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(\ ,"'~111 :21 ;~ I 80 iped bass ent, tanks (control). 'd bass on lden shin- n shiners :ler /fish), s fed se- 01 striped s during :rface. In -e lethar- j shiners oater sur- ;>turing a tanks of lly equal ,d avoid- t bass in >ow trout oairdnerz) )n et al. us tsha- elenium- 'a affinis elenium- 185). lore than e 3). No ; level of :ulation). t bass in- I day 31, tm inges- :r feeding he calcu- liner diet ntrations Ictalurus y feeding t _ it. .:1 .oi ;:j . .~~i o~ ~ 1 1 ~'- -r ~Jj i f ,. -~ ~ J " i'! i 'f; ~ ': i i; :1 "I , DIETARY TOXICITY AND STRIPED BASS .c (/) .0:: " C'I ~ Z120 o t- ~80 C> Z ::E 40 ::> Z ~ 0 W 0 (J) ~(21 .. : .... . TREATMENT . -..- . r, .... . , \ -:.. .... : I' . . '. . I ' J\ :,~-\ ;'111 \,' ?l' ) \I ...,t t .. l; , ~ oJ t~ ~ ~\... ' , " ,..t ~,'., I \ CONTROL .... \:....~ ..~ 20 40' DAY 60 FIGURE 3.-Average daily amount of selenium in- gested by striped bass fed selenium-laden red shiners (treatment, tanks I and 2) or uncontaminated golden shiners (control). studies (Hilton et al. 1980; Gatlin and Wilson 1984; Hicks et al. 1984). All striped bass fed golden shiners survived the 80-d study, whereas by day 78, all striped bass fed selenium-laden red shiners either had died or were killed because they were near death (Figure 4). We observed 15 of20 moribund treatment striped bass; these fish swam singly along the tank perimeter (nonmoribund fish schooled), usually near th~ sur- face, and did not react to our presence. Additional characteristics, though not seen for all treatment striped bass, included coughing, swimming with the mouth open and the head out of the water (gulping), porpoising, difficulty in swimming up- right, and some corneal cloudiness in one or both eyes. Rainbow trout fed excessive selenium dis- played uncoordinated spiral swimming and dis- regard for other fish or obstacles in the exposure chambers about 21-24 h before death (Hilton et al. 1980). The 10 control striped bass fed golden shiners increased their average weight by 39% and their average condition factor (K) by 8% during the ex- periment (Table 2). Six treatment striped bass in tank I and seven in tank 2 were killed while mor- ibund to obtain data on final weight and length, for determination of muscle selenium, and for his- topathological examination. Treatment striped bass in tanks I and 2 increased their average weight by 0.3 and 3%, and decreased their average K by II and 8%, respectively, during the experiment. Unequal survival of control and treatment striped bass confounded comparisons of weight and con- dition factor. An attempt to characterize and ex- amine weight and condition factor for each day of 403 0'0 UJ u ~8 cr u jj6 0::: o 4 o ~ ~2 * o 12F' .- -. TREATMENT .... , 111/ , , ,---- -' I , , I I I , , I . ,--' . , ,---~ -' , : ,------, . , . , . r' .: I : . . , . .. CONTROL 80 o 20 40 60 80 DAY FIGURE 4. - Mortality of striped bass associated with consumption of selenium-laden red shiners (treatment, tanks I and 2) or uncontaminated golden shiners (con- trol). the experiment yielded little additional informa- tion. Tagged or otherwise marked fish and facili- ties to hold equal numbers of control and treat- ment fish would have eliminated these shortcomings. Hilton et al. (I980) reported that Jainbow trout exhibited significantly reduced growth when fed a selenium-supplemented diet (13 J.Lg Se/g dry feed) for 20 weeks, and growth reduction was apparent after only 4 weeks. Despite the reduced food intake and lack of growth of striped bass fed selenium-laden red shiners, these treatment striped bass accumulated a higher average concentration of selenium in skeletal muscle (3.8 J.Lg Se/g wet weight) than con- trol striped bass fed uncontaminated golden shin- ers (1.1 J.Lg Se/g). However, selenium concentra- tions in the muscle of treatment striped bass were less than those found in other wild fish species living in selenium-contaminated water bodies or in fish fed selenium-laden diets in laboratory stud- ies (Table 3). Although duration and degree of selenium exposure differed in these studies, our results indicated that juvenile striped bass are sen- sitive to selenium in the diet or that various fish species can accumulate ingested selenium differ- entially (Bertram and Brooks 1986). An addition- al, untested hypothesis is that selenium concen- trations in the muscle of treatment striped bass were higher during active feeding but that subse- quent reduced feeding activity and concurrent se- lenium depuration lowered the selenium concen- tration in muscle to that measured at the time of sacrifice. Hepatocytes of control striped bass typically were polyhedral and highly vacuolated with gly- cogen. The nuclei were uniform in size and usually condensed (not round) due to glycogen vacuola-