X 

 (3 



>- 

 01 



a 



00- 



96- 



92 



88 



84 



80 



76 



72 



68 



64 



• CONTROL 

  LOW LEVEL 

 » HIGH LEVEL 



WEEK 



Figure 1. -Average weight of each of three groups of striped 

 bass, Morone saxatilis, exposed to three concentrations of 

 benzene (0, 3.5, and 6.0 n\/\\ier) for 4 wk. The dry weight of 

 high-level exposure fish was significantly less (P^O.Ol) than the 

 other two groups at the end of the first week and thereafter. The 

 dry weight of the three groups combined was significantly higher 

 (P<0.05) than in previous weeks. 



mostly to impaired food localization at higher 

 concentrations. A similar effect on the nervous 

 system is documented by Brocksen and Bailey 

 (1973). The energy required to metabolize benzene 

 could also decrease efficient utilization of energy 

 for growth and fat deposition. 



There was an apparent acclimation of the fish to 

 benzene at the low level (3.5 jul/liter) by the end of 

 the 4-wk exposure, as reflected by the dry weight 

 of the fish (Figure 1). After 4 wk at high level (6.0 

 jLil/liter), fish also appeared to begin to recover 

 from effects. This was substantiated by observa- 

 tions of improved feeding response in exposed fish 

 as the experiment progressed. Nevertheless, de- 

 finite effects of benzene on growth parameters 

 were noted at 6.0- and 3.5-jMl/liter levels of ben- 

 zene. Although the fish may be able to adapt by 

 metabolic detoxification and depuration of ben- 

 zene and metabolites, after more prolonged peri- 

 ods the competitive effects on energy utilization 

 may not only decrease growth but also increase 

 mortality or reduce ability to withstand environ- 

 mental stress. 



The parameters measured in this study show- 

 effects at the low /xl/liter levels. In most situations, 

 it is unlikely that fish would be exposed to benzene 

 above the nl/liter level except shortly after catas- 

 trophic spills. Anderson et al. (1974) obtained a 

 concentration of several jal/liter benzene in 

 water-soluble extracts of crude oils. In the marine 

 environment, dilution and volatilization of ben- 

 zene would probably lower the concentration of 

 benzene rapidly. Research on effects at the nl/liter 

 level is needed along with monitoring information 



on actual concentrations of benzene in chronically 

 polluted environments. Such situations may in- 

 duce a reduction in growth rate and fat deposition 

 which would have implications in the reproductive 

 potential of exposed species. Studies of chronic 

 effects of low concentrations of benzene on re- 

 production, including fecundity, egg size, em- 

 bryonic development, and larval survival, are 

 indicated. Some of these studies have been com- 

 pleted at the Tiburon Laboratory and will be 

 reported on later. 



Acknowledgments 



We thank Tina Echeverria and Richard Paris of 

 the NMFS Southwest Fisheries Center Tiburon 

 Laboratory, for calorimetric analyses and assist- 

 ance in data processing respectively. We also 

 thank John Hunter, Southwest Fisheries Center 

 La Jolla Laboratory, and Stanley Rice, Northwest 

 Fisheries Center Auke Bay Fisheries Laboratory, 

 for reviewing the manuscript. 



Literature Cited 



Anderson, J. W., J. M. Neff, B. A. Cox, H. E. Tatem, and G. M. 



HiGHTOWER. 



1974. Characteristics of dispersions and water-soluble 

 extracts of crude and refined oils and their toxicity to 

 estuarine crustaceans and fish. Mar. Biol. (Berl.) 27:75-88. 

 Be.wille, p. E., Jr. and S. Korn. 



1974. A simple apparatus for metering volatile liquids into 

 water. J. Fish. Res. Board Can. 31:367-368. 



Brocksen, R. W., and H. T. Bailey. 



1973. Respiratory response of juvenile chinook salmon and 

 striped bass exposed to benzene, a water-soluble compo- 

 nent of crude oil /» Proceedings of Joint Conference on 

 Prevention and Control of Oil Spills, p. 783-791. Am. Pet. 

 Inst., Environ. Prot. Agency, U.S. Coast Guard, Wash., 

 D.C. 

 Dixon, W. J. (editor). 



1973. BMD biomedical computer programs. Univ. Calif. 

 Press, Berkeley, 773 p. 

 Duncan, D. B. 



1955. Multiple range and multiple F tests. Biometrics 

 11:1-42. 

 Halver, J. E. 



1957. Nutrition of salmonid fishes. III. Water-soluble 

 vitamin requirements of chinook salmon. J. Nutr. 

 62:225-243. 

 KoRN, S. 



1975. Semiclosed seawater system with automatic salinity, 

 temperature, and turbidity control. U.S. Dep. Commer., 

 NOAA Tech. Rep. NMFS SSRF-694, 5 p. 



McAULIFFE, C. 



1966. Solubility in water of paraflin, c\'cloparaflin, olefin, 

 acetylene, cycloolefin, and aromatic hydrocarbons. J. 

 Phys. Chem. 70:1267-1275. 

 Meyerhoff, R. D. 



1975. Acute toxicity of benzene, a component of crude oil, to 



697 



