Mercury levels in commercial mid-trophic level fishes along the Portuguese coast – Relationships with trophic niche and oxidative damage

摘要: Abstract Sardines (Sardina pilchardus) and mackerels (Scomber spp. Trachurus spp.) are amongst the most common fish caught along Iberian coast for human consumption and, as mid-trophic level organisms, they constitute essential prey in diet of several marine predators. Thus, assessment trophic ecology, contamination exposure, stress responses such organisms provides valuable information on environmental health chain potential risks consumers. This study aims to contribute an integrative mercury ecosystem by measuring stable isotopes, levels, oxidative parameters five commercial species northeast Atlantic. Samples muscle liver were collected from a total 116 individuals two fisheries surveys (Spring Autumn) whole Portuguese coast. Mercury concentrations isotope analysis (δ13C δ15N) performed muscle, while (lipid peroxidation DNA damage) measured both liver. found be considerably lower than values recorded previous studies limits set European Union law, which confirms non-toxic status these coast, concerning this harmful element. Interestingly, no differences among three genera, despite clear niches. Still, significantly higher during Autumn Spring, possibly due upwelling events Summer. Moreover, relationships between found. Overall, work provided fishes chain, particularly pelagic (and neritic) regions Atlantic, showing that concentration is low. However, it important note focused small- medium-sized specimens (overall ranging 13–25 cm length), thus may present larger bioaccumulation.