Document Type : Original Research Paper
Authors
1
Department of Botany, Faculty of science, University of Benghazi
2
Department of Botany, Faculty of science, University of Benghazi, Beng., Libya
10.22059/poll.2025.394619.2912
Abstract
Abstract
The present study investigates the relationship between water quality parameters and microalgae diversity in a brackish lake ecosystem. Water samples were collected across four seasons, from October 2022 to July 2023, from the surface of six sites distributed throughout the seven northern lakes of Benghazi. Water quality parameters—including electrical conductivity, pH, temperature, alkalinity, and nutrient concentrations—were analyzed. Microalgae were identified, counted, and their abundance estimated using the Utermöhl method. Microalgae diversity was assessed using Shannon, Simpson, species richness, and evenness indices. A total of 33 species belonging to 27 genera and five divisions were recorded. The most diverse group was Chlorophyta (49%), followed by Cyanophyta (21%), Bacillariophyta (12%), Euglenophyta (9%), and Dinophyta (9%). The highest species diversity, according to the Shannon–Weaver index, was observed in winter, while the lowest occurred in summer. The Simpson index was highest in autumn and lowest in summer. Principal Component Analysis (PCA) extracted two components from 14 environmental variables after Varimax rotation, explaining 46.47% of the total variance. Canonical Correspondence Analysis (CCA) identified two factors—F1 (41.35%) and F2 (17.77%)—which together accounted for 59.11% of the total data variance, with eigenvalues of 0.48 and 0.44, respectively. These results illustrate the relationship between microalgae species and environmental variables. Overall, the findings provide a foundation for developing sustainable conservation strategies to preserve the biodiversity of brackish lakes
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