Effects of dietary copper on the Australian freshwater crayfish Cherax destructor

Little information is available on the effects of metals in the diet of parastacids, despite the importance of the freshwater crayfish industry worldwide. There have been no published studies on the effect of either dissolved or dietary copper on the Australian freshwater crayfish Cherax destructor. Herein is reported a study on the bioaccumulation of copper through a simple food chain. The copper was first absorbed by the floating aquatic macrophyte Lemna minor to an average concentration of 74 microg/g, before being fed to C. destructor. In the crayfish, the highest copper concentrations were found in the muscle (56.4-1299.6 microg/g), gills (86.8-714.3 microg/g) and hemolymph (14.8-293.5 microg/g). There was no bioaccumulation or bioconcentration of copper from contaminated dietary material. A general linear model indicated that such treatment had no effect on copper concentrations in the crayfish. The results are consistent with the regulation of copper by C. destructor, with the gills being the main site for absorption and depuration of copper to and from the water column. C. destructor does not appear to be sensitive to dietary copper.