The aromatic hydrocarbon, benzene, is one of 

 the major water-soluble components of crude oil. 

 Anderson et al. (1974) reported 6.75 and 3.36"/»o in 

 the water-soluble fractions of south Louisiana and 

 Kuwait crude oil standards respectively. In addi- 

 tion to being relatively soluble in water (1,780 "/ou - 

 McAuliffe 1966), benzene is one of the most 

 toxic components of petroleum. 



The acute 96-h, TL-50 lethal level (10-11 nl/Yiter) 

 of constant benzene exposure for juvenile striped 

 bass was determined previously at our laboratory 

 by Meyerhoff (1975). The objective of experiments 

 described here was to see if sublethal levels of 

 benzene, although not inducing death, would 

 inhibit efficient energy utilization by the fish as 

 measured by growth (wet weight, dry weight), fat 

 content, and caloric content. Because the exper- 

 imental period of 4 wk was relatively short, the 

 juvenile striped bass were exposed to mean high- 

 sublethal concentrations (3.5 /il/liter, SD 1.4; 6.0 

 ,ul/liter, SD 1.6) to determine the efi'ects of benzene 

 on growth. 



Methods 



Juvenile striped bass (mean standard length 

 18.1 cm, SD 2.3; mean total wet weight 3.39 g, SD 

 1.1) were obtained from the Tracy pumping plant 

 operated by the Bureau of Reclamation, Tracy, 

 Calif. After being transported by truck to our 

 facility (Korn 1975) the fish were changed to saline 

 water (267»ii) during a 3-day period. Juvenile fish 

 occur naturally at this salinity as well as in fresh 

 water. The fish were acclimated for 2 wk to test 

 conditions (salinity 26"/n(i, temperature 15°-16°C, 

 pH 7.8). Thirty-five fish were then placed into each 

 of nine 80-liter fiber glass aquariums and ac- 

 climated for one more week. Halver's diet (1957) in 

 pelleted form (5.350 kcal/g) was fed at the rate of 

 3% of fish body weight per day. 



Benzene concentrations were maintained in 

 three aquariums at 3.5 jul/liter benzene and in 

 three at 6 jul/liter benzene; three others served as 

 controls (0 jul/liter). Relatively constant benzene 

 concentrations were maintained using the method 

 of Benville and Korn (1974). The input of ben- 

 zene-saturated air was balanced by a continuous 2 

 liters/min water flow through the aquariums. 



Benzene concentrations were monitored daily 

 using the gas chromatograph procedure of Ben- 

 ville and Korn (1974). Water quality conditions 

 during the test were as follows: temperature, 

 15.2°-16.4°C; oxygen, 7.5-7.9 mg/liter; salinity, 

 25-267to; pH, 7.7-7.8; ammonia, <0.5 mg/liter. 



Seven fish were sampled from each aquarium at 

 0, 7, 14, 21, and 28 days. The animals were anesthe- 

 tized with MS-222,' killed by severing the spinal 

 cord, blotted dry, weighed individually, dried in a 

 70°C oven for 4 days, cooled in a desiccator, and 

 reweighed. Three of the fish were then processed 

 for caloric analyses and four for fat analyses. 



Calorimetric content was analyzed by in- 

 dividually processing three fish in a Parr adiabatic 

 calorimeter, model 1241. 



For fat analyses, the four dried fish were blend- 

 ed with 150-ml MF Freon (monoflourotrichloro- 

 methane) in a high-speed blender. The mixture 

 was poured and rinsed into a Buchner vacuum 

 filter through No. 1 filter paper. The filtrate was 

 put into preweighed beakers and evaporated in a 

 hood to dryness. After reweighing the beakers, fat 

 content was calculated. 



Data were analyzed with an analysis of variance 

 for factorial design program (BMD 02V— Dixon 

 1973). The independent factors of tank, week, 

 concentration, and their interactions were tested 

 for significance of effect on the dependent varia- 

 bles of wet weight, dry weight, fat content, and 

 caloric value. Duncan's new multiple-range test 

 (Duncan 1955; Pachares 1959) was used to deter- 

 mine the significant diflferences between means of 

 levels for treatments found significant in the 

 analysis of variance. 



Results 



Benzene concentrations varied because of fluc- 

 tuations in water flow caused by particulate ma- 

 terial clogging the valves. The high-level treat- 

 ment varied from 3.6 to 8.1 jul/liter during the 4-wk 

 test; the low-level treatment varied from 1.5 to 5.4 

 jul/liter. Analysis of variance of the benzene water 

 concentration showed a significant (P<0.01) in- 

 crease at both levels over the test period. However, 

 the means of low (3.5 jul/liter, SD 1.4) and high (6.0 

 jul/liter, SD 1.6) concentrations were significantly 

 different (P<0.01). 



The start of benzene exposure caused pro- 

 nounced hyperactivity at the high level and a 

 moderate effect at the low level. The fish reacted 

 by attempting to jump out of the water. Fish 

 exposed to the high level attempted to feed but 

 were unable to locate and consume their ration. 

 Random jerking movements were observed when 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



695 



