs
authors.forename: Keve Tihamér
authors.initials: KT
authors.lastname: Kiss
authors.forename: Júlia Katalin
authors.initials: JK
authors.lastname: Török
mesh_terms: D000818:Animals; D044822:Biodiversity; D056890:Eukaryota / Q000502:physiology*; D006814:Hungary; D010933:Plankton / Q000502:physiology*; D045483:Rivers; D012621:Seasons; D013997:Time Factors