Abstract
This research was conducted to investigate the statistical correlation between microplastic contamination and potentially toxic elements in Kutum populations (Rutilus kutum) at three sampling stations: Kiashar, Anzali and Astara, located along the Southwestern coast of the Caspian Sea. The results from analysis of 60 fish samples indicated that all samples were contaminated with microplastics. The highest mean abundance of microplastic, 53.75±35.50 (particles per fish), was observed at Anzali sampling station. The results of the elemental concentration analysis showed that Iron had the highest concentration, with a mean value of  23111 ± 5945.33  µg/kg at Anzali station. At Kiashar station, a significant negative correlation was observed between the abundance of microplastics and the concentrations of Cadmium and Nickel (rs˃-0.4, p˂0.05). At Astara station, a significant positive correlation was found between the abundance of microplastics and the concentrations of Arsenic and Nickel (rs˃0.4, p˂0.05). According to the comparison of elemental concentrations with FAO/WHO standards, only the concentration of Arsenic in fish from various stations exceeded the permissible limit. These findings indicate the complex interactions between microplastic contamination and elemental concentrations in Kutum (R. kutum) from the Caspian Sea, necessitating further research to evaluate the environmental impacts and the health of the Caspian Sea ecosystem.