Seasonal ecological patterns and environmental drivers of phytoplankton assemblages in Dorudzan reservoir

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Volume 15, Issue 3 (Autmn 2025) J. Aqua. Eco 2025, 15(3): 32-44 | Back to browse issues page

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Seasonal ecological patterns and environmental drivers of phytoplankton assemblages in Dorudzan reservoir. J. Aqua. Eco 2025; 15 (3) :32-44
URL: http://jae.hormozgan.ac.ir/article-1-1152-en.html

Seasonal ecological patterns and environmental drivers of phytoplankton assemblages in Dorudzan reservoir

Abstract: (205 Views)

This study examines the seasonal variability and community structure of phytoplankton, along with the environmental factors shaping their dynamics, in Dorudzan Reservoir. As a critical freshwater source for Fars Province—supplying drinking water to more than 1.2 million residents—the ecological stability of the reservoir plays a vital role in maintaining water quality. Phytoplankton and zooplankton were sampled across four seasons from nine stations at five depths (0–4 m). Over the one-year survey, 43 phytoplankton genera belonging to six major taxonomic groups were identified. Mean total abundance ranged from a minimum of 1,073 ± 146 cells/L in summer to a maximum of 8,101 ± 1,407 cells/L in spring. Seasonal peaks in phytoplankton abundance were strongly linked to increases in water temperature (9 °C in winter to 26 °C in summer), light availability, and nutrient concentrations, particularly nitrogen and phosphorus. Myzozoa were the dominant group in all seasons, constituting approximately 45% of total phytoplankton, followed by Cyanobacteria, Chlorophyta, and Ochrophyta, which showed their highest abundances in autumn, winter, and summer, respectively. Statistical analyses revealed significant correlations between phytoplankton biomass and environmental variables such as pH (7.2–8.4), dissolved oxygen (8.3–10.8 mg/L), and nutrient levels. Grazing by zooplankton and fish also influenced phytoplankton dynamics, as evidenced by an approximate 30% decline in phytoplankton density during periods of heightened zooplankton activity at the end of summer. Overall, the findings highlight the combined effects of biotic and abiotic drivers on phytoplankton dynamics and underscore the importance of continuous ecological monitoring for effective water quality management. Given the substantial climatic fluctuations and increasing human pressures that threaten the aquatic ecosystem of Dorudzan Reservoir, these results provide essential data to support the development of sustainable conservation and management strategies.

Keywords: Algae, Fars, Lake, Seasonal dynamics, Ecosystem balance

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Type of Study: Research | Subject: Special
Published: 2025/11/1