Under-Ice Development of Silica-Scaled Chrysophytes with Different Trophic Mode in Two Ultraoligotrophic Lakes of Yakutia

Abstract

Silica-scaled chrysophytes are a widespread group of microeukaryotes, an important component of aquatic habitats. They belong to different evolutionary lineages and they are characterized by the presence of siliceous scales, but differ in trophic mode. We studied the diversity of these organisms in different months of the ice cover period in two subarctic lakes of Yakutia, Labynkyr and Vorota. Silica-scaled chrysophytes, due to various trophic modes, have a competitive advantage in conditions of a long period of ice cover. Statistical analysis has shown the relationship between the relative abundance of mixotrophic and photoautotrophic representatives of silica-scaled chrysophytes with the thickness of the snow cover and the transparency of the ice. An increase in snow cover thickness and the process of melting ice with a decrease in its transparency reduce the relative abundance of photoautotrophic and mixotrophic species. Photoautotrophic representatives of silica-scaled chrysophytes begin to develop already in April, when a thick, solid, and transparent layer of ice and a small layer of snow were observed. During the research period, from April to June, the relative abundance of colorless heterotrophic silica-scaled chrysophytes genera Paraphysomonas and Lepidochromonas was more or less stable. A new species of Spiniferomonas heterospina sp. nov. has been discovered in Lake Labynkyr.