Assessing the Lethal Concentration (LC50) of Cadmium Chloride on Mediterranean Mussel (Mytilus galloprovincialis)

Abstract

Heavy metal pollution of industrial and domestic origin in aquatic ecosystems is a critical environmental problem that threatens human health through the food chain. The aim of this study was to determine the acute toxicity levels of cadmium chloride and early-stage ecotoxicological responses in Mediterranean mussels (Mytilus galloprovincialis) obtained from a cultivation facility (the Mussel and Oyster Cultivation Facility established at Sinop University). During the 96-hour static bioassays conducted in filtered seawater, the average water temperature was maintained at 17.78±0.03 °C, and the pH at 7.93±0.05. The average length of the mussel specimens used in the experiment was measured as 40.48 ± 0.82 mm, and the width as 20.58 ± 0.42 mm. In the triplicate experiments, the organisms were exposed to cadmium concentrations of 0.5, 1, 5, 10, and 15 ppm, in addition to the control group. During the first 24 hours of exposure, distinct physiological stress and avoidance behaviors such as valve closure, immobility, and increased fecal production were observed, particularly at high doses of 10 ppm and above. Based on mortality data at the end of the observation period, a Probit analysis determined the 96-hour median lethal concentration (LC₅₀) value for M. galloprovincialis to be 3.03326 ppm, indicating that the species possesses a high tolerance threshold to acute cadmium exposure. The numerical findings obtained serve as an early warning criterion for food safety risk analysis and monitoring programs in bivalve aquaculture in the region. This preliminary study provides a foundational dataset for future sublethal chronic studies designed at lower concentrations and for elucidating the cellular level mechanisms of cadmium’s toxic effects on bioindicator species.