Response of metallothionein concentrations in a freshwater bivalve (Anodonta grandis) along an environmental cadmium gradient

Abstract

Surficial (oxic) sediments, overlying water, and specimens of the freshwater bivalve Anodonta grandis were collected by divers at 11 littoral lacustrine sites located along a geochemical gradient of pH, [Cd], Dl, and [Z n in an area influenced by mining and smelting activities. The molluscs were dissected (gills; 1 hepatopancreas; remaining tissues) and analyzed for Cd, Cu, Zn, and metallothioneins (MT). Tissue concentrations of MT in A. grandis varied between 100 and 440 nmol metal binding sites (g dry wt-l. Metallothionein levels in the gills, the remaining tissues, and the whole organism were significantly correlated (P < 0.01) with tissue Cd concentrations.In contrast, correlations between [MT] and tissue levels of Cu or Zn were weak or nonexistent. The intersite variations in MT concentrations were best related, not to total dissolved metal concentrations at the time of sampling, nor to extractable metal concentrations in the sediments, but to the free Cd2+ concentration at the sediment-water interface, as estimated from sediment-water sorptive equilibria. These observations suggest that Cd2' activity is the key environmental factor to which metallothionein levels in A. grandis are responding in the studied lakes. The mollusc condition indices (C.I. = 1,000 x total dry wt of flesh of the animals/total intervalval volume) deteriorated as Ld concentrations in the tissues increased.Freshwater and marine molluscs are recognized for their capacity to concentrate metals from their environment (Phillips 1980). Their tolerance of the resulting metal burdens has been attributed to the existence of an effective detoxification mechanism involving the trapping of the incoming metals by specific ligands present in the cytosol (Viarengo 1989). Possible candidates for this role include metallothioneins (MT), low-molecular-weight, cysteine-rich metal-binding proteins with high affinity for group IB and IIB metal ions. Stability constants measured in vitro for metal ions such as Cd2+, Cu2+, Hg2+, and Zn2+ are

Seasonal and Regional Variations of Metal Contamination and Condition Indicators in Yellow Perch (Perca flavescens) along Two Polymetallic Gradients. I. Factors Influencing Tissue Metal Concentrations

“…Lakes surrounding the industrial region of Rouyn-Noranda in northwestern Québec have been affected by mining and smelting operations since about 1927 (Couillard et al 1993). Although the extent of industrial contamination is considerably smaller in the Rouyn-Noranda region than in Sudbury, recent studies have demonstrated elevated concentrations of Cd, Cu, and Zn in contaminated lakes relative to background concentrations (Couillard et al 1993;Brodeur et al 1997;Laflamme et al 2000;Sherwood et al 2000;Levesque et al 2002).…”

Réponses de trois espèces sentinelles aquatiques à la contamination en métaux traces dans deux rivières de l'Abitibi, Québec

“…Les échantillons ont été conservés à -20 °C jusqu'au moment de l'analyse qui fut réalisée à l'automne. Les détails des procédures d'extraction et d'analyse en laboratoire sont donnés dans COUILLARD et al (1993).…”

“…Le surnageant était analysé pour la MT à l'aide d'une technique de saturation au mercure dont la méthode est décrite plus en détail dans COUILLARD et al (1993). Comme contrôle de qualité, le pourcentage de récupération d'un standard de MT (foie de lapin, Sigma Chemical Co.) a été déterminé à chaque essai analytique.…”

Enzymatic correlates of energy status in wild yellow perch inhabiting clean and contaminated environments

“…Metals have contaminated many lakes in the area, and their effects on fish and invertebrates in the region have been regularly studied since the early 1990s [1][2][3][4]. Research has also demonstrated that the physiology of yellow perch (Perca flavescens) living in these contaminated systems is affected [5][6][7][8].…”