Characterization of Rapana thomasiana as an indicator of environmental quality of the Black Sea coast of Bulgaria

The aim of this investigation was to determine the contents of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), minerals, trace elements and bioactivity in the gastropod Rapana thomasiana, which can be used as an environmental bioindicator organism. The chemical differences between Rapana thomasiana from polluted (RapaPol) and non-polluted (RapaNPol) sites of the Black Sea coast in Bulgarian were investigated. Chromatography and high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) were used for evaluation of PAHs, PCBs, minerals and trace elements. Methanol extracts from RapaPol and RapaNPol (to a lesser degree) contained relatively high amounts of free phenolics (2.50 ± 0.3 and 1.57 ± 0.18 mgGAE/g DW, respectively) and exhibited the following respective levels of antioxidant activities determined by two radical-scavenging assays (μMTE/g DW): 1.8 ± 0.2 and 0.98 ± 0.08 by 1-diphenyl-2-picrylhydrazyl method (DPPH); 1.74 ± 0.17 and 1.04 ± 0.12 by cupric reducing antioxidant capacity (CUPRAC). The total amounts of elements, PAHs and PCBs were higher in RapaPol than in RapaNPol. The obtained indices of Rapana thomasiana can serve as a bioindicator of the environmental ecological quality.