FISHERY BULLETIN; VOL. 74, NO. 3 



environmental conditions comparable to those 

 used in experiments. Juvenile striped bass were 

 obtained from the water diversion facilities of the 

 Bureau of Reclamation at Tracy, Calif. Fish were 

 acclimated in 2,000-liter circular tanks for at least 

 2 wk before testing and fed ground squid once 

 daily to satiation. 



In all uptake studies, an appropriate number of 

 fish (Table 1) were transferred into oval 200-liter 

 test tanks and further acclimated for 1 wk. The 

 number of fish per tank was limited to the number 

 («lg/liter) that could be maintained during a 48-h 

 static exposure period when oxygen is a limiting 

 factor. The 48-h static exposure period instead of 

 an open-system constant exposure was necessi- 

 tated by the expense of the '^C-benzene required 

 for a relatively large volume of water. Except for 

 the 48-h static exposure period, a flow of 1 liter/ 

 min of filtered seawater was maintained through- 

 out. During flow periods the salinity and temper- 

 ature of the water were monitored and controlled 

 by the seawater system components (Korn 1975), 

 whereas temperature was not controlled during 

 the static exposure period. 



Stock benzene solutions used for dosing the 

 exposure tanks were prepared as follows: A satur- 

 ated benzene solution (1 ml benzene in 250 ml 

 seawater) was prepared in a separatory funnel by 

 vigorous shaking and then allowed to settle for 1 h. 

 The resulting solution was analyzed by the gas 

 chromatography method of Benville and Korn 

 (1974). Next, "C (99.9% ring-labeled benzene, 



specific activity, 85 juCi/mmol) was mixed with 

 another 200 ml of seawater to make a stock 

 solution and was kept frozen until used. The 

 saturated benzene solution was then mixed with 

 *^C stock solution to the proper specific activity, 

 and the appropriate volume was poured into each 

 tank and mixed by gentle stirring. After mixing, 

 1-ml water samples were added to a scintillator 

 (10-ml Packard Instagel)^ and the benzene con- 

 centration was measured. Carbon 14 counting was 

 done on a Packard Model 2008 Tri-Carb liquid 

 scintillation spectrometer system. Internal stan- 

 dardization yielded 85% counting eflficiency, and all 

 water values were corrected accordingly. 



Uptake, distribution, and depuration were de- 

 termined by sampling fish, rinsing them exter- 

 nally with methanol to remove adsorbed benzene, 

 dissecting out tissues, weighing tissue samples 

 (<200 mg), placing each tissue in a vial with tissue 

 digester solution (1 ml/100 mg tissue Packard 

 Soluene-100), and allowing 48-h digestion at room 

 temperature. Scintillator (10-ml Packard 

 Dimilume) was added to these samples and '^C 

 radioactivity measured. Approximate mean 

 counting efl^ciencies of 60% and 67% were cal- 

 culated from spiked samples and used to correct 

 anchovy and striped bass tissue residue values 

 respectively. Water and tissue samples yielding 

 below 40 counts per minute were considered below 

 the detectable limits of our system. 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Table 1. -Summary of experimental conditions for '^C-benzene uptake and depuration tests with northern anchovy and striped bass. 



Salinity was 24-267oo 



Species and 

 test number 



Initial mean Tanks 



Specific benzene per Fish 



activity concentration' concen- per 



(cpm/nl) (jUl/liter) trafion tank 



Time of tissue 



sampling^ 



(days) 



Total wet wt (g) 



Mean 



SD 



Type of tissue examined 



3 

 4 

 4 

 4 



4 



8 0.042,0.125, 



0,25, 1, 2 

 8 0.042,0.25,1,2,4 



8 0.042,0.25,1,2,4 



8 0.25,1,2,3,4,7 



8 0.25,1,2,3,4,7 



0.25, 1,2,3,4, 

 5,6, 7,8,9 



17.03 6.55 Liver, brain, gill, muscle 



12.93 

 11.70 

 12.74 

 13.94 



5.04 

 4.74 

 3.35 

 4.46 



76.87 34.60 



Liver, brain, gill, muscle, 



gallbladder, intestine 

 Liver, brain, gill, muscle, 



gallbladder, intestine 

 Liver, brain, gill, muscle, 



gallbladder, intestine 

 Liver, brain, gill, muscle, 



gallbladder, intestine 



Liver, brain, gill, muscle, 

 gallbladder, intestine, 

 mesenteric fat, colon, 

 heart, stomach 



'Exposure to '■'C-benzene w/as static for 48 h followed by resumption of water flow for the duration. Recent analyses by gas-liquid chro- 

 matography yielded 0. 00015-0. OOlOjUl/liter background benzene concentration in the seawater at this facility which is not included in these 

 values. 



'One fish per tank at each sampling time. 



546 



