Diatom Flora and Seasonal Variation in Raja-Rani Lake, Letang, Morang, Nepal

Abstract

Diatoms are the largest group of algae, consisting of microscopic, unicellular, diploid, and non-flagellated organisms that have a unique silica-based cell wall. In this study, diatom samples were collected by squeezing submerged macrophytes from the Raja-Rani Lake during the winter, summer, and rainy seasons. A total of 41 diatoms under 15 genera were reported including 16 species being new for Nepal. The most abundant genus was Pinnularia (24.39%), followed by Eunotia (12.19%) and then Gomphonema, Neidium, and Stauroneis (each 9.75%). The greatest diversity of diatoms was observed in winter (60.97%), followed by summer (56.09%), with the lowest recorded in the rainy season (43.9%). Eunotia bilunaris and Navicula radiosa were dominant across all seasons, while E. bilunaris, Iconella linearis, N. radiosa, and Sellaphora capitata were common throughout the year. Rare species included Iconella curvula in winter, Craticula ambigua in summer, and Gomphonema pumilum in the rainy season. The dominance of certain species, such as Eunotia bilunaris and Navicula radiosa, across all seasons, underscores their ecological adaptability. These findings contribute to the understanding of diatom diversity and offer insights for future studies on freshwater ecosystems in Nepal.