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Krisztina Buczkó, Agata Z. Wojtal and Enikő K. Magyari

Abstract

Nupela pocsii Buczkó & Wojtal, sp. nov., a new species from the Retezat Mountains (S. Carpathians), is described. High asymmetry (along apical and transapical axes and in raphe pattern) and small dimensions are the most characteristic features of this taxon. Nupela pocsii was found during paleolimnological research in early Holocene sediment of Lake Brazi. Seven other representatives of the genus Nupela were detected in high-resolution diatom analyses of three lake sediment sequences of the Retezat Mts: Nupela fennica (Hustedt) Lange-Bertalot, N. imperfecta (Schimanski) Lange-Bertalot, N. impexiformis (Lange-Bertalot) Lange-Bertalot, N. lapidosa (Krasske) Lange-Bertalot, N. paludigena (R. P. Scherer) Lange-Bertalot, N. vitiosa (Schimanski) Siver & Hamilton and an unidentified Nupela Vyverman & Compere species. Our results suggest high diversity of oligotraphenic species in these mountain lakes during their ontogeny, which began 17,000-15,000 years ago. In addition to the newly described species this is also the first record of N. paludigena in European lakes, although its occurrence was previously documented by SEM and LM from Lake Saint Anna without correct identification.

Open access

Csilla Kövér, János Korponai, Sándor Harangi and Krisztina Buczkó

Abstract

Diadesmis fukushimae, a rare oligotraphenic diatom, was found in some high mountain lakes of Romania. Its occurrence in the Parâng and Retezat Mountains is the second European record of the species. To date D. fukushimae has been known only from the type locality (Shenandoah National Park, Virginia, USA) and from a spring (Grotta Guernica, Dolomiti Bellunesi National Park (south-eastern Alps, Italy). Investigation by scanning electron microscopy showed that this species should be transferred to the recently established genus Humidophila. A new combination is proposed, Humidophila fukushimae. The morphological details of the European population are also presented.

Open access

Viktória B-Béres, István Bácsi, Enikő T-Krasznai, Zsuzsanna Kókai and Krisztina Buczkó

Abstract

In Hungary Navicula jakovljevicii was firstly recorded in biofilm of Elodea nuttallii in 2005 in an oxbow of the catchment area of the River Danube. Subsequently, in 2006, N. jakovljevicii was also found in the same oxbow on reed stems as well. In the following years it appeared in another oxbow, suggesting an expanding distribution in the tributaries of the Danube in Hungary. The Hungarian population can be characterised as having mixed morphological features in comparison with other known N. jakovljevicii populations of Europe. When the morphological study was expanded, a similar, but 'giant form' was detect ed in fossil material. We found similarities and a possible connection between N. jakovljevicii and Navicula lucida, a diatom taxon described from a Neogene deposit in the Carpathian Basin. Despite the morphological similarities in the shape, apices, striae pattern and raphe structure of these two species, there are significant differences in valve dimensions: the valves of N. lucida are larger and more heavily silicified than N. jakovljevicii.

Open access

Zsuzsanna Kókai, István Bácsi, Péter Török, Krisztina Buczkó, Enikő T-Krasznai, Csaba Balogh, Béla Tóthmérész and Viktória Béres

Abstract

The occurrence and spread of halophilic diatom taxa in freshwater lotic ecosystems are influenced both by natural processes and anthropogenic pollution. Diatom assemblages were regularly monitored in lowland lotic systems in Hungary (Central Europe) during the unusually dry year of 2012. Highly pronounced changes in diatom composition were observed from spring to autumn. Halophilic taxa (especially Nitzschia sensu lato species) appeared in the dry autumn. In addition, the total relative abundances of halophilic species also increased up to autumn. Abundance of Nitzschia cf. lorenziana and Nitzschia tryblionella showed a positive correlation with chloride and phosphate concentration, while that of other taxa like Tryblionella apiculata or Tryblionella calida showed a positive correlation with the concentration of nitrate. Our findings clearly demonstrated that these halophilic and mesohalophilic diatom taxa were sensitive indicators of even short-term changes in lowland lotic ecosystems, such as the increasing salt concentration from spring to autumn caused by the lack of rainfall and/or environmental loads.