B-Béres, Viktória

Balogh, Csaba

Bácsi, István

Dobronoki, Dalma

Kókai, Zsuzsanna

Lukács, Áron

Nagy, Sándor Alex

T-Krasznai, Enikő

Tóthmérész, Béla

Török, Péter

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Successional changes in diatom ecological guilds and cell-sizeclasses' composition during colonization in a lowland streamB-Béres, Viktória", Lukács, Arorr', Török, Péter', Kókai, Zsuzsanna', T-Krasznai, Enikő',Dobronoki, Dalrna", Nagy, Sándor Alex", Balogh, Csaba', Tóthmérész, Béla3 & Bácsi, lstván"'Environmental Protection and Nature Conservation Authority, Trans-Tisza Region,Debrecen, 16. Hatvan street. 16, H-4025 Hungary2University of Debrecen, Department of Hydrobiology, Debrecen, 1. Egyetem square, H-4032, Hungary3MTA-DE Biodiversity and Ecosystem Services Research Group, Debrecen, 1. Egyetemsquare, H-4032, Hungary'Contact author: beres.viktoria@gmail.comColonisation processes in diatom assemblages were studied in an experiment using semi-artificial substrates in Tócó-stream (a lowland stream) during 83 days. We focused on thechanges in composition and abundance of diatom ecological guilds and cell-size classes.Changes in the relative abundance of low profile guild show their decisive role at thebeginning of colonisation, and in the initiation of re-colonization processes. The abundancewas high from the first hour, than remarkably decreased; finally there was a twofold increaseafter the 31st day. Changes in the relative abundance of the high profile and motile guild (20-40% and continuous increase to the zo" day, respectively, and remarkable decrease afterthe 31st day) reflected the changes in environmental circumstances (mainly the watertemperature due to the variable spring weather). The relative abundance of small-sized taxa(S1, S2) decreased from 30% to 18% in the first three weeks, after that its relativeabundance increased up to 35%. Relative abundance of large sized taxa (S5) was high atthe beginning of the experiment, decreased in the first day, than increased to the 20th day,and drastically decreased to the end of the study period. The relative abundance of mediumsized taxa (S3, S4) was high during the whole sampling period. These phenomena highlightthe importance of mature biofilm in the colonization processes in shallow, lowlandwatercourses, and draw attention to late re-colonization processes. Taxa replacementappeared between some dominant large sized taxa (Meridion circulare, Surirella brebissonii,Melosira varians) during the experiment, which indicate the interactions between certainguilds. Meridion circulare (Iow profile guild) was present in high numbers at the first period ofthe colonisation (tili the 20th day), but its relative abundance continuously decreased tili theend of the experiment. Melosira varians (high profi le guild) was relatively abundant tili the20th day, but after the 31st day its relative abundance decreased considerably, similarly tothat of Surirella brebissonii (motile guild).Our results highlighted the special features (changes in proportion of ecological guilds andcell size classes) of colonization processes of lowland streams due to the shallowness andsemistatic character of these kinds of watercourses. These specialities should be taken intoconsideration during environmental status assessment.35

Successional changes in diatom ecological guilds and cell-size classes' composition during colonization in a lowland stream

Successional changes in diatom ecological guilds and cell-size classes' composition during colonization in a lowland stream

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