Environmental Investigations and Tissue Bioaccumulation of Heavy Metals in Grey Mullet from the Black Sea (Bulgaria) and the Ionian Sea (Italy)

SIMPLE SUMMARY: The environmental monitoring of dangerous chemicals and how these affect the aquatic biota is of fundamental importance in defining the health status of fish. Pollution with chemical elements is of great environmental concern, since fish and marine organisms can uptake various toxicants and subsequently transfer them to man through the food web. Moreover, the accumulation of toxic elements could be a cause of pathology insurgence in fish. These organisms represent a good indicator of the status of coastal water. Flathead grey mullet (Mugil cephalus) is a coastal species, bottom dwelling and feeding on detritus, invertebrates, and algae. The main aim of the present study was to determine the total concentration of nine elements (Cd, Cr, Pb, Ni, Al, Cu, Fe, Mn, and Zn) in the fish species M. cephalus and in coastal marine waters collected from various sampling points along the Black Sea (Bulgaria) and the Ionian Sea (Italy) and to apply those results to the prediction of the pollution status of those coastal marine environments. To achieve this goal, metal concentrations were analyzed in various fish tissues (gills, liver, and muscle) of grey mullet (M. cephalus) and in marine water samples collected from the sampling stations across both areas (Ionian Sea (Italy) and Black Sea (Bulgaria)). The results revealed significant differences within the tissues examined and the marine water samples, principally attributable to the pollution of the area, the bioavailability of metals, and the hydrological conditions. The present study represents the first attempt to compare the data obtained from analyzing sampling points in order to define the different elemental concentrations in M. cephalus muscle tissue and how they reflect environmental ones. ABSTRACT: The environmental monitoring of chemical toxicants has been a widely studied topic in the last few decades. The main aim of the present study was to determine the total concentration of nine elements (Cd, Cr, Pb, Ni, Al, Cu, Fe, Mn, and Zn) in the fish species grey mullet (M. cephalus) and in the coastal marine waters collected from various sampling points along the Black Sea (Bulgaria) and the Ionian Sea (Italy). Further, those results were applied to predict the pollution degree in those coastal marine environments. The fish samples were subject to acid digestion followed by appropriate analytical determination. The metal concentrations in marine water samples collected from the Black Sea (Bulgaria) and the Ionian Sea (Italy) were also analyzed. Unpaired Student’s t-test and the one-way ANOVA were applied for the statistical analysis of the data. The statistical results revealed a significant variation (p < 0.0001) in the concentration of various fish tissues. The accumulation of toxic and essential elements differs significantly in grey mullet species caught from the Black Sea (Bulgaria) and the Ionian Sea (Italy). The results from this study may serve as a convenient approach during marine pollution programs set by both countries (Italy and Bulgaria).