Significance of physicochemical forms of storage in microalgae in predicting copper transfer to filter-feeding oysters (Crassostrea gigas).
Copper distribution has been examined in two microalgae (Haslea ostrearia, Diatom; Tetraselmis suecica, Prasinophyceae) exposed to Cu at 30 microg/L(-1). Exchangeable copper linked at the cell surface was desorbed using 8-hydroxyquinoline-5-sulfonate as complexing agent. Then, incorporated copper was separated between soluble and insoluble fractions. In addition, algae were resuspended in acid solutions, the pHs of which covered the range existing in the digestive tract of bivalves. Considering that the soluble fraction is the most easily transferred in the food chain and that exchangeable Cu is easily desorbed, the percentages of Cu potentially available in microalgae have been assessed. These percentages have been compared with those retained in oysters Crassostrea gigas fed with contaminated microalgae in previous studies. In H. ostrearia, the potentially available fraction of Cu (90%) was very similar to the percentage retained by oysters (93%) when the bivalves were acclimated to this food for 3 weeks. Only half (21%) of the potentially available Cu of T. suecica (42%) was readily assimilated in oysters after 3 weeks. This is in agreement with the results of the desorption tests at physiological pHs which showed that only 15-25% of Cu was lost, despite solubilization of other constituents of T. suecica as demonstrated by the decrease in their dry weight. Bioavailability determined from metal speciation in food allows a relevant prediction of the trophic transfer in the case of H. ostrearia, but caution is recommended in generalizing this mode of assessment as shown in the case of T. suecica.
Amiard-Triquet
Claude
C
Service d'Ecotoxicologie, SMAB/Ple Mer et Littoral, Université de Nantes, 2 Rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France. Claude.Amiard-Triquet@univ-nantes.fr
Berthet
Brigitte
B
Joux
Lamia
L
Perrein-Ettajani
Hanane
H
D000818:Animals; D002614:Chelating Agents / Q000737:chemistry; D000460:Chlorophyta; D003300:Copper / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D049896:Crassostrea / Q000378:metabolism*; D017377:Diatoms; D020387:Food Chain; D006863:Hydrogen-Ion Concentration; D015125:Oxyquinoline / Q000031:analogs & derivatives / Q000737:chemistry; D012995:Solubility
D002614:Chelating Agents; D015125:Oxyquinoline; D003300:Copper; C013053:8-hydroxyquinoline-5-sulfonic acid