Original paper

Colonization of periphyton algae in a temperate floodplain lake under a fluctuating spring hydrological regime

Mihaljević, Melita; Pfeiffer, Tanja Žuna

Abstract

The colonization process of periphyton algae was studied in the Danubian floodplain (Lake Sakadaš, Nature Park Kopački Rit, Croatia) under variable spring hydrological conditions. We used an in situ experiment, with artificial substrata, to examine changes in the algal community composition during the early phase of periphyton formation. A few flood pulses characterized the hydrological conditions during the period of investigation (April-May, 2010) and altered the physical and chemical environment of the lake. The periphyton formation was initiated very early, on the first day of deployment, due to the rapid formation of bacterial biofilm. Total periphyton biomass continuously increased during the colonization period with changes in the trophic nature from the prevalence of organic matter to the prevalence of inorganic matter after day 15. The composition of periphyton algal assemblages and abundance changed gradually during the colonization period and the following sequences can be defined: the initial phase (days 1-9, dominated by planktonic cyanobacteria and horizontally positioned diatoms), the intermediate phase (days 12-18 characterised by stalk-forming diatoms (Gomphonema and Cymbella)) and the late phase (days 21-42 dominated by vertically positioned diatoms (Nitzschia)). This sequence of algal colonization is similar to that found in other freshwater habitats. Achnanthidium minutissimum was particularly abundant in the late phase of colonisation which was characterised by flooding and indicated natural disturbance.

Keywords

danubian floodplainperiphytonartificial substratumalgal communitydiatomsflooding