Diversity and Seasonal Fluctuation of Phytoplankton in Kot Dam, Jhunjhunu District, Rajasthan

Plankton communities serve as sensitive bioindicators of freshwater ecosystem health. The present study evaluates the phytoplankton diversity, composition, and seasonal dynamics of Kot Dam, Rajasthan, over two consecutive years (2021–22 and 2022–23). Quantitative analysis revealed the presence of six major phytoplankton classes, with Chlorophyceae and Bacillariophyceae collectively contributing over 60% of the total population. Seasonal trends indicated winter dominance of green algae and diatoms, summer proliferation of cyanobacteria, and monsoonal decline across all groups due to dilution and turbidity effects. Inter-annual comparison showed overall stability in total phytoplankton density, although a notable increase in Myxophyceae during the second year suggests rising nutrient enrichment and early eutrophication signals. Graphical tools and comparative analysis confirmed consistent community structure with emerging ecological stress. The study highlights the effectiveness of plankton-based assessment for monitoring reservoir health in semi-arid regions.