REPRODUCTIVE TOXICITY AND DISPOSITION OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN IN ADULT BROOK TROUT (SALVELINUS-FONTINALIS) FOLLOWING A DIETARY EXPOSURE

Adult brook trout (Salvelinus fontinalis) were exposed to 2,3,7,8-tetr achlorodibenzo-p-dioxin (TCDD) with a contaminated trout pellet diet t o determine the effects of TCDD on reproduction, to document tissue-sp ecific TCDD distribution, and to establish the maternally derived dose of TCDD to the F-1 generation. Five treatment groups and a control we re exposed to achieve targeted whole body TCDD concentrations of 0, 75 , 150, 300, 600, and 1,200 pg TCDD per gram fish. Net dietary assimila tion of TCDD was estimated to be 89% of the applied dose, and the dist ribution of TCDD generally followed the distribution of lipids in live r, gonad, fat, blood, and muscle. Depuration could not be measured ove r 81 d, but a hypothetical depuration rate was estimated to be 0.002 d (-1) assuming 100% dietary assimilation. The concentration of TCDD in ovaries and spawned eggs was estimated to be 61 and 39% of the whole b ody TCDD concentrations, respectively. Survival, growth, gonadal devel opment, and egg production were not affected in any treatment. The ons et of spawning was delayed by 13 d in the highest treatment group, sug gesting that TCDD might have affected ovulation. Otherwise, the adult life stage was not as sensitive to TCDD as the early life stage.