Page 818 - The Toxicology of Fishes

798 The Toxicology of Fishes

Clark Fork River

Blackfork River
30 Turah
km
30 Deer Lodge
Rock Cr. Flint Creek Tissue Type
25 Butte Reference sites ( )
Silverbow Turah Bridge
Copper in Tissue (µg/g, dry wt.) 15
Creek
Warm Springs Ponds
20

10

5

0
aa b a bc aa b a ab b a bc a b b a a b a b c
Gill Liver Kidney Pyloric Stomach Large Stomach Whole
caeca intestine contents fish
FIGURE 19.12 Bioaccumulation of copper in different tissues of brown trout (Salmo trutta) from below Warm Springs
ponds and from Turah, on the Clark Fork River, compared to fish from uncontaminated reference sites. (Adapted from
Farag, A.M. et al., Can. J. Fish. Aquat. Sci., 52, 2038–2050, 1995.)

The lipid peroxidation observed experimentally was also observed in the liver, pyloric ceca, and large
intestine of brown trout resident in the Clark Fork (Farag et al., 1999). Metals that exist in more than
one valence state (e.g., copper) can initiate lipid peroxidation (Wills, 1985) by interacting with sulfhydryl
groups and oxygen or by inhibiting important antioxidant enzymes. This may ultimately result in tissue
damage or cell death (Sokol et al., 1990), when fatty-acid side chains in cell membranes are the targets
(Halliwell and Gutteridge, 1985). Brown trout from the upper Clark Fork River also contained copper
inclusions in hepatocytes and vacuolation of hepatocyte nuclei. When energy is diverted from cell
metabolism to detoxify metals, cell disruption is noted by both vacuolation of nuclei and the elevated
lipid peroxidation.
The experiments reported above were somewhat controversial because nutritional content and species
composition of the diet were not controlled. Mount et al. (1994) repeated the dietary exposure exper-
iments with rainbow trout (Oncorhynchus mykiss), but they used brine shrimp (Artemia) as a food
source. After 60 days, they could attribute no effects on growth or survival to the diet. Woodward et
al. (1995) and Mount et al. (1994) both, however, documented effects on the intestinal tract of fish fed
diets contaminated with metals. Gut impaction was observed in 3 to 9% brown trout, and constipation
was observed in nearly 50% of the trout fed diets from the uppermost Clark Fork River. Mount et al.
(1994) found that 7 of 18 mortalities observed were associated with actual rupture of the body cavity.
Hansen et al. (2004) controlled the nutritional content of the diet by feeding rainbow trout worms
(Lumbricus variegatus) grown in Clark Fork sediments. They found histopathologic abnormalities in
treated animals, along with unambiguous inhibition of growth. The growth reduction was associated
with reductions in conversion of food energy to biomass (rather than reduced food intake) and correlated
with arsenic bioaccumulation.