Diatom species diversity and their eco-logical patterns on different substrates in two karstic streams in the Slovak karst

摘要

Many karstic streams are threatened both by anthropogenic and climate changes, but little is known about their algalbiodiversity and conservation value, especially in the Slovak Karst. Diatom assemblages occurring on seven substrates,including stones, mud, submerged mosses and filamentous algae: Cladophora glomerata, Vaucheria sp., Ulothrix zonata,Spirogyra sp. in two nameless karstic streams in the Krásnohorská Dlhá Lúka Village and the Gombasek CottageSettlement (the Slavec Village) in the Ko?ice Region of central-eastern Slovakia (the Silická Plateau) were studied. Atotal of 124 diatom taxa were found at four sites, where epilithic and epiphytic diatom assemblages dominated. Bothspecies’ richness and Shannon-Wiener indices showed congruent biotic integrity. The dominant taxa were alkaliphilous,halophobous-oligohalobous, requiring xeno-oligosaprobic and oligotrophic waters. Diatoms include: Diploneiskrammeri, Encyonema ventricosum, Gomphonema acuminatum, Gyrosigma attenuatum, Navicula tripunctata, andParaplaconeis cracoviensis. The latter species is a new report for Slovakia, reflecting the calcareous, geological natureof the Silická Plateau (the Slovak Karst). Diatom assemblages in two karstic streams consisted mainly of small-celledspecies of Achnanthidium, Amphora, Caloneis, Planothidium, and Stauroneis. Our results showed that the diatomassemblages were mostly structured by environmental factors of calcium and pH gradients, confirmed by canonicalvariates analysis (CVA) and Monte Carlo permutation tests. However, unique spatial and biological gradients, specificto different guilds related to each other, were also evident. The Slovak karstic streams should be especially protectedand regularly monitored.