Effect of Al-Dalmaj Marsh Discharge Canal on Copepoda Community and Water Quality in the Main Outfall Drain River in Al-Qadisiya Governorate by Using Biodiversity and CCME-WQ Indices

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Spatial variation indicated that the CMME-WQI recorded its lowest values at Site 3 compared to other sites. This may be attributed to the approximately double concentrations of TDS and turbidity at Site 3, likely influenced by the water from a discharge canal that enters the river about 2 km upstream of this location. The Copepoda community exhibited the highest densities and diversity at Site 3 relative to Sites 1 and 2. This suggests that the discharge canal has a significant impact on Copepoda populations, particularly at Site 3, where brackish water with elevated salinity and dissolved oxygen (DO) levels appears to favor their abundance. The limited number of species in the MOD River may be due to the influence of salinity, which is considered a key factor affecting both species richness and copepod abundance. Species numbers and abundance tend to increase when salinity levels approach those of either freshwater or marine environments, rather than in intermediate brackish conditions

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