Analysis of Manganese Bioaccumulated in Mediterranean Blue Mussel (Mytilus galloprovincialis) from the Bay of Mali Ston (Adriatic Sea, Croatia) during Diarrhetic Shellfish Poisoning Toxicity

Diarrhetic Shellfish Poisoning (DSP) toxicity was revealed in the Mediterranean blue mussel (Mytilus galloprovincialis) from the Bay of Mali Ston, in the south part of the Eastern Adriatic Sea, through the Croatian National Monitoring Programme in the period from January until June of 2011. A survey of DSP toxicity within the frame of regular controls carried out through the mouse bioassay (MBA, at the time the official method for DSP toxins) demonstrated that in some incidents, positive MBA, which manifested by the atypical symptomatology of the animals, dominated. Additional studies were done to explain the atypical results of the conducted biological tests at the time. In the current study, the bioaccumulated manganese concentration in the soft tissues of mussels was measured to investigate its influence on the MBA results. In both DSP negative and DSP positive samples, which were prepared for the analysis according to the modified US EPA 3052 method, the concentration of the bioaccumulated manganese was performed on the atomic absorption spectrometer using flame atomic absorption spectroscopy technique. The analysis revealed higher concentration of manganese in 87% of DSP positive samples and the expressed per wet weight ranged from 0.15 to 5.38 mg kg−1. The mean concentration of manganese for all DSP positive samples was 1.78 mg kg−1, while for DSP negative samples, it was 48% lower (0.93 mg kg−1). The highest concentration of manganese in DSP positive samples was measured in February 2011. Since the low concentrations of lipophilic biotoxins gymnodimines (GYMs) and spirolides (SPXs) were also detected in the analysed DSP positive samples in the parallel studies, the results obtained in this study suggest future investigations of the connection between the concentration of manganese and lipophilic biotoxins.