First report of Navicula jakovljevicii Hustedt (Bacillariophyta) from Hungary: distribution, comparative morphology and a related species

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 \u27giant form\u27 was detected 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

Az extrém száraz időjárás hatása az Achnanthidium minutissimum és Achnanthidium eutrophilum egyedszámára (Sebes-Körös, Körösszakál)

A 2012-es év nyara és az ősz rendkívül száraz volt Magyarországon, aminek köszönhetően hazai vízfolyásaink vízhozama, ill. vízszintje jelentősen csökkent. Vizsgálataink során arra a kérdésre kerestük a választ, miként befolyásolta a 2012-es év extrém száraz időjárása – és az ezzel együtt járó vízhozam csökkenés és tápanyag-dúsulás – a Sebes-Körös (Körösszakál) Achnanthidium minutissimum és A. eutrophilum populációinak dinamikáját. A két Achnanthidium taxon minél pontosabb határozása azért fontos, mert eltérő ökológiai állapotú vizek indikátor fajai. Eredményeink alapján elmondható, hogy míg az A. minutissium egyedszám-változása pozitívan korrelált a vízhozammal és negatívan a nitrátkoncentrációval, addig az A. eutrophilum esetében az előzőekkel ellentétes tendenciát figyeltünk meg. Eredményeink rávilágítanak arra, hogy még egy stabilan jó ökológiai állapottal jellemezhető vízfolyás kovaalga-közössége is feltűnően érzékenyen reagálhat a szélsőséges időjárási viszonyok okozta vízhozam csökkenésre és az ezzel szorosan összefüggő tápanyag-koncentrálódásra

Rarely mentioned species in Hungary: Can we step into the same lake?

International and national protection strategies and directives focus mainly on macroscopic organism and attempt to maintain their endangered habitats. However, microscopic communities are also threatened by decreasing biodiversity and many species including freshwater algae can disappear without even knowing they were present in the habitat. Defining rarity of microscopic taxa is not easy. The species’ rarity is based on detailed knowledge of distribution and abundance of species. But only limited information is available about rare algal species especially in a given ecoregion. Reducing the data gaps, here, we present altogether 20 phytoplankton taxa rare in Hungary: three species of Chlorophyceae, eight species of Trebouxiophyceae, two taxa of Euglenophyceae, one-one species of Cyanobacteria, Bacillariophyceae and Mediophyceae and three species of Xanthophyceae. One of them, the Cylindrotheca gracilis is on the Hungarian Red List. Physical and ecological characteristics of standing waters where these species were found as well as their former occurrence all over the world are also reviewed

Halophilic diatom taxa are sensitive indicators of even short term changes in lowland lotic systems

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 fi ndings 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

Network embedding aided vaccine skepticism detection

We investigate automatic methods to assess COVID vaccination views in Twitter content. Vaccine skepticism has been a controversial topic of long history that has become more important than ever with the COVID-19 pandemic. Our main goal is to demonstrate the importance of network effects in detecting vaccination skeptic content. Towards this end, we collected and manually labeled vaccination-related Twitter content in the first half of 2021. Our experiments confirm that the network carries information that can be exploited to improve the accuracy of classifying attitudes towards vaccination over content classification as baseline. We evaluate a variety of network embedding algorithms, which we combine with text embedding to obtain classifiers for vaccination skeptic content. In our experiments, by using Walklets, we improve the AUC of the best classifier with no network information by. We publicly release our labels, Tweet IDs and source codes on GitHub