The Occurrence of Diatoms from Genus Kobayasiella in Southern Poland

The Kobayasiella genus develops mostly in oligoor dystrophic freshwaters with low to medium electrolyte content. The studies carried out from 2008 to 2016 in southern Poland showed the presence of four Kobayasiella species. These species usually occurred individually in peatland areas or in the upper sections of small rivers and streams. The species presented in the study were most frequently found in oligotrophic peatbogs, characterized by acidic or very acidic waters with low or medium conductivity values.


MATERIALS AND METHODS
The field studies were conducted from 2008 to 2016 in various types of waters (mainly in flowing waters and on peat bogs) in southern Poland. The material was collected from all available habitats: stones, mud or sand, and submerged plants. Two types of samples (diatom material and water for chemical analyses) were collected from spring to autumn over the year (sites on rivers and streams) or only in spring and autumn (sites in peatland areas). The collected material was processed in the laboratory, in line with the methods commonly The Occurrence of Diatoms from Genus Kobayasiella in Southern Poland used in diatom studies (Kawecka, 2012;Noga et al. 2014a). The pH and electrolytic conductivity were measured in situ at every site, during the field studies. Other chemical parameters were measured using a Thermo scientific DIONEX ICS-5000 + DC ion chromatograph in the laboratory at the Department of Soil Science, Environmental Chemistry and Hydrology, University of Rzeszow. Diatoms were identified and counted at 1000× magnification under oil immersion using a Nikon ECLIPSE 80i and Carl Zeiss Axio Imager A2 light microscopes. The following literature was used for diatom identification: Krammer and Lange-Bertalot (Krammer & Lange-Bertalot, 1986), Lange-Bertalot (1996,1999) and Buczkó et al. (2009). The species abundance was obtained by counting diatom valves up to 400 in random transects of the light microscope. The species with over 5% share in a sample were considered as dominants.

RESULTS
The studies of the freshwater diatoms in the southern Poland revealed four species of the ge-  Fig. 1). The abovementioned species occurred in peatland areas. Moreover K. tintinnus was also found in the Krupiec stream. Kobayasiella subtilissima was recorded in the upper sections of flowing waters (the Mleczka and Morwawa rivers).
All noted Kobayasiella species occurred in most studied samples, but occasionally, as single valves. Only one species -K. parasubtilissima formed numerous populations and dominated in the diatom assemblages. On the Wołosate peat bog, K. parasubtilissima reached from 30% to 85% share in assemblages, developing among various Sphagnum species. On the Orawa peatland, species formed numerous populations (˃50%) in small depressions, filled with water and overgrowth by peat moss (Sphagnum spp.). The water samples from peat bog areas were characterized by low pH (˂5), while the pH values the samples from flowing waters (rivers and streams) exceed 5.
The conductivity values in peat bogs were low or medium and usually did not exceed 200 μS·cm -1 . At sites in rivers and streams conductivity was higher (˃300 μS·cm -1 ). Other chemical parameters had low values on most sites, often below the limit of determination. Generally, elevated values of nitrates occurred mainly in flowing waters, the highest (9.42 mg·dm -3 ) was observed in the Krupiec stream, where a large amount of dead organic matter (mainly in the form of leaf litter) was deposited in a stream bed (Table 1).
In the peatbog areas, where Kobayasiella species developed most often, the diatom assemblages were mainly composed of the following species:

DISCUSSION
Many species of the genus Kobayasiella occur in freshwaters with low or medium content of electrolytes -oligotrophic or dystrophic (Lange-Bertalot 1996). Among the four species presented in this work, K. subtilissima was observed the most often. This cosmopolitan species develops frequently on raised bogs occurring in small depressions filled with water and overgrown by Sphagnum spp. and characterized by extremely low pH as well as electrolyte content (Krammer & Lange-Bertalot, 1986). Fairly rare species -K. okadae and K. parasubtilissima have similar ecology to K. subtilissima (Krammer & Lange-Bertalot, 1986;Lange-Bertalot & Metzeltin, 1996). The least frequently recorded species in Poland and also in the world is K. tintinnus. The species was described from the St. Anne Lake in Romania (Buczkó et al. 2009), then recorded also in peat bogs in the Roztocze National Park (Poland) (Noga et al. 2014b) and in the Netherlands (Veen et al. 2015). Detailed information on the occurrence and ecology of K. okadae, K. subtilissima and K. tintinnus is presented in Noga et al. (2014b). In the investigated material, all three species always

CONCLUSIONS
The studies confirmed that species of the genus Kobayasiella prefer acid or very acid oligotrophic waters of with low or medium values of conductivity. They develop mainly on peat bogs, usually in the form of individual valves, very rarely creating numerous populations, whereas in rivers and streams they probably appear accidentally and only in the upper sections. For this reason, the authors inscribed all four species found in southern Poland on the Red List of algae in Poland (Siemińska et al. 2006), to the category of vulnerable (V) or at least rare (R).