Toxicity of heavy metals dissolved in sea water and influences of sex and size on metal accumulation and tissue distribution in the norway lobster Nephrops norvegicus

Abstract

Norway lobsters Nephrops norvegicus were exposed to organic mercury (MeHg), inorganic mercury (Hg), copper (Cu), cadmium (Cd), lead (Pb) and zinc (Zn) in solution in sea water to determine lethal levels of these metals and to study the influence of sex and size on metal accumulation and tissue distribution (carapace, hepatopancreas, gills, tail muscle, ovary and external eggs). Hg, MeHg, Cd and Pb were accumulated by tissues of N. norvegicus. At sublethal metal concentrations, the highest concentrations of Hg and MeHg were found in the gill tissues. Highest tissue burdens of MeHg were in tail muscle (41%) and gills (32%), while for Hg they were in gill tissue (63%) and hepatopancreas (17%). Highest concentrations of Cd were in hepatopancreas and gills, while the highest tissue burdens of Cd were in the hepatopancreas (91%). Maximum concentrations of Pb were found in the gills and carapace, while most of the burden of Pb was in carapace (42%) and hepatopancreas (25%). Accumulation of MeHg was significantly greater than that of Hg. MeHg was also more toxic than Hg. Exposure to 10 μg Cu l −1 increased Cu concentrations of carapace, gills, tail muscle and ovary, but not hepatopancreas or external eggs. However, the highest concentrations of copper were found in the hepatopancreas and gill, while the largest tissue burden of the metal was in the hepatopancreas (65%). Exposure to 100 μg Zn l −1 increased Zn concentrations of carapace, hepatopancreas, gills and ovary, but not in tail muscle or external eggs. Highest concentrations of Zn were in hepatopancreas and gills, while highest tissue burdens were in the hepatopancreas (55%) and tail muscle (31%). Hepatopancreas Hg and MeHg accumulation were greater in males than in females. Accumulation of Hg, MeHg and Cd in the gills was higher in smaller animals. The adsorption onto the carapace surface was found to be very important in determining metal concentrations of the carapace.