Dakhla Bay is a paralic environment distinguished by various potentialities, including fishing, aquaculture, and tourism. However, the development of these human activities can lead to negative impacts on this environment, posing a threat to human health. This situation requires special attention to the environment and the implementation of a program for the protection and preservation of this ecosystem. This study aims to identify solutions to protect the marine environment from cadmium contamination by the macroalgae Gracilaria gracilis. The results of cadmium analyses in different compartments of Dakhla Bay, including bivalve molluscs, seawater, sediment, and macroalgae, indicate a difference in cadmium accumulation across the various studied compartments. The highest levels of cadmium are noted in macroalgae, with concentrations ranging from a minimum of 0.9 mg/kg fresh weight in the summer of 2019 to a maximum of approximately 2.55 mg/kg fresh weight recorded during the summer of 2022 at the Lassargua station. In comparison, bivalve molluscs such as Perna perna showed Cd levels ranging from 0.2 mg/kg to 1.4 mg/kg fresh weight at the same station. The sediment samples revealed average Cd levels ranging from 0.02 to 1.39 mg/kg dry weight in samples collected from Lassargua, while seawater concentrations were recorded at approximately 0.65 μg/L. The decontamination of cadmium by the macroalgae Gracilaria gracilis without impacting the quality of the algae has been well confirmed. Indeed, cadmium levels noted in macroalgae remain below the thresholds set by the regulations in force. In conclusion, the results of this study encourage the use of algocultures in Dakhla Bay to protect its ecosystem from various types of pollution.