Bioaccumulation of inorganic Hg by the juvenile cuttlefish Sepia officinalis exposed to 203Hg radiolabelled seawater and food

Abstract

Uptake and depuration kinetics of inorganic mercury (Hg) were investigated in the juvenile common cuttlefish Sepia officinalis following exposures via seawater and food using a sensitive radiotracer technique ( Hg when exposed via seawater, with whole body concentration factors > 260 after only 10 d of exposure. The total Hg accumulated from seawater was depurated relatively fast with a radiotracer biological half-life (Tb ! ) of 17 d. During both exposure and depuration periods, accumulated Hg was mainly (> 70%) associated with the muscular parts of the cuttlefish. However, the proportion of the whole-body Hg content associated with the digestive gland increased during exposure and depuration phases, suggesting that the metal was transferred from the muscles towards this organ for detoxification. When fed with radiolabelled food, cuttlefish displayed high assimilation efficiency (> 90%) and the metal was found to be mainly located in the digestive gland (60% of the whole Hg content). Nevertheless, high depuration rates resulted in short Tb ! (i.e. 4 d), suggesting that this organ has a major role in Hg detoxification and depuration. Whatever the exposure pathway, a low proportion of Hg (< 2%) was found in the cuttlebone. Assessment of the relative contribution of the dietary and dissolved exposure pathways to inorganic Hg bioaccumulation in juvenile cuttlefish revealed that Hg was mainly accumulated from food, which contributed 77 ± 16% of the global metal bioaccumulation.

Seasonal Survey of Contaminants (Cd and Hg) and Micronutrients (Cu and Zn) in Edible Tissues of Cephalopods from Tunisia: Assessment of Risk and Nutritional Benefits

“…The same trend was detected for both muscle tissues in the 3 analyzed species: significantly higher concentrations (KW, P < 0.001) were found in the arms and mantle of squid (0.062 and 0.072 μg g −1 ), followed by cuttlefish (0.049 and 0.057 μg/g) and octopuses (0.027 and 0.031 μg/g; Table ). This different Hg distribution among the studied species is in accordance with the process of bioaccumulation of this metal in cephalopods, which is dominated by the diet (Lacoue‐Labarthe and others ). The highest concentration of Hg found in squid reflets their behavior of feeding mainly on fish and other cephalopod species (Pierce and others ; Coelho and others ).…”

Inter-specific and ontogenic differences in δ13C and δ15N values and Hg and Cd concentrations in cephalopods

“…Hg speciation has not been determined in this study, but it is likely that bioaccumulated Hg was the organic form methyl-Hg, which represents the most important form of Hg in cephalopod muscle , Raimundo et al 2010. The role of the digestive gland in the storage and detoxification of Hg is still controversial , 2008, Pierce et al 2008, Lacoue-Labarthe et al 2009). A preferential redistribution of methyl-Hg from the digestive gland to the muscle is expected , where it may bind with sulphydryl groups of muscular proteins (Bloom 1992) and accumulate during ontogenesis.…”

“…In addition, these voracious predators can accumulate high metal concentrations in their tissues, especially in the digestive gland (Martin & Flegal 1975, Miramand & Bentley 1992. Food is generally considered as a major source for several metals in cephalopods, especially for Cd and Hg (Koyama et al 2000, Bustamante et al 2002a, Lacoue-Labarthe et al 2009). Finally, as prey, cephalopods can transfer these metals to their predators, as described previously in the case of Cd in the Northeast Atlantic Ocean (Caurant & Amiard-Triquet 1995, Bustamante et al 1998, Lahaye et al 2005.…”

“…Total Hg analyses were conducted on the mantle muscle of all species, while Cd was analysed in the digestive gland. Hg is known to mainly accumulate in its organic form in the muscle tissue of cephalopods , whereas the role of the digestive gland in the storage and detoxification of Hg in cephalopods is not well defined , Pierce et al 2008, Lacoue-Labarthe et al 2009). In contrast, the digestive gland is well recognized as the key organ in bioaccumulation and detoxification of Cd in cephalopods (Miramand & Bentley 1992, Bustamante et al 2002a, Pierce et al 2008).…”

“…4 & 5) since food intake is the major source of Hg in cephalopods (Lacoue-Labarthe et al 2009). Hg speciation has not been determined in this study, but it is likely that bioaccumulated Hg was the organic form methyl-Hg, which represents the most important form of Hg in cephalopod muscle , Raimundo et al 2010.…”