The Davachy Port extends 11.2 km along the western coast of the Middle Caspian Sea, serving as a vital freshwater reservoir. This study focuses on the composition of species, biomass, and seasonal distribution of macrozoobenthos in the port, considering historical and recent research findings. Over the study period from 2018 to 2019, 50 species of invertebrates were identified, with chironomid larvae dominating in both abundance and biomass. Seasonal variations significantly influenced species diversity, with the highest diversity observed in spring and the lowest in winter. The study highlights long-term changes in the harbor’s fauna, the impact of environmental factors on macrozoobenthos, and the ecological significance of the port as a habitat for various aquatic organisms. The findings contribute to understanding biodiversity shifts and provide a foundation for future conservation efforts.