Tissue uptake of cadmium in brook trout during chronic sublethal exposure

Abstract

Brook trout exposed to one ppb Cd; added as cadmium chloride in the holding water, accumulated the metal in the gills, kidneys, and livers with time. The greatest uptake was in the gills and posterior kidneys which showed similar accumulation patterns (r=0.99 and 0.94 respectively) with an exposure time of 93 days. Cd levels in the posterior kidneys were always higher than those in the anterior (head) kidneys in both Cd-exposed and the control fish. The Cd content in the gills and posterior kidneys in both the control and Cd-exposed fish was much higher than in the other tissues, and the levels in the muscle of the exposed fish were generally about three-fold higher than those found in the controls, but they remained low (0.030±0.014 ppm). The Cd content of the whole blood and plasma, heart, spleen, testes, stomach and skin of the Cd-exposed fish after 77 and 93 days were higher than those of the control fish. Brook trout injected with 1 μg Cd/g body weight, intramuscularly (i.m.), once a week for 16 weeks also accumulated the metal, primarily in the posterior kidneys and gills, but there was less accumulation in the gills than in the fish exposed to one ppb Cd in water. Unlike the Cd-water study, a significant uptake of the metal occurred in the red cells, blood plasma, and muscle. No significant uptake occurred in the gonads. The red cells and gills had about the same Cd content (0.500–0.550 ppm), suggesting that much of the Cd in the gills may have come from the blood content, an observation which was not apparent in the fish that were exposed to Cd in the water.

The results suggest that the gills and posterior kidneys were sensitive organs for testing the effects of chronic sublethal exposure of brook trout to Cd.