Cadmium accumulation and loss in the Pacific oyster Crassostrea gigas along the west coast of the USA

Abstract

Oysters can accumulate cadmium (Cd) in very high concentrations in their tissues and there is now increasing concern for the seafood safety of farmed oysters worldwide. Bioaccumulation and biokinetics of Cd (dietary assimilation, uptake from the dissolved phase, and efflux) were measured in different populations of Pacific oyster Crassostrea gigas collected along the west coast of the USA in 2 different seasons. Triploid juvenile oysters were first transplanted to 5 Washington sites and 1 Oregon site for 3 mo, then transported back to the laboratory for tissue Cd measurements and biokinetic experiments. A second group of seed oysters was collected from California and Washington for additional analysis. Oysters from all sites had Cd concentrations lower than the food standard limit and there was spatial difference in tissue Cd concentrations. A significant fraction of Cd was associated with metallothionein-like proteins, implying that the oysters can detoxify Cd by induction of metallothionein. The difference in Cd dietary assimilation (using diatoms as a food source) and efflux in oysters transplanted to different locations was not significant. The uptake rate constants for Cd from the dissolved phase, however, differed markedly among the transplanted populations, and appeared to be affected by the oysters' clearance rate, depending on the population. This uptake rate was also negatively affected by the size of oysters. Dietary assimilation of Cd was comparable at diatom food concentrations below 2 to 5 mg l -1 , and was lower with ingested sediments than with diatoms. Measurements of Cd kinetics in different populations of Pacific oysters under a variety of environmental conditions provide an insight into the Cd accumulation in this commercially important species.

Copper and zinc contamination in oysters: Subcellular distribution and detoxification

“…Little work has previously been conducted on the subcellular distribution of metals in oysters [34][35][36]. In our study, cellular debris appeared to be an important pool of material that bound with different metals (Ag, As, Cd, Cu, Pb, and Zn), especially at stations 1, 2, and 3.…”

Roles of regional hydrodynamic and trophic contamination in cadmium bioaccumulation by Pacific oysters in the Marennes-Oléron Bay (France)

“…After 3 months, enrichment factors ([Cd]3M/[Cd]control) of Cd in tissues of oysters exposed from T and B were respectively 3.0 and 2.2 in gills, 4 .7 and 3.2 in digestive glands and 4.9 and 3.4 in the rest of tissues. Thus, Cd accumulation was clearly higher in oysters growing in the water column than near the bottom, as it has been observed for oyster larvae in eastern North America (Ng et al, 2010). We also determined the bioaccumulation factor (BAF), defined as the ratio of Cd concentration in the organism to the concentration in water (Gobas and Morrison, 20 00 ;DeForest et al, 2007).…”

“…Characterising cadmium bioaccumulation pathways of oysters in a specific environment is of a high economic concern and remains a present important issue (Baudrimont et al, 2005;Lekhi et al, 2008;Bendell and Feng, 2009;Ng et al, 2010). Oyster production and trade are limited by the Cd consumption safety level, varying from 1 l g g -1 wet weight in the European Union (or 5 l g g -1 dry weight), to 2 l g g -1 ww in the Hong-Kong market and 4 l g g -1 ww in the US (Food and Drug Administration).…”

Tracing cadmium contamination kinetics and pathways in oysters (Crassostrea gigas) by multiple stable Cd isotope spike experiments

“…Oyster cultures are economically important in coastal areas. Oysters are filter-feeding bivalves that easily accumulate trace metals, especially cadmium (Baudrimont et al, 2005;Lekhi et al, 2008;Bendell and Feng, 2009;Christie and Bendell, 2009;Ng et al, 2010). Due to known human health effects (Bragigand et al, 2004;Cheng and Gobas, 2007;Copes et al, 2008;Widmeyer and Bendell-Young, 2008;Saratug et al, 2010), consumption of oysters has been limited to 5 mg g -1 dw in Europe (CE No.…”