Mercury Uptake and Enzymatic Response of Posidonia Oceanica After an Experimental Exposure to Organic and Inorganic Forms

Abstract

The aim of this study was to examine the experimental uptake of mercury and the enzymatic response, i.e., glutathione S-transferase (GST) activity, to this metal introduced into the medium under organic (methylmercury chloride) and nonorganic (mercury chloride) forms. Shoots of Posidonia oceanica were collected in a nonpolluted area in the northwestern Mediterranean Sea and were treated in aquaria with increasing mercury concentrations/exposure times (48, 96, and 144 h). Compared with the controls, a significant uptake was noted in the blades contaminated by HgCl2, whereas in the sheaths, a significant decrease of total mercury was noted. The blades exposed to CH3HgCl exhibited higher mercury concentrations than the controls; after 144 h exposure to organic mercury, the levels found in the blades were approximately sevenfold the values of the controls. The uptake noted in the sheaths treated with organic mercury followed the same pattern as with HgCl2 (decreased value compared with the controls) except after 144 h, where a slight increase in mercury was found in this tissue. The percentage of organic mercury in controls and treated blades and sheaths (treatment with both forms of mercury) represented always more than 50% of the total mercury in the plant. Glutathione S-transferase activities were significantly increased in the blades and sheaths of P. oceanica exposed to mercury chloride, whereas exposure to methylmercury was not significant. The presence of a GST isoform of 31 kDa was demonstrated by immunochemical methods (Western blotting) in the sheaths but not in the blades of the phanerogam.

Nonnutrient anthropogenic chemicals in seagrass ecosystems: Fate and effects

“…At least five seagrass species have been found to bioconcentrate mercury at concentrations between 4 and 51,500 ng/g dry weight. Nonorganic mercury was more bioavailable to P. oceanica than organic mercury in a laboratory exposure and glutathione-S-transferase activity significantly increased in some tissues as mercury uptake increased [74]. Organic mercury was at least 50% of the total mercury bioconcentrated in that study.…”

Monitoring polycyclic aromatic hydrocarbons in the Northeast Aegean Sea using Posidonia oceanica seagrass and synthetic passive samplers

“…Although many studies have highlighted the usefulness of P. oceanica as a recorder of ambient trace metal pollution (Maserti et al, 1988;Catsiki and Panayotidis, 1993;Malea, 1993;Malea et al, 1994;Warnau et al, 1995;Pergent-Martini, 1998;Delgado et al, 1999;Ferrat et al, 2002;Ancora et al, 2004;Balestri et al, 2004;Gosselin et al, 2006), much less information is available regarding the content of organic contaminants in this seagrass. However, the few studies that have reported on bioaccumulation of organic contaminants in P. oceanica tissues (e.g., Viso et al, 1993;Lewis and Devereux, 2009;Pergent et al, 2011) highlight the potential of this plant to serve as an indicator of organic pollutants in the Mediterranean Sea.…”

Mercury contamination in human hair and some marine species from Sfax coasts of Tunisia: levels and risk assessment

“…Following this disaster, most concern has centred on the presence of mercury in fish, and extensive surveys have been carried out in a number of countries to evaluate the presence of mercury in aquatic biota (Monteiro et al 1996;Nakagawa et al 1997;Pergent and Pergent-Martini 1999;Sanchiz et al 1999;Frodello et al 2000;Pirrone et al 2001;Ferrat et al 2002Ferrat et al , 2003Storelli et al 2002;Love et al 2003;Kucuksezgin et al 2006). However, only one study concerning the gulf of Gabes has been published to date (Hadj Ali et al 1986).…”