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• Water contraction drives stronger the formation of diatom assemblages in stream than human induced microhabitat-variability

  211-228

  Stefánia Kiss

  Zsuzsanna Nemes-Kókai

  Áron Lukács

  Enikő Török-Krasznai

  Viktória B-Béres

  Views:

  205

  Today, climate change, together with other anthropogenic influences is considered as a major threat affecting aquatic ecosystems in several ways. Here, altering water contraction (standing and flowing phases) and human-induced habitat variability (natural and artificial stream sections) were studied as modifying factors driving community changes in benthic diatom assemblages of a Hungarian small lowland stream (Létai-ér). We assumed notable compositional differences between phases and habitats, but we expected these differences to decrease with drying. Moreover, lower diversity was hypothesized in assemblages of both artificial section and flowing phase. While taxonomic composition did not reveal significant differences between the sections, well pronounced compositional changes were found between phases. Surprisingly, no significant diversity changes were observed during water contraction. Compared to the natural microhabitat, however, artificial stream section was found to maintain more diverse diatom community. These results emphasize that modification effects of climate change induced hydrological extremes can lead to remarkable compositional changes in benthic algal assemblages even on a short time scale, that must be taken into account in both water management and nature conservation strategies.

• Contributions to the algal flora of a recently-formed peat moss bog near Kőszeg (W Hungary)

  113–130

  Sándor Bancsó

  Views:

  367

  The Alsó-erdő peat bog near Kőszeg has undergone a significant transformation since its first mention in the literature. In addition to the original single patch, a smaller one appeared a few decades later. The process did not stop and a third unit, discussed here, was formed. The succession of its macrovegetation towards the typical peat moss association started slowly but surely, due to balanced water regime and other optimal environmental conditions. The process is more advanced for the algal vegetation, which shows the characteristics of peat bogs already. The high species diversity found makes the habitat highly valuable itself. Although a special, unique algal species has not been found in previous studies, 27 Desmidiales taxa listed as endangered occur sometimes with high density and make the habitat even more valuable. Based on our results, the area deserves special attention both from the habitat conservation and research point of view. At the same time, its further monitoring can provide crucial information for exploring and understanding the succession of similar habitats, and thereby for their more efficient protection.