Comparative Study of Plankton Population Changes During Day and Night Hours and Their Relationship with Environmental Ecological Factors in Surface Water of Chahnimeh III Reservoir, Sistan and Baluchestan, Iran

Ataei Gazik, Raseleh; Haji Abbasi, Fatemeh; Okati, Ehsan

doi:10.22034/ibhf.2025.557726.1043

Comparative Study of Plankton Population Changes During Day and Night Hours and Their Relationship with Environmental Ecological Factors in Surface Water of Chahnimeh III Reservoir, Sistan and Baluchestan, Iran

Document Type : Original Article

Authors

raseleh Ataei gazik ¹

fatemeh haji abbasi ²

Ehsan Okati ³

¹ Central Water and Wastewater Biology Laboratory, Sistan and Baluchestan Province, Iran

² Food Microbiology Laboratory, Mashhad, Iran.

³ -Zabol Water and Wastewater Company, Iran

10.22034/ibhf.2025.557726.1043

Abstract

Plankton constitute the foundation of aquatic food webs and serve as sensitive indicators of ecosystem health.This study aimed to investigate diel (day–night) variations in plankton density and their relationship with physicochemical parameters and light intensity in the surface waters of Chahnimeh III reservoir. Sampling was conducted on 10 different dates between August and December 2024 at 10:00 a.m. and 10:00 p.m. Surface water samples were analyzed to determine the abundance of major planktonic groups (Diatoms, Chlorophyceae, Cyanophyceae, Protozoa, Rotifera, and Crustacea) as well as physicochemical parameters including temperature, pH, EC, and turbidity. Diatoms showed the highest abundance among the studied groups. Cyanophyceae density significantly decreased at night, whereas Chlorophyceae and Diatoms exhibited a positive and significant correlation with diel changes. Temperature and turbidity also showed a marked decrease during nighttime. The findings indicate that plankton density in Chahnimeh III is influenced by diel patterns, with temperature playing a major role in these variations. Considering the time of sampling is crucial for accurate monitoring and ecological assessment of aquatic ecosystems.

Keywords

Plankton

Diurnal variations

Ecological Factors

Chahnimeh Reservoir

Subjects