Distribution of metals during digestion by cutthroat trout fed benthic invertebrates contaminated in the Clark Fork River, Montana and the Coeur d'Alene River, Idaho, USA, and fed artificially contaminated Artemia

The concentrations of essential amino acids in three, undigested invertebra te diets collected from the Clark Fork River (CFR) for cutthroat trout were similar to each other, but were c. 25-75% less than Artemia that were expo sed to a mixture of arsenic, copper, cadmium, lead and zinc in the laborato ry. The Artemia diet appeared less palatable and the texture, quantity and appearance of the intestinal contents differed between fish fed the Artemia and CFR diets. The Pb% in the fluid fraction of the intestinal contents wa s greater for the Artemia (29%) than for the CFR diets (10-17%), and the Cu % in the amino acid plus metal fraction of the intestinal contents was grea ter for the Artemia (78%) than for two of the three CFR diets (67% and 70%) . Intestinal contents of fish fed invertebrate diets collected from various sites on the Coeur d'Alene River (CDA), Idaho, were similar in texture, qu antity, and appearance. For fish fed the CDA diets, differences in the dist ribution of metals among fractions of the digestive fluids appeared to be r elated to concentrations of metals in the invertebrate diets. Pb% was lowes t of all metals in the fluid portion of the intestinal contents. However, > 80% of all metals in the hind gut were associated with the particulate frac tion where they may still be available for uptake through pinocytosis. (C) 2000 The Fisheries Society of the British Isles.