European Journal of Molecular & Clinical Medicine

The biosphere is the living objects’ natural world. It includes the planet and comprises surface portions of the lithosphere, the body and the hydrosphere. For species to live in the atmosphere, a reasonably homeostatic condition is important. To track any abnormal transition due to economic advancement and consequential growth of civilization, this includes the analysis of the chemical composition of air, water, and soil. Over the last few decades, the volume of water waste worldwide has risen. One of the most important water contamination sources is the application of extremely hazardous and non-degradable heavy metals (such as Lead, Cadmium, etc.) The effect on marine ecosystems is very fantastic. These heavy metals are taken explicitly from the water by water creatures, and indirectly by other animals belonging to the food chains. Since heavy metal ingestion is involved, certain physiological modifications are happening within the heavy metals such as reduction in growth and developmental defects and reduction in survival. Some organisms such as the Atlantic mackerel (Scomber scombrus) are used for calculation of heavy metal emissions as bioindicators and biomonitors. The purpose of this study is to discuss the significance of this organism in observing both the volume and quality aspects in relation to heavy metals, particularly lead and cadmium, in the water bodies' surroundings and how this heavy metal exposure can be avoided or managed.

The present study included species composition of fish and some ecological factors in haji Ali drainage in the Babylon province. Three stations were chosen for the purpose of the study, the station of first is placed at the beginning of the drain(St1), the second in the middle(St2) and the third at the end(St3), monthly samples were selected from June 2019 to May 2020. Water temperature showed slight changes to the stations were recorded between(11.8C°-28.9C°).Salinity ranged between 0.12gm/l -2.55 gm/l. pH values tended in some months of study to the acidic side and in other months to the basic side has recorded from (6.4-9.3). Dissolved oxygen values ranged from (1.71-
8 .86)mg/l.Biological oxygen demand values ranged between (0.04-4.59) mg/l.Throughout the period mentioned above, a total of 5 397 fish were obtained, belonging to 14 species and 7 families, 11 species of them were native species whereas 3 of them were alien species. The most abundant species was Carassius auratus constituted 31.28% of the total caught of the first station, the value of the dominance index (D3) in first station was 78.53%. The most abundant species in second station was C. auratus constituted 31.46% of the total caught, the value of the dominance index (D3) in the second station was 70.03%. The most abundant species in third station was Planiliza abu constituted 28.08% of the total caught, the index of dominance value (D3) in the third station was 75.68%. Richness index (D) was ranged between (0.66-1.92) and diversity index (H) recorded (1.07-2.01),while evenness index (J) ranged (0.55-0.70).