Diatom Flora in a Channel fed by Lake Biwa on the campus of the University of Shiga Prefecture, Japan

抄録

We conducted a survey of diatom flora in a channel located on the campus of the University of Shiga Prefecture (Hikone, Shiga, Japan). This channel receives water from Lake Biwa via fish farming ponds operated by the Shiga Prefectural Fishery Experiment Station. Diatom samples were collected from 10 sites during 2022 and 2023, and examined using both light and scanning electron microscopes. In total, 174 species were recorded, including 19 unidentified taxa, representing 62 genera. The genus with most taxa was Gomphonema, followed by Nitzschia and Navicula. More than a dozen taxa formerly classified within the genus Fragilaria, such as Staurosira, Pseudostaurosira, and Nanofrustulum were observed. These observed species suggested eutrophic and slightly alkaline conditions. The diatom taxa occurred in this study had commonly been reported from the littoral zone of Lake Biwa. Additionally, several potentially introduced species were detected, indicating possible anthropogenic introductions associated with human-mediated transfer of fishes and mussels during field coursework or research activities.