## 4 Discussion
barbatus_ spends its juvenile life stage mainly in the coastal waters before migrating to open deeper seas [35]. Thus, higher levels of Hg found in open sea specimens could be explained by a higher average age of these fish than coastal specimens, and a consequently longer exposure time to this metal. This is also confirmed by another study carried out in the Adriatic Sea, where lower Hg values were recorded in coastal areas [6]. Since mercury accumulates over time in fish tissues, it is probable that older fish will have absorbed higher levels of this metal. Moreover, _M. barbatus_ lives close to the sea floor, so they are probably exposed to higher concentrations of dissolved methylmercury produced from the methylation activity of microorganisms living in the sediment. In addition, food habits represent an important pathway for the transport of heavy metals, such as mercury. _M. barbatus_ lives in close contact with the marine sediment, feeding on benthic prey such as crustaceans and polychaetes. It is known that benthic preys are richer in mercury than pelagic organisms, and this has been found in the Adriatic Sea as well as in other areas [36; 37]. Thus, an important contribution to the different bioaccumulations of Hg could due to the different feeding strategies of specimens that migrate to deeper waters. Males showed a non-statistically significant lower average Hg content, and this could be due to a lower growth rate in biomass than for females [38]. The decrease in Hg levels in edible tissue for females after the spawning phase was also confirmed by several studies for other contaminants [16; 39]. This could derive both from Hg bioaccumulation inside the egg cells (and therefore a release of Hg during the spawning phase), and from a reduction in predatory activity that occurs in post-spawning specimens. In fact, this pattern does not occur in males, in which the bioaccumulation of this element increases during the reproductive stages. The lipid content was higher in females than males, and during the spawning phase it did not influence Hg levels, as demonstrated by [PERSON] et al., 2012 [23], for red mullet, and for other species by [PERSON] et al., 2017, and [PERSON] et al., 2018 [40; 41]. Considering the safety threshold set by EU regulations [31; 42], which sets the limits for the mercury content in fresh tissue of _M. barbatus_ at 1 mg kg\({}^{-1}\), all the samples analyzed in this study were found to be well below this threshold. Therefore, considering the toxic effects due to the intake of Hg, the average consumption of this product does not compromise human health. The Joint Food and Agriculture Organization/World Health Organization (FAO/WHO) Expert Committee on Food Additives has established regulatory guidelines regarding dietary mercury intake. It recommends a provisional tolerable weekly intake (PTWI) for methylmercury of 1.6 \(\upmu\)g kg\({}^{-1}\) body weight (b.w. ), and of 4 \(\upmu\)g kg\({}^{-1}\) b.w. for inorganic mercury [32]. For fish meat, fish products, fish offal, and unspecified fish and seafood, the EFSA suggests evaluating the exposure assessment, and applying a conversion factor of 1.0 for methylmercury, and 0.2 for inorganic mercury. Based on the EFSA's Comprehensive European Food Consumption Database (fish, seafood, amphibians, reptiles, and invertebrate), the Greek  
brates) [43], we assessed the intake of inorganic Hg and methylmercury, based on gender and age, resulting from consumption of this species in the Italian population (Figure 4). Although there were no exceedances for inorganic Hg intake, the results showed that methylmercury intake in the lower age groups always exceeded the limit set by the EFSA. In particular, toddlers were the most at risk, and showed an intake that is three to four times (4.9 and 6.2 ug kg\({}^{-1}\) b.w. per week, respectively) above the EFSA's limit of 1.6 ug kg\({}^{-1}\) b.w. per week.