Mercury concentrations in fish species caught at Mid-Atlantic Ridge hydrothermal vent fields

Abstract

Concentrations of total mercury and methyl mercury were determined in muscle and liver samples of 8 fish species caught at the Menez Gwen, Lucky Strike and Rainbow hydrothermal vents (Mid-Atlantic Ridge). The species studied were Hydrolagus pallidus, H. affinis, Synapho- branchus kaupi, Epigonus telescopus, Mora moro, Antimora rostrata, Deania calceus and Etmopterus princeps. Median total mercury concentrations found in muscle tissue of the 8 species ranged between 0.6 and 1.9 µg g -1 wet weight and between 0.1 and 1.7 µg g -1 wet weight for liver tissue in 5 of the species. Differences in total mercury concentration in species caught at the different hydrothermal vents, comparisons between tissues and correlation with total length are described. In general, liver tissues present lower total mercury concentrations than muscle. Methyl mercury accu- mulated in fish from this study comprises, on average, >80% of the total mercury. The total mercury concentrations found were higher than those previously published for deep-sea fish. These fish spe- cies were exposed to high levels of mercury, due not only to bioavailability of toxic and stable forms of mercury in the water, but also to predation on organisms exposed to this metal.