Evaluation of the level of phytoplankton primary productivity in the Karmat Ali River, southern Iraq

The study of primary productivity in the Karmat Ali River in the southern Iraq, is the first study that addressed this topic, which aimed to evaluate the level of primary productivity in that area by identifying four sites along the river, namely (Al-Najibiya, Al-Mashhab , Al-Nagara and Al-Salal). Samples were collected seasonally starting from Winter until Autumn from year 2022, with reference to some environmental factors that may affect the values of primary productivity. The results of the study showed that the lowest level of primary productivity was in the Summer at site Al-Najibiya, as it reached 25.5 mg Carbon/m3 .hr., while its highest level appeared during the Spring at site (Al-Mashhab ), as it reached 342.18 mg Carbon/m3.hr., while the temperature ranged between 11.8-33.4 Cͦ, salinity between 2.6-9.5 ppt , pH 7-8.6 , dissolved oxygen 1.6-15.5mg/l , turbidity 1.3-33.5NTU , reactive phosphate 0.01-0.21 mg/l, reactive nitrate 0.32-19.9mg/l , and as for the biomass represented by chlorophyll-a-, it ranged between 7.3-39.32mg/m3. The results also showed, through canonical correspondence analysis (CCA), that primary productivity values were closely related to chlorophyll a values, while turbidity was in the opposite direction.