engleski

Primary colonization process of ciliated protozoa in a temperate floodplain lake periphyton

The primary colonization of artificial substrata by periphytic ciliates was studied in a Danubian floodplain lake (Lake Sakadaš, Kopački Rit Nature Park, Croatia) during spring period, from April 6th to May 17th 2010. The periphyton development on glass slides started quite early, on the first day of submersion in lake water. The ciliate abundance and community composition progressively changed in the course of the exposure. The non- metric multidimensional scaling analysis indicates three phases in the ciliate colonization process. The initial phase, which includes the first three days of periphyton formation, was characterized by small motile scuticociliatids (Cinetochilum margaritaceum as the most abundant) and cyrtophorids, as well as the sessile peritrich species Vorticella campanula. The first two ciliate groups comprise of typical pioneer species, frequently found during the initial phase of colonization on the newly exposed substrates. Vorticella species rapidly colonize new surfaces because of the presence of a free swimming motile phase in their life cycle. During the intermediate phase of colonization (day 6 to day 12), ciliate community became more diverse, with bacterivorous Chilodonella species and bacterivorous-algivorous Vorticella species as dominant. Scuticociliatids, mostly bacterivores and algivores, were also abundant and high abundance of omnivores and predators was recorded. Sessile suspension-feeding ciliates, Vorticella species (bacterivores and algivores) and Stentor roeselii (omnivore), dominated in the late phase of colonization (day 15 to day 42). This phase was characterized by high concentration of chlorophyll a in water and increased periphyton biomass, indicating food source and habitat complexity as the most important parameters for the structuring of the ciliate community.

Ciliophora; periphyton formation; artificial substrata; trophic structure; lentic ecosystem

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