Temporal and spatial changes in mercury concentrations in the North Atlantic as indicated by museum specimens of glacier lanternfish Benthosema glaciale (Pisces: Myctophidae).

Museum specimens of glacier lanternfish Benthosema glaciale were used to investigate long-term variations in mercury concentration of mesopelagic organisms from the North Atlantic. B. glaciale is an abundant mesopelagic fish species in the boreal and sub-polar pelagic regions of the North Atlantic, playing an important role in the cycling of energy in the oceanic food webs of these systems. We used 35 museum specimens of lanternfish, collected from the Gulf Stream biogeographic region between 1936 and 1993, to test for long-term variations in mercury concentrations. In addition, we studied the mercury concentrations throughout the geographical range of the species, using 105 specimens collected around 1970s. Mercury concentrations were similar over time; however there was evidence of a noteworthy increase in mercury contamination during the World War II (1941) followed by a general decrease with lowest concentrations being found in 1954 and 1993. Significant differences were found between the different studied areas, probably reflecting different degrees of anthropogenic contamination. The results presented here indicate that museum myctophids may be suitable for the assessment of historical changes in mercury contamination of marine ecosystems.