Accumulation and distribution of dietary nickel in lake whitefish (Coregonus clupeaformis)

Benthic-feeding fish residing in Ni-contaminated systems are exposed to Ni through ingestion of contaminated food items and sediments. Lake whitefish (Coregonus clupeaformis) were fed diets at a ration of 0.5% of body weight three times a week containing 0, 10, 100, and 1000 microg Ni/g (as NiSO(4)) for 10, 31, and 104 days. Stomach, pyloric caeca, intestine, kidney, liver, gall bladder, gonad, gill, bone, muscle, skin, and scales were analyzed to evaluate the accumulation and distribution of Ni. Fish fed the medium and high dose diets accumulated significant amounts of Ni in a majority of the tissues sampled, even after only 10 days of exposure. Ni concentrations were highest in intestine and pyloric caeca of whitefish fed 1000 microg Ni/g on day 10, but decreased on subsequent sampling days, possibly due to protective mechanisms. Ni accumulation in stomach, kidney, liver, gill, skin, and scales was dose and duration-dependent. Ni concentrations measured in bone, gall bladder, gonad, and muscle of fish fed the control diet for 10 days and fish fed the high dose diet for all durations appeared to increase in a duration-dependent manner. Exposure to Ni altered the concentrations of Cu and Zn in tissues of lake whitefish. However, Cu and Zn concentrations in the tissues analyzed were variable and did not follow a common pattern or trend. The tissues that best assess dietary Ni bioavailability are kidney and scales. The toxicology of Ni in these fish is described in the next manuscript (Aquat. Toxicol., in press (b)).