Trace elements in the muscle, ova and seminal fluid of key clupeid representatives from the Gdansk Bay (South Baltic Sea) and Iberian Peninsula (North-East Atlantic)

Background: Baltic herring and European sardine are pelagic, fish of particular ecological importance, on the one hand control numbers of planktonic organisms, and on the other hand exist as food for predators on higher trophic levels. Moreover, these fish are among the main species caught for human consumption. Rare earth elements (REEs) come mainly from geogenic sources but, due to their use in technology, agriculture and medicine, the importance of anthropogenic sources is growing steadily. Methods: Samples used for the study were available on the market. Fresh materials of fish muscle, ova and seminal fluid were mineralized and elements were determined by means of inductively coupled plasma - mass spectrometry (ICP-MS). Results: The conducted research indicated the presence of REEs in the muscles of the Baltic herring (FREE = 0.076 +/- 0.047 mg/kg) and European sardine (FREE = 0.191 +/- 0.163 mg/kg), with a clear dominance of heavy REEs in both fish species. Trace elements (TE) in the muscles of the tested fish demonstrated a similar system of concentration (Baltic herring: Zn > As > Se > Cu > Cr > Ni > Pb > Cd; European sardine: Zn > As > Se > Cu > Ni > Cr > Pb > Cd). REEs and TEs in these fish were presence in ova and seminal fluid indicates intergenerational transfer. Conclusion: Changes in the concentrations of some trace elements (As, Cu, Cd) in the muscles of herring indicate increases compared to the historical data. The availability of metals in the aquatic environment may be determined by ongoing climate changes, effected water salinity and warming increased availability of labile forms of trace metals. Decline trends in the condition of pelagic fish need to extend the research in the context of contemporary environmental threats.

Automated summary

The research revealed the presence of rare earth elements and trace elements in the muscles of Baltic herring and European sardine, with intergenerational transfer of REEs and TEs in ova and seminal fluid. The increasing concentrations of some trace elements in herring muscles compared to historical data may be affected by ongoing climate changes and the availability of labile forms of metals in the aquatic environment. Further research on the decline trends of pelagic fish is needed in the context of contemporary environmental threats.