Accumulation of trace metals in the digestive gland and muscle of the common octopus (Octopus vulgaris) from the northwestern Atlantic coast of Morocco

Abstract

The present study aimed to assess trace metal (TM) accumulation in the digestive gland and muscle of Octopus vulgaris, collected along the northwestern Atlantic coast of Morocco. Essential TMs (Cu and Zn) were the most abundant in tissues, with the following sequence: Cu > Zn > Cd > Cr in the digestive gland and Zn > Cu > Cr > Cd in muscle. In addition, TM concentrations were consistently and significantly higher in the digestive gland. For non-essential TMs, Cd was significantly more elevated in digestive glands than in muscle, with concentrations up to 702 times higher, and exhibited greater interindividual variability. Also, significant relationships were found in the digestive gland between Cd and Cu levels and the size of samples. In contrast, sex and maturity stage had no effect on TM content or distribution pattern among tissues. Metal ratios (Cd/Zn and Cd/Cu) in the digestive gland clearly correlated with biometric traits and TM levels, indicating a complex interactive behavior between these pollutants during the bioaccumulation process. These findings enhance our understanding of metal partitioning in O. vulgaris and highlight their potential as bioindicators.