Algal Diversity and its Relationship with Seasonal Variation of Water Quality in Gajedi Lake, Rupandehi District, Nepal

Abstract

The current study focuses on the algal diversity of Gajedi Lake in different seasons in connection to the lake's water quality indicators. Algae and water samples were collected from eight peripheral sites of the lake in summer, rainy, and winter seasons in 2021. The water temperature, conductivity, total dissolved solids, hardness, alkalinity, phosphorus, free CO<sub>2</sub>, and dissolved oxygen were recorded as high during the summer season while water pH was high during the rainy season. Altogether 93 species of algae were reported under 52 genera, 30 families, 7 classes and 6 phyla in this study. The largest phylum was <i>Bacillariophyta </i>(44.08%) followed by <i>Chlorophyta </i>(17.20%), <i>Euglenozoa </i>(10.97%), <i>Cyanobacteria </i>(12.90%), <i>Charophyta</i> (10.75%) and <i>Miozoa </i>(1.07%). The Shannon-Weiner diversity index indicated high abundance during the summer season, with more evenly distributed algal species. More algal species were recorded in the winter season. <i>Trachelomonas, Navicula</i>, and <i>Nitzschia </i>were dominant genera during summer; <i>Anagostidinema, Desmodesmus</i>, and <i>Pinnularia</i> were dominant during rainy; and <i>Trachelomonas, Tetradesmus</i>, and <i>Gomphonema </i>were dominant during winter. The redundancy analysis ordination showed that the algal composition varied along with the seasonal changes in physico-chemical parameters. Temperature, pH, and conductivity were thus identified as significant factors influencing species richness.