Estimation of Mercury Levels in Non-Edible Tissues (viscera and Brain) of the Common Octopus from the Western Tripoli Coast

الملخص

This study aimed to evaluate mercury (Hg) accumulation in tissues of the common octopus (Octopus vulgaris) collected from two distinct sites with contrasting levels of environmental contamination: Zawia Refinery and Marsa Zawagha-Sabratha. A total of 5 specimens were collected from Zawia Refinery and 3 specimens from Marsa Zawagha-Sabratha. Tissue samples, including viscera and brain, were analyzed to determine Hg concentrations. Octopus viscera from the Zawia Refinery exhibited Hg levels ranging from 0.052 to 0.165 mg/kg, with the highest concentration observed in the largest individual weighing 1.5 kg. In contrast, viscera from Marsa Zawagha-Sabratha showed substantially lower Hg levels (0.0285–0.0329 mg/kg). Brain tissue analysis revealed even higher Hg accumulation than viscera in the same locality, with concentrations ranging from 0.11 to 0.31 mg/kg in Zawia, whereas brain Hg levels in Marsa Zawagha-Sabratha were minimal (0.01–0.0121 mg/kg). The study also demonstrated a size-dependent trend, with larger octopus’s individuals accumulating higher Hg concentrations in viscera, reflecting prolonged exposure and increased dietary intake over time. A direct comparison between organs indicated selective tissue accumulation, as Hg concentrations in the brain were nearly double those in the viscera, suggesting preferential retention in protein- and lipid-rich neural tissues, which may facilitate biomagnification. These findings highlight the significant influence of local environmental conditions, particularly proximity to industrial discharges, on Hg bioaccumulation patterns in octopus. The results emphasize the need for tissue-specific monitoring of heavy metals in marine organisms and stricter control of industrial pollution to safeguard seafood safety and marine ecosystem health.