Fate and effects of soluble or sediment-bound arsenic in oysters (Crassostrea gigas thun.)

Abstract

Contaminated sediments are a possible source of stress to the benthic biota. In order to examine this way of transfer concurrently with direct exposure, oysters were exposed to As dissolved in natural seawater or loaded to particles. The sediment used as a vector of transfer was a mud from a coastal area devoted to oyster culture, the finest particles of which have been selected. It was submitted to experimental contamination then to in vitro desorption tests, in which enzymes and pH changes were used to mimic the digestive processes in Molluscs. Although different enzymes or pH induced the desorption of 3 to 24% of sediment-bound arsenic, the accumulation of this element in the soft tissues of oysters remained low after exposure to contaminated particles. The uptake of soluble arsenic was also limited although checking the level of arsenic in seawater every day revealed no significant decrease of the contaminant in the experimental medium. However, cytological effects were noted in oysters exposed to sediment-bound arsenic and moreover to soluble arsenic. They consisted of structural alterations of mitochondria and nuclei, suggesting a disturbance of both the cellular respiratory metabolism and nucleotid incorporation.

Shellfish and Residual Chemical Contaminants: Hazards, Monitoring, and Health Risk Assessment Along French Coasts

“…In laboratory experiments, the oyster C. virginica bioaccumulates little inorganic arsenic and only a fraction of the organic arsenic present in the phytoplankton (Sanders et al 1989). The arsenic fixed on inert particles of seston is poorly bioconcentrated in the oyster C. gigas (Ettajani et al 1996), but the small amount that passes through the oyster causes intense erosion of the mitochondrial cristae, leading eventually to cellular respiratory failure. In the peppery furrow shell (or sand gaper) Scrobicularia plana, bioconcentrated arsenic levels match the levels of sediment contamination (Langston 1983).…”

From Incorporation to Toxicity

“…Biological extractants such as digestive fluids of endobenthic invertebrates (polychaetes, sipunculans) and fish have been also used for the extraction of trace elements, polyaromatic hydrocarbons (PAHs), or PCBs (Mayer et al, 1996(Mayer et al, , 2001Weston and Maruya, 2002;Goto and Wallace, 2009;Baumann et al, 2012;Wang et al, 2012). Artificial gut fluids consisting of chemical extractants able to recreate conditions relatively similar to those encountered in guts of invertebrates or fish were also used, such as acid solutions at physiological pH levels for metal extraction (Amiard et al, 1995Ettajani et al, 1996;Peña-Icart et al, 2014) or sodium dodecyl sulfate for PAHs (Ahrens et al, 2005).…”