Nearshore benthic blooms of filamentous green algae in Lake Baikal

Abstract For the first time, species of the genus Spirogyra , non-typical of the open nearshore waters of Lake Baikal, formed algal mats with Ulothrix zonata , Ulothrix tenerrima , and Ulothrix tenuissima near the village of Listvyanka, Russia. Normally widely distributed in the 0- to 1.5-m depth range, the growth of U. zonata was now evident and dominant (63% of the biomass) in the 2- to 5-m depth range. The overgrowth of the lake bottom by filamentous green algae, changes in distributional boundaries, the emergence and mass development of species of the genus Spirogyra , the presence of the eutrophic diatom indicator Fragilaria capucina var. vaucheriae , elevated abundances of coliform bacteria, and elevated levels of nutrients suggest an early stage of cultural eutrophication in the nearshore of Lake Baikal near Listvyanka, a popular tourist destination. The unusual abundance of Fragilaria associated with the filamentous green algae consisted of long-ribbon colonies of F. capucina var. vaucheriae , a eutrophic species, wound around the filamentous green algae, enhancing the dense algae mats. Historically dominant species, such as Didymosphenia geminata , Tetraspora cylindrica var. bullosa , and Draparnaldioides baicalensis typically observed at deeper depths of Lake Baikal, are now subdominants or minor species in the nearshore along the shoreline near Listvyanka.