Short-term colonization sequence of periphyton on glass slides in a large river (River Danube, near Budapest)

Ács, Éva and Kiss, Keve Tihamér and Szabó-Taylor, Katalin and Makk, Judit (2000) Short-term colonization sequence of periphyton on glass slides in a large river (River Danube, near Budapest). Acta Botanica Croatia, 100 (136 su). pp. 135-156. ISSN 0365-0588

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Abstract

The colonization, structure and composition of the periphyton which developed on the artificial substratum (sand-blasted matglass-slides) positioned into current line were studied in the main arm of the River Danube at Göd (1669 riv. km) in the summer of 1997, during a low water period. Five replicates were taken on the first day in the 3rd, 6th, 9th and 24th hour, after that every day for a week, then every three days for another two weeks. Phytoplankton samples were taken four times during the study (on the 1st, 6th, 13th and 20th day) to compare the composition of benthic and planktic algae. Altogether 222 taxa were identified 95 taxa from the phytoplankton and 176 from the periphyton. The number of common species was 50. after three hours from the immersion, only coccoid bacteria (mainly colineforms) were found on the substratum but after 6 hours the first algae. The first colonizer was Diatoma vulgaris, which adheres with on apical pad. In the first few hours only a few species formed the community and low diversity and low evenness was the consequence. After 24 hours the community was already diverse with a total of 35 species. During the first week of colonization the periphyton was composed almost exclusively of quick reproduction rate R (ruderal strategy) selected species, the evenness showed an increase parallel to species richness. The basal-layer of the Danube periphyton developed at that time, where diatoms attached to the substratum mainly with on apical pad. From the second week there was a small decrease in the evenness, when the rate of slower multiplying C, C-S (competitive strategy, stress tolerant strategy) selected species increased. In the second week stalk forming species formed an intermediate layer adhering with long, branching gelatinous stalk. The thick periphyton cover filtered out planktic species from the water like a net, and more and more euplanktic Centrales species were found in the samples.

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