Mapping metal (Hg, As, Se), lipid and protein levels within fish muscular system in two fish species (Striped Bass and Northern Pike)

Abstract

Current guidelines tend to limitfish consumption based on mercury (Hg) or monomethylmercury(MeHg) content infishflesh, without considering the presence of antagonist chemical elements thatcould modulate Hg toxicity. However, it is difficult to assess the potential for antagonistic interactions ofthese elements since their covariation within muscle tissues is poorly known. Here we present thefirststudy simultaneously mapping multiple metal(oid)s (Hg, As and Se), lipids and proteins infishfillets inorder to assess the magnitude of intra-organ variability of metals and the potential for antagonisticinteractions. We mapped twofish species (Striped Bass and Northern Pike) with contrasting muscularstructure with respect to the presence of white, intermediate and red muscles. In individual Striped Bassmuscle tissues, metals varied on average by 2.2-fold. Methylmercury and selenium covaried strongly andwere related to protein content as assessed by % N; arsenic was inversely related to these elements andwas associated with the lipid fraction of the muscle. In Pike, no such relationship was found because thecontents in proteins and lipids were less variable. Arsenic speciation revealed that arsenobetaine andarsenolipids were the only As species in thosefish species, whereas the toxic inorganic As species (As3þ)was under the detection limit. Arsenobetaine was related to % N, whereas arsenolipids covaried with %lipids. Elemental associations found with muscle lipids and proteins could help explain changes inbioaccumulation patterns within and between individuals with potential implications onfish toxicology,biomonitoring and human consumption guidelines.